A lattice cement-based composite material with a superstructure interface and a design method thereof

Abstract

The present invention belongs to the technical field of preparation of lattice cement-based composite materials, and specifically discloses a lattice cement-based composite material with a meta-structure interface and a design method thereof, comprising the following steps: S1, modeling is performed using modeling software to obtain a lattice; S2, meta-material geometric units are distributed hierarchically on the surface of a single rod along the axial direction, and at the same time, the distances between each point of the meta-material geometric unit and the longitudinal center axis of the single rod are controlled to be equal, each point is connected to form a curved surface a, and the curved surface a is projected onto the single rod to form a curved surface b, and each corresponding point of the curved surface a and the curved surface b is connected to form a body, so as to obtain a lattice forming a meta-material interface; S3, a lattice with a meta-material interface is produced using 3D printing technology; S4, the lattice obtained in S3 is built into a mold, and a heavy object is pressed on the lattice to fix the lattice. The present invention adopts the above-mentioned lattice cement-based composite material with a meta-structure interface and a design method thereof to solve the problem of low interface bonding strength between existing lattice cement-based composite materials.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of lattice cement-based composite materials, in particular to a lattice cement-based composite material with a super-structured interface and a design method thereof. Background Art

[0002] In traditional reinforced concrete structures, steel bars are prone to rust in alkaline environments, resulting in reduced structural durability. In addition, reinforced concrete structures are heavy, consume a lot of cement-based materials, have limitations in digital material design, and have a low degree of automated construction. In recent years, various methods for improving interface strength have mostly relied on chemical synthesis, which cannot improve interface strength in the long term.

[0003] Metamaterials are engineered materials that are carefully designed from geometrical units of materials and replicated and combined into a whole through basic units. Their material properties are controlled by the geometrical units of materials. In recent years, with the continuous innovation of computing power, theoretical concepts, design methods and manufacturing technologies, people have begun to deeply design and optimize the geometrical units of materials, improve material utilization and obtain mechanical properties that surpass those of natural materials, which has received widespread attention in various disciplines.

[0004] In the prior art, the Chinese invention patent with publication number CN118700329A discloses a 3D printed meter-scale lattice skeleton reinforced reinforced concrete beam component, which embeds the 3D printed meter-scale lattice into the steel cage as a reinforced skeleton of high-strength concrete, and uses the pore structure and light weight and high strength characteristics of the lattice to interpenetrate and embed with the concrete matrix material to form a lattice-concrete composite structure, which can reduce the consumption of cement-based materials and reduce the overall weight of the component. However, the lattice skeleton has a smooth interface and no interface treatment, so the synergy between the lattice and concrete is weak.

[0005] The Chinese invention patent with publication number CN202310887283 discloses a self-bonding FRP bar for cement concrete structure and its preparation method and application, which is obtained by impregnating the FRP bar with a resin system, coating the surface with nanocrystalline seeds, and finally curing it at high temperature. However, the resin system used relies on chemical synthesis and cannot improve the interface strength for a long time.

[0006] In summary, the existing preparation methods of lattice cement-based composite materials have the following problems:

[0007] 1. The lattice surface has not been subjected to interface treatment;

[0008] 2. Interface bonding relies on chemical synthesis and cannot improve interface strength over a long period of time. Summary of the invention

[0009] The purpose of the present invention is to provide a lattice cement-based composite material with a meta-structured interface and a design method thereof, by manufacturing a lattice with a metamaterial surface through 3D printing, and utilizing the geometric mechanical properties of the metamaterial to strengthen the mechanical bite between the lattice and concrete, thereby significantly improving the interfacial bonding performance of the lattice cement-based composite material.

[0010] To achieve the above object, the present invention provides a design method for a lattice cement-based composite material with a superstructure interface, comprising the following steps:

[0011] S1. Modeling is performed using modeling software to obtain a lattice;

[0012] S2, distributing the metamaterial geometric units hierarchically on the surface of the single rod along the axial direction, while controlling the distance between each point of the metamaterial geometric unit and the longitudinal center axis of the single rod to be equal, connecting each point to form a curved surface a, projecting the curved surface a onto the single rod to form a curved surface b, connecting each corresponding point of the curved surface a and the curved surface b to form a body, and obtaining a lattice forming the metamaterial interface;

[0013] S3, using 3D printing technology to make lattices with metamaterial interfaces;

[0014] S4, placing the lattice obtained in S3 into a mold, pressing a heavy object on the lattice to fix it, pouring concrete mortar and performing curing.

[0015] Preferably, in S1, the lattice is an octagonal structure of an array, and the four endpoints in each face of the octagon are diagonally connected by a single rod through the face center and the body center, and the single rod includes a plurality of vertical oblique rods and horizontal rods.

[0016] Preferably, in S2, the metamaterial geometric unit is one or a combination of a concave honeycomb or a conventional honeycomb, and the design formula of the concave honeycomb or the conventional honeycomb is as follows:

[0017] ;

[0018] ;

[0019] ;

[0020] in, is the height of the metamaterial geometric unit, is the length of the metamaterial geometric unit, is the assumed Poisson's ratio, is the length of the vertical bar of the metamaterial geometric unit; is the length of the diagonal rod of the metamaterial geometric unit; θ It is the bevel angle. The bevel angle of the concave honeycomb is negative, and the bevel angle of the regular honeycomb is positive.

[0021] Preferably, in S2, the metamaterial geometric units are hierarchically distributed in the non-end region of the single rod along the axial direction, and the non-end region is a region that accounts for 7 / 8 of the total length of the single rod.

[0022] Preferably, in S2, the metamaterial geometric units are fully distributed or partially distributed on the surface of the vertical inclined rod or the horizontal rod.

[0023] Preferably, in S3, the parameters of the 3D printing technology are set as follows: printing speed is 100 mm / s~120 mm / s, filling density is 100%, layer height is 0.08 mm~0.1 mm, nozzle temperature is 195°C~220°C, and printing material is polylactic acid filament PLA.

[0024] Preferably, in S3, the concrete mortar comprises the following components:

[0025] Cement, fly ash, fine sand, thickener, water reducing agent.

[0026] To achieve the above-mentioned purpose, the present invention also provides a lattice cement-based composite material with a super-structured interface, comprising concrete and a plurality of lattices arranged along the length direction of the concrete, wherein the lattices are located at the center of the concrete, and the volume of the concrete is 6.0 to 6.4 times the volume of the lattices.

[0027] Therefore, the present invention adopts the above-mentioned lattice cement-based composite material with a superstructure interface and the design method thereof, and the beneficial effects are as follows:

[0028] (1) The present invention designs a metamaterial interface and manufactures a lattice having the metamaterial interface through 3D printing technology. The special geometric structure of the metamaterial interface forms a better mechanical bite effect with the cement base, thereby enhancing the bonding performance between the lattice and concrete, thereby improving the mechanical properties of the composite material.

[0029] (2) The present invention utilizes the good tensile properties of the lattice to have better bending bearing capacity under bending load. The ribbed lattice and concrete form a good synergistic effect, absorb more fracture energy, enhance the ductility and impact resistance of this type of beam component, and have significantly improved static load bending performance.

[0030] (3) The present invention adopts lattice cement-based components, which can reduce the consumption of cement-based materials and lighten the overall weight of the components. By using 3D printing technology, the digital design and intelligent construction level of reinforced concrete modular components can be increased, providing customized solutions for the design of lightweight load-bearing components.

[0031] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a test piece of an embodiment of a lattice cement-based composite material with a super-structured interface of the present invention;

[0033] Figure 2 It is a schematic diagram of the structure of the lattice metamaterial interface of a lattice cement-based composite material embodiment of the present invention, wherein (a) is a concave honeycomb, and (b) is a conventional honeycomb;

[0034] Figure 3 It is a lattice top view of a partial distribution of metamaterial geometric units of a lattice cement-based composite material embodiment of a metastructure interface of the present invention;

[0035] Figure 4 It is a schematic diagram of the lattice structure of the partial distribution of the metamaterial geometric units of an embodiment of a lattice cement-based composite material with a metastructure interface of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0037] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0038] Embodiment 1

[0039] A super-structured interface lattice cement-based composite material, using concrete and five lattices arranged along the length of the concrete, the dimensions of a single lattice are: 45mm long, 45mm wide and 45mm high, and the diameter of a single rod is 4.5mm. The dimensions of the concrete are: 215mm long, 50mm wide and 50mm high. (The five lattice single rods have overlapping parts, and the total length is 207mm)

[0040] The design formulas for concave honeycombs and regular honeycombs are as follows:

[0041] ;

[0042] ;

[0043] ;

[0044] in, is the height of the metamaterial geometric unit, is the length of the metamaterial geometric unit, is the assumed Poisson's ratio, is the length of the vertical bar of the metamaterial geometric unit; is the length of the diagonal rod of the metamaterial geometric unit; θ It is the bevel angle. The bevel angle of the concave honeycomb is negative, and the bevel angle of the regular honeycomb is positive.

[0045] The geometric unit of the metamaterial interface is a concave honeycomb = -0.6, =7.85mm, =7.85mm, the cell wall thickness is 0.23mm, and the rib height of the lattice with the metamaterial interface is 1mm.

[0046] The lattice is an octagonal structure. The four endpoints in each face of the octagon are connected diagonally through a single rod through the face center and the body center. The single rod includes a number of vertical diagonal rods and horizontal rods. The metamaterial geometric units are distributed on the surface of all vertical diagonal rods and horizontal rods. This distribution form is full distribution.

[0047] The lattice uses PLA, a polylactic acid filament, for printing, which has a tensile strength of 54.5 MPa, an elastic modulus of 3329.8 MPa, and a density of .

[0048] The parameters of the 3D printing technology are: printing speed of 120 mm / s, filling density of 100%, layer height of 0.1 mm, and nozzle temperature of 210 °C.

[0049] The concrete paste comprises the following components by weight:

[0050] 323.21 parts of cement, 754.17 parts of fly ash, 355.54 parts of fine sand, 0.54 parts of thickener, and 6.25 parts of water reducer.

[0051] The 3D printed lattice with metamaterial interface is built into the mold as a reinforced skeleton of concrete. The metamaterial interface and cement base produce better mechanical bite effect, and the octagonal structure of the lattice itself has better tensile properties. It is interpenetrated with concrete mortar to form a lattice-concrete composite material. The specimen is obtained by curing and is recorded as ER.

[0052] Embodiment 2

[0053] The difference from the first embodiment is that the metamaterial interface geometric unit is a conventional honeycomb , the rib height of the lattice with the metamaterial interface is 1 mm.

[0054] The 3D printed lattice with metamaterial interface is built into the mold as a reinforced skeleton of concrete. The metamaterial interface and cement base produce better mechanical bite effect, and the octagonal structure of the lattice itself has better tensile properties. It is interpenetrated with concrete mortar to form a lattice-concrete composite material. The specimen is obtained by curing and recorded as HR.

[0055] Embodiment 3

[0056] The difference from Example 1 is that a 3D printed lattice without a metamaterial interface (the lattice surface is a smooth interface) is built into a mold as a reinforced skeleton of concrete. The octagonal structure of the lattice itself has better tensile properties, and is interpenetrated with concrete mortar to form a lattice-concrete composite material. The specimen is cured and recorded as SR.

[0057] Embodiment 4

[0058] The metamaterial geometric units are not distributed on all vertical and horizontal rod surfaces, and the distribution form is partial distribution. The difference from the first embodiment is that only the concave honeycombs are selected to be distributed on the vertical and horizontal rod surfaces along the length direction of the concrete, and the horizontal rods are not designed with concave honeycombs.

[0059] The 3D printed lattice with metamaterial interface is built into the mold as a reinforced skeleton of concrete. The metamaterial interface and cement base produce better mechanical bite effect, and the octagonal structure of the lattice itself has better tensile properties. It is interpenetrated with concrete mortar to form a lattice-concrete composite material. The specimen is obtained by curing and recorded as PER.

[0060] Experimental Testing

[0061] The present invention provides a method for evaluating the three-point bending static load bending performance of a specimen, which specifically comprises the following steps:

[0062] Hinged supports are used at both ends of the specimen, with an effective span of 170mm. A press is used in the middle of the span to load the steel plate at a single point. The loading is controlled by displacement, with a loading rate of 2mm / min. Loading is stopped when the specimen is completely destroyed, and the loading force value is tested during the loading process.

[0063] Three-point bending static load bending tests were carried out on the test pieces prepared in Example 1, Example 2, Example 3 and Example 4, respectively, and the bending strength, absorbed energy and ductility results obtained under quasi-static loading under three-point bending were obtained, as shown in Table 1.

[0064] Table 1 Flexural strength, absorbed energy and ductility results of specimens

[0065] ;

[0066] As shown in Table 1, the lattice specimens with metamaterial interfaces have higher concrete strength. The flexural strength of the lattice reinforced concrete components with concave honeycombs (ER) and conventional honeycombs (HR) is increased by 22.2% and 8.3% respectively compared with the smooth interface (SR). Among them, the lattice specimens with concave honeycombs as metamaterial geometric units have the best flexural strength. Because the geometric characteristics of the metamaterial interface can produce better mechanical bite with concrete, and at the same time, using the high-precision characteristics of 3D printing technology, the lattice with a metamaterial interface and concrete can fully exert synergy when subjected to load, and better utilize the tensile strength of the lattice with an octagonal structure, thereby improving the flexural performance of the lattice specimens.

[0067] Compared with the lattice with smooth interface, the lattice of fully distributed metamaterial geometric units has a lower absorption energy and ductility of the specimen, and then optimization treatment is carried out. No metamaterial interface is designed on the horizontal bars of the lattice, and the metamaterial interface is designed only on the vertical diagonal bars. The lattice with metamaterial interface distributed on the vertical diagonal bars has an increase of 16.7% and 19.3% in bending strength and energy compared with the lattice with smooth interface, and the ductility is equivalent. Because the force characteristics of the octagonal lattice unit are horizontal bars under tension and vertical diagonal bars under compression, when the bonding strength between the horizontal bars and concrete increases and forms a good synergistic performance, the horizontal bars are easy to break, thereby destroying the good tensile resistance of the lattice components. Therefore, by utilizing the customizable characteristics of 3D printing technology, the metamaterial interface is distributed only at the vertical diagonal bars, which retains the synergy between the lattice and concrete while avoiding the damage of the lattice to the specimen. While improving the bending strength and energy absorption, the ductility is guaranteed to be equivalent.

[0068] Therefore, the present invention adopts the above-mentioned lattice cement-based composite material with a super-structure interface and its design method to enhance the bending bearing capacity, ductility and energy dissipation capacity of concrete beam components, while reducing the consumption of cement-based materials, reducing the overall weight of the components, and increasing the digital design and intelligent construction level of concrete modular components.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A design method for a lattice cement-based composite material with a superstructure interface, characterized in that: The following steps are involved: S1. Modeling is performed using modeling software to obtain a lattice; S2, distributing the metamaterial geometric units hierarchically on the surface of the single rod along the axial direction, while controlling the distance between each point of the metamaterial geometric unit and the longitudinal center axis of the single rod to be equal, connecting each point to form a curved surface a, projecting the curved surface a onto the single rod to form a curved surface b, connecting each corresponding point of the curved surface a and the curved surface b to form a body, and obtaining a lattice forming the metamaterial interface; S3, using 3D printing technology to make lattices with metamaterial interfaces; S4, placing the lattice obtained in S3 into a mold, pressing a heavy object on the lattice to fix it, pouring concrete mortar and performing curing; In S1, the lattice is an octagonal structure, and the four endpoints in each face of the octagon are connected diagonally through a single rod through the face center and the body center, and the single rod includes a plurality of vertical diagonal rods and horizontal rods; In S2, the metamaterial geometric units are distributed hierarchically along the axial direction in the non-end region of the single rod, and the non-end region is a region that accounts for 7 / 8 of the total length of the single rod.

2. The method for designing a lattice cement-based composite material with a superstructure interface according to claim 1, characterized in that: In S2, the metamaterial geometric unit is one or a combination of a concave honeycomb or a conventional honeycomb, and the design formula of the concave honeycomb or the conventional honeycomb is as follows: ； ； ； in, is the height of the metamaterial geometric unit, is the length of the metamaterial geometric unit, is the assumed Poisson's ratio, is the length of the vertical bar of the metamaterial geometric unit; is the length of the diagonal rod of the metamaterial geometric unit; θ It is the bevel angle. The bevel angle of the concave honeycomb is negative, and the bevel angle of the regular honeycomb is positive.

3. The method for designing a lattice cement-based composite material with a superstructure interface according to claim 2, characterized in that: In S2, the metamaterial geometric units are distributed completely or partially on the surface of the vertical inclined rod or the horizontal rod.

4. The method for designing a lattice cement-based composite material with a superstructure interface according to claim 3, characterized in that: In S3, the parameters of the 3D printing technology are set as follows: printing speed is 100 mm / s~120 mm / s, filling density is 100%, layer height is 0.08 mm~0.1 mm, nozzle temperature is 195°C~220°C, and printing material is polylactic acid filament PLA.

5. The method for designing a lattice cement-based composite material with a superstructure interface according to claim 4, characterized in that: In S4, the concrete mortar comprises the following components: Cement, fly ash, fine sand, thickener, water reducing agent.

6. A lattice cement-based composite material with a superstructure interface prepared by the design method of a lattice cement-based composite material with a superstructure interface as described in any one of claims 1 to 5.

7. The lattice cement-based composite material with a superstructure interface according to claim 6, characterized in that: It comprises concrete and a plurality of lattices arranged along the length direction of the concrete, wherein the lattices are located at the center of the concrete, and the volume of the concrete is 6.0 to 6.4 times the volume of the lattices.

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