Design method of foam aluminum filled folded paper sandwich structure

Abstract

The application provides a design method of a novel foam aluminum filled origami sandwich structure, inspired by ancient architectural structures or biological structures in nature, and based on origami art, a novel foam aluminum filled origami sandwich structure, such as a pyramid-like origami structure, is invented. The novel foam aluminum filled origami sandwich structure is further filled with foam aluminum in the origami structure, while the energy absorption capacity of the novel origami sandwich structure is improved, and the lightweight advantage is maintained. 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 application relates to a design method of a foam aluminum filled paper-folding sandwich structure and belongs to the technical field of buffer energy consumption structures. BACKGROUND

[0002] Traditional energy consumption component design ideas generally increase the section of the component, improve the strength of the material, and fill concrete to improve the impact resistance of the structure. The method indeed improves the safety performance of the structure, but also increases the self-weight of the building and the construction cost, and even causes problems such as rust expansion due to long-term exposure of steel to air or a humid environment, and cannot meet the actual engineering requirements of large-span space structures and other buildings. Therefore, a new generation of protective energy consumption structural component needs to be developed, which not only meets the requirements of structural assembly and light weight, but also quickly realizes function-structure integration design through an intelligent algorithm to meet the engineering safety needs.

[0003] Paper-folding structures are those inspired by traditional paper-folding art and designed using similar folding techniques to create geometric structures of materials. Through ingenious design, these metamaterials can exhibit properties that conventional structures do not possess, such as negative Poisson's ratio, high compressibility, and special mechanical behavior. In addition, paper-folding structures have the advantages of continuous manufacturing and easy slotting design. In structural engineering, these unique properties of paper-folding structures make them have potential application value in the design of lightweight structures, impact protection structures, and energy absorption devices.

[0004] The paper-folding sandwich structure designed based on the inspiration of paper-folding structures cuts and folds the traditional corrugated core part vertically and fills the core material to make it. Foam aluminum is a very commonly used filling core, and foam aluminum is a lightweight high-strength material with high specific stiffness and good energy absorption effect. The combination of foam aluminum and paper-folding core absorbs energy through the buckling and folding deformation of the paper-folding core, the compression deformation of the foam aluminum core, and the friction between the foam aluminum and the paper-folding core. Compared with traditional corrugated cores, the paper-folding sandwich structure has significantly improved impact resistance, low initial peak force, uniform platform stress, higher energy absorption capacity, and low sensitivity to defects. SUMMARY

[0005] The application aims to provide a design method of a foam aluminum filled paper-folding sandwich structure to overcome the problems of existing protective energy consumption structures.

[0006] The application can be implemented through the following technical solutions:

[0007] A design method of a foam aluminum filled paper-folding sandwich structure, comprising the following steps:

[0008] Step one, carry out heuristic design based on biological structure in nature or ancient architectural structure, and determine general configuration characteristics of the structure according to kinematic constraint requirements of the origami structure, that is, the structure can be completely unfolded into a plane, folding only occurs at the crease, and each face is not deformed in the folding process; carry out comparative analysis with similar existing excellent configurations, and ensure that the configuration has the optimization potential of low peak force F p , high plateau force F ave , high load efficiency CFE, and high specific energy absorption SEA.

[0009] Step two, determine the geometric unfolding form and basic size parameters of the origami sandwich structure, analyze the parameter relationship, and then carry out parameter optimization for independent size parameters, that is, control other sizes unchanged, and adjust a certain size alone to see the performance change, and determine the subsequent optimization parameters.

[0010] Step three, further, according to the optimization target, abstract the structure to be optimized into a mathematical expression of a multi-objective optimization problem, and carry out multi-objective optimization based on NSGA-II.

[0011] Step four, obtain the Pareto front optimization result, and according to the optimization target, compare and select several groups of configurations; compare the multi-objective optimization algorithm results of the several groups of configurations with the finite element analysis calculation results, and according to the peak force F p , plateau force F ave , load efficiency CFE, specific energy absorption SEA, and total energy absorption EA obtained by the optimization algorithm and the finite element results, verify the accuracy of the optimization method; analyze the improvement effect of the structure after the algorithm optimization in the above performance parameters to verify the excellent energy absorption performance of the structure.

[0012] Step five, according to the size parameters of the structure, laser cutting obtains the foam aluminum and assembles into the structure to form the foam aluminum filled origami sandwich structure; and then according to the actual demand, through stacking, reverse buckling and other forms, various foam aluminum filled origami sandwich structures are obtained.

[0013] As a further preferred scheme, in step one, the formed origami sandwich structure is inspired by the pyramid structure, has a pyramid-like configuration, has four valley creases and 16 mountain creases, and can be completely unfolded into a plane, and folding only occurs at the crease, while the face is not deformed in the folding process. The interior is a hollow structure after folding, and the relative density is extremely low.

[0014] As a further preferred scheme, in step two, the size parameters of the formed origami sandwich structure include: the side lengths a, b, c, d, e, and 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 / sinα

[0019] f=h / sinβ.

[0020] As a further preferred solution, in the step two, the independent parameters that can be adjusted for optimization include the values of a, b, h, t, and alpha. The performance evaluation indicators are the initial peak force, plateau force, total energy absorption, specific energy absorption, and load efficiency of the structure, wherein the optimization goal is the minimum peak force, and the rest are maximum.

[0021] As a further preferred solution, in the step three, when designing the algorithm, a multi-objective optimization solution is carried out using an intelligent genetic algorithm. The multi-objective optimization genetic algorithm NSGA-II used has the characteristics of fast iteration speed and high diversity of solution set, and can obtain the Pareto optimal solution of the problem. In the specific parameter design, a, b, and alpha among the five independent parameters are set as variables, while h and t are constants, and the total energy absorption and load efficiency are set as constraint conditions. At this time, all the results obtained by solving satisfy the constraint conditions, and the specific expression is:

[0022] minimize Fp(a,b,α)

[0023] maximize Fave(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(α,b,α)>0.6.

[0030] As a further preferred solution, in the step five, the finally formed structure includes the upper panel, the lower panel, and the foam aluminum filling type 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 stack, and vertical stack.

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

[0032] I. The provided design method can be used in various types of cushioning and energy dissipation structure products, such as the design of armor protection structure, or the design of anti-collision structure of vehicle bumper, etc.

[0033] II. The provided design method determines the general characteristics of the origami structure designed by nature inspiration; and the optimization design results of the intelligent optimization algorithm are verified, the accuracy and efficiency of the algorithm optimization method are determined, and the problems of local optimization or difficulty in finding the optimal solution of the traditional optimization method are avoided.

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

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

[0036] In order to further illustrate the flow and characteristics of each embodiment of the present application, more specific descriptions of each embodiment of the present application will be presented with reference to the accompanying drawings. It should be considered that these drawings only depict typical embodiments of the present application, and therefore should not be considered as limiting the scope thereof.

[0037] Figure 1 Process diagram for heuristic design of foam aluminum filled origami sandwich structure;

[0038] Figure 2 Unfolded diagram and folded geometric parameter diagram for structural unit;

[0039] Figure 3 Comparison diagram of structural unit and existing structural unit quasi-static compression performance;

[0040] Figure 4 Pareto front diagram obtained after optimization by multi-objective optimization algorithm;

[0041] Figure 5 Diagram for processing of foam aluminum filled origami sandwich structure;

[0042] Figure 6 Diagram for assembly of foam aluminum filled origami sandwich structure unit;

[0043] Figure 7 Diagram for other assembly forms provided by the present application. DETAILED DESCRIPTION

[0044] In order to make the purpose and technical scheme of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings.

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

[0046] 1. AsFigure 1 , gives a design inspiration of a kind of foam aluminum filled origami sandwich structure mentioned in this application. The inspiration design 1 comes from the ancient pyramid structure in Egypt ①, and the characteristic lines are extracted after the pyramid is abstracted to get the structure ②. The origami kinematics analysis of the structure is carried out, and it is necessary to ensure that the structure can be completely unfolded into a plane, and the folding only occurs at the crease, while the surface folding process has no deformation. The structure ③ is designed, and it is named as pyramid-like origami sandwich structure according to the design process. The inspiration design 2 comes from the turtle back structure ①, and the characteristic lines are extracted after the turtle back is abstracted to get the structure ②. The origami kinematics analysis of the structure is carried out, and it is necessary to ensure that the structure can be completely unfolded into a plane, and the folding only occurs at the crease, while the surface folding process has no deformation. The structure ③ is designed, and it is named as turtle back-like origami sandwich structure. The structures generated by the two inspiration methods are extremely simple to process, and only need to be prepared on a plate by laser cutting. They have the characteristics of simple folding process, and the internal structure is hollow, and the relative density is extremely low. The subsequent further design process takes the pyramid-like origami sandwich structure as an example.

[0047] 2、The unfolding and folding diagram of the pyramid-like origami sandwich structure is shown in Figure 2 , and the geometric control parameters of the structure are further analyzed. The four thick lines in the unfolding diagram are valley creases, and the remaining 16 lines are mountain creases, Figure 2 The double-hole rectangular plate protruding on four sides plays a role of constraint fixation after actual manufacturing. Among the various geometric parameters, a, b, c, d, e and f are the side lengths of the structure, h is the height of the structure, and α and β are the angles of the structure. Under the requirements of the origami structure characteristics, the following conditions need to 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 the value of further research of the structure proposed in this application, the structure unit1 is compared with the two origami structures unit2 and unit3 obtained by existing research. For the control variable, the height h of the three structures is 30mm, the thickness t is 0.5mm, and the aluminum plate is used. Considering the difficulty of size design, the mass of the three structures is controlled to be about 6g, and the maximum error is not more than 3%, as shown in Figure 3According to the comparison results of the quasi-static compression performance of the paper folding structure units, the structure unit1 has lower initial peak force, higher platform force, higher specific energy absorption and total energy absorption capacity than the existing same type paper folding structure, which fully shows that the structure has good buffering and energy consumption potential.

[0054] 4、Further, the present research carries out parameter optimization to generate about 700 data sets, and through continuous adjustment and optimization verification of parameters a, b, h, a, t, etc., finally determines the adjustment parameters a, b, a and respectively determines the value range as a e (15mm, 40mm), b e (15mm, 40mm), a e (20°, 70°), and at the same time, the control height h = 30mm, the thickness t = 0.3mm. In order to ensure the optimization effect, the present application adopts the multi-objective genetic algorithm NSGA-II to complete the solution, and the mathematical description of the multi-objective optimization problem is:

[0055] minimize Fp(a,b, a)

[0056] maximize Fave(a,b, a)

[0057] maximize SEA(a,b, a)

[0058] subject to 15≤a≤40

[0059] 15≤b≤40

[0060] 20≤a≤70

[0061] EA(a,b, a)>25J

[0062] CFE(a,b, a)>0.6.

[0063] Wherein: F p is the initial peak force of the structure; F ave is the platform force of the structure; SEQ is the specific energy absorption of the structure; EA is the total energy absorption of the structure; CFE is the load efficiency of the structure.

[0064] 5、As Figure 4 , a plurality of optimal solutions are obtained by solving the multi-objective genetic algorithm, in order to verify the reliability of the algorithm, three optimal solutions corresponding to the structures ①, ② and ③ are randomly selected, and the structure with the highest load efficiency in the optimal solution and the structure with the most total energy absorption are selected, and the finite element quasi-static compression performance analysis is carried out.

[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 optimization results of five typical optimized structure units and finite element results).

[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, the relative errors of the selected five groups of optimization results and the finite element results are all within 10%, which indicates the accuracy of the multi-objective algorithm model optimization.

[0069]

[0070] Table 2

[0071] As shown in Table 3 (performance improvement comparison of optimization results relative to the default initial structure unit), from the comparative analysis of the multi-objective optimization results and the results of the structure 6 without optimization, the structure obtained by the multi-objective optimization algorithm can significantly improve the load bearing characteristics and the energy absorption capacity of the structure, wherein the initial peak force of the structure 3 is reduced by 24.18%, and the specific energy absorption is increased by 93.39%; the plateau force of the structure 2 is increased by 29.02%; the load efficiency of the structure 4 is increased by 63.01%; the total energy absorption of the structure 5 is increased by 70.51%, and the above results fully show that the design method of the foam aluminum filled origami sandwich structure provided in the application can significantly improve the cushioning and energy absorption capacity of the structure.

[0072]

[0073] Table 3

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

[0075] In order to ensure the stability and practicability of the pyramid-like origami sandwich structure, the structure is assembled to form a foam aluminum filled pyramid-like origami sandwich plate structure, such as Figure 6The structure comprises an upper panel, a lower panel and a middle sandwich structure, wherein the thickness of the upper and lower panels can be customized according to actual requirements, and the panels can be made of hard paper, plastic or metal materials. The sandwich structure can also be obtained by folding a panel after laser cutting according to the crease position. The panels and the sandwich structure can be connected by bolts, and the corresponding bolt holes are given in Figure 2 the middle, and the panels and the sandwich structure can also be bonded by glue such as epoxy resin.

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

[0077] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method of designing a foam aluminum filled origami sandwich structure, characterized by, Comprising the following steps: Step one, carry out heuristic design based on ancient architectural structures or biological structures in nature, and determine the general configuration characteristics of the structure according to the kinematic constraint requirements of the origami structure, i.e. the structure can be completely unfolded into a plane, folding only occurs at the crease, and each face is not deformed during folding; ensure that the configuration has low peak force F p , high plateau force F ave , high load efficiency CFE, and optimization potential of high specific energy absorption SEA; Step two, determine the geometric unfolding form and basic size parameters of the origami sandwich structure, analyze the parameter relationship, and then optimize the independent size parameters to determine the subsequent optimization parameters; Step three, further, according to the optimization target, the mathematical expression of the multi-objective optimization problem is abstracted from the structure to be optimized by means of intelligent optimization algorithm, and multi-objective optimization is carried out based on NSGA-II; Step four, obtain the Pareto front optimization results, according to the optimization algorithm and the peak force F of the structure obtained by the finite element results p , platform force F ave , load efficiency CFE, specific energy absorption SEA and total energy absorption EA are compared and verified; Step five, according to the size parameters of the structure, the foam aluminum is cut by laser and assembled into the structure to form the foam aluminum filled origami sandwich structure; and then according to the actual demand, various foam aluminum filled origami sandwich structures are assembled through stacking and reverse buckling.

2. The method of designing a foam aluminum filled corrugated sandwich structure according to claim 1, wherein, In step one, the formed 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 completely unfolded into a plane. The folding only occurs at the fold, and there is no deformation in the surface folding process. The interior is a hollow structure after folding, and the relative density is extremely low.

3. The method of designing a foam aluminum filled corrugated sandwich structure according to claim 2, wherein, In step two, the size parameters of the formed origami sandwich structure include: the side lengths 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 method of designing a foam aluminum filled corrugated sandwich structure according to claim 3, wherein, In step two, the independent parameters that can be used for optimization and adjustment include the values of a, b, h, t, and α; the performance evaluation index is the initial peak force, platform force, total energy absorption, specific energy absorption, and load efficiency of the structure, wherein the optimization target is the minimum peak force, and the others are maximum.

5. The method of designing a foam aluminum filled corrugated sandwich structure according to claim 4, wherein, In step three, when using intelligent genetic algorithm to solve multi-objective optimization, a, b, and α in the five independent parameters can be set as variables, while h and t are constants, and total energy absorption and load efficiency are set as constraint conditions. At this time, all the results obtained by solving satisfy the constraint conditions, and the 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(a,b,α)>0.6 wherein, wherein: F p Fp is the peak force of the structure; F ave Fp is the peak force of the structure; SEA is the specific energy absorption of the structure; EA is the total energy absorption of the structure; and CFE is the load efficiency of the structure.

6. The method of designing a foam aluminum filled corrugated sandwich structure according to claim 5, wherein, In step five, the finally formed structure includes an upper panel, a lower panel, and a foam aluminum filled pyramid-like origami sandwich structure between the upper and lower panels, and the connection form is bolted or bonded; the assembly form includes horizontal array, reverse stacking and vertical stacking.

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