Frangible additively manufactured attachment

Abstract

A frangible attachment to attach the top of a monument (10) includes an elongated shaft (400) having different portions (401, 4023, 403) with a solid external layer (411), a variable density infill (420, 430), and a designed failure geometry (413). The elongated shaft (400) includes a first portion (401), a second portion (402), and a third portion (403). Each of the first portion (401) and the second portion (402) include a solid external layer (411), and at least one variable density infill inner layer (420, 430). The first portion (401) is longer than the second portion (402). The solid external layer (411) is configured to withstand bending forces. The third portion (403) is between the first portion (401) and the second portion (402). The third portion (403) includes a designed failure geometry (403) (e.g., an indent) to control bending of the elongated shaft (400) and withstand a specified shear force.

Description

FRANGIBLE ADDITIVELY MANUFACTURED ATTACHMENTBACKGROUND

[0001] Frangible rods are designed to attach to the top of a monument (e.g., a galley frame, a wardrobe) within an aircraft. The frangible rods secure the monuments and are designed to withstand certain static and dynamic loads while in service and in flight. A frangible rod can include a frangible portion with the design based on a moment connection applied slightly below and slightly above a frangible point. Such frangible point cracks or fractures at a specified load condition. However, the loading conditions may vary during operation, installation, and / or locations of the monuments within the aircraft and the frangible rod may not satisfy failure specifications under several of the loading conditions.BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Various embodiments in accordance with the present disclosure will be described with reference to the drawings, in which:

[0003] FIG. 1 illustrates a monument of an aircraft attached using a top attachment.

[0004] FIG. 2A and FIG. 2B illustrate an existing top attachment of the monument in FIG. 1.

[0005] FIG. 3 illustrates an example attachment assembly, according to various embodiments.

[0006] FIG. 4 is a cross-sectional view of the example attachment assembly of FIG. 3.

[0007] FIG. 5 is a cross-sectional view of an example frangible attachment, according to various embodiments.

[0008] FIG. 6 is a cross-sectional view along a plane perpendicular to the longitudinal axis of the frangible attachment in FIG. 3.

[0009] FIG. 7A illustrates a shear loading condition on the frangible attachment of FIG. 4.

[0010] FIG. 7B illustrates a bending loading condition on the frangible attachment of FIG.4.

[0011] FIG. 8 illustrates an example bracket of the attachment assembly of FIG. 3.

[0012] FIG. 9 illustrates another example bracket of the attachment assembly of FIG. 3.

[0013] FIG. 10A, FIG. 10B, and FIG. 10C illustrate various loading conditions on the frangible attachment of FIG. 4. i

[0014] FIG. 11 illustrates a honeycomb panel to which the attachment assembly and a monument are connected, according to various embodiments.SUMMARY

[0015] According to some embodiments, attachments for a monument of an aircraft can include structures configured to withstand several dynamic and static loading conditions while being light weight compared to existing rods. Specific embodiments relate to a frangible attachment manufactured using additive manufacturing (e.g., three-dimensional (3D) printing). The frangible attachment herein can be substantially lighter and stronger compared to existing metal rods (e.g., typically used in aircraft, automotive or other applications). This provides substantial weight benefits in several applications (e.g., aircraft).

[0016] According to an aspect of the present disclosure, a frangible attachment includes an elongated shaft having different portions with a solid external layer, a variable density infill, and a designed failure geometry. In many embodiments, the elongated shaft can include a first portion, a second portion, and a third portion. Each of the first portion and the second portion can include a solid external layer, and at least one variable density infill inner layer. The first portion can be longer than the second portion. The solid external layer can be configured to withstand bending forces. The third portion can be between the first portion and the second portion. The third portion can include a designed failure geometry (e.g., an indent) to control bending of the elongated shaft and withstand a specified shear force. In some embodiments, the indent can be a designed failure point under various loading conditions. Additionally or alternatively, the elongated shaft can include a coupling portion extending from the second portion configured to securely couple the elongated shaft.

[0017] In some embodiments, the solid external layer can be made of a metal or a metal alloy, a composite material, or a combination thereof. In some embodiments, the solid external layer can be made of the composite material include one or more continuous fibers extending continuously along a length of the elongated shaft. The solid external layer can be made of a first material, and the at least one variable density infill inner layer can be made of a second material, which can be same as the first material.

[0018] In many embodiments, the at least one variable density infill inner layer can have a sparse lattice geometry compared to the solid external layer. The sparse lattice geometry of the at least one variable density infill inner layer can indicate a lattice geometry that changes form to allow gradually greater air space in a volume towards a center of the elongate shaft.The at least one variable density infill inner layer can have an infill pattern including a triangular mesh. In some embodiments, the at least one variable density infill inner layer can include a first infill layer, and a second infill layer on an inner side the first infill layer. The second infill layer can have lower density than the first infill layer. The first infill layer can have a variable density from the first infill layer to the second infill layer ranges from 90% to 20%. Additionally or alternatively, the at least one variable density infill inner layer can further include a third infill layer inside the second infill layer, the third infill layer having lower density than the second infill layer, The third layer can have a variable density ranging from 30% to 20% and an infill pattern including a triangular mesh. The at least one variable density infill inner layer of the first portion can be spaced from the at least one variable density infill inner layer of the second portion. The at least one variable density infill inner layer of the first portion can have a first geometric shape and the at least one variable density infill inner layer of the second portion can have a second geometric shape. In some embodiments, the first geometric shape can be spaced from the second geometric shape. In some embodiments, the first geometric shape and the second geometric shape are the same. In some embodiments, the first geometric shape and / or the second geometric shape can include at least one of: a rounded rectangular cross-sectional shape or an elongated oval cross-sectional shape, where the cross-section shape extends in a cross-section plane passing through a longitudinal axis of the elongated shaft and extending along a length of the elongated shaft.

[0019] In many embodiments, the third portion can include the solid external layer continuously extending from the first portion to the second portion, and a variable density infill layer. The variable density infill layer of the third portion can have a lower density than the at least one variable density infill inner layer of the first and second portions. A longitudinal cross-section of the variable density infill layer of the third portion has an approximately conical shape. The conical shape can have a base and tapering sides. The base can be disposed adjacent to the solid external layer to control bending, and the sides taper towards a center of the elongated shaft. The base of the conical shape can extend radially along a circumference of the solid external layer and tapering sides extend towards a center of the elongated shaft to form a cup-like shape.

[0020] In many embodiments, the frangible attachment can further include a bracket configured to couple with a honeycomb panel of an aircraft interior. The bracket can include fiber infused solid layer made of metal by additively adding one short fiber layer over another. In some embodiments, the bracket can include a plurality of continuous fibers layersurrounding the fiber infused solid layer, the fiber infused solid layer comprising fibers having shorter length than the continuous fibers. Additionally or alternatively, the bracket can include variable infill layers. The plurality of continuous fibers layer can include a set of continuous fibers forming a closed loop.

[0021] In many embodiments, the frangible attachment can further include a seat configured to securely receive the coupling portion of the elongated shaft. The coupling portion and the seat are configured to form a threaded locking system, slot-based locking system, or a quarter turn locking system. The seat can be couplable to the bracket.

[0022] According to another aspect of the present disclosure, a method of manufacturing (e.g., three-dimension (3D) printing) of a frangible attachment is disclosed. The method can include additively building (e.g., via a 3D printer) an elongated first portion comprising a solid external layer simultaneously with at least one variable density infill inner layer. Additively building (e.g., via the 3D printer) an elongated second portion comprising a solid external layer simultaneously with at least one variable density infill inner layer. The second portion is longitudinally spaced from the first portion. Additively building (e.g., via the 3D printer) a third portion between the first portion and the second portion. The third portion includes an indent. Additively building (e.g., via the 3D printer) a coupling portion extending from the second portion. The first portion, the second portion, the third portion, and the coupling portion form an elongated shaft.

[0023] In many embodiments, the variable density infill layer of the third portion has an approximately conical shape, where the additively building comprises: printing a base adjacent to the solid external layer; and progressively moving inward toward a center of the elongated shaft to build tapering sides of the conical shape.

[0024] In many embodiments, the additively building of the solid external layer comprises configuring a first set of parameters comprises a first material, and a geometry of the solid external layer of the first portion and the second portion. In many embodiments, the additively building of the at least one variable density infill inner layer comprises configuring a second set of parameters comprises a second material, and location information along a length of the elongated shaft. In many embodiments, the additively building of the solid external layer and the at least one variable density infill inner layer is performed simultaneously. In many embodiments, the additively building of the elongated shaft comprises printing in a vertical direction, wherein the printing comprises simultaneously printing a plurality of elongated shafts.DETAILED DESCRIPTION

[0025] In the following description, various embodiments will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

[0026] Existing attachments for attaching a top portion of a monument within an aircraft can include pins, rods, or cylindrical shafts. These pins or shafts are slender structural elements typically designed to connect two parts and carry tensile load. For example, a pin can include a frange portion designed to fail at certain loading condition or specification (e.g., a maximum shear or bending load). The current design of the pin assumes a moment loading between connected parts. For example, moment forces may be applied just below and just above the frange portion of the pin. However, conditions in various installations are different from local subsystem test conditions and the monument attachment assumptions. In other words, many failure modes related to the local subsystems and monuments may not be considered in the current design and test conditions. The pin may well be involved in many of the loading conditions - especially the side and aft loadings, where a crash and hard turbulence loading conditions including fitting factors do not exceed the pin loads for the expected conditions for most installations. The present disclosure provides an additively manufactured frangible attachment that can be tuned to various load conditions including a combination of loading conditions (e.g., including bending and shear) that may not be accounted in current pin designs. Advantageously, the frangible attachment can provide additional certification testing with possible downstream overhead bin crash impacts.

[0027] FIG. 1 illustrates a monument 10 attached using an attachment assembly within an aircraft, for example. FIG. 2A and FIG. 2B illustrate an existing attachment assembly including pins 101, 102 and an aligner 105. The pins 101, 102 can be used to securely couple the monument 10 (e.g., a galley structure) to a top panel 20. The aligner 105 can be used to align the monument 10 to the top panel 20. The top panel 20 can be a honeycomb panel (e.g., see FIG. 11) typically used in an aircraft interior. The top panel 20 can include pin holes (e.g., 21 and 22 in FIG. 11) and an alignment slot (e.g., 23 in FIG. 11) to receive pins 101, 102 and the aligner 105 of an attachment assembly.

[0028] Referring to FIG. 2B, a pin 101 can include a first portion 111, a second portion 112, and a frange portion 113. The first portion 111 can be coupled to the top panel 20. The second portion 112 can be coupled to the monument 10. The frange portion 113 is designed to break at a specified load condition. As shown, the frange portion 113 has a smaller diameter compared to the diameters of the first portion 111 and the second portion 112. Under certain loading conditions, the frange portion 113 will break before the portions 111 and 112. However, the frange portion 113 is not configured to sustain various loading conditions that may be experienced during a flight of an aircraft. Hence, and improved attachment means is desired that can sustain various loading conditions experienced during the flight of an aircraft.

[0029] The present disclosure provides an additively manufactured attachment assembly that includes a frangible pin. Design of the frangible pin can be tuned or adjusted to include different shapes, materials, density, or other material properties so that the frangible pin can sustain various loading conditions, which existing pin cannot. The additively manufactured attachment assembly of present disclosure provides significantly lighter frangible attachment with improved tensile strength, shear strength, bending strength, compression strength, or a combination thereof. The frangible pin can be manufactured additively using a three- dimensional (3D) printer. The frangible pin can be designed based on a large number of loading conditions stress analysis, force flow paths, etc. Such analysis can result in a frangible pin having a complex 3D geometry having complex internal structure. The design information (e.g., 3D geometry) of frangible pin can be used to determine 3D printing information including structural features of the frangible pin. Based on the 3D printing information, a 3D printer can be configured to print the frangible pin and / or other components of the attachment assembly. For example, the frangible pin can be 3D printed to include a composite structure of a solid layer, continuous fibers extending along a length of a shaft, complex variable density infill patterns, a failure initiation structure (e.g., an indent), or other composite structure made of same or different materials. Such attachment assembly of composite structure and / or material can be light weight without being limited by manufacturing costs.

[0030] Technical challenges related to additive manufacturing of the attachment assembly and its components optimization of structural and manufacturing parameters, which is not a trivial task. For example, shape, size, materials, and / or cost of the attachment assembly can be highly variable. The optimization process to involve tuning of various design and manufacturing parameters. For example, one or more optimization parameters can include, butnot limited to, taking advantage of extreme geometry flexibility for complexity of function and appearance of different parts, consolidate parts, low to moderate part volumes, part nesting for economy, include many failure modes in design optimizations, include secondary treatment and finish considerations, and include polymer, metal and / or composite design comparisons.

[0031] FIGS. 3 and 4 illustrate an example attachment assembly 300 comprising additively manufactured components, according to various embodiments. In many embodiments, the frangible attachment assembly 300 is optimized for failure in shear, tension or bending, and combined shear and tension or bending. The frangible attachment assembly 300 can include an additively manufactured frangible attachment 400, a pin-seat 500, and an additively manufactured moment bracket 600. The frangible attachment 400 can be designed to include geometric shapes, material composition, and / or density that can sustain various loading conditions and failure modes. For example, the frangible attachment 400 has a thin outer layer and shear center indented design with variable infdl thickness to optimize both stress and strain behavior. The pin-seat 500 can be coupled to the frangible attachment 400 via a quick release mechanism such as threaded connection, a quarter turn lock and unlock mechanism (e.g., including slot and locking flange (not illustrated)), or other coupling assembly. In the illustrated embodiments, the frangible attachment 400 is coupled to the pinseat 500 using threads without limiting the scope of the present disclosure.

[0032] Referring to FIG. 4 and FIG. 5 the frangible attachment 400 can be or include an elongated shaft or a pin. However, the frangible attachment 400 may have other shapes without limiting the scope of the present disclosure. In many embodiments, the frangible attachment 400 can be alternatively referred as an elongated shaft 400 or a pin 400. The elongated shaft 400 can include a first portion 401, a second portion 402, and a third portion 403. One or more of the first 401, second 402, and the third portions 403 can include different structures facilitating various loading conditions compared to existing pins used as top attachments. In many embodiments, each of the first portion 401 and the second portion 402 can include a solid external layer (e.g., 411) or an outer layer, and at least one variable density infill inner layer (e.g., 420, 430). The first portion 401 can be longer than the second portion 402. The solid external layer 411 can be configured to withstand bending forces. For example, the bending of the shaft can cause tensile stress on an outer side and compression stress on an inner side.

[0033] In many embodiments, the solid external layer 411 can be made of a metal (e.g., aluminum, steel, etc.) or a metal alloy. In another example, the solid external layer 411 can bemade of a composite material, or a combination metal and composite material. In some embodiments, the solid external layer 411 made of the composite material can include one or more continuous fibers extending continuously along a length of the elongated shaft 400. In many embodiments, the solid external layer 411 is made of a first material, and the at least one variable density infill inner layer (e.g., 420, 430) can be made of a second material. The second material can be same as the first material. However, in another example, the first material and the second material can be different.

[0034] FIG. 5 and FIG. 6 illustrate an example structure of different layers of the frangible attachment 400. In many embodiments, the at least one variable density infill inner layer (e.g., 420, 430, and 440) has a sparse lattice geometry compared to the solid external layer 411. The sparse lattice geometry indicates a lattice geometry which changes form to allow gradually greater air space in volume towards a center of the elongate shaft. In this way, a variable density infill layer can be formed.

[0035] In many embodiments, the at least one variable density infill inner layer (e.g., 420, 430, and 440) can have an infill pattern including a triangular mesh. However, grid infill pattern, or other patterns are possible. In many embodiments, the at least one variable density infill inner layer 420 of the first portion 401 and the at least one variable density infill inner layer 430 of the second portion 402 can be structurally similar. The at least one variable density infill layers (e.g., 420, 430, 440) can include one, two, three, or more layers. For example, the infill layers 420, 430 can have three nested layers and the infill layer 440 can have one layer. In many embodiments, the number of layers can be determined based on stress and strain behavior for different loading conditions.

[0036] In the illustrated embodiment in FIG. 5, the at least one variable density infill layer 420 can include a first layer, a second layer and a third layer. In some embodiments, the infill layers 421, 422, 423 can be collectively referred as the infill layer 420. Similar to the infill layer 420, the at least one variable density infill layer 430 can include a first layer 431, a second layer 432, and / or a third layer 433. In the illustrated embodiment, the infill layers 420 and 430 can be structurally similar. In some embodiments, the infill layers 421, 422, 423 can be collectively referred as the infill layer 420, and the infill layers 431, 432, 433 can be collectively referred as the infill layer 430.

[0037] In many embodiments, the first layer 421 can be adjacent to the solid external layer 411. The second infill layer 422 on an inner side the first infill layer 421. The third infill layer 423 can be on an inner side of the second infill layer 422. The second infill layer 422 can have a lower density than the first infill layer 421. As an example, the density can vary fromthe first infill layer 421 to the second infill layer 422 in a range from 90% to 20%. The third infill layer 423 can have a lower density than the second infill layer 422. The third layer 423 can have a variable density ranging from 30% to 20% and an infill pattern including a triangular mesh, grid, or other infill patterns. The layers 431, 432, and 433 can be configured similar to the layers 421, 422, 423.

[0038] In many embodiments, the infill inner layer 420 of the first portion 401 can be laterally spaced from the infill inner layer 430 of the second portion 402. The infill inner layer 420 of the first portion 401 can have a first geometric shape and the infill inner layer 430 of the second portion 402 can have a second geometric shape. The first geometric shape can be laterally spaced from the second geometric shape. In many embodiments, the first geometric shape and the second geometric shape are the same. For example, the first geometric shape and / or the second geometric shape can include at least one of: a rounded rectangular cross-sectional shape or an elongated oval cross-sectional shape. In the illustrated embodiment, in FIG. 5, the cross-section shape extends in a cross-section plane passing through a longitudinal axis of the elongated shaft 400 and extend along a length of the elongated shaft 400. In this cross-section, each of the variable density infill layer 421, 422, 423 has a rounded rectangular outline.

[0039] In many embodiments, the third portion 403 of the elongated shaft 400 can be between the first portion 401 and the second portion 402. The third portion 403 of the elongated shaft 400 can have a different geometry and structure from the first portion 401 and the second portion 402. In many embodiments, the third portion 403 can include one or more features configured to initiate failure (e.g., cracking, tearing, or breaking) within the third portion 403 of the elongated shaft 400 under different load conditions. For example, the third portion 403 can include an indent 413 (see FIG. 4). The indent 413 can be located on the external solid layer and can control bending of the elongated shaft 400. Additionally or alternatively, the indent 413 can be configured to withstand a specified shear force. The indent 413 on the external layer and infill layers adjacent to the indent 413 can be a designed failure portion configured to sustain a specified amount of shear, bending, tension, compression or a combination thereof under various loading conditions. The shape and size of the indent 413 may vary depending on the different materials, composition of the variable density infill layer, loading conditions, etc.

[0040] In many embodiments, the third portion 403 can include a solid external layer (e.g., 411) and a variable density infill layer 440. In the illustrated embodiments of FIGS. 3 and 5, the solid external layer 411 of the third portion 403 can be continuously extending from thoseof the first portion 401 and the second portion 402. In many embodiments, the variable density infill layer 440 of the third portion 403 can have a lower density than the at least one variable density infill inner layer 420 of the first portion 401 and second portion 402. In some embodiments, the variable density infill layer 440 of the third portion 403 is same as the third infill layer 423, 433 of the first portion 401 and second portion 402.

[0041] In an illustrated embodiment, in FIG. 5, a longitudinal cross-section of the variable density infill layer 440 of the third portion 403 can have an approximately conical shape. The conical shape can have a base and tapering sides. The base being disposed adjacent to the solid external layer 411 to control bending, and the sides taper towards a center of the elongated shaft 400 to control shear. As shown in FIG. 3, the base of the conical shape can extend radially along a circumference of the solid external layer 411 and tapering sides extend towards a center of the elongated shaft 400 to form a cup-like shape.

[0042] In some embodiments, the elongated shaft 400 can include a coupling portion 405 configured to securely couple the elongated shaft 400 within the attachment assembly (e.g., 300 in FIG. 3). For example, as shown in FIG. 5, the coupling portion 405 can extend from the second portion 402. The coupling portion 405 can be a threaded portion configured to threadingly engage with internal threads of the pin seat (e.g., 500 in FIG. 4). The present disclosure is not limited to threads as the coupling means, and other coupling or fastening means (e.g., a quarter turn lock and unlock, slot and flange arrangement) are possible. The other end (top end) of the elongated shaft 400 can be coupled to a honeycomb panel (e.g., at holes 31, 32, 33 in FIG. 11).

[0043] FIG. 7A illustrates a shear loading condition SI on the frangible attachment 400 and how different portions of the frangible attachment 400 take or share the load. For example, the solid external layer 411 can sustain a minimum shear. The indent 413 can serve as a crack initiation point and to relieve an unreliable crack initiation load peak. The variable density infdl layers (e.g., 440) can control shearing from an outer side to a center of the elongated shaft 400. This way, different portions e.g., the solid external layer 411, the third portion 403 with the indent 413, the variable density infdl layers 440 can share forces or stress in different ways enabling the elongated shaft 400 to be subjected to various loading conditions that existing pins cannot handle.

[0044] FIG. 7B illustrates a bending loading condition Bl on the frangible attachment 400 and how different portions of the frangible attachment 400 take or share the load. For example, the solid external layer 411 can provide controllable bending failure by sustaining tension on one side (e.g., 411a) or edge and compression on an opposite side (e.g., 411b) oredge of the elongated shaft 400. The indent 413 can serve as a crack initiation point and to relieve an unreliable crack initiation load peak. The variable density infill layer (e.g., 440) can provide minimum bending resistance at a center of the elongated shaft 400 by a shorter layer edge 414 or less dense inner layer portion 414. This way, different portions e.g., the solid external layer 411, the third portion 403 with an indent 413, the variable density infill layer 440 can share forces or stress in different ways enabling the elongated shaft 400 to be subjected to various loading conditions that existing pins cannot handle.

[0045] Comparing the effects of the shear and bending loading conditions of FIG. 7A and 7B, the elongated shaft 400 includes various portions having specific structural features that can undergo various loading conditions while providing controlled stress and strain behavior. Such advantages can allow the frangible attachment to meet a number of additional certification standards of an aircraft that a traditional top-attachment of wardrobe or other monuments. This can be because of design and manufacturing limitations imposed by the traditional manufacturing process a pin. For example, traditional pins manufactured using injection molding or lathes cannot be designed or manufactured to include variable density infill layers or other structural features so that the traditional pin can behave differently under different loading conditions.

[0046] FIG. 10 A, FIG. 10B, and FIG. 10C illustrate various main loading conditions that can be imposed on a frangible attachment (e.g., 400). For example, forces F, F2, and F3 may be applied at different locations on the frangible attachment 400. These forces induce shear (e.g., in FIG. 10A), bending (e.g., in FIG. 10B and 10C), tension and compression (e.g., along longitudinal portions on either side of the center of the elongated shaft 400), etc. in different portions of the frangible attachment 400. Based on such loading conditions, structure of the frangible attachment (e.g., 400) can have an optimized load and failure path for multiple loading and failure scenarios. A combination of these illustrated loading conditions and any additional loading conditions can be complex, which can result in a complex structure (e.g., including shapes, infills, material, etc.) of the frangible attachment (e.g., 400). Based on the complex structure, additive manufacturing process parameters should be optimized or selected to enable manufacturing of the frangible attachment (e.g., 400). Typical manufacturing processes may not be readily available or modifiable to manufacture complex structures of the frangible attachment herein.

[0047] In many embodiments, the attachment assembly can employ a bracket (e.g., 600). The bracket can be structured in different ways. FIGS. 8 and 9 illustrate two examples of a bracket (e.g., 600) of the attachment assembly 300. The bracket (e.g., 600) can be configuredto couple with a honeycomb panel of an aircraft interior. In an illustrated embodiment of FIG. 8, a bracket 600A can be additively manufactured using solid material (e.g., aluminum) with holes 601, 602 and / or slots 605. The holes 601, 602 and / or slots can be sized and positioned to couple a pin seat, an aligner, or other components of an attachment assembly.

[0048] In the illustrated embodiment of FIG. 9, a bracket 600B can be additively manufactured to include fiber infused solid layers 611 made of metal by additively adding one short fiber layer over another. As shown in FIG. 9, the bracket 600B can include a plurality of continuous fibers layer 612 surrounding the fiber infused solid layer. The fiber infused solid layer 611 can include fibers having shorter length than the continuous fibers 612. The bracket 600B can further include one or more variable infill layers 613 to control a stress and / or strain behavior at a center portion of the bracket 600B. The plurality of continuous fibers layer 612 can include a set of continuous fibers forming a closed loop.

[0049] In some embodiments, as shown in FIG. 4, the bracket 600 includes integrated wire guide / guard 650 and potting. The bracket 600 does not use a large rectangular hole 605 at a current machined version, but uses the stiffness of the panel to reduce size while increasing stiffness. The stiffness is maximized to make the fixed base analysis assumption more realistic in the various installations.

[0050] In some embodiments, shown in FIGS. 3 and 4, the pin seat 500 can be a cylindrical part. The pin seat 500 can be configured to securely receive the coupling portion 405 of the elongated shaft 400. The coupling portion 405 and the seat 500 are configured to form a threaded locking system, slot-based locking system, or a quarter turn locking system. The seat can be couplable to the bracket 600. For example, the seat 500 can be a stepped hollow cylinder receivable in a hole of the bracket 600.

[0051] In many embodiments, the pin seat 500 or mount can be printed in aluminum or composite economically. The elongated shaft 400 can be securely coupled to the pin seat 500. For example, the pin 400 can be screwed to the pin seat 500. The pin seat 500 can be further screwed into the base bracket 600. The screw action has a final detent snap action for resistance to loosening from vibration.

[0052] In many embodiments, the attachment assembly 300 herein provides several advantages. For example, the attachment assembly 300 uses less raw material, weighs less, improve loading performance, require less labor resource, requires less time to install (including on-aircraft installation), costs less, and can be recyclable.

[0053] In many embodiments, the frangible attachment 400 and / or the bracket 600 can include continuous long fiber in combination with variable density infills (e.g., formed as short fiber infused polymers) made by an additive manufacturing (e.g., 3D printing) process. From a strength of materials perspective, continuous long fibers can allow for high-strength tension (e.g., higher than the best alloy metals). Variable density infills can provide much higher shear and compression than the polymer and / or polymer and long fiber combinations. Short fibers may also provide cross-linking between individual filament laydown lines and also between deposition layers.

[0054] From a manufacturing perspective, the frangible attachment (e.g., 400) may be additively manufactured in a horizontal orientation, where continuous fibers (e.g., polymer) or solid material (e.g., aluminum) can be formed as flat layers (e.g., each layer being in a plane) parallel to a build plate. In another example, the elongated shaft 400 can be manufactured in a vertical orientation, where continuous fibers (e.g., polymer) or solid material (e.g., aluminum) can be deposited vertically on the build plate. In some embodiments, the frangible attachment 400 can include threaded end so that several frangible attachments can be printed simultaneously per build plate in a vertical direction for economic cost in aluminum or composite.

[0055] In many embodiments, a process of additively manufacturing the frangible attachment (e.g., 400) herein includes specific configuration of a 3D printer (e.g., Mark II printer). For example, a manufacturing layout of the solid outer layer or continuous fibers, variable density infills, and crack-initiating structural features can be determined based on stress analysis, and force flow lines. Based on the manufacturing layout, one or more printing parameters of a 3D printer can be determined. For example, one or more parameters can be print path and directions, a fiber thickness, a speed of printing, a print length, temperature, number of repetitions of the continuous fibers, density of infill and fiber placement, temperature and humidity of the storage environment and printing environment, postprocessing finishes, and support structure parameters.

[0056] The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the disclosure as set forth in the claims.

[0057] Other variations are within the spirit of the present disclosure. Thus, while the disclosed techniques are susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been describedabove in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure, as defined in the appended claims.

[0058] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosed embodiments (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

[0059] Disjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is intended to be understood within the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and / or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain embodiments require at least one of X, at least one of Y, or at least one of Z to each be present.

Claims

CLAIMSThat which is claimed is:

1. A frangible attachment comprising: an elongated shaft comprising: a first portion and a second portion, each of the first portion and the second portion comprising a solid external layer, and at least one variable density infill inner layer, the first portion being longer than the second portion, the solid external layer configured to withstand bending forces; a third portion between the first portion and the second portion, the third portion comprising an indent to control bending of the elongated shaft and withstand a specified shear force, the indent being a designed failure portion under various loading conditions; and a coupling portion extending from the second portion configured to securely couple the elongated shaft.

2. The frangible attachment of claim 1, wherein the solid external layer is made of a metal or a metal alloy, a composite material, or a combination thereof.

3. The frangible attachment of claim 2, wherein the solid external layer is made of the composite material comprises: one or more continuous fibers extending continuously along a length of the elongated shaft.

4. The frangible attachment of any one of claims 1-3, wherein the solid external layer is made of a first material, and the at least one variable density infill inner layer is made of a second material same as the first material, the at least one variable density infill inner layer has a sparse lattice geometry compared to the solid external layer.

5. The frangible attachment of any one of claims 1-4, wherein the sparse lattice geometry of the at least one variable density infill inner layer, wherein a variable density indicates a lattice geometry changing form to allow gradually greater air space in a volume towards a center of the elongate shaft.

6. The frangible attachment of any one of claims 1-5, wherein the at least one variable density infill inner layer has an infill pattern comprising a triangular mesh.

7. The frangible attachment of any one of claims 1-6, wherein the at least one variable density infill inner layer comprises a first infill layer, and a second infill layer on an inner side the first infill layer, the second infill layer having lower density than the first infill layer, wherein the first infill layer has a variable density from the first infill layer to the second infill layer ranges from 90% to 20%.

8. The frangible attachment of claim 6, wherein the at least one variable density infill inner layer further comprises: a third infill layer inside the second infill layer, the third infill layer having lower density than the second infill layer, wherein the third layer has a variable density ranging from 30% to 20% and an infill pattern comprising a triangular mesh.

9. The frangible attachment of any one of claims 1-8, wherein the at least one variable density infill inner layer of the first portion is spaced from the at least one variable density infill inner layer of the second portion.

10. The frangible attachment of claim 9, wherein the at least one variable density infill inner layer of the first portion has a first geometric shape and the at least one variable density infill inner layer of the second portion has a second geometric shape, the first geometric shape being spaced from the second geometric shape.

11. The frangible attachment of claim 10, wherein the first geometric shape and the second geometric shape are the same.

12. The frangible attachment of claim 10, wherein the first geometric shape and / or the second geometric shape comprises at least one of: a rounded rectangular cross-sectional shape or an elongated oval cross-sectional shape, wherein the cross-section shape extending in a cross-section plane passing through a longitudinal axis of the elongated shaft and extending along a length of the elongated shaft.

13. The frangible attachment of any one of claims 1-12, wherein the third portion comprises the solid external layer continuously extending from the first portion to the second portion, and a variable density infill layer.

14. The frangible attachment of claim 13, wherein the variable density infill layer of the third portion has a lower density than the at least one variable density infill inner layer of the first and second portions.

15. The frangible attachment of claim 14, wherein a longitudinal cross-section of the variable density infill layer of the third portion has an approximately conical shape.

16. The frangible attachment of claim 15, wherein the conical shape has a base and tapering sides, the base being disposed adjacent to the solid external layer to control bending, and the sides taper towards a center of the elongated shaft.

17. The frangible attachment of claim 15, wherein the base of the conical shape extend radially along a circumference of the solid external layer and tapering sides extend towards a center of the elongated shaft to form a cup-like shape.

18. The frangible attachment of any one of claims 1-17, further comprising a bracket configured to couple with a honeycomb panel of an aircraft interior.

19. The frangible attachment of claim 18, wherein the bracket comprises fiber infused solid layer made of metal by additively adding one short fiber layer over another.

20. The frangible attachment of claim 19, wherein the bracket comprises a plurality of continuous fibers layer surrounding the fiber infused solid layer, the fiber infused solid layer comprising fibers having shorter length than the continuous fibers.

21. The frangible attachment of claim 20, wherein the bracket comprises variable infill layers.

22. The frangible attachment of claim 20, wherein the plurality of continuous fibers layer comprises a set of continuous fibers forming a closed loop.

23. The frangible attachment of any one of claims 18-22, further comprising a seat configured to securely receive the coupling portion of the elongated shaft, wherein the coupling portion and the seat are configured to form a threaded locking system, slot-based locking system, or a quarter turn locking system, wherein the seat is couplable to the bracket.

24. A method of additive manufacturing of a frangible attachment, the method comprising: additively building, via a 3D printer, an elongated first portion comprising a solid external layer simultaneously with at least one variable density infill inner layer; additively building, via the 3D printer, an elongated second portion comprising a solid external layer simultaneously with at least one variable density infill inner layer, the second portion being longitudinally spaced from the first portion; additively building, via the 3D printer, a third portion between the first portion and the second portion, the third portion comprising an indent; and additively building, via the 3D printer, a coupling portion extending from the second portion, wherein the first portion, the second portion, the third portion, and the coupling portion form an elongated shaft.

25. The method of claim 24, wherein the at least one variable density infill inner layer of the first portion and the second portion comprises a first infill layer, and a second infill layer inside the first infill layer, the second infill layer having lower density than the first infill layer.

26. The method of claim 25, wherein the at least one variable density infill inner layer of the first portion and the second portion further comprises: a third infill layer inside the second infill layer, the third infill layer having lower density than the second infill layer.

27. The method of any one of claims 24-26, wherein the at least one variable density infill inner layer of the first portion is spaced from the at least one variable density infill inner layer of the second portion.

28. The method of any one of claims 24-27, wherein the third portion comprises the solid external layer, and a variable density infill layer.

29. The method of claim 28, wherein the variable density infill layer of the third portion has a lower density than the at least one variable density infill inner layer of the first and second portions.

30. The method of claim 29, wherein the variable density infill layer of the third portion has an approximately conical shape, wherein the additively building comprises: printing a base adjacent to the solid external layer; and progressively moving inward toward a center of the elongated shaft to build tapering sides of the conical shape.

31. The method of any one of claims 24-30, wherein the additively building of the solid external layer comprises: configuring a first set of parameters comprises a first material, a geometry of the solid external layer of the first portion and the second portion.

32. The method of any one of claims 24-31, wherein the additively building of the at least one variable density infill inner layer comprises: configuring a second set of parameters comprises a second material, and location information along a length of the elongated shaft.

33. The method of any one of claims 24-32, wherein the additively building of the solid external layer and the at least one variable density infill inner layer is performed simultaneously.

34. The method of any one of claims 24-33, wherein the additively building of the elongated shaft comprises printing in a vertical direction, wherein the printing comprises simultaneously printing a plurality of elongated shafts.

Images