Lightweight prefabricated home foundation manufactured via industrial large scale polymer additive manufacturing (ilspam)

Abstract

A novel sustainable prefabricated foundation design is presented that is, preferably, intended to be made entirely of polymers (e.g., recycled thermoplastic polymers such as polyethylene terephthalate (PET)).

Description

Lightweight Prefabricated Home Foundation Manufactured Via Industrial Large Scale Polymer Additive Manufacturing (ILSPAM)CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Application No. 63 / 553,772, filed February 15, 2024, which is hereby incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present invention relates generally to the field of prefabricated home foundations. More specifically, the present invention is related to lightweight prefabricated home foundation manufactured via industrial large scale polymer additive manufacturing (ILSPAM). BACKGROUND OF THE INVENTION

[0003] New scalable ways are needed to manufacture sustainable homes that are inexpensive enough and desirable enough for the un(der)housed poor to want to buy. Accordingly, what is needed are novel foundation designs made of recycled polymers using industrial large scale polymer additive manufacturing.

[0004] Embodiments of the present invention are an improvement over prior art systems and methods.SUMMARY OF THE INVENTION

[0005] In one embodiment, the present invention provides a pre-fabricated modular foundation, the pre-fabricated modular foundation comprising at least one polymer (e.g., thermoplastic polymer), where the pre-fabricated modular foundation is manufactured off-site prior to being deployed on-site. In one embodiment, the pre-fabricated modular foundation is manufactured via any of the following manufacturing techniques: injection molding, thermal forming, additive manufacturing, or 3D printing. In one embodiment, the polymer is a recycled thermoplastic polymer. In one embodiment, the recycled thermoplastic polymer is polyethylene terephthalate (PET). In one embodiment, in addition to the at least one thermoplastic polymer, the pre-fabricated modular foundation further comprising at least one fiber material. In one embodiment, the at least one polymer is Acrylonitrile Butadiene Styrene (ABS) and the at least one fiber material is carbon fiber.

[0006] In one embodiment, the above-noted prefabricated modular foundation comprises: (a) a base (201), (b) a first exterior wall (202) extending vertically from a first end (210) of the base (201); (c) a second exterior wall (204) extending vertically from a second end (212) of the base (201), the second end (212) opposite that of the first end (210); (d) a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the firstexterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) at least one interior wall (206) extending on either side of the central wall (208), the interior wall (206) parallel to the first and second external walls (202, 204), and the interior wall (206) disposed vertically with regards to the central wall (208); and (f) a plurality of cells (214), and (i) in the instance of one interior wall (206), each of the plurality of cells (214) open on one side and enclosed on three sides by portions of the first exterior wall (202), the central wall (208), and the one interior wall (206), and (ii) in the instance of a plurality of interior walls (206), each of the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208). In one embodiment, a cross-section of each cell (214) is a U- or V-shaped structure. In one embodiment, the U- or V-shaped structure comprises two adjacent five-sided polygonal structures. In one embodiment, the prefabricated foundation is a monolithic structure. In one embodiment, the prefabricated foundation comprises a plurality of modular prefabricated foundation structures that, when put together, comprise the prefabricated foundation. In one embodiment, the prefabricated foundation is made via an additive manufacturing process. In one embodiment, the prefabricated foundation is made via a thermoplastic manufacturing process. In one embodiment, the prefabricated foundation is made from any of the following: recycled plastics, upcycled polyethylene terephthalate (PET), or combinations of plastics and glass. In one embodiment, the prefabricated foundation further comprises dirt excavated on-site, filling each of the plurality of cells (214). In one embodiment, the dirt provides anchoring resistance in the range of 6,860-9,800 lbs. In one embodiment, the prefabricated foundation is part of a slab foundation. In one embodiment, the prefabricated foundation is part of a crawlspace foundation. In one embodiment, any one of the base (201), the first exterior wall (202), the second exterior wall (204), and the interior wall (206) comprises partially hollowed out structures.

[0007] In one embodiment, the prefabricated modular foundation comprises: (a) a base (201), (b) a first exterior wall (202) extending vertically from a first end (210) of the base (201); (c) a second exterior wall (204) extending vertically from a second end (212) of the base (201), the second end (212) opposite that of the first end (210); (d) a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) a plurality of interior walls (206), the plurality of interior walls (206) evenly spaced along the central wall (208) and extending on either side of the central wall (208), each of the interiorwalls (206) parallel to the first and second external walls (202, 204), and each of the interior walls (206) disposed vertically with regards to the central wall (208); and (f) a plurality of cells (214), each cell (214) within the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208). In one embodiment, a cross-section of each cell (214) is a II- or V-shaped structure. In one embodiment, the U- or V-shaped structure comprises two adjacent five-sided polygonal structures. In one embodiment, the prefabricated foundation is a monolithic structure. In one embodiment, the prefabricated foundation comprises a plurality of modular prefabricated foundation structures that, when put together, comprise the prefabricated foundation. In one embodiment, the prefabricated foundation is made via an additive manufacturing process. In one embodiment, the prefabricated foundation is made via a thermoplastic manufacturing process. In one embodiment, the prefabricated foundation is made from any of the following: recycled plastics, upcycled polyethylene terephthalate (PET), or combinations of plastics and glass. In one embodiment, the prefabricated foundation further comprises dirt excavated on-site, filling each of the plurality of cells (214). In one embodiment, the dirt provides anchoring resistance in the range of 6,860-9,800 lbs. In one embodiment, the prefabricated foundation is part of a slab foundation. In one embodiment, the prefabricated foundation is part of a crawlspace foundation.

[0008] In one embodiment, the present invention provides a method comprising: (a) manufacturing, at an off-site location remote from a construction site, a prefabricated modular foundation comprising at least one polymer; (b) transporting the prefabricated modular foundation to the construction site; (c) filling the prefabricated modular foundation with concrete at the construction site; and (d) integrating the prefabricated modular foundation filled with either concrete or dirt excavated on-site into a slab foundation. In one embodiment, the step of manufacturing the prefabricated modular foundation comprises injection molding the prefabricated modular foundation at the off-site location remote from the construction site. In another embodiment, the step of manufacturing the prefabricated modular foundation comprises thermal forming the prefabricated modular foundation at the off-site location remote from the construction site. In yet another embodiment, the step of manufacturing the prefabricated modular foundation comprises additive manufacturing the prefabricated modular foundation at the off-site location remote from the construction site. In another embodiment, the prefabricated modular foundation comprises 3D printing the prefabricated modular foundation at the off-site location remote from the construction site. In one embodiment, the step of manufacturing, off-site, aprefabricated modular foundation further comprises: (a) forming a base (201), (b) forming a first exterior wall (202) extending vertically at a first end (210) of the base (201); (c) forming a second exterior wall (204) extending vertically at a second end (212) of the base (201), the second end (212) opposite that of the first end (210); (d) forming a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) forming at least one interior wall (206) extending on either side of the central wall (208), the interior wall (206) parallel to the first and second external walls (202, 204), and the interior wall (206) disposed vertically with regards to the central wall (208); and wherein a plurality of cells (214) are formed, and (i) in the instance of one interior wall (206), each of the plurality of cells (214) open on one side and enclosed on three sides by portions of the first exterior wall (202), the central wall (208), and the one interior wall (206), and (ii) in the instance of a plurality of interior walls (206), each of the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208).BRIEF DESCRIPTION OF FIGURES

[0009] The present disclosure, in accordance with one or more various examples, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict examples of the disclosure. These drawings are provided to facilitate the reader's understanding of the disclosure and should not be considered limiting of the breadth, scope, or applicability of the disclosure. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale.

[0010] FIG. 1 depicts a table containing a list of sixteen design criteria used for concept selection, organized according to the design quality.

[0011] FIGS. 2(a)-(f) depicts a prefabricated monolithic coffered foundation concept according to the present invention.

[0012] FIG. 3 depicts a 2D cross section of prefabricated volumetric modular foundation unit block.

[0013] FIG. 4 depicts a CAD rendering of the prefabricated volumetric modular foundation design attached directly to fourteen standard wood joists and four subfloor sheathing plywood panels.

[0014] FIG. 5 shows the results of the solid block technique mass reduction survey conducted on the prefabricated volumetric modular rPET foundation.

[0015] FIG. 6 depicts a table containing a list of nine foundation designs created.

[0016] FIG. 7 depicts foundation v2.0 as a mesh ready for simulation.

[0017] FIG. 8 shows a table comparing the vertical compressive performance of each of the nine foundation design iterations CAD shown.

[0018] FIG. 9 depicts the quantitative results of the FEA study.

[0019] FIG. 10 depicts a toolpath rendering of the ORNL g-code produced after slicing foundation v1.1.

[0020] FIG. 11 depicts the ORNL slicer closed loop bead feature requirement.

[0021] FIG. 12 depicts CAD shape versus ORNL slicer output.

[0022] FIG. 13 depicts ILSPAM unsupported overhand CAD design.

[0023] FIG. 14 shows a table comparison of rPET foundation BAAM CAD iterations v3.8- v3.11.

[0024] FIG. 15 depicts the ORNL ILSPAM slicer machine parameters and highlights the eight critical input parameters used to produce BAAM readable g-code.

[0025] FIG. 16 depicts the ORNL ILSPAM flow rate calculator and highlights the seven critical design parameters used to calculate flow rate.

[0026] FIG. 17 depicts ILSPAM foundation v3.8 CAD versus g-code.

[0027] FIG. 18 depicts foundation design v3.8 BAAM FEA CAD simulation results.

[0028] FIG. 19 shows a table containing high level design requirements.

[0029] FIG. 20 shows a table containing Ultimaker Cura slicer input parameters for BASF rPET.

[0030] FIG. 21 depicts photos of the Ultimaker S5 during printing and after sample.

[0031] FIG. 22 shows a table containing the nine foundation CAD designs prepared forFFF force-displacement testing.

[0032] FIG. 23 shows the loading method used for compressive force-displacement testing of FFF foundation samples with the rPET back plate attached.

[0033] FIG. 24 shows the setup used for compressive force-displacement testing of FFF foundation samples with the rPET back plate.

[0034] FIG. 25 shows the loading method used for 3-point bending force-displacement testing of FFF foundation samples without the rPET back plate attached.

[0035] FIG. 26 shows the loading method used for 4-point bending force-displacement testing of FFF foundation samples without the rPET back plate attached.

[0036] FIG. 27 shows a table containing details about the preparation of foundation v3.8 prototypes manufactured by Additive Engineering Solutions (AES) in Akron, Ohio.

[0037] FIG. 28 depicts photos of ABS / 20% CF foundation v3.8 prototypes inside Cl BAAM806.

[0038] FIG. 29 depicts photos of AES annealing oven and foundation transportation via box truck.

[0039] FIG. 30 depicts a 2D computer rendering of the Baldwin force-displacement device.

[0040] FIG. 31 depicts photos of MIT CEE’s Baldwin 300kN force-displacement testing machine.

[0041] FIG. 32 shows photos of the two cyclical axial compression experimental.

[0042] FIG. 33 depicts photos of the axial compression until yield experimental setup.

[0043] FIG. 34 shows a table summary of FFF foundation testing results.

[0044] FIG. 35 shows a table of FFF rPET foundation Instron compression with back results.

[0045] FIG. 36 shows a table of FFF rPET foundation Instron compression without back results.

[0046] FIG. 37 shows a table of FFF rPET foundation Instron 3-point bending without back results.

[0047] FIG. 38 shows a table of FFF rPET foundation Instron 4-point bending without back results.

[0048] FIG. 39 shows a table with results from cyclical axial compression testing conducted on specimens 1 , 2, 3 and 5 using MIT CEE’s Baldwin 300kN hydraulic forcedisplacement machine.

[0049] FIG. 40 shows a photo of foundation BAAM v3.8 specimen 1 with 11.2kN load applied.

[0050] FIG. 41 shows a photo of foundation BAAM v3.8 specimen 5 with 22.4kN load applied.

[0051] FIG. 42 depicts a plot of foundation v3.8 BAAM specimen 5 cyclical compression displacement versus time data.

[0052] FIG. 43 depicts photos of Baldwin control testing setup.

[0053] FIG. 44 depicts a plot of cyclical compression control (no wood) displacement versus time data.

[0054] FIG. 45 depicts a plot of foundation v3.8 specimen 5 compression to yield data.

[0055] FIG. 46 depicts a plot of control test compression to yield load versus displacement data.

[0056] FIG. 47 shows photos of foundation BAAM v3.8 ABS / CF specimen 5 during and after axial compression yield test.

[0057] FIG. 48 shows photos of neoprene plate after use in specimen 5 axial compression yield test.

[0058] FIG. 49 shows photos of wood screws driven into foundation BAAM v3.8 ABS / CF prototype.

[0059] FIG. 50 shows BAAM v3.8 ABS / 20% CF specimen 4 samples used for microscopy.

[0060] FIG. 51 shows photos of 2 microscopy samples collected from foundation v3.8 specimen 4.

[0061] FIG. 52 depicts microscopy images of BAAM ABS / 20% CF sample 1 fracture surface.

[0062] FIG. 53 depicts microscopy images of BAAM ABS / 20% CF sample 1 interlaminar cut surface.

[0063] FIG. 54 depicts microscopy image of BAAM ABS / 20% CF sample 1 shear surface.

[0064] FIG. 55 depicts microscopy images of BAAM ABS / 20% CF sample 2 cut surface.DETAILED DESCRIPTION

[0065] While this invention is illustrated and described in a preferred embodiment, the invention may be produced in many different configurations. There is depicted in the drawings, and will herein be described in detail, a preferred embodiment of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and the associated functional specifications for its construction and is not intended to limit the invention to the embodiment illustrated. Those skilled in the art will envision many other possible variations within the scope of the present invention.

[0066] Note that in this description, references to “one embodiment” or “an embodiment” mean that the feature being referred to is included in at least one embodiment of the invention. Further, separate references to “one embodiment” in this description do not necessarily refer to the same embodiment; however, neither are such embodiments mutually exclusive, unless so stated and except as will be readily apparent to those of ordinary skill in the art. Thus, the present invention can include any variety of combinations and / or integrations of the embodiments described herein.

[0067] The exploration of status quo concrete slab, pad, and strip foundation designs informed the concept ideation and refinement process. The exploration of status quo solutions and their limitations ultimately led to the selected choice of pursuing prefabricated home foundations made of recycled PET via industrial large scale polymer additive manufacturing.Many of the initial design solution concepts explored were inspired by Kieran & Timberlake’s advice that “the product engineer needs to take the blinders off and focus on permutations of elements rather than on single parts and separate materials.” As discussed in the remainder of this section, many of the design concepts capitalize on symmetric permutations or translations of embodied geometries. Dozens of concepts were considered over the course of this research investigation ranging from dense slabs (approaching 100% solid) to hollow (external shell only) designs. The concepts considered also included internal structural trusses (triangles and columns), lattices (diamonds, honeycombs, and other geometric tessellations).

[0068] In the end, sixteen criteria were determined to evaluate, compare, and down select from the full concept space to a single concept to move forward. These sixteen criteria align with one of three product qualities: 1) manufacturability, 2) sustainability, and 3) desirability. The quality alignment, sixteen criteria, and brief description of each criteria are organized and detailed in FIG. 1. A quantitative PUGH weighted criteria selection process was used to identify the top concept to move forward in the remaining steps of the 12-step design process. Given the inherent bias and sensitivity associated with the pseudo-quantitative PUGH weighted criteria selection process, a qualitative PUGH method was also used to capture the motivation for the criteria selection, chosen weights, and quantitative score assigned to each concept.

[0069] FIG. 1 : Design qualities, criteria, and descriptions used for selection

[0070] This table contains a list of sixteen design criteria used for concept selection (column b) organized according to the design quality (column a). Each of the sixteen design criteria is briefly described in column c.

[0071] FIGS. 2A and 2B depict prefabricated foundation concept examples.

[0072] FIG. 2A CAD (a) depicts a prefabricated monolithic coffered foundation concept. There are eight coffered cells intended to contain dirt excavated from the local construction site to provide sufficient mass resistance to uplift forces. FIG. 2A CAD (b) is similar to (a) but the coffering is rotated 90° and consolidated to four cells with a total volume of 98 ft3. When filled, the dirt adds between 6860 lbs and 9800 lbs of anchoring resistance. FIG. 2A CAD (c) is the same geometry concept as (b) but is modular rather than monolithic to improve manufacturability and allow for multiple different configurations in use (i.e. slab OR crawlspace foundation). Note: all of these concepts are intended to be made using rPET via ILSPAM.

[0073] Based upon these criteria, a modular prefabricated coffered foundation concept was selected that entails using excavated earth to fill in the hollow sections of the foundation (three different examples shown in FIGS. 2(a)-(c)). The purpose of filling the coffered cells and hollow internal structure of the foundation with excavated dirt from the home construction site isto provide additional mass to the home-foundation system without having to ship the excess material to the construction site. This concept allows for a light-weight prefabricated polymer foundation to be easily transported (i.e. pickup truck vs flatbed semi) to the construction site while still providing substantial mass necessary to resist home uplift. For manufacturability using state- of-the-art industrial large-scale polymer AM, a volumetric modular design was pursued (FIG. 2(c)) as opposed to a monolithic design (FIG. 2 (a) & (b)). The volumetric modular design shown in FIG. 2 (c) enables multiple use cases where normally a concrete slab foundation, concrete pad foundation, concrete strip foundation, or a crawlspace foundation would normally be used.

[0074] In one embodiment, as depicted in FIG. 2(d)-(e), the above-noted prefabricated modular foundation comprises: (a) a base (201), (b) a first exterior wall (202) extending vertically from a first end (210) of the base (201); (c) a second exterior wall (204) extending vertically from a second end (212) of the base (201), the second end (212) opposite that of the first end (210);(d) a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) at least one interior wall (206) extending on either side of the central wall (208), the interior wall (206) parallel to the first and second external walls (202, 204), and the interior wall (206) disposed vertically with regards to the central wall (208); and (f) a plurality of cells (214), and (i) in the instance of one interior wall (206), each of the plurality of cells (214) open on one side and enclosed on three sides by portions of the first exterior wall (202), the central wall (208), and the one interior wall (206), and (ii) in the instance of a plurality of interior walls (206), each of the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208). In one embodiment, a crosssection of each cell (214) is a U- or V-shaped structure. In one embodiment, the U- or V-shaped structure comprises two adjacent five-sided polygonal structures. In one embodiment, the prefabricated foundation is a monolithic structure. In one embodiment, the prefabricated foundation comprises a plurality of modular prefabricated foundation structures that, when put together, comprise the prefabricated foundation. In one embodiment, the prefabricated foundation is made via an additive manufacturing process. In one embodiment, the prefabricated foundation is made via a thermoplastic manufacturing process. In one embodiment, the prefabricated foundation is made from any of the following: recycled plastics, upcycled polyethylene terephthalate (PET), or combinations of plastics and glass. In one embodiment, the prefabricated foundation further comprises dirt excavated on-site, filling each of the plurality of cells (214). Inone embodiment, the dirt provides anchoring resistance in the range of 6,860-9,800 lbs. In one embodiment, the prefabricated foundation is part of a slab foundation. In one embodiment, the prefabricated foundation is part of a crawlspace foundation. In one embodiment, any one of the base (201), the first exterior wall (202), the second exterior wall (204), the interior wall (206), the interior walls (206) comprises partially hollowed out structures.

[0075] In another embodiment, as depicted in FIG. 2(d)-(e), the prefabricated modular foundation comprises: (a) a base (201), (b) a first exterior wall (202) extending vertically from a first end (210) of the base (201); (c) a second exterior wall (204) extending vertically from a second end (212) of the base (201), the second end (212) opposite that of the first end (210); (d) a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) a plurality of interior walls (206), the plurality of interior walls (206) evenly spaced along the central wall (208) and extending on either side of the central wall (208), each of the interior walls (206) parallel to the first and second external walls (202, 204), and each of the interior walls (206) disposed vertically with regards to the central wall (208); and (f) a plurality of cells (214), each cell (214) within the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208). In one embodiment, a cross-section of each cell (214) is a U- or V-shaped structure. In one embodiment, the U- or V- shaped structure comprises two adjacent five-sided polygonal structures. In one embodiment, the prefabricated foundation is a monolithic structure. In one embodiment, the prefabricated foundation comprises a plurality of modular prefabricated foundation structures that, when put together, comprise the prefabricated foundation. In one embodiment, the prefabricated foundation is made via an additive manufacturing process. In one embodiment, the prefabricated foundation is made via a thermoplastic manufacturing process. In one embodiment, the prefabricated foundation is made from any of the following: recycled plastics, upcycled polyethylene terephthalate (PET), or combinations of plastics and glass. In one embodiment, the prefabricated foundation further comprises dirt excavated on-site, filling each of the plurality of cells (214). In one embodiment, the dirt provides anchoring resistance in the range of 6,860-9,800 lbs. In one embodiment, the prefabricated foundation is part of a slab foundation. In one embodiment, the prefabricated foundation is part of a crawlspace foundation.

[0076] In one embodiment, the present invention provides a method comprising: (a) manufacturing, at an off-site location remote from a construction site, a prefabricated modularfoundation comprising at least one polymer; (b) transporting the prefabricated modular foundation to the construction site; (c) filling the prefabricated modular foundation with concrete at the construction site; and (d) integrating the prefabricated modular foundation filled with either concrete or dirt excavated on-site into a slab foundation. In one embodiment, the step of manufacturing the prefabricated modular foundation comprises injection molding the prefabricated modular foundation at the off-site location remote from the construction site. In another embodiment, the step of manufacturing the prefabricated modular foundation comprises thermal forming the prefabricated modular foundation at the off-site location remote from the construction site. In yet another embodiment, the step of manufacturing the prefabricated modular foundation comprises additive manufacturing the prefabricated modular foundation at the off-site location remote from the construction site. In another embodiment, the prefabricated modular foundation comprises 3D printing the prefabricated modular foundation at the off-site location remote from the construction site. In one embodiment, the step of manufacturing, off-site, a prefabricated modular foundation further comprises: (a) forming a base (201), (b) forming a first exterior wall (202) extending vertically at a first end (210) of the base (201); (c) forming a second exterior wall (204) extending vertically at a second end (212) of the base (201), the second end (212) opposite that of the first end (210); (d) forming a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); (e) forming at least one interior wall (206) extending on either side of the central wall (208), the interior wall (206) parallel to the first and second external walls (202, 204), and the interior wall (206) disposed vertically with regards to the central wall (208); and wherein a plurality of cells (214) are formed, and (i) in the instance of one interior wall (206), each of the plurality of cells (214) open on one side and enclosed on three sides by portions of the first exterior wall (202), the central wall (208), and the one interior wall (206), and (ii) in the instance of a plurality of interior walls (206), each of the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208).

[0077] FIG. 2(f) depicts an embodiment where a plurality of modular E-shaped prefabricated foundation elements are combined with a central wall module to form the final prefabricated foundation. In this non-limiting example, the first module comprises a base (201-1), a first exterior wall (202-1), a first interior wall (206-1), and a second exterior wall (204-1). Similarly, the second module comprises a base (201-2), a first exterior wall (202-2), a first interiorwall (206-2), and a second exterior wall (204-2). Likewise, the third module comprises a base (201-3), a first exterior wall (202-3), a first interior wall (206-3), and a second exterior wall (204- 3). The central wall module comprises a central wall (208) and a base (204-C). The fourth module comprises a base (201-4), a first exterior wall (202-4), a first interior wall (206-4), and a second exterior wall (204-4). The fifth module comprises a base (201-5), a first exterior wall (202-5), a first interior wall (206-5), and a second exterior wall (204-5). Finally, the sixth module comprises a base (201-6), a first exterior wall (202-6), a first interior wall (206-6), and a second exterior wall (204-6). The modules are assembled in the following order to form the resultant prefabricated foundation: first module, second module, third module, central wall module, fourth module, fifth module, and sixth module.

[0078] The 2D design shown in FIG. 3 has two cells to hold soil and three primary columns to support the home. The intended 3D foundation design has dimensions of 8 ft wide, 16 feet long, and 2 feet deep. This implies that the foundation would support at least a 128 ft2home sufficient to accommodate a couple or small family as shown in FIG. 3. The depth variable of the foundation design is potentially adjustable to match the expected climate of the construction site. In a non-limiting example, 2 feet was chosen because frost is not expected. When the volumetric modular foundation blocks are assembled into a continuous monolithic structure, the pockets may hold up to -2300 lbs. of soil with 32 cubic feet of compactable space. The outer corners are filleted to reduce unwanted stress concentrations. The 2:1 length to width ratio is justified because rectangles reduce soil shear and improve soil settlement characteristics when compared to other conventional shapes such as solid circular supports, square supports, and 3:2 rectangles. These dimensions also provide many other functional and logistical advantages. Using the dimensions described above, it is likely that stacking six prefabricated foundations would be considered street legal in the United States for road transportation.

[0079] FIG. 3: 2D cross section of prefabricated volumetric modular foundation until block

[0080] Outline of basic 2D sketch of foundation with key shape design variables including: 1) width (W), 2) height (H), 3) pocket height (h), 4) column width (t), and fillet radius (f).

[0081] In addition to manufacturability benefits, the unit block of the volumetric modular design (on the order of 300 lb) is significantly lighter than the monolithic counterparts (on the order of 2,600 lb). The reduced weight of the volumetric modular prefabricated foundation decreases the logistics complexity and cost relative to the monolithic counterparts. At 300 lb it is possible that 2 to 4 laborers could position the module in place by hand, whereas at 2,600 lb the monolithic designs would require substantial mechanical advantage (i.e. cranes, winches, ramps, rollersetc.). Up next we explore the design of and demonstrate the feasibility of the volumetric modular prefabricated rPET foundation made via ILSPAM.

[0082] FIG. 4: Isometric view of prefabricated volumetric modular foundation and floor

[0083] This figure depicts a CAD rendering of the prefabricated volumetric modular foundation design attached directly to fourteen standard wood joists and four subfloor sheathing plywood panels. The purpose of this rendering is to show how one might attach a typical wood floor system to the prefabricated volumetric modular foundation. Future researchers may need to study the use of traditional wood fasteners in order to attach traditional superstructure building materials to the rPET foundation. Note, close attention must be paid to the pull out strength of different types of fasteners (i.e. screws, bolts, nails, etc.). If traditional fastening methods fail to satisfy code, future researchers should investigate alternative joining methods such as gluing, chemical bonding, thermal bonding, and pressfits.

[0084] Generative design

[0085] In order to make the prefabricated volumetric modular foundation design lighter and stronger, alternative internal structure geometries were explored. Generative design is a powerful computational design tool which leverages machine learning and artificial intelligence to automatically produce light-weight structures. The user inputs certain design constraints such as bounding geometry, mating faces, critical dimensions, and materials. In addition to design constraints, the user defines the loading conditions such as forces, pressures, and moments. The software then ‘efficiently’ searches the space of possible design configurations that maximize the structural performance for the given constraints (i.e. mass, bounding geometry, material, etc.) in order to present the user with the ‘optimal’ design. It is important to note, however, contemporary generative design software does not automatically consider the unique vagaries of the ILSPAM process (refer to the section CAD and slicing for BAAM / ILSPAM for details).

[0086] Rather than constrain the internal structure geometry exploration by the ILSPAM process, a progressive mass reduction study was conducted using Autodesk Fusion generative design software to inform subsequent CAD iterations. In collaboration with Mr. John Malloy, the ‘Solid Block Technique’ was used, which requires a solid version of the design (CAD file shown in FIG. 3 and FIG. 4) along with the expected loading conditions, spatial constraints, and target mass. Using these user defined inputs, the generative design software adjusts the geometry on a scale from “Must Keep” to “OK to remove”. The generative design software then suggests a reduced mass design in which the material is placed where it maximizes structural integrity. FIG. 5 shows the results of a progressive mass reduction study.

[0087] FIG. 5: Generative design solid block technique mass reduction study

[0088] This figure shows the results of the solid block technique mass reduction survey conducted on the prefabricated volumetric modular rPET foundation. This study was conducted at 90%, 70%, and 50% mass marked (-10%), (-30%), and (-50%) respectively. A 5800 lb dead load was applied on each of the columns. A soil lateral load of 680*h psf was applied along the length of the outer column walls. The underside of the foundation was constrained in X, Y, and Z because the foundation is not expected to move significantly. A 0.2” minimum thickness constraint was placed on the outer perimeter of the foundation to ensure at least one bead thick. Although much heavier than the intended final weight, the results of the generative design offer insight into the placement of internal support material. Section marked (1) indicates that the central column supports the least load and can be safely hollowed. This aligns with intuition because the dead loads are applied on the outer columns and the center column is aligned with the neutral axis. Section marked (2) can be safely hollowed because soil pressure increases with depth. Section marked (3) indicates that the eternal corners resist the dead load; however, the internal corners can be hollowed significantly. Section marked (4) indicates that substantial material is required along the edges and across the hollowed section to resist buckling induced by the combination of dead load and lateral soil pressure. Section marked (5) shows that internal vertical columns remain in the hollowed center to transfer the compressive forces to the soil.

[0089] Computer Aided Design (CAD) and slicing for FFF

[0090] This section discusses the iterative use of CAD software in the 12-step design process and the role of CAD software in the context of the FFF prototyping step. This section discusses several CAD foundation iterations, specifically v2.2-2.10, as examples as shown in FIG. 6; however, this section does not aim to comprehensively cover all of the design iterations created. The purpose of this section is to demonstrate to the reader the ways that CAD software is used for early design steps (i.e. concepts, generative design, FEA) and how to utilize CAD tools in the context of comparing the results of FFF prototyping.

[0091] Even for experienced designers, CAD can be a time consuming process. Often, it is faster and easier to sketch initial concepts by hand. Herein the only included CAD renderings are the top three concepts that made it to the CAD stage. Dozens of 2D and isometric hand drawn concepts were not included. However, simple CAD files are appropriate in order to quickly and effectively compare the weight, production time, and structural performance of each concept.

[0092] Contemporary generative design software, finite element analysis (FEA) software, and digital fabrication processes (i.e. additive manufacturing, CNC machining, etc.) require users to input CAD files, typically made via parametric CAD software (i.e. Autodesk Fusion, Solidworks, OnShape, etc.). As discussed in the Generative design section, generative design softwarerequires the user to input a basic CAD file in addition to constraints in order to guide the ‘solid block technique’ mass reduction study. In addition, FEA simulations require the user input a CAD file in addition to loading and boundary conditions in order to assess the stress, strain, and deformation response of each foundation design. In summary, CAD enables the designer to effectively communicate visual concepts, analyze structural performance, and estimate critical design parameters for iterative comparison (i.e. weight, production time, etc.).

[0093] While concept formulation, concept selection, weight estimation, and structural analysis can arguably be done entirely by hand, digital fabrication cannot. In the context of digital fabrication via polymer extrusion additive manufacturing, specifically FFF, it is imperative that the designer has CAD files representative of the intended product in order to slice the CAD file into machine code. In the author’s experience the print time estimates produced by commercial and open source FFF slicing software do not yield accurate estimates. FFF 3D printing slicer input parameters do not need to be optimal but instead simply need to be held constant for purposes of comparing the relative differences of each design iterations to one another.

[0094] The CAD files shown in FIG. 6 column (b) to estimate the foundation weight via Autodesk Fusion estimates shown in column (d) and to estimate the print time via Ultimaker Cura slicing software estimates shown in column (e). For purposes of weight estimates, preprogrammed PET density values found in Autodesk Fusion software were used. For purposes of print time estimates calculated via Ultimaker Cura slicer software, settings recommended by Ultimaker for BASF ultrafuse filament were used and held constant across each design file v2.2- 2.10. The purpose of analyzing and comparing design iterations is to identify which features improve structural performance the most (i.e. compression, bending, torsion) for the least weight increase and least print time increase. The lessons learned from this comparison enable the superposition of the best features of each FFF scale model into the subsequent full scale CAD model intended for ILSPAM.

[0095] FIG. 6: Design intent of rPET foundation iterations v2.2-v2.10 CAD

[0096] This table contains a list of nine foundation designs created. The nine design iterations (column a) were created using CAD tools (column b). The intention is that each CAD file contains both similarities and differences to the other eight designs. The intent of the design change is described in column c. Column (d) contains the estimated weight. Column (e) contains the print time estimated by Cura slicer.

[0097] Finite Element Analysis (FEA) simulations for FFF

[0098] Modern FEA simulation tools provide insights into the stress and deformation behavior of complex 3D structures under user defined loading conditions. FEA is a cheap (freefor students) and fast (-minutes for each simulation) alternative to physical experiments (i.e. prototyping and force-displacement testing). However, FEA does have its limitations. Unlike physical experiments which are path dependent and transient, each FEA simulation is a fresh start. For example, the structural failure of a prototype in one experiment has adverse effects on subsequent experiments. On the other hand, FEA does not account for these transient path dependence effects. Therefore, in the context of this 12-step design process, FEA is used primarily to compare the initial load response structural performance of stress, strain, and displacement across designs. Several commercial FEA packages are available for free student use, namely Autodesk Fusion 360 and Solidworks. The simulations discussed in this section and shown in FIG. 7 were conducted using Autodesk Fusion 360. Other simulations, not detailed here, were conducted using Solidworks.

[0099] In a collaboration with Mr. John Malloy, Autodesk Fusion 360 was used to characterize the performance of foundation design v2.0 under 3 combined loads: 1) 6,000 lb dead load distributed across the three foundation spines, 2) 2,300 lb dead load distributed across the pockets, and 3) 4.9 psi lateral soil pressure applied to all outward facing faces of the foundation (note: an overestimate; assumes max depth hydrostatic lateral soil load applied at all depths). While detailed studies are useful for comparison to physical experiments, not all FEA simulations need to be comprehensive (i.e. FIG. 8). This 12-step design process encourages fast and frequent iteration.

[0100] FIG. 7: Foundation design v2.0 FEA simulation results

[0101] Image (a) depicts foundation v2.0 as a mesh ready for simulation. The blue arrows represent the home superstructure dead load of 6,000 lbs. The red arrow indicates the location where the soil fills the pocket, estimated at 2,300 lbs dead load. Lastly, the green arrows indicated the direction of the lateral soil loads, estimated at 4.9 psi. Note: these arrows appear as points to keep the image clutter free. However, in the simulation software, these are all modeled as distributed loads or pressures. Image (b) highlights the areas of high stress. Notice the max stress (red / yellow) occurs along the internal curvature where each spine meets the pocket radius. The simulation data indicate the maximum stress value of 5.4MPa. Based upon typical PET and rPET yield stress data, the stresses experienced resulting from the loading conditions (a) are approximately 1 / 1 Oth to 1 / 11th of yield stress values. Image (c) depicts the areas of maximum displacement. Unsurprisingly, these occur at the mid-span of the outer spines. Combined, these stress (b) and displacement (c) results inform future design iterations in three ways: 1) the rounded corner of the dirt pocket is a stress concentration and needs reinforcement to avoid failure, 2) the spine needs mid-span reinforcement to limit deflections, and 3) the outer walls needadditional reinforcement to resist soil pressure induced buckling modes. Note: elastic stiffening is possible.

[0102] The simulation data shown in FIG. 8 were captured using Autodesk Fusion finite element software provided by MIT IS&T. In collaboration with Tyler Godfrey, the simulations were conducted using the following material assumptions: 1) Material database - PET, 2) Young’s modulus - 2.758 GPa, 3) Poisson’s ratio - 0.417, 4) Density - 1 ,541 kg / m3, 5) Temperature - 298K (~25°C, ~77°F). In addition to material assumptions, Fusion static simulations require both load and boundary conditions. To compare across the designs, the loads and boundary conditions are held constant across the nine foundation design static loading simulations. For these simulations an applied distributed vertical compressive load of 44,482 N over two square feet (or 5,000 lbs per square foot). For these simulations all of the nine foundation designs were rigidly fixed on the bottom surface. While not a perfect representation of intended use loading boundary conditions (i.e. soil is not a rigid fixture), the applied load is ~5x greater than the expected home superstructure net applied load. These conditions were chosen to match the capabilities of typical uniaxial force-displacement measurement devices (i.e. Instron). Therefore, note that these simulations ignore the lateral soil load and soil dead load.

[0103] To run these simulations, several simplifying assumptions were made including: 1) Material isotropy - commercial simulation software uses typical isotropic material properties of injection molded PET while FFF and ILSPAM are both known to be anisotropic, 2) Material elasticity - based upon typical virgin PET injection molded values not 3D printed rPET values, 3) Thermal conditions - assumes isothermal environment when thermal cycling is likely. Therefore, the accuracy or precision of the absolute magnitude of these results is questionable. However, the assumptions and model issues aside, the simulations still yield useful results for design iterations because these assumptions are also held constant across simulations.

[0104] FIG. 8: FEA simulation stress results of foundation CAD v2.2-v2.10

[0105] This table compares the vertical compressive performance of each of the nine foundation design iterations (column a) CAD shown (column b). Column (c) describes the location of maximum stress in the foundation structure. Column (d) contains the maximum simulated stress value. Column (e) contains the estimated weight. Column (f) contains the print time estimated by Cura slicer. For these simulations a uniform compressive load was applied simultaneously across the top surface of each of the three columns with a fixed constraint along the bottom surface.

[0106] Iterative FEA simulations of FFF scale foundation models indicate that the foundation supports the required static loads. The performance improves when internalstructures, such as columns and trusses, are added. Preliminary small scale FEA simulations indicate that the prefabricated polymer foundation designs should sufficiently support the net static load that arises from the combination of the home dead load, soil dead load, and lateral soil pressure. FIG. 9 plots the results of preliminary FEA simulations which indicate that weight and safety factors may be positively correlated while simultaneously negatively correlated with maximum material stress. The FEA simulations reveal the possibility of stress concentrations on the soil cells and outer corners of the foundation. To reduce stress concentrations and reduce the probability of catastrophic failure, subsequent ILSPAM scale designs should evenly distribute stress. Common strategies to reduce stress include eliminating sharp corners and jagged edges.

[0107] FIG. 9: Quantitative FEA mass reduction study results

[0108] These figures show the quantitative results of the FEA study. Plot (a) shows the outer wall thickness (in) plotted against the engineering safety factor. Note the positively correlated linear relationship. Plot (b) shows the outer wall thickness (in) plotted against the estimated total weight of the 16’ x 8’ x 2’ foundation. Note the positively correlated linear relationship. Plot (c) shows the outer wall thickness (inches) plotted against the maximum calculated stress (MPa). Note the negatively correlated non-linear relationship. These plots indicate that weight and safety factors may be positively correlated while simultaneously negatively correlated with maximum material stress. This study was conducted in collaboration with Mr. John Malloy.

[0109] FFF prototyping & testing

[0110] FFF prototyping is a well studied domain. Engineers typically use FFF to make rough concept prototypes to convey an idea through a physical form or, in some cases, to even make an end use part. However, FFF is rather limited in both size dimensions and throughput. In the context of the 12-step design process the FFF process is used as a comparative modeling tool as opposed to an extrapolative tool. That is to say the time that it takes to produce an FFF prototype does not scale linearly to ILSPAM. As well, not all features that FFF 3D printers are able to produce can be produced on ILSPAM. On the other hand, the author is not aware of any geometric features (other than size) that are feasible on ILSPAM that FFF cannot produce. Meaning if FFF cannot produce a specific feature, then that feature is not possible on ILSPAM. Therefore, FFF scale prototyping and testing is used simply as a tool to study and compare the relative performance between CAD designs at the FFF scale. The physical testing is a necessary compliment because FEA simulations do not capture transient loading effects or physical defects.

[0111] The primary purpose of FFF prototyping in the context of this 12-step design process is to determine which features are printable at the small scale. The FFF prototypingprocess allows the designer to eliminate features from FFF designs which are unprintable at the small scale and therefore also unprintable at the ILSPAM scale. Once the designer has determined the printability of the geometric features of each design at the FFF scale, the next step is to study the nature of the deformation and relative performance of each of the FFF prototypes compared to one another. The purpose of these tests is to reasonably compare the performance of each design iteration to one another. Therefore, each of the various design iterations should be 3D printed using a standard off the shelf prosumer desktop 3D printer using the same filament. The goal of this test is not to study the vagaries of the FFF 3D printing process; rather, the purpose is to simply use FFF 3D printing as a consistent fabrication process. The variables tested are the structural (and as the author found out, non-structural) features of the various CAD iterations.

[0112] In order to make this comparison, a thorough force-displacement study was done involving four mechanical testing configurations: 1) compression with back plate, 2) compression without back plate, 3) 3-point bending without back plate, and 4) 4-point bending without back plate. The back plate encloses the outer surface where the foundation interfaces with the 3D printer plate. In hindsight, if the experiments described in the FFF scale rPET foundation prototypes & testing procedure section and the results shown in the FFF scale rPET foundation force displacement results section were repeated the new test procedure would eliminate test 1) compression with back plate because it was determined ex post facto that while printable on FFF scale, the back plate is not likely printable or efficient to produce on ILSPAM. For all tests, the same force-displacement measurement system should be used to ensure the results are comparable between test configurations. Refer to the sections “FFF scale rPET foundation prototypes & testing procedure”, through ”4-point bending without back plate” for setup and procedure details.

[0113] Once the force-displacement testing is completed, the collected data should be plotted and analyzed. The various design iterations should be compared within each testing configuration as well as given a net score for performance across all four testing configurations. The comparison analysis should factor in the stiffness, any obvious statistical variation, and in- situ performance (i.e. buckling, cracking, etc.). The purpose of scoring and subsequently rank ordering the various design iterations is to identify which CAD files performed the best and which performed the worst. From this ranking, the best features should be extracted and combined via structural superposition in subsequent design iterations while the worst performing (i.e. redundant) features should be removed and excluded from future design iterations.

[0114] CAD and slicing for BAAM / ILSPAM

[0115] While Thermwood LSAM ILSPAM systems are larger and faster than Cl BAAM ILSPAM systems, there are no 3rd party contract manufacturing service providers who offer Thermwood LSAM prototyping services. Therefore, Cl BAAM hardware and CRN L slicer software were used. The remainder of this section discusses the geometric limitations imposed on designs made via Cl BAAM ILSPAM systems using publicly available ORNL slicer software. New slicers may reduce the geometric limitations but these capabilities have not yet been released to the public.

[0116] Unlike ILSPAM, the small bead size and low printhead travel speeds commonly used in desktop FFF 3D printing slicer programs enables the fabrication of seemingly arbitrary geometries at the desktop FFF scale (i.e. steep overhangs, crossing toolpaths, thin walls, etc.). This is not the case for ILSPAM slicing software. For example, foundation design v1 .1 sliced fine on the Ultimaker Cura FFF slicer but failed to slice correctly. The failure to slice correctly revealed several problems in the design. One of the issues identified is the quantization of layers - Cl BAAM ILSPAM systems using the ORNL slicer software require that all beads have the same dimensions (width and height) and that all features be some positive, non-zero integer multiple of the bead size. FIG. 10 shows a rendering of the g-code produced by the ORNL slicer for foundation design v1.1 . Note the incomplete toolpath on the internal sections of the foundation. In addition to bead quantization limitations, the ORNL slicer imposes a closed loop bead requirement as depicted in FIG. 11 - single bead lines are not possible (FIG. 11(a)); instead, all features must constitute a closed loop (FIG. 11(b)). FIG. 12 shows how the closed loop constraint extends to non-linear shapes (i.e. triangles and cylinders).

[0117] FIG. 10: G code rendering of foundation v1.1 ORNL slicer failure

[0118] This figure depicts a toolpath rendering of the ORNL g-code produced after slicing foundation v1.1 . Note how the ORNL slicer failed to produce toolpaths for the outermost walls and internal structure of the foundation due to (A) bead quantization limitations and (B) inability to produce a closed loop.

[0119] FIG. 11: ORNL slicer closed loop bead feature requirement

[0120] Feature (a), a single bead line, is not printable on ILSPAM. Feature (b), a closed loop, is printable on ILSPAM. To design around this constraint, it was useful to first sketch the layer or feature by hand. In doing so, the designer can quickly determine if a feature is printable or not by simply leaving their pen or pencil in contact with the page until the loop closes. If lines cross during sketching or the pen(cil) must be lifted mid-loop then the feature is not printable using state of the art ILSPAM slicing algorithms. Note, this limitation extends to more complex shapes.

[0121] FIG. 12: CAD shape versus ORNL slicer output

[0122] CAD for ORNL ILSPAM slicer is complicated and confusing at times. This figure shows the CAD shapes on the left which were necessary to produce the green closed loop tool paths shown on the right. Note that for each of these files, the closed loop CAD design was used in conjunction with the ORNL ILSPAM slicer zero infill setting to produce the respective hollow shapes shown on the right.

[0123] On the other hand, CAD for ILSPAM design guidelines do bear some similarities to CAD for FFF. Take overhangs for example. FIG. 13(a) shows a completely horizontal overhang. For short gaps, this feature is possible (~1” span). For gaps much greater than ~1”, this feature leads to sagging and layer buildup failures. To avoid this sagging failure, Cl design guidelines recommend building up these gaps at least 45° angles as shown in FIG. 13(b). While 3D printed or manually inserted in-situ supports are possible, they are not recommended due to cost increase, negative rate impacts, and practicality of removal (not possible to remove for closed internal features). While angles greater than 45° are possible, they are not recommended to the increased probability of sagging failure during the ILSPAM production process.

[0124] FIG. 13: ILSPAM unsupported overhang CAD design guidelines

[0125] Image (a) depicts an unsupported overhang gap. When this gap is much greater than ~1” or ~5x the bead height, this type of unsupported overhang gap feature leads to a sagging failure. Image (b) depicts a recommended progressive gap alternative feature design to mitigate this sagging failure.

[0126] In order to effectively use CAD for ILSPAM, designers must combine the closed loop constraints, layer quantization effects, and overhang limitations. In collaboration with Mr. Kenan Sehnawi foundation CAD iterations v3.1-3.11 were developed using Autodesk Fusion software. For purposes of this summary, iterations v3.1-3.7 are excluded due to printability issues. FIG. 14 contains a CAD snapshot, weight estimate, and print time estimate of four designs (v3.8- 3.11) which were deemed printable. The author selected v3.8 (FIG. 17) due to weight savings and print time savings. Refer to the BAAM foundation v3.8 prototypes & experiment procedure section for further discussion.

[0127] FIG. 14: Comparison of rPET foundation BAAM CAD iterations v3.8-v3.11

[0128] This table contains foundation v3.8-3.11 (column a) along with a CAD rendering (column b). Column c contains the ORNL slicer mass estimate. Column d contains the ORNL slicer print time estimate. Column e contains the contract manufacturers price quote. Note, this is not the minimum cost as it includes the contract manufacturer's margin for one part ordered (i.e. no volume discount).

[0129] Working with Additive Engineering Solutions, the ORNL slicer (FIG. 15) and flow rate calculator (FIG. 16) were used in order to compute the estimated print times contained in FIG. 14. While not inclusive of all of the machine and slicing parameters, FIG. 15 shows and discusses the primary machine parameters that affect print time. These parameters can be organized into two categories: 1) machine parameters and 2) material parameters. Machine parameters include the hardware specific limitations of the BAAM such as print orientation, extruder temperature, speed of extruder head. Material parameters include the thermal characteristics of the polymer and flow characteristics.

[0130] FIG. 15: ORNL ILSPAM slicer machine parameters

[0131] This figure depicts the ORNL ILSPAM slicer machine parameters and highlights the eight critical input parameters used to produce BAAM readable g-code: 1) nozzle diameter (inches), also called die size; 2) first layer height (inches) is usually around the die diameter (inches) divided by 2; 3) subsequent layer height is usually same as (2); 4) first layer bead width (inches) varies based on the machine and die used and is typically the same as the die diameter or up to 25% larger; 5) subsequent layer bead width is usually same as (4); 6) refer to flow rate calculator (FIG. 16); 7) extruder speed in RPM usually max of 400 for BAAM; and 8) minimum feature length for BAAM to retract and lower the extruder for rapids. Note for shorter sections ORNL slicer will attempt to connect the lines if closed loop is possible.

[0132] FIG. 16: ORNL ILSPAM flow rate calculator

[0133] This figure depicts the ORNL ILSPAM flow rate calculator and highlights the seven critical design parameters used to calculate flow rate: 1) speed in revolutions per minute recommended max of 400 RPM for Cl BAAM 806; 2) maximum flow rate of 100 lb / hour for Cl BAAM 806; 3) desired bead width (inches) which varies based on the machine and die used and is typically the same as the die diameter or up to 25% larger; 4) layer height (inches) is usually around the die diameter (inches) divided by 2; 5) desired average mass flow rate during production in lbs per hour; 6) a drop down menu that allows the user to select the desired material for production; 7) if the material is not available in the database, the user can manually override the typical material density in grams per cubic centimeter.

[0134] FEA for BAAM / ILSPAM

[0135] The purpose of this section is to discuss the modeling challenges faced when conducting FEA simulations to predict the behavior of parts made via BAAM (or generally ILSPAM). This section discusses these challenges in comparison to both modeling for traditional manufacturing (i.e. machining) and modeling for FFF. This section highlights and notes the key differences.

[0136] FEA has its limitations. Commercial FEA packages are designed to simulate mechanical performance of bulk materials (i.e. machined aluminum, injection molded PET, etc.). FEA software has not yet been specialized for extrusion AM or ILSPAM. Of particular note, commercial FEA packages do not account for either the interlayer adhesion anisotropy or the interbead adhesion anisotropy. Furthermore, due to discrepancies in the rPET material literature, commercial FEA packages do not have an accurate material model of rPET (i.e. Young’s modulus, toughness, UTS, etc.). Unlike physical experiments which are path dependent and transient, each FEA simulation is a fresh start. Therefore, FEA does not account for these transient path dependence effects.

[0137] In a non-limiting example, both Autodesk Fusion and Solidworks FEA packages were used. In collaboration with AES and Mr. Kenan Sehnawi the foundation v3.8 CAD file and post ORNL slicing 2D g-code renderings shown in FIG. 17 were produced. As discussed in the section CAD and slicing for BAAM I ILSPAM, CAD must be heavily modified for use in ILSPAM. BAAM CAD looks chunky and does not look like the actual part that it produces after 3D printing. Therefore, any FEA simulations conducted using BAAM CAD will yield misleading, and arguably incorrect, results. Instead, to yield meaningful simulation results, BAAM FEA CAD must depict the intended geometry after BAAM printing, including the bead gaps.

[0138] FIG. 17: ILSPAM foundation v3.8 CAD versus g-code

[0139] The rendered CAD file shown in (1) depicts the foundation v3.8 BAAM CAD file. It appears to be a mostly solid structure. The rendered 2D g-code shown in (2) depicts the foundation v3.8 BAAM CAD file g-code post slicing. The rendered 2D g-code indicates the actual intended shape as printed whereas the CAD file does not represent the as-printed form. Note: the red circles indicate unsupported regions of high stress in the outermost perimeter bead. Also note: BAAM CAD looks chunky and does not look like the actual part that it produces.

[0140] Autodesk Fusion was used to characterize the performance of foundation design v3.8 made from isotropic PET under a 22.4kN compressive load distributed across ~50 points along the top surface of the central column as shown in FIG. 18(a). The stress response is shown in FIG. 18(b) indicating stress concentrations above the plate supporting the midspan of the top surface of the central column. Additional FEA simulations were conducted under the same conditions except with ABS / 20% carbon fiber, indicating the foundation should support at least 230kN and possibly up to 310kN.

[0141] FIG. 18: Foundation design v3.8 BAAM FEA CAD simulation results

[0142] Image (a) shows a close up of the point load distribution used for this simulation. Image (b) shows the overall predicted stress response of the as-printed v3.8 BAAM FEA CAD.The simulation data shown were captured using Autodesk Fusion finite element software provided by MIT IS&T. The static simulations were conducted using the following material assumptions: 1) Material database - PET, 2) Young’s modulus - 2.96 GPa, 3) Poisson’s ratio - 0.37, 4) Density - 1 ,420 kg / m3, 5) Temperature - 298K (~25°C, ~77°F). In addition to material assumptions, Autodesk Fusion static simulations require both load and boundary conditions. For these simulations a distributed vertical compressive load of 22,239 N over one square foot (or 5,000 lbs per square foot) load was applied. For these simulations the foundation was rigidly fixed on the bottom surface. While not a perfect representation of intended use loading boundary conditions (i.e. soil is not a rigid fixture), the applied load is ~5x greater than the expected home superstructure net applied load. These conditions were chosen to match the capabilities of MIT CEE’s large scale uniaxial force-displacement measurement devices (i.e. Baldwin 300kN hydraulic). Therefore, note, these simulations ignore the lateral soil load and soil dead load.

[0143] BAAM prototyping & testing

[0144] The purpose of this section is to briefly discuss the role of BAAM prototyping and testing as the final step in the 12-step design process. For physical structures, especially a foundation made via industrial large scale polymer AM, physical experiments and valid results are imperative. Based upon the relative weight, print time, price data shown in FIG. 14 and discussion in the section CAD and slicing for BAAM / ILSPAM, foundation design v3.8 was selected for BAAM prototyping.

[0145] Full scale BAAM prototyping and testing has three primary research goals: 1) determine if foundation design v3.8 is indeed manufacturable via ILSPAM, 2) if yes to (1), identify and categorize any manufacturing process defects, and 3) determine if the foundation v3.8 functions as designed in spite of the (2) manufacturing process defects. The possible outcomes for the first full-scale ILSPAM prototype are either: 1) the design fails to print or 2) the design prints successfully. In either case, important design for ILSPAM insights will be gathered (discussed in the BAAM foundation v3.8 prototypes & experiment procedure section) and analyzed (discussed in the section ’’BAAM v3.8 foundation force-displacement results”). Unfortunately, at the time of this research, MIT did not possess BAAM or any other type of ILSPAM prototyping capability on campus. Therefore, Additive Engineering Solutions (AES), a leading ILSPAM contract manufacturing service provider based in Akron, OH, was chosen to manufacture the single prototype of foundation design v3.8 using a Cl BAAM 806 ILSPAM machine.

[0146] Unpublished early experiments at ORNL and AES indicate PET and rPET are difficult to manufacture using I LSPAM processes due to: 1 ) warping, 2) crystallinity, and 3) thermalproperties. To de-risk the first prototype and increase the probability of successful prototype production to demonstrate the printability of foundation design v3.8, AES advised using ABS / 20% carbon fiber as an alternative polymer for the first BAAM scale v3.8 prototype.

[0147] Design of physical experiments

[0148] In the context of this specific research, rigorous physical experiments are essential to assessing and determining the feasibility of using rPET as a feedstock for industrial large scale polymer additive manufacturing of homes. The physical experiment validation steps of the 12- step design process, therefore, rely on intelligent design of experiments to reduce the cost of: 1) specimen preparation, 2) experimental setup time, and 3) conducting and measuring the experiments.

[0149] Unfortunately, unlike theory which relies heavily on inexpensive computation or human methods, physical experiments possess inherent expense. These expenses include: 1) raw materials or samples, 2) hardware prototyping resources, 3) accurate experimental test setups, 4) high-precision scientific measurement equipment, and 5) tidy, well controlled laboratory space. Depending on the nature of the research, raw material expenses can be significant (i.e. precious metals, rare earth, biological, or physically large etc.) or relatively insignificant (i.e. small samples, commodity plastics etc.). Hardware prototyping resources, accurate experimental setups, and high-precision scientific measurement equipment do not operate and maintain themselves. These resources require trained researchers with expertise to safely and correctly operate the machines as intended. When combined, the total carrying cost of trained research staff, well maintained scientific instruments, and a tidy laboratory environment quickly escalates. In the context of this specific research, FIG. 19 details the resources used, typical cost for academic use, and other useful notes. This section details the physical experiments conducted, issues encountered, and advice to others who seek to recreate all or portions of this work.

[0150] FIG. 19: High level design requirements

[0151] This table contains a list of resources and the respective systems used to conduct physical experiments, expense framework, resource providers, and useful notes for planning future experiments.

[0152] FFF scale rPET foundation prototypes & testing procedure

[0153] In the Computer Aided Design (CAD) and slicing for FFF section, details the design logic behind foundation CAD iterations v2.2-v2.10. FIG. 6 also includes details about the estimated weight and print time of each of the foundation CAD iterations. As discussed in the section FFF prototyping & testing, in the context of the 12-step design for ILSPAM process, thepurpose of small-scale FFF testing is to inexpensively confirm the printability of each design iteration and test the structural performance of each design iteration.

[0154] The printability assessment is binary: 1) yes, the design printed successfully, and 2) no, the design failed to print successfully. This experiment was designed to test both the printability and structural performance of the nine foundation designs (v2.2-2.10) at the FFF scale. The experimental design is captured in FIG. 22. The goal of this experimental design is to produce sufficient useful data to study, identify outliers, and rank relative performance of the nine different foundation designs.

[0155] In collaboration with Kenan Sehnawi, three samples of each of the nine foundation CAD iterations were produced. In total twenty seven samples were made. Using the Ultimaker S5 available in MIT’s LMP, the collaborators produced in total twenty seven samples. Aside from minor plating differences and natural spool-to-spool variation, the printing parameters were held constant during the prototyping of the twenty seven samples. FIG. 20 contains the printing parameters used, and held constant for all twenty seven samples, as recommended by Ultimaker, BASF, and LMP staff. All twenty seven samples representing the nine different foundation designs were printed successfully. Defects, such as stringing were present but not significant. Warping, also known as thermal distortion, was not noticeable and was not significant.

[0156] FIG. 20: Ultimaker Cura slicer input parameters for BASF rPET

[0157] This table contains a list of (a) input parameters and respective (b) values used for FFF sample preparation. These inputs were held constant for all samples.

[0158] Statistical significance remains important; however, given the monetary cost of each sample and each experiment conducted, it was important to reduce the number of samples. The first twenty samples produced were plated in batches of five while the last two samples were produced in a batch of two. In total, six print runs were required. The print cycle time of the first five batches of five prototypes ranged from thirty three to thirty nine hours. The last two samples were produced in about fifteen hours. In total, two spools of BASF Ultrafuse rPET filament were required. Refer to appendix 9 for the BASF Ultrafuse rPET filament technical data sheet. As detailed in FIG. 19, even these small scale FFF tests come with a monetary expense. Under the LMP’s new pricing scheme, the experiments would have cost $90 worth of printer time plus another $100 worth of rPET filament, totaling $190. Instead, had each of the twenty seven foundation design files been printed independently, the sample preparation would have cost $405 worth of printer time plus $100 worth of rPET filament, totaling $505. By plating the designs in batches, $315 or 62% was saved.

[0159] FIG. 21: Photos Ultimaker S5 during and after sample preparation

[0160] Photo (a) shows a side view of the Ultimaker S5 build volume during printing. Notice the rPET is printed directly onto glass. Photo (b) shows an example of how five samples (8”x2”x2”) were batched and nested together to fit a single build.

[0161] The structural performance of each design, on the other hand, requires detailed assessment. It was decided to conduct four types of tests: 1) compression with back plate, 2) compression without back plate, 3) 3-point bending without back plate, and 4) 4-point bending without back plate. Compression tests 1 & 2 intend to emulate how each foundation design responds to axial dead loads. Bending tests 3 & 4 intend to emulate how each foundation design responds to differential soil settlement. As described in the section FFF prototyping & testing, these four tests intend to approximately emulate intended foundation loading conditions. These tests are not realistic comparisons to foundation loading conditions, however, since the tests are applied across all nine designs, they do serve to compare relative performance. FIG. 22 shows the design of this experiment. An Instron with a 20,000 lb reversible load cell was used in position control mode to characterize the force-displacement performance of the nine foundation designs across the four performance tests. In total, five hundred and forty tests were conducted.

[0162] FIG. 22: FFF force-displacement design of experiments

[0163] This table contains the nine foundation CAD designs prepared for FFF forcedisplacement testing. Each of the nine designs, labeled 2.2-2.10 in column (a) and CAD shown in column (b), was made using BASF Ultrafuse rPET filament on an Ultimaker S5 located in the MIT LML. Column (c) includes information about the number of samples produced of each design. Columns (d), (e), (f), and (g) all contain information about the intended number of experimental runs for each of the four force-displacement testing configurations. Instron tests were done in displacement control mode for compression (d) & (e) at 5 mm / min, 3-point bending (f) at 9 mm / min, and 4-point bending (g) at 15 mm / min.

[0164] Distributed compression with back plate

[0165] The purpose of the distributed compression test is to characterize the bulk performance of each foundation design under approximately uniaxial loading conditions. The setup shown in FIG. 23 uses an Instron force-displacement device to apply a distributed load across all three foundation columns simultaneously. This setup intends to emulate the net dead load of a home on top of the foundation assuming a rigid base (i.e. clay or rock as opposed to sand). While not a perfect comparison to the intended use case of the foundation in dirt with a home on top, the consistent application of these tests and the subsequent time series forcedisplacement results will allow for useful comparisons between foundation designs v2.2-2.10 not captured by FEA.

[0166] FIG. 23: Photo of Instron distributed compression with back plate setup

[0167] This figure shows the loading method used for compressive force-displacement testing of FFF foundation samples with the rPET back plate attached. The experiments should be conducted in position control mode to accurately characterize the force-displacement performance of the nine foundation designs. Each FFF foundation sample is mounted to the Instron as shown, effectively sandwiched between two rigid plates. For purposes of this analysis, safely assume that the steel plates are much stiffer than the rPET foundation prototypes.

[0168] Distributed compression without back plate

[0169] The purpose of the distributed compression test without back is to characterize the bulk performance of each foundation design v2.2-2.10 with back plate removed under approximately uniaxial loading conditions. Simply stated, the setup of the two tests is the same but the foundation samples used have had the back plate removed with a knife. The setup shown in FIG. 24 uses an Instron force-displacement device to apply a distributed load across all three foundation columns simultaneously. This setup intends to emulate the net dead load of a home on top of the foundation assuming a rigid base (i.e. clay or rock as opposed to sand). While not a perfect comparison to the intended use case of the foundation in dirt with a home on top, the consistent application of these tests and the subsequent time series force-displacement results will allow for useful comparisons between foundation designs v2.2-2.10 not captured by FEA.

[0170] FIG. 24: Photo of Instron distributed compression without back plate setup

[0171] This figure shows the setup used for compressive force-displacement testing of FFF foundation samples without the rPET back plate. The experiments should be conducted in position control mode to consistently characterize the force-displacement performance of the nine foundation designs. Each FFF foundation sample is mounted to the Instron as shown, sandwiched between two rigid plates. Safely assume that the steel plates are much stiffer than the rPET foundation prototypes.

[0172] 3-point bending without back plate

[0173] The purpose of the 3-point bending without back plate test is to characterize the bending performance of each foundation design v2.2-2.10 under live loads. The setup shown in FIG. 25 uses an Instron force-displacement device to apply a load to the center column of the foundation while supporting the underside of the outer columns on cylindrical rollers. This setup intends to emulate the behavior of a foundation under a concentrated applied live load. While the unsupported underside of the center column does not represent real soil conditions, the consistent application of these bending tests and the subsequent time series force-displacement results will allow for useful comparisons between foundation designs v2.2-2.10 not captured by FEA.

[0174] FIG. 25: Photo of Instron 3-point bending without back plate setup

[0175] This figure shows the loading method used for 3-point bending force-displacement testing of FFF foundation samples without the rPET back plate attached. The experiments should be conducted in position control mode to accurately characterize the force-displacement performance of the nine foundation designs. Each FFF foundation sample is mounted to the Instron as shown. Safely assume the blocks and cylinders are much stiffer than the rPET foundation prototypes.

[0176] 4-point bending without back plate

[0177] The purpose of the 4-point bending without back plate test is to characterize the bending performance of each foundation design under typical dead loads and soil that has undergone phase two soil settlement. The setup shown in FIG. 26 uses an Instron forcedisplacement device to apply a load to the outer two columns of the foundation while supporting the underside of the center column on two cylindrical rollers. This setup intends to emulate the behavior of a foundation experiencing phase two differential soil settlement. The unsupported underside of the outer columns emulates worst case phase two soil settlement conditions. The consistent application of these bending tests and the subsequent time series force-displacement results allows for useful comparisons between foundation designs not captured by FEA.

[0178] FIG. 26: Photo of Instron 4-point bending without back plate setup

[0179] This figure shows the loading method used for 4-point bending force-displacement testing of FFF foundation samples without the rPET back plate attached. The experiments should be conducted in position control mode to accurately characterize the force-displacement performance of the nine foundation designs. Each FFF foundation sample is mounted to the Instron as shown. Safely assume that the blocks & cylinders are much stiffer than the rPET foundation prototypes.

[0180] BAAM foundation v3.8 prototypes & experiment procedure

[0181] For physical structures, especially a foundation made via industrial large scale polymer AM, physical experiments and valid results are imperative. Based upon the relative weight, print time, and cost data shown in FIG. 14 and discussed in the section CAD and slicing for BAAM / ILSPAM, the foundation design v3.8 was selected for prototyping.

[0182] The experiment has three research goals: 1) determine if foundation design v3.8 is indeed manufacturable via ILSPAM, 2) if yes to (1), identify manufacturing process defects, and 3) determine if the foundation v3.8 functions as designed in spite of the (2) manufacturing process defects. The possible outcomes for the first full-scale ILSPAM prototype are either: 1) the design fails to print or 2) the design prints successfully. Additive Engineering Solutions (AES), a leadingILSPAM contract manufacturing service provider based in Akron, OH, was chosen to manufacture the single prototype of foundation design v3.8 using a Cl BAAM 806 ILSPAM machine.

[0183] Unpublished early experiments at ORNL and AES indicate PET and rPET are difficult to manufacture using I LSPAM processes due to: 1 ) warping, 2) crystallinity, and 3) thermal properties. To de-risk the first prototype and increase the probability of successful prototype production to demonstrate the printability of foundation design v3.8, AES advised the use of an alternative polymer for the first v3.8 prototype. At the recommendation of AES, an ABS-glass fiber composite [80% ABS, 20% glass fiber] manufactured by LG was selected. Incidentally, when AES attempted to make the first prototype, the Cl BAAM 806 machine experienced a drive failure at -45% completion resulting in a ‘failed’ run.

[0184] Ultimately, after five attempts, AES managed to manufacture a prototype. Over the course of the trial and error, five processing and slicing parameters were varied: 1) layer height at 0.20” and 0.25”, 2) bed temperature treatments varied from 100°C to heated bed off, 3) powder was used as a bed surface treatment to improve adhesion, 4) material changed from ABS / 20% glass fiber to ABS / 20% carbon fiber, 5) the smear plate was not used for specimen 1 but was used for specimens 2-5. In terms of the verbal agreement with AES, the first four specimens were regarded as failures because none of these samples successfully achieved the 12” height target. However, the fifth specimen did print successfully in under five hours (shown in FIG. 28). Processing details for all 5 specimens are shown in FIG. 27. Therefore, the author considers the first goal, to determine if foundation design v3.8 is manufacturable via ILSPAM, as satisfied. As a happy consequence of failures 1-4, AES graciously provided the author with the failed prototypes in addition to successful specimen #5. Furthermore, unforeseen capacity became available in AES’s annealing oven (shown in FIG. 29). Given this, it was decided to expand the scope of the experiment by treating specimen #2 in the AES annealing oven, cycling the temperature for 15 hours at temperatures up to 210 °F.

[0185] Instead of shipping the parts after completion, the author and Mr. Kenan Sehnawi opted to visit AES’ factory in person to collect the five specimens, learn more about ILSPAM from hands-on observation of the factory in operation, and to demonstrate the simplicity of the logistics involved because of the foundation v3.8 design. As shown in FIG. 29, we rented a U-Haul box truck in Akron, OH, hand loaded the five prototypes into the U-Haul (no CDL required) and drove the box truck -700 miles back to Cambridge, MA for testing.

[0186] FIG. 27: BAAM prototype preparation parameters & problems

[0187] This table contains details about the preparation of foundation v3.8 prototypes manufactured by Additive Engineering Solutions (AES) in Akron, OH. Due to trade secrets andother IP owned by AES and LG, the author is unable to publish the ORNL slicer parameters used, machine configuration used, annealing oven thermal cycling profile, or details provided by the manufacturer about the composite blends.

[0188] FIG. 28: Photos of ABS / 20% CF foundation v3.8 prototypes inside Cl BAAM 806

[0189] Photo (a): Left side of the photo shows specimen #4. Specimen #5 is shown in the middle. ~1.5” from the top layer, notice the flash caused by the warping shown in photo b. Photo (b): View from the far side of specimen #5. Notice that the bottom layers split, delaminated, due to warping. Note, specimen 5 is 12” thick (approximately vertical in the photos), 96” wide (approximately into the depth of the photos), and 24” tall (approximately horizontal in the photos).

[0190] FIG. 29: Photos of AES annealing oven and foundation transportation via box truck

[0191] Photo (a): Large-scale annealing oven used for heat treatment of specimen 3. Photo (b) From left to right, specimen 4, 1 , 3, 2, 5 strapped down in a standard uHaul box truck driven from Akron, OH to Cambridge, MA. Note: AES can crate and ship via freight. The author opted to visit AES and drive back to MIT to demonstrate that the foundation prototypes are easy to carry and do not require CDL to transport.

[0192] Once the foundation v3.8 prototypes arrived at MIT, an initial visual inspection was conducted for defects to satisfy experimental goal #2. The visual inspection identified four defects present in the prototypes: 1) vertical interlayer seam where each layer starts and ends, 2) warping along the long edge, 3) flash present on corners and above where warping is most severe, and 4) layer delamination between 2 layers along the surface of the outer beads. The experiments will show if these defects were purely aesthetic or also structural.

[0193] The purpose of sections ”BAAM foundation v3.8 intended use cyclical compression experiment” and ”BAAM foundation v3.8 compression until yield experiment” is to discuss the specific details of experiments designed to determine if the foundation v3.8 performs in compression as designed in spite of the manufacturing process defects noted above. Unfortunately, the force-displacement hardware owned and operated by MIT’s Department of Mechanical Engineering is far too small in size and incapable of applying sufficient force to yield the prototypes. Therefore, in order to demonstrate the compressive load bearing capabilities of the foundation v3.8 prototypes, the author sought access to MIT’s Department of Civil and Environmental Engineering (MIT CEE) mechanical testing laboratory. Mr. Stephen Rudolph graciously provided access to the laboratory and provided training to the author for the safe operation of MIT CEE’s 300kN Baldwin hydraulic force-displacement measurement device last calibrated by Beau Mooney of American Calibration on 28 June 2019 (certificate #: 190617-BM- M2). FIG. 30 depicts a schematic.

[0194] The author conducted two different types of axial compression experiments: 1) ‘expected use’ cyclical compression and 2) a single yield study. The specific experimental procedure details are discussed in sections ”BAAM foundation v3.8 intended use cyclical compression experiment” and ”BAAM foundation v3.8 compression until yield experiment”. All of the large-scale force-displacement experiments use the same 300kN Baldwin system and ADMET data collection package shown in FIG. 31. Note: CEE’s 900kN Baldwin system is too close to the wall to fit the prototypes for testing.

[0195] FIG. 30: Schematic of Baldwin setup for foundation v3.8 BAAM compression tests

[0196] This figure depicts a 2D computer rendering of the Baldwin force-displacement device. This configuration is only used for the specimen #5 compression yield test. Different, but similar, configurations used for the other tests. The five important machine setup components in the force-displacement testing are: (1) Baldwin position control head; (2) The attachment cylinder enables the safe mounting of the steel plate (3) and for safe load transfer (1) -> (3); (3) Distributes the compressive loads over a larger surface area to emulate expected dead loads on a foundation; (4) Reduces point loads and stress concentrations that would otherwise occur at the steelopolymer interface; and (5) Represents the foundation v3.8 prototype specimens #1 , #2, #3, and #5.

[0197] FIG. 31: Photos of MIT CEE’s Baldwin 300kN force-displacement testing machine

[0198] Photo (a): Photo of MIT CEE’s 300kN Baldwin hydraulic force-displacement testing machine. Note, the 2” steel plate is mounted directly to the hydraulic cylinder for safety purposes during yield testing. Photo (b): Photo of the hardware control system manufactured by ADMET called the MTEST QUATTRO, developed by an MIT CEE alum. The system includes experiment tracking and data logging software not pictured. Photo (c): Photo of the manufacturer's plate, including serial number, product configuration, and date of manufacture. The system was manufactured in 1955 for University use.

[0199] BAAM foundation v3.8 intended use cyclical compression experiment

[0200] In the intended use case for a small home weighing -6,000 lb, the foundation is expected to bear the total weight of the home. Two foundation design v3.8 modules would be used to support the -6,000 lb home (or 3,000 lb per foundation module). Each module contains three columns of 1 ft2load bearing area. While it is expected that in use the dead load of the home will be evenly distributed across the six columns (1 ,000 lb / ft2per column), a cyclical axial compression test for loads ~5x greater than expected (5,000 lb / ft2per column) was designed. We decided to conduct the cyclical test to determine if the differences cycle to cycle were significant. To account for differences in thickness between the samples, loads are calculated ona per square foot basis. The 5.0” and 5.75” specimens were approximated at 0.5 ft2contact area while specimen 5 was approximated at 1 ft2. Cyclical uniaxial compression loads were applied by the Baldwin 300kN hydraulic force-displacement measurement device to emulate 5,000 psf. Therefore, 22.4kN was applied to specimen #5 in axial compression and 11.2kN was applied to specimen #1, #2, and #3. All specimens were loaded on the center column as shown in FIG. 32. For each experiment, the load was applied, held, released, and repeated six times. The Cyclical Loading Experiment Procedure table (below) details the parameters used for the ADMET controller. As noted in FIG. 19, MIT CEE charges for use of the laboratory on an hourly basis. Midway through conducting these cyclical axial compression tests, it was determined that the load rates were too slow given the budget. Table 6.6 indicates that the load rates were doubled for the later trials. As shown in FIG. 32, the setup used to test the prototypes varied slightly test to test. Some used an additional piece of wood between the steel plate and the prototype to improve specimen stability. The specific fixture configurations were varied during the experimentation and are noted in the “BAAM foundation v3.8 intended use cyclical compression results” section.

[0201] Baldwin 300kN cyclical axial compression experimental procedure

[0202] This table (below) contains the step-by-step details of the cyclical axial compression loading procedure used to measure the strength and stiffness of foundation v3.8 prototypes made via ILSPAM. Samples #1, #2, and #3 used target force value of 11.2kN. Sample #5 used target force value of 22.4kN.

[0203] FIG. 32: Photos of the two cyclical axial compression experimental setup

[0204] Left photo (a): 1) Baldwin hydraulic cylinder, 4) foundation prototype specimen #5, steel plate not labeled. Right photo (b): 1) Baldwin hydraulic cylinder, 2) 1.7” pine board emulates sill plate and distributes load, 3) foundation prototype specimen # 3, steel plate not pictured but was later included between (1) and (2).

[0205] BAAM foundation v3.8 compression until yield experiment

[0206] The cyclical axial compression data, which emulates the intended use case of supporting a small home weighing -6,000 lb, does not indicate how close the foundation v3.8 prototypes are to yield when loaded for intended use. Based upon results from FEA simulation methods described in the FEA for BAAM / ILSPAM section and the force-displacement results contained in section BAAM foundation v3.8 intended use cyclical compression results from cyclical axial compression testing, it is estimated that the full scale foundation v3.8 ABS / 20% carbon fiber prototype could support at least 50,000 lbs before yielding or failure. It must be noted that the FEA simulations do not capture anisotropic behavior or AM specific defects, which may negatively impact results. It was expected that the foundation prototype may fail entirely before yielding, therefore, experimentation is necessary.

[0207] This axial compression until yield test was devised to determine the maximum dead load the foundation v3.8 prototypes can safely support. Given the potential destructive nature of this test, it was determined to only test one of the four samples to yield or failure in order to save as many specimens as possible for future investigations. Of the four specimens tested previously, three of the specimens are all less than 6” wide. These narrow specimens pose serious instability issues which could lead to unwanted eccentric loading or possibly even break the Baldwin machine. Therefore, it was decided to test the 1 ft2center column of specimen #5 until yield or failure using displacement control mode ramping at 3mm / sec until the maximum force is reached using the setup as shown in FIG. 33. For this experiment, the intermediary wood layer was replaced with 2x 1” thick neoprene plates to reduce the likelihood of stress concentrations caused by direct steelofoundation v3.8 contact.

[0208] FIG. 33: Photo of the axial compression until yield experimental setup

[0209] Photo of the setup used for axial compression until yield experiment conducted on specimen #5. The setup includes four primary elements: 1) Baldwin hydraulic cylinder, 2) 2” thick steel plate, 3) 2x 1” thick neoprene plates, and 4) foundation prototype specimen #5. Due to the stability of specimen #5, it was agreed that the test did not require the use of a variable cylinder head to allow for out-of-plane misalignment. A fixed head was used.

[0210] Experimental results

[0211] Many physical tests were conducted over the course of this research effort. The purpose of this section is to present and discuss the results captured from the physical experiments following the procedures described in Chapter 5. This section does not cover the numerous bench level experiments, prototyping experiments, or other tests conducted (both individually and in collaboration with other MIT HAUS researchers). While useful conclusions were drawn from the numerous bench level experiments, prototyping experiments, and other tests, the scope and conclusions do not make significant contributions to the literature. Instead, this section focuses on two families of experiments which in combination, make significant contributions to the literature. The polymer foundation experiments are 1) FFF scale prototyping and forcedisplacement testing and 2) ILSPAM scale prototyping and force-displacement testing.

[0212] FFF scale rPET foundation force displacement results

[0213] In collaboration with Mr. Kenan Sehnawi, Ms. Malia Smith, and Professor David Hardt, a designed experiment for foundation designs v2.2-2.10 described in the section ”FFF scale rPET foundation prototypes & testing procedure” was executed. These experiments involved the 3D printing of 27 rPET foundation prototypes on the Ultimaker S5 located in the MIT LMP. These prototypes were mounted to four test fixtures setup on an Instron force-displacement measurement device with a 20,000 lb load cell in displacement control mode. Loads were applied and data was collected. Five hundred forty tests were conducted. FIG. 34 summarizes the findings and qualitatively ranks the relative quantitative performance of each design. FIGS. 35-38 contain the same performance ranking details (column e) as FIG. 34 for each test along with estimates of weight (column c), print time (column d), and photos of the loaded deformed shape (column f).

[0214] FIG. 34: FFF foundation testing results summary

[0215] CWBP is compression with back plate. CW / OBP is compression without back plate. 3PBW / OBP is 3-point bending without back plate. 4PBW / OBP is 4-point bending without back plate. Each sample was tested and measured. The data was subsequently plotted and organized. Each design was then given stiffness and variation scores on a high, medium, low scale. Then, each design was assigned a rank, 1-9, with 1 best and 9 worst.

[0216] N.B. These subjective rankings indicate that v2.3 performed the best in compression with back plate (v2.4 close second), v2.10 performed the best in compression without back plate attributable to the additional mass, v2.6 performed the best in 3-point bending due to the X trusses under the cells, and v2.9 performed the best in 4-point bending due to the rotated X trusses along the cells. From this we learn which features perform the best at FFF scale in order to inform which features to include and exclude from BAAM CAD v3.1-3.11.

[0217] Distributed compression with back plate results

[0218] FIG. 35: FFF rPET foundation Instron compression with back results

[0219] Once again, the nine foundation design iterations (column a) and CAD (column b) are shown. This table contains weight of the design (column c), the estimated FFF print time (column d), the performance rank (column e), and an image, if available, capturing the nature of the cross sectional deformation while loaded (column f). FIG. 35 contains the same performance ranking details (column e) as FIG. 34 (column d) along with estimates of weight (column c), print time (column d), and photos of the loaded deformed shape (column f).

[0220] Distributed compression without back plate results

[0221] FIG. 36: FFF rPET foundation Instron compression without back results

[0222] Once again, the nine foundation design iterations (column a) and CAD (column b) are shown. This table contains weight of the design (column c), the estimated FFF print time (column d), the performance rank (column e), and an image, if available, capturing the nature of the cross sectional deformation while loaded (column f). FIG. 36 contains the same performance ranking details (column e) as FIG. 34 (column d) along with estimates of weight (column c), print time (column d), and photos of the loaded deformed shape (column f).

[0223] 3-point bending without back plate results

[0224] FIG. 37: FFF rPET foundation Instron 3-point bending without back results

[0225] Once again, the nine foundation design iterations (column a) and CAD (column b) are shown. This table contains weight of the design (column c), the estimated FFF print time (column d), the performance rank (column e), and an image, if available, capturing the nature of the cross sectional deformation while loaded (column f). FIG. 37 contains the same performance ranking details (column e) as FIG. 34 (column d) along with estimates of weight (column c), print time (column d), and photos of the loaded deformed shape (column f).

[0226] 4-point bending without back plate results

[0227] FIG. 38: FFF rPET foundation Instron 4-point bending without back results

[0228] Once again, the nine foundation design iterations (column a) and CAD (column b) are shown. This table contains weight of the design (column c), the estimated FFF print time (column d), the performance rank (column e), and an image, if available, capturing the nature of the cross sectional deformation while loaded (column f). FIG. 38 contains the same performance ranking details (column e) as FIG. 34 (column d) along with estimates of weight (column c), print time (column d), and photos of the loaded deformed shape (column f).

[0229] BAAM v3.8 foundation force-displacement results

[0230] To validate the feasibility of using industrial large scale polymer AM to manufacture pre-fabricated polymer foundations, a series of experiments for foundation design v3.8 were executed. These experiments involved the fabrication of five prototypes made by AES as detailed in FIG. 27. These prototypes were set up on MIT CEE’s 300kN Baldwin hydraulic forcedisplacement measurement device. Under the supervision of Mr. Stephen Rudolph who manages MIT CEE’s mechanical testing lab, static loads were applied at various levels and time series force-displacement data was collected. In total six formal recorded tests were conducted.

[0231] For safety purposes, only four of the five specimens produced by AES were tested due to the variation of width of each of the specimens. Specimen #4 was excluded because ~2.75” wide was determined to be unstable and unsafe for high-force testing purposes. Of the four specimens that were tested formally, specimens #1 , #2, and #3 which ranged from ~5” to 5.75” wide, were tested using a setup involving an ~1.7” thick pine board between the sample and the Baldwin machines steel plate. The intention was that the wood would comply and deform to the specimens to keep the compressive loads axially aligned in the event of misalignment between the Baldwin and the specimens. Given the natural stability of specimen #5, which was 12” wide, there were no significant concerns of axial misalignment. However, during yield testing, neoprene plates were added to evenly distribute loads from the Baldwin to specimen #5 to avoid unintended stress concentrations on the individual layer beads projecting from the surface in contact with the 2” steel plate setup.

[0232] BAAM foundation v3.8 intended use cyclical compression results

[0233] FIG. 39 contains a summary of the experimental results from the intended use cyclical axial compression testing described in Chapter 5. Cyclical axial compression tests were conducted on specimens #1, #2, #3, and #5. Each test took about five minutes to set up and fifteen minutes to run. Loads were applied to each of the four specimens on the center column following the experimental procedure (section ”BAAM foundation v3.8 intended use cyclical compression experiment”). FIG. 40 shows the fixture configuration with the 1.7” thick pine wood board. FIG. 41 shows the fixture configuration without wood.

[0234] The data plotted in FIG. 42 presents an example of the timeseries forcedisplacement data collected during this experiment. A simple series spring model allows calculation of the displacement attributable to the specimen by subtracting the control (no specimen) force-displacement data (similar to that shown in FIG. 44) from the specimen 5 cyclical force-displacement data (similar to that shown in FIG. 42). The values calculated from the cyclical axial compression testing indicate that foundation v3.8 specimen #5 vertically displaced (compressed) 0.41 mm under the application of a distributed 22.4kN load.

[0235] Visual inspection of the plotted force-displacement data do not indicate signs of yield nor did any of the four specimens tested exhibit signs of plastic deformation. While not the intended purpose of this experiment, the displacement data shown in FIG. 42 indicate possibility of a slight upward drift. This may indicate either plastic deformation or the onset of phase 1 creep. Given the FEA results and the yield test results on specimen #5, plastic deformation is unlikely to be the attributable cause. In summary, cyclical testing data (22.4kN or 5,000 lb) confirm the load bearing feasibility (less than 1mm deformation) of foundation design v3.8 made of ABS short-fiber composites and made using ILSPAM (Cl BAAM 806).

[0236] FIG. 39: Baldwin cyclical testing results on foundation BAAM v3.8

[0237] This table contains the results from cyclical axial compression testing conducted on specimens #1, #2, #3, and #5 using MIT CEE’s Baldwin 300kN hydraulic force-displacement machine. Column (a) contains the specimen number for each row. Column (b) specifies which LG material was used for that specific specimen. Column (c) specifies the layer height parameter used in ORNL slicer. Column (d) details post processing that was done. Column (e) contains the approximate measured height of each specimen. Column (f) indicates which load target value was used in the test code. Column (g) indicates which load rate value was used in the test code. Column (h) describes the setup configuration. Column (i) contains the measured maximum total system displacement value across the 6 cycles. This displacement is the sum of the Baldwin system, experimental setup, and the foundation specimen.

[0238] FIG. 40: Photo of foundation BAAM v3.8 specimen 1 with 11.2kN load applied

[0239] The author took this photo during cyclical axial compression testing of specimen 1. Notice on the computer screen in the background reads “11.2252”. This field represents the live force in kN data readout from the Baldwin ADMET MTESTQUATTRO force-displacement system. The reader should ignore roman numeral IV marking on the specimen in the photo as this does not indicate the specimen number.

[0240] FIG. 41: Photo of foundation BAAM v3.8 specimen 5 with 22.4kN load applied

[0241] The author took this photo during cyclical axial compression testing of specimen 5. Notice on the computer screen in the background reads “22.4005”. This field represents the live force in kN data readout from the Baldwin ADMET MTESTQUATTRO force-displacement system.

[0242] FIG. 42: Plot of foundation v3.8 BAAM specimen 5 cyclical compression displacement vs time data

[0243] The data presented in graphs (a) and (b) was collected to identify how much vertical displacement specimen 5 experienced under a 22.4kN axial compression load. Note: Thesix peaks shown in graph a indicate the six test cycles. Baldwin has ~0.5 mm to 1.0 mm initial displacement, likely attributable to screw backlash and other stiffness related issues. This effect is seen in all of the data collected and analyzed. Also note: these displacement data are the sum of the displacement of the Baldwin machines, the 2” steel plate, and specimen 5. Graph (b) is a close up of the first cycle of the cyclical loading test data shown in graph (a). The 0.41 mm value shown in graph (b) is a calculated value from the raw data but is drawn here for the reader's benefit to show graphically the logic behind the calculation.

[0244] FIG. 43: Photos of Baldwin control testing setup

[0245] Photo (a) shows the control setup used for experiments labeled in FIG. 39, column (h) “1.7” thick pine wood board.” Note that the Baldwin hydraulic cylinder transfers vertical compressive loads into the 2” steel plate which transfers the vertical compressive loads into the 1.7” wood board. Photo (b) shows the control setup used for experiments labeled in FIG. 39, column (h) Note that the Baldwin hydraulic cylinder transfers vertical compressive loads into the 2” steel plate. The data shown in FIG. 42 (+ specimen 5) and 6.5 both used the setup configuration shown in photo (b).

[0246] FIG. 44: Plot of cyclical compression control (no wood) displacement vs time data

[0247] The data shown in graphs (a) and (b) was collected to identify how much of the displacement measured during each experiment is directly attributable to the setup. By testing the control alone, we can use a linear superposition of springs model to subtract the control displacement data from the displacement measured during the loading of each specimen (as detailed in FIG. 39). Note: The six peaks shown in graph (a) indicate the six test cycles. Baldwin has -0.5 mm to 1.0 mm initial displacement, likely attributable to screw backlash and other stiffness related issues. This effect is seen in all of the data collected and analyzed. Graph (b) is a close up of the first cycle of the control cyclical loading test data shown in graph (a). The 0.57 mm value shown in graph (b) is a calculated value from the raw data but is drawn here for the reader's benefit to show graphically the logic behind the calculation.

[0248] BAAM foundation v3.8 compression until yield results

[0249] The axial compression until yield test was devised to determine the maximum dead load the foundation v3.8 prototypes can safely support. Given the potentially destructive nature of this test, it was decided to test only one of the four samples to yield or failure in order to save as many specimens as possible for future investigations. The 1 ft2center column of specimen #5 was tested until failure using displacement control ramping at 3mm / sec. A vertical compressive load was applied to specimen 5 on the center column following the experimental procedure (section ”BAAM foundation v3.8 compression until yield experiment”). FIG. 40 shows the fixtureconfiguration with the 2x 1” thick neoprene plates to reduce the likelihood of stress concentrations caused by direct steelofoundation v3.8 contact.

[0250] Each test took about 10 minutes to set up and 25 minutes to run. In total, three experimental runs were conducted. The first two runs stopped prematurely of specimen 5 yield or failure because the specimen expressed an extremely high DB ‘pop’ when the internal X truss members delaminated from the outer perimeter shell of specimen 5. The loud pop was attributed to the combination of the failure of interbead welds and structural acoustic resonance.

[0251] FIG. 45 presents a plot of the force-displacement data collected during the third and final run of this experiment. At around 267kN applied load, the top surface of the column suddenly fractured along a line parallel to the load and perpendicular to the AM layer direction. This experimental run was stopped manually based upon the sound exhibited when specimen 5 failed across the top surface of the center column. The photos shown in FIG. 47 show the specimen while loaded to ~250kN before failure (photo a), the fracture line perpendicular to specimen 5’s layers (photo b), and the fracture line from the side view showing the failure is (jaggedly) parallel to the direction of the applied load. It appears that the crack, a jagged interlayer fracture, propagated across the outer bead but did not propagate to internal beads. It was noted that the intralayer fracture is nearly straight. It is unclear what caused the jagged interlayer fracture behavior. It is possible that uneven or random dispersion of chopped carbon fibers influenced the interlayer failure surface geometry.

[0252] Due to the ILSPAM tool path limitations, a large (~0.3”) tool path gap exists directly below the site of the crack. Future design iterations must improve the tool path to eliminate unwanted gaps like this. Given the nature of the failure, it is likely that the induced shear stress, ignored using Euler beam theory (long, slender beam assumption), was indeed a significant stress component. Future designs should instead consider Timoshenko methods for short, wide beams. It is also possible that the entire top surface of the column should instead be modeled as a plate supported by two L-beams with a gap. While not exact, FEA served as a useful guide for stress analysis. Again, the control data deflection (FIG. 46) was subtracted from the measured data (FIG. 45) to yield the true specimen deflection. The data indicates that foundation v3.8 specimen #5 vertically compressed ~1.1 cm under the application of a distributed 267kN load.

[0253] Under intended use conditions, each foundation v3.8 column must bear up to 5kN. These results indicate that specimen 5 failed under a 267kN load. This performance implies a safety factor >50. These results imply that foundation v3.8 specimen 5 exhibited strength to mass ratio >200. Caution is urged in the context of a home foundation because these results exclude: 1) live loads, 2) wind loads, 3) soil loads, 4) transient viscoelastic creep effects, and 5) thermaleffects. Further testing is required before home use. In summary, the compression until yield data confirms the ultimate load bearing feasibility of foundation design v3.8 specimen 5 made of ABS short-fiber composites using ILSPAM (Cl BAAM 806).

[0254] FIG. 45: Plot of foundation v3.8 specimen 5 compression to yield data

[0255] The x-axis is the measured vertical displacement (mm) value and the y-axis is the measured applied axial compressive load (kN) value output by ADMET MTESTQUATTRO software. The initial ~8 mm are a region of low stiffness, potentially attributable to the elastic deformation of the neoprene plates and to the backlash of the Baldwin machine. The blip that occurs around ~18.5 mm is attributed to the failure of interbead weld(s) between an internal X truss member and the outer bead. Around -19.5 mm, coinciding with the drop, sudden interlayer delamination was observed on the outer bead of the center column. It is unclear if the delamination propagated further. At -22 mm the top surface of the column failed abruptly. The experiment was then stopped.

[0256] FIG. 46: Plot of control test compression to yield load vs displacement data

[0257] The x-axis is the measured vertical displacement (mm) value and the y-axis is the measured applied axial compressive load (kN) value output by ADMET MTESTQUATTRO software. The initial -2 mm are a region of low stiffness, potentially attributable to the backlash of the Baldwin machine. Note: this neoprene plate experiment was conducted and the data collected after the compression to yield or failure test on specimen 5. Therefore, it may not be feasible to accurately attribute deformation due to local plastic deformation of the neoprene plate(s). However, a conservative over estimate is possible.

[0258] FIG. 47: Photos of foundation BAAM v3.8 ABS / CF specimen #5 during and after axial compression yield test

[0259] (a) Side view photo of foundation BAAM v3.8 ABS / CF prototype under load applied by Baldwin hydraulic press just prior to failure. Note the warping of the unconstrained surfaces of the neoprene plates, (b) Photo of top surface of foundation BAAM v3.8 ABS / CF after failure. Note the fracture line along the center, (c) Close up side view photo of foundation BAAM v3.8 ABS / CF after failure. Note the fracture appears to have initiated right above the void defect at the top of the central plate column.

[0260] FIG. 48: Photos of neoprene plate after use in specimen #5 axial compression yield test

[0261] (a) Close up photo of neoprene plate surface mated with the foundation v3.8 specimen 5 after yield testing. Note the evidence of plastic deformation on the surface of the neoprene plate at interface with specimen 5 layer seam, (b) Neoprene plate surface which matedwith the foundation BAAM v3.8 ABS / CF specimen #5 during yield testing. Note the mirror image of the prototype foundation fracture surface is permanently embossed in the neoprene plate.

[0262] BAAM foundation v3.8 prototype microscopy and other bench level testing

[0263] As indicated in the section BAAM foundation v3.8 prototypes & experiment procedure, numerous defects were identified in all five of the foundation v3.8 specimens made by AES. A visual inspection identified four defects present in the prototypes: 1) vertical interlayer seam where each layer starts and ends, 2) warping along the long edge, 3) flash present on corners and near warping, and 4) signs of layer delamination.

[0264] In light of the inability to safely conduct force-displacement tests on specimen #4 (-2.75” thick), it was decided to conduct several bench level experiments designed to emulate expected use in home construction. These tests were: 1) drilling, 2) screwing, 3) striking with a hammer, and 4) striking with a sledge hammer. Using a battery powered hand drill and a standard1 / 8” titanium bit, pilot holes were pre-drilled Then, a standard 2.5” wood screw was driven through several layers (perpendicular to interlayer bond) and through several beads (parallel to interlayer bonds and perpendicular to beads). Both drilling and screwing felt the same as wood. The results of 1) drilling and 2) screwing are shown in FIG. 49.

[0265] To simulate typical construction assembly methods (i.e. hammer) and demolition methods (i.e. sledge hammer) specimen #4 was struck with a framing hammer in several locations. Interestingly, after repeated localized striking the interbead and interlayer welds failed on one of the internal X members causing the 3-layer specimen shown in FIG. 50 to pop out. It was noted that carbon fibers are not obvious to the naked eye. The specimen was then struck with the blunt side of a combination sledge hammer - wood splitting ax. The specimen survived with some localized layer splitting along long, unsupported external spans. The purpose of the remainder of this section is to present photos and qualitative results from qualitative microscopy using Axiocam 105 and other interesting bench level tests described previously in this section.

[0266] FIG. 49: Photos of wood screws driven into foundation BAAM v3.8 ABS / CF prototype

[0267] (a) Photo of standard wood screw driven through several layers (perpendicular to interlayer bond) of foundation BAAM v3.8 ABS / CF prototype, (b) Close up photo of standard wood screw driven through several beads (parallel to interlayer bonds and perpendicular to beads) of foundation BAAM v3.8 ABS / CF prototype.

[0268] FIG. 50: BAAM v3.8 ABS / 20% CF specimen #4 samples used for microscopy

[0269] (a) Top view of rectangular section removed from BAAM v3.8 ABS / 20% CF prototype (dimensions ~8”x6”x0.6”). (b) Top view of rectangular section removed from BAAM v3.8prototype (~0.6” wide), (c) Zoom in on the surface between two layers as shown in (b). Note: This sample was removed from specimen 4 by hitting it repeatedly with a framing hammer. The interbead welds failed allowing the sample to remain intact after removal. Carbon fibers are not obvious to the naked eye. Must zoom in further.

[0270] FIG. 51: Photos of 2 microscopy samples collected from foundation v3.8 specimen 4

[0271] (a) Fractured side of sample 1 . (b) Polished side of sample 1. (c) Sheared cut side of sample 1. (d) Cut side of sample 2. (e) Polished side of sample 2. These five samples were then mounted in resin for examination in a standard microscope using typical metallurgical methods.

[0272] FIG. 52: Microscopy images of BAAM ABS / 20% CP sample 1 fracture surface

[0273] (top left) Fractured side of sample 1 at 5x magnification with 200Jum scale, (top right) Fractured side of sample 1 at 10x magnification with 100 / zm scale, (bottom left) Fractured side of sample 1 at 20x magnification with 50 m scale, (bottom right) Fractured side of sample 1 at 50x magnification with 20lum scale. Note: edges along the fracture surface with chopped carbon fibers visible and protruding from the surface.

[0274] FIG. 53: Microscopy images of BAAM ABS / 20% CF sample 1 interlaminar cut surface

[0275] (top left) Interlaminar cut of sample 1 at 5x magnification with 200 / zm scale, (top right) Interlaminar cut of sample 1 at 10x magnification with 100 / zm scale, (bottom left) Interlaminar cut of sample 1 at 20x magnification with 50 m scale, (bottom right) Interlaminar cut of sample 1 at 50x magnification with 20Jum scale. Note edges along the fracture surface with chopped carbon fibers visible and protruding from the surface.

[0276] FIG. 54: Microscopy images of BAAM ABS / 20% CF sample 1 shear surface

[0277] (top left) Interlaminar sheared surface of sample 1 at 5x magnification with 200 / zm scale, (top right) Interlaminar sheared surface of sample 1 at 10x magnification with 100fim scale, (bottom left) Interlaminar sheared surface of sample 1 at 20x magnification with 50 / zm scale, (bottom right) Interlaminar sheared surface of sample 1 at 50x magnification with 20 / zm scale. Note edges along the fracture surface with chopped carbon fibers visible and protruding from the surface. The chopped carbon fibers seem randomly oriented.

[0278] FIG. 55: Microscopy images of BAAM ABS / 20% CF sample 2 cut surface

[0279] (top left) Cut surface of sample 2 at 5x magnification with 200^m scale, (top right) Cut surface of sample 2 at 10x magnification with 100 / zm scale, (bottom left) Cut surface of sample 2 at 20x magnification with 50 / zm scale, (bottom right) Cut surface of sample 2 at 50xmagnification with 20 / zm scale. Note edges along the fracture surface with chopped carbon fibers visible and protruding from the surface. The chopped carbon fibers appear randomly oriented.

[0280] The above-described features and applications can be implemented as software processes that are specified as a set of instructions recorded on a computer readable storage medium (also referred to as computer readable medium). When these instructions are executed by one or more processing unit(s) (e.g., one or more processors, cores of processors, or other processing units), they cause the processing unit(s) to perform the actions indicated in the instructions. Embodiments within the scope of the present disclosure may also include tangible and / or non-transitory computer-readable storage media for carrying or having computerexecutable instructions or data structures stored thereon. Such non-transitory computer-readable storage media can be any available media that can be accessed by a general purpose or special purpose computer, including the functional design of any special purpose processor. By way of example, and not limitation, such non-transitory computer-readable media can include flash memory, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer-executable instructions, data structures, or processor chip design. The computer readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections.

[0281] Computer-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Computer-executable instructions also include program modules that are executed by computers in stand-alone or network environments. Generally, program modules include routines, programs, components, data structures, objects, and the functions inherent in the design of special-purpose processors, etc. that perform particular tasks or implement particular abstract data types. Computerexecutable instructions, associated data structures, and program modules represent examples of the program code means for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps.

[0282] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for performing or executing instructions and one or more memory devices forstoring instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few.

[0283] In this specification, the term “software” is meant to include firmware residing in read-only memory or applications stored in magnetic storage or flash storage, for example, a solid-state drive, which can be read into memory for processing by a processor. Also, in some implementations, multiple software technologies can be implemented as sub-parts of a larger program while remaining distinct software technologies. In some implementations, multiple software technologies can also be implemented as separate programs. Finally, any combination of separate programs that together implement a software technology described here is within the scope of the subject technology. In some implementations, the software programs, when installed to operate on one or more electronic systems, define one or more specific machine implementations that execute and perform the operations of the software programs.

[0284] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0285] These functions described above can be implemented in digital electronic circuitry, in computer software, firmware or hardware. The techniques can be implemented using one or more computer program products. Programmable processors and computers can be included in or packaged as mobile devices. The processes and logic flows can be performed by one or more programmable processors and by one or more programmable logic circuitry. General and specialpurpose computing devices and storage devices can be interconnected through communication networks.

[0286] Some implementations include electronic components, for example microprocessors, storage and memory that store computer program instructions in a machine- readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable / rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media can store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, for example is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter.

[0287] While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some implementations are performed by one or more integrated circuits, for example application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In some implementations, such integrated circuits execute instructions that are stored on the circuit itself.

[0288] As used in this specification and any claims of this application, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification and any claims of this application, the terms “computer readable medium” and “computer readable media” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals.

[0289] To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user canprovide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user's client device in response to requests received from the web browser.

[0290] The subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks).

[0291] Those of skill in the art will appreciate that other embodiments of the disclosure may be practiced in network computing environments with many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination thereof) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0292] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. In some aspects of the disclosed subject matter, a server transmits data (e.g., an HTML page) to a client device (e.g., for purposes of displaying data to and receiving user input from a user interacting with the client device). Data generated at the client device (e.g., a result of the user interaction) can be received from the client device at the server.

[0293] It is understood that any specific order or hierarchy of steps in the processes disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged, or that all illustrated steps be performed. Some of the steps may be performed simultaneously. For example, in certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components illustrated above should not be understood as requiring such separation, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0294] Various modifications to these aspects will be readily apparent, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, where reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the subject technology.

[0295] A phrase, for example, an “aspect” does not imply that the aspect is essential to the subject technology or that the aspect applies to all configurations of the subject technology. A disclosure relating to an aspect may apply to all configurations, or one or more configurations. A phrase, for example, an aspect may refer to one or more aspects and vice versa. A phrase, for example, a “configuration” does not imply that such configuration is essential to the subject technology or that such configuration applies to all configurations of the subject technology. A disclosure relating to a configuration may apply to all configurations, or one or more configurations. A phrase, for example, a configuration may refer to one or more configurations and vice versa.

[0296] The various embodiments described above are provided by way of illustration only and should not be construed to limit the scope of the disclosure. Those skilled in the art will readily recognize various modifications and changes that may be made to the principles described herein without following the example embodiments and applications illustrated and described herein, and without departing from the spirit and scope of the disclosure.

[0297] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particularinventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0298] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0299] As noted above, particular embodiments of the subject matter have been described, but other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous.CONCLUSION

[0300] A system and method have been shown in the above embodiments for the effective implementation of a System, Method and Article of Manufacture for pre-fabricated foundation made from a polymer. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications falling within the spirit and scope of the invention, as defined in the appended claims. For example, the present invention should not be limited by software / program, computing environment, or specific computing hardware.

Claims

WHAT IS CLAIMED IS:1 . A pre-fabricated modular foundation, the pre-fabricated modular foundation comprising at least one polymer, where the pre-fabricated modular foundation is manufactured off-site prior to being deployed on-site.

2. The pre-fabricated modular foundation of claim 1 , wherein the pre-fabricated modular foundation is manufactured via any of the following manufacturing techniques: injection molding, thermal forming, additive manufacturing, or 3D printing.

3. The pre-fabricated modular foundation of claim 1 , wherein the polymer is a recycled thermoplastic polymer.

4. The pre-fabricated modular foundation of claim 3, wherein the recycled thermoplastic polymer is polyethylene terephthalate (PET).

5. The pre-fabricated modular foundation of claim 1 , wherein, in addition to the at least one polymer, the pre-fabricated modular foundation further comprising at least one fiber material or fiber glass.

6. The pre-fabricated modular foundation of claim 5, wherein the at least one polymer is Acrylonitrile Butadiene Styrene (ABS) and the at least one fiber material is carbon fiber.

7. The pre-fabricated modular foundation of claim 1 , wherein the prefabricated modular foundation comprises: a. a base (201), b. a first exterior wall (202) extending vertically from a first end (210) of the base (201); c. a second exterior wall (204) extending vertically from a second end (212) of the base (201), the second end (212) opposite that of the first end (210);d. a central wall (208) extending vertically from a middle of the first end (210) of the base (201) and a middle of the first exterior wall (202) to a middle of the second end (212) of the base (201) and a middle of the second exterior wall (204); e. at least one interior wall (206) extending on either side of the central wall (208), the interior wall (206) parallel to the first and second external walls (202, 204), and the interior wall (206) disposed vertically with regards to the central wall (208); and f. a plurality of cells (214), and i. in the instance of one interior wall (206), each of the plurality of cells (214) open on one side and enclosed on three sides by portions of the first exterior wall (202), the central wall (208), and the one interior wall (206), and ii. in the instance of a plurality of interior walls (206), each of the plurality of cells (214) open on one side and enclosed on three sides by either portions of the first exterior wall (202), the central wall (208), and an interior wall (206) within the plurality of interior walls (206), or portions of two interior walls (206) within the plurality of interior walls (206) and the central wall (208).

8. The pre-fabricated modular foundation of claim 7, wherein a cross-section of each cell is an U- or V-shaped structure.

9. The pre-fabricated modular foundation of claim 8, wherein the U- or V-shaped structure comprises two adjacent five-sided polygonal structures.

10. The pre-fabricated modular foundation of claim 7, wherein the prefabricated foundation is a monolithic structure.

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