Design method of novel foamed aluminum filled paper folding sandwich structure

Abstract

The invention provides a design method of a novel foamed aluminum filled origami sandwich structure, which is inspired by an ancient building structure or a natural biological structure, and the novel foamed aluminum filled origami sandwich structure, such as a pyramid-like origami structure, is invented on the basis of origami art. The interior of the paper folding structure is further filled with foamed aluminum to form the novel foamed aluminum filled paper folding sandwich structure, and the energy absorption capacity of the novel paper folding sandwich structure is improved while the advantage of light weight is remarkably kept. The novel structure has the characteristics of low initial peak force, high platform force, high load efficiency, high specific energy absorption capacity and the like, and is a composite structure with good impact resistance and high energy consumption.

Description

Technical Field

[0001] The invention relates to a design method for a novel foam aluminum filled origami sandwich structure, belonging to the technical field of buffer energy dissipation structures. Background Art

[0002] The traditional design idea of ​​energy-consuming components is generally to improve the impact resistance of the structure by increasing the cross-section of the component, improving the material strength, and filling concrete. This method can indeed improve the safety performance of the structure, but it also increases the weight and construction cost of the building. Even because the steel is exposed to the air or humid environment for a long time, it is easy to rust and expand, and cannot meet the actual engineering requirements of buildings such as large-span space structures. Therefore, it is necessary to develop a new generation of protective energy-consuming structural components, which must not only meet the requirements of structural assembly and lightweight, but also quickly realize the function-structure integrated design through intelligent algorithms to meet the needs of engineering safety.

[0003] Origami structures refer to geometric structures that are inspired by the traditional art of origami and use similar folding techniques to design materials. Through sophisticated design, these metamaterials can exhibit properties that conventional structures do not have, such as negative Poisson's ratio, high compressibility, and special mechanical behavior. In addition, origami structures have the advantages of continuous manufacturing and easy slot design. In structural engineering, these unique properties of origami structures make them potentially useful in designing lightweight structures, impact protection structures, and energy absorption devices.

[0004] The origami sandwich structure is inspired by the origami structure. The traditional corrugated core is cut and folded vertically, and then filled with core materials. Among them, foamed aluminum is a very commonly used filling core. Foamed aluminum is a lightweight, high-strength material with high specific stiffness and good energy absorption. The foamed aluminum is combined with the origami core to absorb energy through the deformation of the origami core such as buckling and folding, the compression deformation of the foamed aluminum core, and the friction between the foamed aluminum and the origami core. Compared with the traditional corrugated core, the origami sandwich structure has been significantly improved in impact resistance, with low initial peak force, uniform platform stress, higher energy absorption capacity and low sensitivity to defects. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the existing protective energy-consuming structures and to provide a novel design method for an origami sandwich structure filled with foam aluminum.

[0006] The present invention can be implemented by the following technical solutions:

[0007] A design method for a novel foam aluminum filled origami sandwich structure comprises the following steps:

[0008] Step 1: Conduct heuristic design based on biological structures or ancient architectural structures in nature, and determine the general configuration characteristics of the new structure according to the kinematic constraints of the origami structure, that is, the new structure can be fully unfolded into a plane, folding only occurs at the crease, and each surface is not deformed during the folding process; conduct comparative analysis with existing similar excellent configurations to ensure that the configuration has a low peak force F p , High platform force F ave , optimization potential of high load efficiency CFE and high specific energy absorption SEA;

[0009] Step 2: Determine the geometric expansion form and basic dimensional parameters of the origami sandwich structure, analyze the parameter relationship, and then optimize the parameters for independent dimensional parameters, that is, control other dimensions unchanged, adjust a certain dimension alone to see the performance change, and determine the subsequent optimization parameters;

[0010] Step 3: Further, with the help of intelligent optimization algorithm, the mathematical expression of the multi-objective optimization problem is abstracted from the optimal structure according to the optimization goal, and multi-objective optimization is carried out based on NSGA-Ⅱ;

[0011] Step 4: Obtain the Pareto front optimization results, and compare and select several groups of configurations based on the optimization objectives; compare the multi-objective optimization algorithm results of several groups of configuration structures with the finite element analysis calculation results, and calculate the peak force F of the structure obtained by the optimization algorithm and the finite element results. p 、Platform force F ave , load efficiency CFE, specific energy absorption SEA and total energy absorption EA to verify the accuracy of the optimization method; analyze the improvement effect of the new structure after algorithm optimization and the original structure in the above performance parameters to verify the excellent energy absorption performance of the new structure;

[0012] Step 5: According to the size parameters of the structure, the foam aluminum is obtained by laser cutting and assembled into the structure to form a new foam aluminum filled origami sandwich structure; then, according to actual needs, various types of foam aluminum filled origami sandwich structures are assembled by stacking and inverting.

[0013] As a further preferred scheme, in step one, the new origami sandwich structure formed is inspired by the pyramid structure, has a pyramid-like configuration, has 4 valley folds and 16 mountain folds, and can be fully unfolded into a plane. Folding only occurs at the creases, and there is no deformation during the folding process. After folding, the interior is a hollow structure with extremely low relative density.

[0014] As a further preferred solution, in step 2, the size parameters of the new origami sandwich structure formed include: the lengths of the sides a, b, c, d, e, f of the structure, the height h of the structure, the thickness t of the structure, the angles α and β of the structure, and satisfy:

[0015] α+β=90°

[0016] c=h / cosα

[0017] d=h / cosβ

[0018] e=h / sinαα

[0019] f = h / sinβ.

[0020] As a further preferred solution, in step 2, the independent parameters that can be adjusted in the optimization include the values ​​of a, b, h, t, and α. The performance evaluation indicators are the initial peak force, platform force, total energy absorption, specific energy absorption, and load efficiency of the structure, among which the optimization objectives are to maximize the peak force except for the minimum peak force.

[0021] As a further preferred solution, in step 3, when designing the algorithm, an intelligent genetic algorithm is used to carry out multi-objective optimization solution. The multi-objective optimization genetic algorithm NSGA-II used has the characteristics of fast iteration speed and high solution set diversity, and can solve the problem to obtain the Pareto optimal solution. When designing specific parameters, a, b, and α of the five independent parameters can be set as variables, while h and t are constants, and the total energy absorption and load efficiency are set as constraints. At this time, all the results obtained by the solution meet the constraints. The specific expression is:

[0022] minimize Fp(a,b,α)

[0023] maximize Faυe(a,b,α)

[0024] maximize SEA(a,b,α)

[0025] subject to 15≤a≤40

[0026] 15≤b≤40

[0027] 20≤α≤70

[0028] EA(a, b, α)>25J

[0029] CFE(a, b, α)>0.6.

[0030] As a further preferred scheme, in step five, the final structure formed includes an upper panel, a lower panel and a foam aluminum filled pyramid origami sandwich structure arranged between the upper and lower panels, and the connection form is bolted or bonded; the assembly form includes horizontal array, inverted stacking and vertical stacking.

[0031] The beneficial effects of the present invention are:

[0032] 1. The provided design method can be used in various types of buffer energy-absorbing structural products, such as the design of armor protection structure or the anti-collision structure design of vehicle bumper, etc.

[0033] 2. The design method provided clarifies the general characteristics that origami structures inspired by nature should have; and verifies the optimization design results of the intelligent optimization algorithm, determines the accuracy and efficiency of the algorithm optimization method, and can avoid the problem that traditional optimization methods fall into local optimality or find it difficult to find the optimal solution.

[0034] 3. The new foam aluminum filled origami sandwich structure has the following characteristics: simple processing and preparation, various assembly forms, and convenient transportation and carrying.

[0035] 4. The new foam aluminum filled origami sandwich structure has the following advantages: highly lightweight design, excellent energy absorption performance, good corrosion resistance and low defect sensitivity compared to traditional structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to further clarify the process of the present invention and the features of each embodiment, a more specific description of each embodiment of the present invention will be presented with reference to the accompanying drawings. It should be understood that these drawings are only typical embodiments of the present invention and are not to be considered as limiting the scope thereof.

[0037] Figure 1 Diagram of the heuristic design process for a new aluminum foam-filled origami sandwich structure;

[0038] Figure 2 It is the schematic diagram of the geometric parameters of the structural unit after unfolding and folding;

[0039] Figure 3 This is a comparison chart of the quasi-static compression performance between the new structural unit and the existing structural unit;

[0040] Figure 4 It is the Pareto frontier diagram obtained after optimization by the multi-objective optimization algorithm;

[0041] Figure 5 This is a schematic diagram of the foam aluminum after filling processing;

[0042] Figure 6 This is a schematic diagram of the new foam aluminum filled origami sandwich structure unit after assembly;

[0043] Figure 7 Schematic diagram of other assembly forms provided by the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose and technical solution of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings.

[0045] A design method of a novel foam aluminum filled origami sandwich structure of the present invention comprises the following steps:

[0046] 1. If Figure 1 , giving the design inspiration of a new type of foam aluminum filled origami sandwich structure mentioned in this application. Among them, the inspiration design 1 comes from the structure of the ancient Egyptian pyramid ①. The structure ② is obtained by abstractly extracting the characteristic lines of the pyramid. The origami kinematic analysis of the structure is carried out. It is necessary to ensure that the structure can be fully unfolded into a plane, and the folding only occurs at the crease, and there is no deformation during the folding process of the surface. The structure ③ is designed. According to the design process, it is named as a pyramid-like origami sandwich structure. Among them, the inspiration design 2 comes from the turtle's back structure ①. The structure ② is obtained by abstractly extracting the characteristic lines of the turtle's back. The origami kinematic analysis of the structure is carried out. It is necessary to ensure that the structure can be fully unfolded into a plane, and the folding only occurs at the crease, and there is no deformation during the folding process of the surface. The structure ③ is designed. According to the design process, it is named as a turtle-like origami sandwich structure. The structures generated by these two inspiration methods are extremely simple to process. They can be prepared by laser cutting on a plate. They have the characteristics of a simple folding process, and the interior is a hollow structure with extremely low relative density. The subsequent further design process is carried out with the pyramid-like origami sandwich structure as an example.

[0047] 2. The unfolding and folding diagram of the pyramid-like origami sandwich structure is as follows Figure 2 As shown, the geometric control parameters of the structure are obtained through further analysis. The 4 bold fold lines in the expanded diagram are valley folds, and the remaining 16 fold lines are mountain folds. Figure 2 The rectangular plate with double holes protruding from the four sides plays a role of constraint and fixation after actual manufacturing. Among the geometric parameters, a, b, c, d, e, and f are the lengths of the sides of the structure, h is the height of the structure, and α and β are the angles of the structure. Under the requirements of origami structure characteristics, the following must be met:

[0048] α+β=90°

[0049] c=h / cosα

[0050] d=h / cosβ

[0051] e=h / sinα

[0052] f = h / sinβ.

[0053] 3. To verify that the structure proposed in this application is worth further research, the structure unit1 is compared with the two origami structures unit2 and unit3 obtained from existing research. As the control variable, the height h of the three structures is 30 mm, the thickness t is 0.5 mm, and the plate material used is aluminum plate. Considering the difficulty of size design, the mass of the three structures is controlled to be about 6 g, and the maximum error does not exceed 3%. Figure 3 According to the comparison results of the quasi-static compression performance of origami structural units, the structure unit1 proposed in this application has lower initial peak force, higher platform force, higher specific energy absorption and total energy absorption capacity than the existing origami structures of the same type, which fully demonstrates that the new structure proposed in this application has good buffering energy consumption potential.

[0054] 4. Furthermore, this study conducted parameter optimization and generated about 700 data sets. By continuously adjusting and optimizing parameters such as a, b, h, α, and t, the adjustment parameters a, b, and α were finally determined, and the value ranges were determined as parameters a∈(15mm, 40mm), b∈(15mm, 40mm), and α∈(20°, 70°). At the same time, the height h=30mm and the thickness t=0.3mm were controlled. To ensure the optimization effect, this application uses the multi-objective genetic algorithm NSGA-II to complete the solution. The mathematical description of the multi-objective optimization problem is:

[0055] minimize Fp(a,b,α)

[0056] maximize Faυe(a,b,α)

[0057] maximize SEA(a,b,α)

[0058] subject to15≤a≤40

[0059] 15≤b≤40

[0060] 20≤α≤70

[0061] EA(a, b, α)>25J

[0062] CFE(a, b, α)>0.6.

[0063] Among them: F p is the initial peak force of the structure; F aυe is the structural platform force; SEA is the structural specific energy absorption; EA is the structural total energy absorption; CFE is the structural load efficiency.

[0064] 5. If Figure 4 , multiple groups of optimal solutions were obtained according to the multi-objective genetic algorithm. In order to verify the reliability of the algorithm, structures ①②③ corresponding to three groups of optimal solutions were randomly selected, and the structure ④ with the highest load efficiency and the structure ⑤ with the largest total energy absorption in the optimal solutions were selected to carry out finite element quasi-static compression performance analysis.

[0065] The results obtained by the multi-objective optimization algorithm and the results obtained by the finite element analysis are shown in Table 1 (Comparison of the optimization results of 5 typical optimized structural units and the finite element results). Among them, the default dimensions of the unoptimized structure ⑥ are a = 30 mm, b = 30 mm, α = 45°, h = 30 mm, and t = 0.3 mm.

[0066]

[0067] Table 1

[0068] As shown in Table 2 (Error comparison of algorithm optimization results relative to finite element results), from the comparative analysis of the multi-objective optimization results and the finite element calculation results, it can be seen that the relative errors of the selected 5 groups of optimization results and the finite element results are all within 10%, which illustrates the accuracy of the multi-objective algorithm model optimization.

[0069]

[0070] Table 2

[0071] As shown in Table 3 (performance improvement comparison chart of optimization results compared with default initial structural units), from the comparison analysis of the multi-objective optimization results and the results of the unoptimized structure ⑥, it can be seen that the structure obtained by the multi-objective optimization algorithm can significantly improve the structural bearing characteristics and improve the structural energy absorption capacity, among which the initial peak force of structure ③ is reduced by 24.18%, and the specific energy absorption is improved by 93.39%; the platform force of structure ② is increased by 29.02%; the load efficiency of structure ④ is increased by 63.01%; the total energy absorption of structure ⑤ is increased by 70.51%. The above results fully illustrate that the design method of a novel foam aluminum filled origami sandwich structure proposed in this application can significantly improve the buffering energy absorption capacity of the structure.

[0072]

[0073] Table 3

[0074] like Figure 5 The foam aluminum is obtained by laser cutting according to the size information of the hollow area inside the pyramid origami sandwich structure. The foam aluminum material used in this application is closed-cell foam aluminum with a relative density between 0.1 and 0.3. The foam aluminum is filled into the pyramid origami sandwich structure to obtain the foam aluminum filled pyramid origami sandwich structure.

[0075] In order to ensure the stability and practicality of the pyramid-like origami sandwich structure, the structure is assembled to form a foam aluminum filled pyramid-like origami sandwich panel structure, such as Figure 6The structure includes an upper panel, a lower panel and a sandwich structure in the middle. The thickness of the upper and lower panels can be customized according to actual needs. The panels can be made of cardboard, plastic or metal. The sandwich structure can also be obtained by laser cutting a panel according to the folding position and then folding it. The panel and the sandwich structure can be connected by bolts, and the corresponding screw holes are Figure 2 As given in, it can also be bonded by glue such as epoxy resin.

[0076] Furthermore, in order to improve the energy absorption performance, two layers of foam aluminum filled pyramid origami sandwich panels can be assembled upside down or multiple layers of foam aluminum filled pyramid origami sandwich panels can be assembled in layers, such as Figure 7 .

[0077] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A novel design method for an origami sandwich structure filled with foam aluminum, characterized in that: The following steps are involved: Step 1: Conduct heuristic design based on ancient architectural structures or biological structures in nature, and determine the general configuration characteristics of the new structure according to the kinematic constraints of the origami structure, that is, the new structure can be fully unfolded into a plane, folding only occurs at the crease, and each surface does not deform during the folding process; Compare and analyze with existing similar excellent configurations to ensure that the configuration has low peak force F p , High platform force F ave , optimization potential of high load efficiency CFE and high specific energy absorption SEA; Step 2: determine the geometric development form and basic dimensional parameters of the origami sandwich structure, analyze the parameter relationship, and then perform parameter optimization for independent dimensional parameters to determine subsequent optimization parameters; Step 3: Further, with the help of intelligent optimization algorithm, the mathematical expression of the multi-objective optimization problem is abstracted from the optimal structure according to the optimization goal, and multi-objective optimization is carried out based on NSGA-Ⅱ; Step 4: Obtain the Pareto front optimization result, and compare and select several groups of configurations based on the optimization objective; The multi-objective optimization algorithm results of several groups of configuration structures were compared with the finite element analysis calculation results. The peak force F p 、Platform force F ave , load efficiency CFE, specific energy absorption SEA and total energy absorption EA to verify the accuracy of the optimization method; The improvement effect of the above performance parameters on the new structure after algorithm optimization and the original structure is analyzed to verify the excellent energy absorption performance of the new structure; Step 5: According to the size parameters of the structure, the foam aluminum is obtained by laser cutting and assembled into the structure to form a new foam aluminum filled origami sandwich structure; then, according to actual needs, various types of foam aluminum filled origami sandwich structures are assembled by stacking and inverting.

2. The design method of a novel foam aluminum filled origami sandwich structure according to claim 1, characterized in that: In the step 1, the novel origami sandwich structure is inspired by the pyramid structure, has a pyramid-like configuration, has 4 valley folds and 16 mountain folds, and can be fully unfolded into a plane. Folding occurs only at the folds, and there is no deformation during the folding process. After folding, the interior is a hollow structure with an extremely low relative density.

3. The design method of a novel foam aluminum filled origami sandwich structure according to claim 2 is characterized in that: In the step 2, the size parameters of the new origami sandwich structure formed include: the lengths of the sides a, b, c, d, e, f of the structure, the height h of the structure, the thickness t of the structure, the angles α and β of the structure, and satisfy: α+β＝90 c=h / cosα d=h / cosβ e=h / sinα f = h / sinβ.

4. The design method of a novel foam aluminum filled origami sandwich structure according to claim 3 is characterized in that: In step 2, the independent parameters that can be used for adjustment in the optimization include the values ​​of a, b, h, t, and α; the performance evaluation indicators are the initial peak force, platform force, total energy absorption, specific energy absorption, and load efficiency of the structure, among which the optimization objectives are all maximized except for the minimum peak force.

5. The design method of a novel foam aluminum filled origami sandwich structure according to claim 4 is characterized in that: In step 3, when using the intelligent genetic algorithm to carry out multi-objective optimization solution, a, b, α among the five independent parameters can be set as variables, while h and t can be set as constants, and the total energy absorption and load efficiency can be set as constraints. At this time, all the results obtained by the solution meet the constraints. The specific expression is: minimize Fp(a,b,α) maximize Fave(a,b,α) maximize SEA(a,b,α) subject to 15≤a≤40 15≤b≤40 20≤α≤70 EA(a,b,α)>25J CFE(α, b, α)>0.

6.

6. The design method of a novel foam aluminum filled origami sandwich structure according to claim 5, characterized in that: In the step five, the final structure formed includes an upper panel, a lower panel and a foam aluminum filled pyramid origami sandwich structure arranged between the upper and lower panels, and the connection form is bolted or bonded; the assembly form includes horizontal array, inverted stacking and vertical stacking.

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