Design and optimization method of bionic structure automobile anti-collision beam

Abstract

The application discloses a design and optimization method of a bionic structure automobile anti-collision beam, adopts the steps of simplifying a tortoise shell structure, analyzing free modal of the anti-collision beam, analyzing strength performance and impact performance of the anti-collision beam, and multi-target optimization of the anti-collision beam, sets tortoise shell performance test, three-point static test of the bionic structure anti-collision beam, high-speed and low-speed collision impact test in HyperMesh combined with Ls-Dyna simulation, and comprehensively considers strength, stiffness, vibration characteristics, impact performance and lightweight performance of the bionic structure anti-collision beam; the application designs the curved surface characteristics and the internal bionic reinforcing rib structure of the bionic anti-collision beam, the two can avoid the current situation of only increasing the material thickness or replacing the high-strength material, can coordinate the strength performance, the material cost, the process cost and the lightweight, and can improve the anti-collision performance while considering the collision energy absorption performance.

Description

Technical Field

[0001] The present invention relates to the field of lightweight design of automotive parts, in particular to a design and optimization method for a bionic structure automotive bumper beam, and specifically to a manufacturing method for an automotive bumper beam with a turtle shell-like structure. Background Art

[0002] It is known that collision is one of the most main forms of accidents in current traffic accidents. In accidents causing serious injuries and deaths, the front bumper of an automobile has important significance for the frontal collision safety performance of the whole vehicle. The front bumper of an automobile undergoes elastic deformation in a low-speed collision to absorb collision energy, which is an important structure for protecting the components behind it and effectively reducing the repair cost; in a high-speed collision, it can reasonably transmit and distribute the impact force to the entire vehicle body structure to avoid local severe deformation, so as to ensure that the occupants have sufficient living space, etc. Improving the crashworthiness of the bumper can reduce the casualties and vehicle damage in frontal collisions. On the other hand, with the increasingly serious problems of the oil crisis and environmental pollution, lightweight has become an important topic in the automotive industry. Research data shows that when the mass of an automobile is reduced by 10%, the fuel consumption can be correspondingly reduced by 6% - 8%. Therefore, when researchers design a bumper, they should comprehensively consider its crashworthiness and lightweight factors.

[0003] Currently, the design of most automotive bumper beams is mainly carried out according to traditional experience and methods, and the cross-section of the bumper beam is in the shape of a square, a rectangle, a cross, a grid, etc. The above cross-section designs are extremely convenient for processing and manufacturing and reduce the process cost. However, in terms of improving mechanical properties and crashworthiness, etc., only the material thickness can be simply increased or high-strength materials can be replaced, and it is impossible to achieve the coordination of strength performance, material cost, process cost, and lightweight, and it is difficult to take into account the collision energy absorption performance while improving the crashworthiness, there are many design defects and potential safety hazards, posing a great threat to the life safety of the occupants. Therefore, there is an urgent need to propose a new processing method for the bumper beam to improve its strength performance, collision energy absorption performance, and lightweight level, etc.

[0004] The development of bionics has provided a new way for human invention and creation. Currently, bionic structures have been widely applied in engineering, especially in agricultural machinery, and are gradually expanding to automotive structure design. Research shows that: the turtle shell is an exoskeleton structure that has evolved in nature for hundreds of millions of years, and its loading form has reached an almost perfect level, and it is almost impossible to find a similar and better structure as the structure form of the turtle shell. The special reinforcing rib form connecting the carapace and plastron, and the special layered structure form in the turtle shell, these extremely characteristic structure forms are integrated into a turtle shell structure with beautiful shape and excellent mechanical properties.

[0005] Automotive crash beams are constructed from rolled steel or aluminum alloy sheets. To enhance their impact resistance and energy absorption, internal support structures or reinforcing ribs are added, often using casting processes, which reduces their mechanical properties. Increasing thickness to ensure safety, however, reduces weight reduction. Therefore, developing a biomimetic design and optimization method for automotive crash beams is crucial. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a design and optimization method for a biomimetic automotive anti-collision beam. This invention designs a curved surface feature and an internal biomimetic reinforcing rib structure for the anti-collision beam. The combination of these two features avoids the current predicament of simply increasing material thickness or replacing it with high-strength materials. It achieves a balance between strength performance, material cost, process cost, and lightweighting. Furthermore, it is difficult to simultaneously improve collision resistance and collision energy absorption performance. The anti-collision beam made by this invention has superior collision resistance and buffer energy absorption performance compared to traditional anti-collision beams.

[0007] To achieve the aforementioned inventive objectives, the present invention employs the following technical solution:

[0008] A design and optimization method for a biomimetic automotive anti-collision beam, the method specifically includes the following steps:

[0009] The first step is to analyze the shape of the anti-collision beam and the actual working condition of the stiffeners, and combine them with the curved surface characteristics of the tortoise shell to extract the similarity between the two in terms of structure, load and function. Since the tortoise shell and the anti-collision beam are very similar, they are regarded as similar systems. The similarity theory is used to analyze the similarity between the anti-collision beam and the tortoise shell to obtain the similarity.

[0010] The second step is to use HANDYSCAN3D handheld 3D laser scanning to obtain a tortoise shell carapace with good surface condition. After reconstructing the tortoise shell surface using reverse engineering technology, a 3D geometric model is established. The 3D geometric model is then imported into HyperWorks for preprocessing and then imported into Ls-Dyna for collision analysis to study the role of the tortoise shell surface and reinforcing ribs in its deformation resistance characteristics.

[0011] The third step is to extract the structural features of the tortoise shell and conduct biomimetic design of the anti-collision beam. The curved surface features of the top of the tortoise shell are extracted as the curved surface structure of the shell of the biomimetic anti-collision beam, and the shell shape curved surface structure of the biomimetic anti-collision beam is obtained. Then, a diaphragm structure connecting the carapace and the plastron of the tortoise shell is used as a reinforcing rib. The tortoise shell reinforcing rib is applied to the anti-collision beam and simplified in engineering to obtain the outline curve of the reinforcing rib beam structure of the biomimetic anti-collision beam. Then, a three-dimensional model of the biomimetic automotive anti-collision beam is constructed based on the extracted structural feature parameters.

[0012] The fourth step is to import the geometric model of the front bumper beam into HyperMesh software, use shell elements for mesh generation, establish a finite element model of the steel front bumper beam, use the OptiStruct solver for calculation, analyze the performance of the front bumper beam, and use finite element analysis software to perform free modal simulation analysis on the bumper beam to solve for the natural frequency, damping and mode shape of the bumper beam. The analysis results help to avoid the excitation frequency of the car when designing the bionic bumper beam, avoid resonance, and thus ensure the car's good quietness and safety.

[0013] The fifth step involves importing the three-dimensional model of the biomimetic anti-collision beam into HyperMesh for three-point static pressure finite element modeling, and then performing simulation analysis in Nastran software. The strength of the biomimetic anti-collision beam is studied through three-point static pressure tests and simulation analysis. The static pressure-displacement curves obtained from the tests and simulation analysis are analyzed for errors. The timing of the peak values ​​is also quite consistent, verifying the effectiveness and reliability of the biomimetic method and establishing evaluation indicators for the strength performance of the biomimetic anti-collision beam.

[0014] Step 6: In HyperMesh, establish the geometric model of the front end of the car and the rigid wall, and simplify the whole vehicle connected to the front longitudinal beam as a rigid plate. In the pre-processing software HyperMesh, shell elements are used to mesh the established model. In Ls-Dyna software, according to the C-NCAP regulations of China Automotive Technology Research Center, the results of high-speed frontal collision simulation and test are compared and analyzed.

[0015] Step 7: According to relevant standards, using the established finite element model of the vehicle front end, in the low-speed frontal collision simulation, the collider is used to replace the rigid wall in the high-speed model, and solid elements are used to mesh it. The collision results are analyzed. After the collision simulation is completed, the energy change curves during the simulation calculation process are output in HyperGraph software. Each energy curve is smooth without abrupt changes, and the maximum hourglass energy is lower than 4% to 6% of the total energy, proving that the low-speed frontal collision simulation calculation results are reliable.

[0016] Step 8: Replace the original steel anti-collision beam and energy-absorbing box with a biomimetic automotive anti-collision beam and aluminum alloy energy-absorbing box. The thickness of the energy-absorbing box is the same as that of the original steel energy-absorbing box. Low-speed collision simulation is conducted to obtain the anti-collision beam mass, energy-absorbing box mass, intrusion amount, energy absorption, and collision force parameters of the two structures. The biomimetic structure has greater stiffness, resulting in a smaller intrusion amount and an excessively large peak collision force. The various performance indicators of the front end of the car should be appropriate. Excessive stiffness will also prevent it from playing a protective role in low-speed collisions. Therefore, the performance parameters of the steel front end structure are used as a reference to optimize the biomimetic automotive anti-collision beam and aluminum alloy energy-absorbing box through multi-objective optimization.

[0017] Step 9: Using integrated molding technology can more completely restore the high performance of the bionic structure car crash beam design. According to the designed bionic structure car crash beam 3D model, the bionic structure car crash beam casting is 3D modeled in CATIA according to the gating system scheme. The gating system model structure of the bionic structure car crash beam casting is printed using SLA molding equipment to obtain the bionic structure car crash beam casting assembly wax model.

[0018] Step 10: The wax model of the casting is wrapped and covered with shell-making slurry. After the slurry solidifies, it is baked and heated in a dewaxing kettle. The wax model inside will slowly melt and flow out, and be completely removed at 750-850℃. Since the casting pouring temperature affects the solidification time, it is necessary to control the pouring time, pouring temperature, shell temperature, and solidification temperature of the casting to ensure that the casting is successfully stamped. Then, the semi-finished product is modified and processed according to the process requirements.

[0019] The aforementioned design and optimization method for biomimetic automotive anti-collision beams, in the first step where the tortoise shell and the anti-collision beam are considered as similar systems, is denoted by Q, where the similarity between the tortoise shell and the anti-collision beam is expressed by the formula... Confirmed, formula:

[0020]

[0021] In the formula, Q represents the similarity between similar elements, and β... i The weighting coefficient is β when 0 < β i <1, and q(u i ) represents the similarity of similar elements;

[0022] Selecting coefficient β i The evaluation factor set is U = {u1, u2, u3}, where u1, u2, and u3 are the similarity elements extracted between the two in terms of structure, load, and function, respectively. Based on the evaluation factor set and matrix scaling, the judgment matrix is ​​as follows:

[0023]

[0024] In matrix p, u ij >0,u ii =1,u ij =u ji -1 ,i=(1,2,…,N),j=(1,2,…,N);

[0025] Furthermore, the similarity element serves as the judgment matrix p for evaluating similar systems, and the eigenvectors of matrix p are calculated to be β = (β1, β2, ..., β). TTo avoid the influence of subjective factors on the judgment matrix p and ensure the accuracy and reliability of the matrix, a consistency check is performed on it. The consistency check formula is as follows:

[0026]

[0027] In the formula, CR is the random consistency ratio, CI is the consistency index, and RI is the average random consistency index.

[0028]

[0029] In the formula λ max To determine the maximum value of a matrix, n is the matrix order;

[0030]

[0031] The similarity element is used as the judgment matrix p for evaluating similar systems. The consistency calculation of matrix p yields a ratio CR < 0.1. CR < 0.1 indicates that the inconsistency of matrix p is within an acceptable range and is reasonable. The similarity of the similarity elements between the tortoise shell and the crash beam similar systems is: q = (a, b, c), a = q(u1), b = q(u2), c = q(u3). The similarity between the tortoise shell and the crash beam similar systems is Q = {β1a + β2b + β3c}, where Q ranges from 0 to 1. Through similarity calculation analysis, the tortoise shell structure and the crash beam have a high degree of similarity.

[0032] The design and optimization method of the biomimetic structure car anti-collision beam, in the third step, the design of the biomimetic structure car anti-collision beam is based on the parameters obtained by biomimicking the shape of a tortoise shell for the special curved surface structure of the outer layer. According to the principle of bionics, the evolution diagram of the tortoise shell curved surface structure is extracted. The curved surface structure of the anti-collision beam shell is the first step of the extraction and evolution of the curved surface structure of the tortoise shell at the top of the middle position of the curved surface of the tortoise shell. The top curved surface features of the tortoise shell are extracted as the curved surface structure of the biomimetic anti-collision beam shell. The tail of the tortoise shell plays a major role in transmitting stress. In the process of designing the biomimetic anti-collision beam, the second and third steps of the extraction and evolution of the curved surface structure of the tortoise shell are symmetrically processed after the cut tortoise shell tail. In the fourth step of the extraction and evolution of the curved surface structure of the tortoise shell, the curved surface at the connection between the anti-collision beam and the energy absorption box is changed to an arc with a radius of 2800mm, thus obtaining the curved surface structure of the shell of the biomimetic anti-collision beam.

[0033] In the design of biomimetic automotive anti-collision beams, the internal reinforcing ribs of the biomimetic anti-collision beams are designed to mimic the characteristics of a diaphragm structure connecting the carapace and plastron of a tortoise. Through biomimetic principles, the beams are simplified in engineering to obtain a simplified longitudinal diagram of the reinforcing ribs. The biomimetic reinforcing ribs of the anti-collision beams are biomimetic simplified designs of the internal structure of the tortoise shell model in the simplified design of the biomimetic reinforcing ribs. The carapace of the tortoise shell structure is simplified to the front collision side of the original reinforcing rib beam, and the plastron of the tortoise shell structure is simplified to the rear side of the original reinforcing rib beam. The reinforcing ribs connecting the carapace and plastron of the tortoise shell in the exoskeleton structure of the tortoise shell are simplified to the original reinforcing rib beam reinforcing rib plate.

[0034] The body of the biomimetic anti-collision beam reinforcing crossbeam is composed of arc-shaped curves. The inner boundary curve of the reinforcing crossbeam is two arches. The inner contour constraint curve is a simplified design of the cross-section of a diaphragm structure, which is a tortoise shell carapace and plastron. The contour curve is obtained from the evolution diagram of the biomimetic anti-collision beam reinforcing crossbeam structure.

[0035] The design and optimization method of the biomimetic structure car anti-collision beam, in the sixth step, establishes a geometric model of the front end of the car and the rigid wall in HyperMesh, considering the influence of strain and strain rate hardening on the material of the front end of the car body during the impact process, and sets the strain rate when establishing the steel material model in the pre-processing software HyperMesh.

[0036] The design and optimization method of the biomimetic structure automotive anti-collision beam, the standard in the seventh step is GB17354-1998 "Automotive Front and Rear End Protection Devices" standard.

[0037] In the design and optimization method of the biomimetic automotive anti-collision beam, in the seventh step of the low-speed frontal collision simulation, a collider is used to replace the rigid wall in the high-speed model. Solid elements are used to mesh it, and the collider is given an initial velocity of 1111.11 mm / s along the positive X-axis. All degrees of freedom except for translation in the X-axis direction are constrained. The mass of the actual vehicle is given to the collider, and all degrees of freedom of the simplified rigid plate are constrained. The remaining settings are the same as those in the high-speed collision in step six.

[0038] The design and optimization method for the biomimetic automotive anti-collision beam, as described in step eight, suffers from high stiffness, resulting in a small intrusion volume and an excessively large peak collision force. Therefore, using the performance parameters of the steel front-end structure as a reference, multi-objective optimization is performed on the biomimetic automotive anti-collision beam and the aluminum alloy energy-absorbing box. The optimal cross-sectional thickness of the anti-collision beam and the energy-absorbing box is determined using the beam thickness and the box cross-sectional thickness as design variables. The thickness of each component is discretely selected with a value interval of 0.5 mm. The value ranges of each design variable are as follows:

[0039] x1,x2,x3,x4,x5,x6∈[1,1.5,2,2.5,3]

[0040] Where: x1 is the thickness of the front plate of the anti-collision beam; x2 is the thickness of the upper plate of the anti-collision beam; x3 is the thickness of the rear plate of the anti-collision beam; x4 is the thickness of the reinforcing rib plate of the anti-collision beam; x5 is the thickness of the lower plate of the anti-collision beam; x6 is the thickness of the energy-absorbing box.

[0041] The biomimetic anti-collision beam and aluminum alloy energy-absorbing box underwent multi-objective optimization. The maximum energy absorption, peak collision force at the energy-absorbing box cross-section, and various design variables were used as constraint functions, while the maximum intrusion of the anti-collision beam and the mass of the anti-collision beam and energy-absorbing box were used as objective functions. The NSGA-II genetic algorithm was employed to perform multi-objective optimization on the response surface approximation model. The optimized mathematical model is as follows:

[0042]

[0043] In the formula: m1(x) is the mass of the crash beam; m2(x) is the mass of the energy-absorbing box; D(x) is the maximum intrusion amount; E(x) is the maximum energy absorbed, E L E U Its upper and lower limits are 770J and 800J respectively; F(x) is the peak collision force, F L F U Its upper and lower limits are set to 15kN and 25kN respectively; x i For the thickness of the anti-collision beam and energy-absorbing box, x L and x U Its upper and lower limits are set to 1mm and 3mm, respectively;

[0044] Multi-objective optimization of the biomimetic anti-collision beam and aluminum alloy energy-absorbing box was performed by setting a population size of 40, an evolutionary number of 200, and a crossover probability of 0.9. After 8000 iterations, the Pareto solution set for multi-objective optimization was obtained. While ensuring that the intrusion amount does not exceed that of the steel structure, the mass of the anti-collision beam and energy-absorbing box was minimized. A compromise solution was selected from the Pareto front, and the compromise solution was determined and rounded to:

[0045] [x1,x2,x3,x4,x5,x6] = [1.5,1.4,2.2,1.4,1.4,1]

[0046] The response values ​​for maximum energy absorption E, peak impact force F, maximum intrusion of the crash beam D, crash beam mass M1, and energy absorption box mass M2 are:

[0047] [E,F,D,M1,M2]=[776.3,21.605,-62.562,0.84488,0.12467]

[0048] The collision results were obtained by establishing a low-speed collision model based on the optimized anti-collision beam and energy-absorbing box cross-sectional thickness. The collision simulation results and the optimization results obtained in HyperStudy were used to verify the error between the performance index values ​​obtained after the optimization of the approximate model and the collision simulation values, and to verify the accuracy of the approximate model and the compromise solution obtained by the NSGA-II genetic algorithm.

[0049] The design and optimization method for the biomimetic automotive anti-collision beam, specifically the manufacturing method of the wax model of the biomimetic automotive anti-collision beam casting in step ten, includes the following steps:

[0050] A. 3D modeling of the biomimetic automotive crash beam casting according to the gating system scheme: 3D modeling of the biomimetic automotive crash beam according to the gating system scheme is performed using CATIA to obtain the casting model tree;

[0051] B. Printing pattern: Using casting photosensitive resin as raw material, the tree pattern of the casting model is printed using photocuring molding technology;

[0052] C. Preparation of slurry: When preparing the slurry for shell making, first close the slurry tank and put in silica sol, wetting agent and refractory quartz sand. Then open the "L"-shaped slurry mixing tank and stir continuously until the slurry is completely mixed and well wetted. Then add defoamer and continue stirring until fully mixed. Prepare a specific slurry according to the characteristics and performance requirements of the resin and alloy.

[0053] D. The pre-prepared slurry is repeatedly dipped and sanded to standardize the shell of the biomimetic structure of the anti-collision beam. The shell is made of five and a half layers and covered with short carbon fiber to enhance the pull-out and fracture effect during the shell fracture process.

[0054] E. Dewaxing: Dewaxing is used to obtain the mold shell. The resin is completely removed by heating a steam dewaxing kettle to obtain the mold shell of the biomimetic car anti-collision beam structure tree. First, the steam dewaxing kettle is heated to 150°C, and then the mold shell is placed in it. The steam dewaxing kettle is then rapidly heated to 380°C and held for 0.5 hours. Then, it is heated to 800°C and held at that temperature. Finally, it is heated to 1000°C for calcination. Most of the resin has been removed at 380°C and completely removed at 800°C to obtain the wax model shell.

[0055] F. Casting: Wrap the thin-walled area of ​​the wax model shell with two layers, especially in the thin-walled area where the temperature field is low and there is a tendency to loosen, add an extra layer of heat insulation felt to control its too fast solidification. The casting time is 10 seconds, the casting temperature is 1480℃, and the mold shell temperature is 1200℃ to ensure that the wax model shell is successfully punched.

[0056] G. Cleaning the shell: Clean the casting shell with a high pressure and high speed water flow of 70-120Mpa at a cleaning efficiency of 20-30 sets / h.

[0057] H. Cleaning the casting: Separate the casting from the gating system. After separation, use a grinding wheel to grind the riser residue of the casting. Trim the edges according to the process requirements to obtain the prepared biomimetic automotive anti-collision beam.

[0058] By employing the technical solution described above, the present invention has the following advantages:

[0059] This invention employs a simplified tortoise-shell structure engineering approach, free modal analysis of the crash beam, strength and impact performance analysis of the crash beam, and multi-objective optimization of the crash beam. It incorporates tortoise-shell performance tests, three-point static pressure tests, and high-speed and low-speed impact tests of the biomimetic crash beam in HyperMesh combined with Ls-Dyna simulation. The invention comprehensively considers the strength, stiffness, vibration characteristics, impact performance, and lightweight performance of the biomimetic crash beam. By designing a curved surface feature and internal biomimetic reinforcing rib structure for the biomimetic crash beam, this invention avoids the current predicament of simply increasing material thickness or replacing materials with high-strength ones. It achieves a balance between strength performance, material cost, manufacturing cost, and lightweighting, while simultaneously improving crash resistance and minimizing impact energy absorption. The crash beam fabricated using this invention exhibits superior crash resistance and energy absorption performance compared to traditional crash beams. This invention can be extended to the design of lightweight, energy-absorbing components in vehicles and other applications. Attached Figure Description

[0060] Figure 1 This is a model diagram of the turtle shell collision in an embodiment of the present invention;

[0061] Figure 2 This is a model diagram of cuboid collision in an embodiment of the present invention;

[0062] Figure 3 This is a Von Mises stress distribution diagram of the tortoise shell in an embodiment of the present invention;

[0063] Figure 4 This is a Von Mises stress distribution diagram of the plate material in an embodiment of the present invention;

[0064] Figure 5 This is a collision model diagram of the tortoise shell curved surface with and without reinforcing ribs in an embodiment of the present invention;

[0065] Figure 6 This is a Von Mises stress distribution diagram of the unreinforced tortoise shell curved surface in an embodiment of the present invention;

[0066] Figure 7This is a Von Mises stress distribution diagram of a reinforced tortoise shell curved surface in an embodiment of the present invention;

[0067] Figure 8 This is a partial deformation diagram of the unreinforced tortoise shell surface in an embodiment of the present invention;

[0068] Figure 9 This is a partial deformation diagram of the reinforced tortoise shell curved surface in an embodiment of the present invention;

[0069] Figure 10 This is a tortoise shell model in an embodiment of the present invention;

[0070] Figure 11 This is an evolution diagram of the extracted features of the tortoise shell curved surface structure in an embodiment of the present invention;

[0071] Figure 12 This is a simplified design diagram of the biomimetic reinforcing rib structure in an embodiment of the present invention;

[0072] Figure 13 This is a diagram illustrating the evolution of the biomimetic anti-collision beam reinforcing crossbeam structure in this invention embodiment;

[0073] Figure 14 This is an isometric side view of the biomimetic automotive anti-collision beam structure in an embodiment of the present invention;

[0074] Figure 15 This is a vibration mode diagram of the biomimetic anti-collision beam in an embodiment of the present invention;

[0075] Figure 16 This is the three-point static pressure test device in the embodiment of the present invention;

[0076] Figure 17 This is a three-point hydrostatic finite element model in an embodiment of the present invention;

[0077] Figure 18 These are the static pressure-displacement curves obtained from experiments and simulation analyses in the embodiments of this invention;

[0078] Figure 19 This is a schematic diagram of the trolley structure in an embodiment of the present invention;

[0079] Figure 20 This is a schematic diagram of the installation of the trolley and the body-in-white in an embodiment of the present invention;

[0080] Figure 21 This is the stress-strain curve of B340 steel in an embodiment of the present invention;

[0081] Figure 22 This is a geometric model diagram of the front end of the car and the rigid wall in an embodiment of the present invention;

[0082] Figure 23 This is a simulated deformation diagram of the front part of the vehicle body in an embodiment of the present invention;

[0083] Figure 24 This is a test deformation diagram of the front part of the vehicle body in an embodiment of the present invention;

[0084] Figure 25 This is a finite element model of a low-speed collision at the front end of the vehicle body in an embodiment of the present invention;

[0085] Figure 26 This is the energy change curve in an embodiment of the present invention;

[0086] Figure 27 This is the impact force variation curve of the energy-absorbing box cross-section in an embodiment of the present invention;

[0087] Figure 28 This is the invasive amount change curve in an embodiment of the present invention;

[0088] Figure 29 This is a cross-sectional view of the anti-collision beam and energy-absorbing box in an embodiment of the present invention;

[0089] Figure 30 This is the Pareto front in the embodiments of the present invention;

[0090] Figure 31 This is a tree diagram of the model group of the biomimetic structure automobile anti-collision beam casting system in this embodiment of the invention;

[0091] In the diagram: 1. Fix point 1 on the edge of the turtle shell; 2. Fix point 2 on the edge of the turtle shell; 3. Fix point 3 on the edge of the turtle shell; 4. Fix point 4 on the edge of the turtle shell; 5. Fix point 1 at the apex of the board; 6. Fix point 2 at the apex of the board; 7. Fix point 3 at the apex of the board; 8. Fix point 4 at the apex of the board; 9. Tail of the turtle shell; 10. Top center of the turtle shell; 11. Carapace of the turtle shell; 12. Reinforcing rib. 13. Tortoise shell plastron; 14. Front collision side of the original reinforcing beam; 15. Reinforcing plate of the original reinforcing beam; 16. Rear side of the original reinforcing beam; 17. Bionic reinforcing rib of the anti-collision beam; 18. Bionic outer shell of the anti-collision beam; 19. Thickness of the front plate of the anti-collision beam; 20. Thickness of the upper plate of the anti-collision beam; 21. Thickness of the rear plate of the anti-collision beam; 22. Thickness of the reinforcing plate of the anti-collision beam; 23. Thickness of the lower plate of the anti-collision beam; 24. Thickness of the energy-absorbing box; 25. Compromise solution. Detailed Implementation

[0092] The present invention can be explained in more detail through the following embodiments, but the present invention is not limited to the following embodiments;

[0093] Combined with appendix Figures 1-31 The design and optimization method of the biomimetic automotive anti-collision beam includes the following steps:

[0094] The first step involves analyzing the shape of the anti-collision beam and the actual working condition of the stiffeners, taking into account the curved surface characteristics of the tortoise shell, to extract the similarities between the two in terms of structure, load, and function. Since the tortoise shell and the anti-collision beam are highly similar, they are considered as a similar system. Similarity theory is then used to analyze the similarity between the anti-collision beam and the tortoise shell, and the similarity is calculated. In the process of structural biomimicry, the similarity between the biomimetic prototype and the mechanical structure is measured according to the evaluation criteria for the degree of similarity between the two.

[0095] Furthermore, the thin-shell structure of the tortoise shell meets the requirements for impact resistance. Combining the curved surface characteristics of the tortoise shell carapace, we can extract the similarities between the two in terms of structure, load, and function: both the thin-shell structure and the stiffening plate rely on the rationality of their geometric shapes to ensure their strength; the impacts on the tortoise shell and the collisions on the anti-collision beam have great physical similarities; in terms of function, the special curved surface structure of the tortoise shell plays a role in protecting and transferring loads.

[0096] In practice, a turtle shell with a regular shape and appropriate size is selected as the research object. The biomimetic effect of the mechanical structure is determined by the degree of similarity between the biological prototype and the mechanical structure. The thin shell structure of the turtle shell meets the impact resistance target requirements, and its special arched curved surface structure can resist external pressure and impact.

[0097] In implementation, when the tortoise shell and the crash beam are considered as similar systems, the similarity between the tortoise shell and the crash beam is denoted as Q, which is derived from the formula... Confirmed, formula:

[0098]

[0099] In the formula, Q represents the similarity between similar elements, and β... i The weighting coefficient is β when 0 < β i <1, and Similarity of similar elements;

[0100] Furthermore, select coefficient β i The evaluation factor set is U = {u1, u2, u3}, where u1, u2, and u3 are the similarity elements extracted between the two components in terms of structure, load, and function, respectively. Based on the evaluation factor set and matrix scaling, the judgment matrix is ​​as follows:

[0101]

[0102] In matrix p, u ij >0,u ii =1,u ij =u ji -1 ,i=(1,2,…,N), j=(1,2,…,N).

[0103] Furthermore, the similarity element serves as the judgment matrix p for evaluating similar systems, and the eigenvectors of matrix p are calculated to be β = (β1, β2, ..., β). T To avoid the influence of subjective factors on the judgment matrix p and ensure the accuracy and reliability of the matrix, a consistency check is performed on it. The consistency check formula is as follows:

[0104]

[0105] In the formula, CR is the random consistency ratio, CI is the consistency index, and RI is the average random consistency index.

[0106]

[0107] In the formula λ max To determine the maximum value of a matrix, n is the matrix order;

[0108]

[0109] The similarity element is used as the judgment matrix p for evaluating similar systems. The consistency calculation of matrix p yields a ratio CR < 0.1. CR < 0.1 indicates that the inconsistency of matrix p is within an acceptable range and is reasonable. The similarity of the similarity elements between the tortoise shell and the anti-collision beam similar systems is: q = (a, b, c), a = q(u1), b = q(u2), c = q(u3). The similarity between the tortoise shell and the anti-collision beam similar systems is Q = {β1a + β2b + β3c}, where Q ranges from 0 to 1. Through similarity calculation analysis, the tortoise shell structure and the anti-collision beam have a high similarity, and the rationality of the tortoise shell structure as the biomimetic prototype of the anti-collision beam's shape and stiffener design is verified.

[0110] The second step involves using the HANDYSCAN3D handheld 3D laser scanning device to obtain a well-maintained tortoise shell carapace surface, based on the high similarity between the tortoise shell structure and the anti-collision beam from the previous step. Reverse engineering is then employed to reconstruct the tortoise shell surface and establish a 3D geometric model. This model is then imported into HyperWorks for preprocessing and subsequently imported into Ls-Dyna for collision analysis to study the role of the tortoise shell surface and reinforcing ribs in its deformation resistance characteristics.

[0111] During implementation, the HANDYSCAN3D handheld 3D laser scanning device was used to scan the research object and collect triangular mesh model data of the curved surface. Using Vxelement software, a single curved surface that fits the scanned data was obtained. By adjusting the parameters, the surface met the design requirements in terms of fit and smoothness. Then, the single curved surface was imported into CATIA software, the edges of the surface were trimmed to obtain the smooth surface used for modeling, a 3D geometric model was established, and feature surfaces were selected for analysis.

[0112] Based on the geometric model, the impact resistance performance of the tortoise shell was analyzed according to engineering requirements. First, a collision model of the tortoise shell and the plate was established in HyperMesh, and LS-DYNA software was used for simulation calculations to analyze the impact performance of the tortoise shell. The rationality of the tortoise shell structure was verified. A collision model of the tortoise shell and a collision model with and without reinforcing ribs were established in the HyperMesh finite element preprocessing software, and LS-DYNA software was used for simulation calculations to analyze the impact performance of the tortoise shell. Then, the VonMises stress distribution diagram of the collision simulation was viewed in HyperView. The relationship between the described performance characteristics and the anti-collision beam structure was studied to verify whether the performance parameters of the tortoise shell meet the requirements.

[0113] Furthermore, the collision simulation analysis model for the impact resistance of the tortoise shell was established in HyperMesh. Figure 1 For turtle shell collision model, Figure 2 The collision model is a cuboid. The main model used in the collision simulation includes a 30mm diameter circular tube, which serves as the punch, made of 45 steel. The punch is set as a rigid body and impacts the turtle shell perpendicularly at a speed of 6km / h. Four nodes 1-4 on the edge of the turtle shell finite element model are fixed, i.e., attached... Figure 1 Fixing points 1, 2, 3, and 4 on the edge of the tortoise shell, and analyzing their stress distribution and deformation within 0.1 seconds of impact.

[0114] Furthermore, in the collision simulation analysis of the tortoise shell's impact resistance, a cuboid plate with the same length, width, and thickness as the tortoise shell was selected for comparison. The material and initial boundary conditions were the same as those of the tortoise shell collision model. Figure 1 Similarly, fixed constraints are applied to nodes 5-8 at the four vertices of the plate, i.e., attached... Figure 2 The collision model includes fixed points 5, 6, 7, 8, and 1 (the first and second fixed points of the plate vertices), and fixed points 1, 2, 3, 4, and 5 (the third and fourth fixed points of the plate vertices). Figure 2 .

[0115] Furthermore, the Von Mises stress distribution diagrams of the tortoise shell and the plate are as follows: Figure 3 , Figure 4 Compared to sheet metal, the stress value of most areas of the tortoise shell structure is lower during the collision, the overall stress distribution is more uniform, and there is no large stress concentration phenomenon. The tail of the tortoise shell not only plays a role in transmitting load during the collision, but also plays a major role in resisting the bending deformation of the tortoise shell. The structure of the tortoise shell is more reasonable, which prepares for the design and optimization of a biomimetic automotive anti-collision beam.

[0116] Furthermore, the finite element model of the tortoise shell with and without reinforcing ribs was established in HyperMesh. In LS-DYNA software, the stress distribution and deformation of the tortoise shell with and without reinforcing ribs during the collision were compared and analyzed. The tortoise shell was fixed to a rigid plate, and a cylindrical punch impacted the tortoise shell at a speed of 15 km / h. Fixed constraints were applied to the rigid plate, and its material and boundary conditions were the same as those in the tortoise shell's impact resistance collision model. Figure 1 With identical settings, the turtle shell collision model with and without reinforcing ribs is as follows: Figure 5 As shown.

[0117] Furthermore, the impact performance of the tortoise shell is determined by the obtained Von Mises stress distribution diagram of the curved surface of the tortoise shell with and without reinforcement, such as... Figure 6 (VonMises stress distribution diagram of tortoise shell curved surface) Figure 7 (Von Mises stress distribution diagram of the reinforced tortoise shell surface) shows that the stress of the unreinforced tortoise shell reaches its maximum value 0.01s after impact, and the stress is mainly concentrated in the impact area of ​​the cylindrical punch. Figure 8 It can be seen that a significant indentation and substantial deformation occurred in the collision area. Figure 7 , 9 It can be seen that the stress of the reinforced tortoise shell is concentrated in the area where the top circle and skirt of the tortoise shell contact the rigid plate, which is greater than the stress value of the unreinforced tortoise shell. The reinforcing ribs play an important role in the collision process, which prepares for the design and optimization of a biomimetic automotive anti-collision beam.

[0118] The third step is to extract the structural features of the tortoise shell and conduct biomimetic design of the anti-collision beam. The curved surface features of the top of the tortoise shell are extracted as the curved surface structure of the shell of the biomimetic anti-collision beam, and the shell shape curved surface structure of the biomimetic anti-collision beam is obtained. Then, a diaphragm structure connecting the carapace and the plastron of the tortoise shell is used as a reinforcing rib. The tortoise shell reinforcing rib is applied to the anti-collision beam and simplified in engineering to obtain the outline curve of the reinforcing rib beam structure of the biomimetic anti-collision beam. Then, a three-dimensional model of the biomimetic automotive anti-collision beam is constructed based on the extracted structural feature parameters.

[0119] During implementation, the structural features of a tortoise shell were extracted to design the crash beam using biomimetic techniques. Based on the unique curved surface and internal reinforcing ribs of the tortoise shell, these two structural characteristics were incorporated into the biomimetic design of the crash beam. The biomimetic crash beam consists of two parts: an outer biomimetic curved surface structure and internal biomimetic reinforcing ribs. First, the curved surface structure of the tortoise shell was extracted. Based on these structural characteristics, the external curved surface structure of the biomimetic crash beam was derived. Then, by observing the internal structure of the tortoise shell, the reinforcing ribs, a diaphragm structure connecting the carapace and plastron, were redesigned using a biomimetic curved surface configuration to evolve the rib structure. Thus, the biomimetic rib plate of the crash beam was designed.

[0120] Furthermore, the aforementioned biomimetic automotive anti-collision beam design utilizes parameters derived from the outer layer's special curved surface structure, which is biomimetic to the shape of a tortoise shell. (See tortoise shell model.) Figure 10 Extraction and evolution of the structural features of tortoise shell surface Figure 11 Based on the principles of bionics, the curved surface structure of the crash beam shell is derived from the characteristics of the curved surface structure of a tortoise shell. Figure 11 Three-dimensional turtle shell model Figure 10 The first step in the extraction and evolution of the curved surface structure of the tortoise shell at position 10 in the middle of the shell involves cutting it to a width of 110mm. The curved surface features of the top of the tortoise shell are extracted as the curved surface structure of the biomimetic anti-collision beam shell. The tail of the tortoise shell at position 9 plays a major role in transmitting stress. Therefore, in the design of the biomimetic anti-collision beam, the second and third steps of the extraction and evolution of the curved surface structure features of the tortoise shell involve symmetrical processing of the cut tail of the tortoise shell at position 9. The fourth step of the extraction and evolution of the curved surface structure features of the tortoise shell involves changing the curved surface at the connection between the biomimetic beam and the energy-absorbing box to an arc with a radius of 2800mm, thus obtaining the outer curved surface structure of the biomimetic anti-collision beam shell.

[0121] Furthermore, in the design of biomimetic automotive crash beams, the internal reinforcing ribs are designed to mimic the characteristics of a diaphragm structure connecting the carapace and plastron of a tortoise. Through biomimetic principles, this design is simplified for engineering purposes, resulting in a simplified longitudinal diagram of the reinforcing ribs. (See attached diagram.) Figure 12 and Figure 13 , 14 The biomimetic anti-collision beam of the present invention includes a biomimetic reinforcing rib 17 for the anti-collision beam crossbeam and a biomimetic outer shell 18 for the anti-collision beam crossbeam. The biomimetic reinforcing rib 17 for the anti-collision beam crossbeam is a simplified biomimetic design of the internal structure of the turtle shell model in the simplified design of the biomimetic reinforcing rib 12. The turtle shell carapace 11 in the turtle shell structure is simplified to the front collision side 14 of the original reinforcing rib crossbeam. The turtle shell plastron 13 in the turtle shell structure is simplified to the rear side 16 of the original reinforcing rib crossbeam. The reinforcing rib 12 connecting the turtle shell carapace 11 and the turtle shell plastron 13 in the exoskeleton structure of the turtle shell is simplified to the original reinforcing rib crossbeam reinforcing rib plate 15.

[0122] Furthermore, the biomimetic anti-collision beam's reinforcing crossbeam is composed of arc-shaped curves. The inner boundary curves of the reinforcing crossbeam are two arches, and the inner contour constraint curves resemble the reinforcing ribs of a tortoise shell's carapace and plastron. This is a simplified design of a diaphragm structure, and the biomimetic anti-collision beam's reinforcing crossbeam structure has evolved in form. Figure 13 The resulting contour curve;

[0123] The fourth step is to import the geometric model of the front bumper beam into HyperMesh software, use shell elements for mesh generation, establish a finite element model of the steel front bumper beam, use the OptiStruct solver for calculation, analyze the performance of the front bumper beam, and use finite element analysis software to perform free modal simulation analysis on the bumper beam to solve for the natural frequency, damping and mode shape of the bumper beam. The analysis results help to avoid the excitation frequency of the car when designing the bionic bumper beam, avoid resonance, and thus ensure the car's good quietness and safety.

[0124] During implementation, to directly reflect the inherent characteristics of the crash beam and reduce errors, finite element analysis software was used to perform free modal simulation analysis on the crash beam. This involved solving for the natural frequencies, damping, and mode shapes of the crash beam under undamped and unconstrained conditions. The analysis results help avoid the excitation frequencies of the vehicle during crash beam design, preventing resonance and thus ensuring good vehicle quietness and safety.

[0125] Furthermore, the free modal simulation analysis of the aforementioned anti-collision beam involves simplifying its geometric model, importing it into HyperMesh software, and using shell elements for mesh generation to establish a finite element model of the steel front anti-collision beam. The OptiStruct solver is used for calculation to analyze the lightweight performance of the front anti-collision beam. In free modal analysis, the first six modes are called rigid body modes, which do not produce elastic deformation, and the calculated natural frequencies approach or equal to 0. Their main manifestation is the translation or rotation of the object in space; therefore, rigid body modes can be ignored. To filter out the influence of vibrations from other components, starting from the seventh mode, i.e., the first elastic mode (the first mode refers to the first elastic mode, which is the seventh mode), only the first six modes of beam vibration are selected for analysis. Figure 15 As shown in the mode diagram, the vibration of the crash beam in each mode consists of three types: longitudinal bending, transverse bending, and torsion. The vibration amplitude is relatively small, with the maximum amplitude not exceeding 40 mm. The analysis results help to avoid the excitation frequency of the vehicle when designing crash beams, thus preventing resonance and ensuring good vehicle quietness and safety.

[0126] The fifth step involves importing the three-dimensional model of the biomimetic anti-collision beam into HyperMesh for three-point static pressure finite element modeling, and then performing simulation analysis in Nastran software. The strength of the biomimetic anti-collision beam is studied through three-point static pressure tests and simulation analysis. The static pressure-displacement curves obtained from the tests and simulation analysis are analyzed for errors. The peak times are also quite consistent, with a maximum error of only 6.15%, which verifies the effectiveness and reliability of the biomimetic method and establishes the evaluation index for the strength performance of the biomimetic anti-collision beam.

[0127] During implementation, the performance of the biomimetic automotive anti-collision beam was studied through three-point static pressure tests and simulation analysis, and the strength performance of the anti-collision beam was evaluated by the peak value of the reaction force of the injection punch.

[0128] Furthermore, the three-point static pressure simulation analysis involves using the three-dimensional model of the biomimetic structural anti-collision beam, such as... Figure 14 The image shows the import of HyperMesh for three-point hydrostatic finite element modeling. Figure 17 Referring to the experimental conditions, a rigid cylindrical injection punch was pressed downwards by 100 mm along the x-axis at a speed of 1 m / s. Automatic surface-to-surface contact was used between the injection punch and the biomimetic automotive anti-collision beam, with a static friction coefficient of 0.15 and a dynamic friction coefficient of 0.1. The model was saved as a k-file and imported into LS-DYNA for joint solution.

[0129] Furthermore, the three-point static pressure test was conducted using a PLS-L50B4 motor servo component testing system and a YE2539 high-speed static strain gauge. For example... Figure 16 As shown, strain gauges were attached to the middle of the crash beam and the side of the energy-absorbing box before the test. A cylindrical injection punch with a radius of 152 mm was moved down until it just made contact with the middle of the crash beam. The loading speed was set to 0.001 m / s, and loading was stopped when the loading distance reached 100 mm.

[0130] Furthermore, the strength performance of the biomimetic anti-collision beam is derived from the static pressure-displacement curve obtained through experimental and simulation analysis, as shown in the figure. Figure 18 The two curves show consistent trends and their peak times are also quite similar, thus the established finite element model of the biomimetic anti-collision beam is considered to be highly accurate.

[0131] Step 6: In HyperMesh, establish the geometric model of the front end of the car and the rigid wall, and simplify the whole vehicle connected to the front longitudinal beam as a rigid plate. In the pre-processing software HyperMesh, shell elements are used to mesh the established model. In Ls-Dyna software, according to the C-NCAP regulations of China Automotive Technology Research Center, the results of high-speed frontal collision simulation and test are compared and analyzed.

[0132] In practice, a geometric model of the front end of the car and the rigid wall is established in HyperMesh. The influence of strain and strain rate hardening on the material of the front end of the car body during the impact process is considered. The strain rate is set when the steel material model is established in the pre-processing software HyperMesh.

[0133] During implementation, a finite element model of the front end of a passenger vehicle undergoing high-speed collision was established. Figure 22 According to the C-NCAP management rules issued by the China Automotive Technology and Research Center, a high-speed frontal collision test was conducted on the front end of the original steel vehicle body using LS-DYNA software. The accuracy of the finite element model was verified through high-speed frontal collision simulation and testing.

[0134] Furthermore, the high-speed frontal collision test of the original steel body front end is conducted according to C-NCAP regulations. The test vehicle used in this invention mainly consists of a body-in-white and a sled provided by the passenger car company. The sled measures 3400mm × 2000mm × 117mm, with a wheel diameter of 400mm. The body-in-white and the sled are connected by bolts, with a total mass of 1300kg. Figure 19 This is a trolley. When installing the body-in-white, the front end of the body must extend beyond the trolley, such as... Figure 20 As shown.

[0135] Furthermore, the aforementioned high-speed head-on collision finite element model Figure 22 The model was created using HyperMesh, establishing the geometric model of the car's front end and rigid wall, and simplifying the entire vehicle connected to the front longitudinal beam as a rigid plate. Shell elements were used to mesh the model in HyperMesh, with 10mm elements for the front end and 15mm elements for the rigid wall and simplified rigid plate, resulting in 31,534 elements and 32,688 nodes. The front end was set as a MAT24 material model, endowed with the material properties of steel: density 7.85×10⁻⁹ t / mm³, elastic modulus 2.1×10⁵ MPa, and Poisson's ratio 0.3. Considering the effects of strain and strain rate hardening on the material during impact, a strain rate was set when creating the steel material model. Taking B340 material as an example... Figure 21 As shown, stress-strain test data were set at eight strain rates, with values ​​of 0.003 s⁻¹. -1 0.01s -1 0.1s -1 1s -1 10s -1 25s -1 100s -1 and 1000s -1 Using the stress-strain curves at these strain rates as a benchmark, stress data at any strain rate during the collision were constructed. A rigid wall and a simplified rigid plate were set as a MAT20 rigid material model, with density, elastic modulus, and Poisson's ratio using the performance parameters of steel. All degrees of freedom of the rigid wall were constrained. The actual vehicle mass was assigned to the simplified rigid plate. An initial velocity of 13888.89 mm / s was assigned to the front end of the vehicle body along the negative X-axis. Figure 22 This is a finite element model of the front end of a passenger vehicle undergoing a high-speed collision.

[0136] Furthermore, the accuracy of the finite element model was verified through comparative analysis of high-speed collision simulation and experimental results, combined with the attached... Figure 22 , 23 24, 25 Figure 23 ,Depend on Figure 22 and Figure 23 It can be seen that the front structure of the vehicle body absorbs the collision energy and undergoes collapse deformation. The simulated deformation of the front of the vehicle body is consistent with the experimental deformation, which verifies the accuracy of the finite element model of the front of the vehicle body.

[0137] Step 7: According to the GB17354-1998 standard "Front and Rear Protective Devices for Automobiles", the established finite element model of the front end of the vehicle body was used. In the low-speed frontal collision simulation, the collider was used to replace the rigid wall in the high-speed model. Solid elements were used to mesh it. The collision results were analyzed. After the collision simulation, the energy change curves during the simulation calculation were output in HyperGraph software. Each energy curve was smooth without abrupt changes, and the maximum hourglass energy was lower than 4% to 6% of the total energy, proving that the low-speed frontal collision simulation calculation results were reliable.

[0138] In implementation, during the low-speed frontal collision simulation, a collider is used instead of the rigid wall in the high-speed model. Solid elements are used to mesh the collider, and an initial velocity of 1111.11 mm / s is given to the collider in the positive X-axis direction. All degrees of freedom except for translation in the X-axis direction are constrained. The mass of the actual vehicle is given to the collider, and all degrees of freedom of the simplified rigid plate are constrained. The rest of the settings are the same as those in the high-speed collision in step six.

[0139] During implementation, in accordance with the GB17354-1998 standard "Front and Rear Protective Devices for Automobiles", the maximum energy absorption, the peak collision force of the energy absorption box section, and the maximum intrusion of the anti-collision beam were used as collision performance evaluation indicators. A finite element model of a low-speed collision at the front end of a passenger vehicle was established, and its collision results were analyzed.

[0140] Furthermore, in establishing the low-speed collision finite element model of the vehicle's front end, during the low-speed frontal collision simulation, a collider is used instead of the rigid wall in the high-speed model. Solid elements are used to mesh the collider with a mesh size of 15mm. The collider is given an initial velocity of 1111.11 mm / s along the positive X-axis. All degrees of freedom except for translation along the X-axis are constrained. The actual vehicle mass is assigned to the collider. All degrees of freedom of the simplified rigid plate are constrained. The remaining settings are the same as in step six for the high-speed collision. Figure 8 This is a finite element model of a low-speed collision at the front end of the vehicle body.

[0141] Furthermore, regarding the collision result analysis, after the collision simulation is completed, the energy change curve during the simulation calculation process is output in the HyperGraph software, such as... Figure 26 As shown in Figure 26, the energy curves are smooth without abrupt changes, and the maximum hourglass energy is 11.033 J, which is less than 5% of the total energy, proving the reliability of the simulation results for low-speed frontal collisions. Figure 27As shown in the figure, the change in force across the energy-absorbing box cross-section during the simulation calculation has a peak value of 15.827 kN. The change in the intrusion amount of the anti-collision beam is as follows. Figure 28 As shown, its maximum value is -67.6731 mm.

[0142] Step 8: Replace the original steel crash beam and energy-absorbing box with a biomimetic automotive crash beam and aluminum alloy energy-absorbing box. The thickness of the energy-absorbing box is the same as the original steel energy-absorbing box. Conduct low-speed collision simulations to obtain the crash beam mass, energy-absorbing box mass, intrusion amount, energy absorption, and collision force parameters for both structures. Compared with the original crash beam and energy-absorbing box, the new crash beam and energy-absorbing box are 0.4 times lighter. In terms of collision performance, the maximum energy absorption is not significantly different, the intrusion amount is reduced by nearly 2.3 times compared to the original structure, and the peak collision force is increased by 3.8 times. Due to the greater stiffness of the biomimetic structure, the intrusion amount is smaller and the peak collision force is too large. The various performance indicators of the front end of the car should be appropriate. Excessive stiffness will also prevent it from providing protection in low-speed collisions. Therefore, using the performance parameters of the steel front end structure as a reference, multi-objective optimization of the biomimetic automotive crash beam and aluminum alloy energy-absorbing box is carried out to meet the usage requirements.

[0143] During implementation, the biomimetic automotive anti-collision beam exhibits high stiffness, resulting in a small intrusion volume and an excessively large peak collision force. Therefore, using the performance parameters of the steel front-end structure as a reference, multi-objective optimization is performed on the biomimetic automotive anti-collision beam and the aluminum alloy energy-absorbing box. The optimal cross-sectional thickness of the anti-collision beam and the energy-absorbing box is determined using the thickness of the anti-collision beam and the cross-sectional thickness of the energy-absorbing box as design variables. The thickness of each component is discretely selected with a value interval of 0.5 mm. The value ranges of each design variable are as follows:

[0144] x1,x2,x3,x4,x5,x6∈[1,1.5,2,2.5,3]

[0145] Where: x1 is the thickness of the front plate of the anti-collision beam (19); x2 is the thickness of the upper plate of the anti-collision beam (20); x3 is the thickness of the rear plate of the anti-collision beam (21); x4 is the thickness of the reinforcing rib plate of the anti-collision beam (22); x5 is the thickness of the lower plate of the anti-collision beam (23); x6 is the thickness of the energy-absorbing box (24).

[0146] The biomimetic anti-collision beam and aluminum alloy energy-absorbing box underwent multi-objective optimization. The maximum energy absorption, peak collision force at the energy-absorbing box cross-section, and various design variables were used as constraint functions, while the maximum intrusion of the anti-collision beam and the mass of the anti-collision beam and energy-absorbing box were used as objective functions. The NSGA-II genetic algorithm was employed to perform multi-objective optimization on the response surface approximation model. The optimized mathematical model is as follows:

[0147]

[0148] In the formula: m1(x) is the mass of the crash beam; m2(x) is the mass of the energy-absorbing box; D(x) is the maximum intrusion amount; E(x) is the maximum energy absorbed, E L EU Its upper and lower limits are 770J and 800J respectively; F(x) is the peak collision force, F L F U Its upper and lower limits are set to 15kN and 25kN respectively; x i For the thickness of the anti-collision beam and energy-absorbing box, x L and x U Its upper and lower limits are set to 1mm and 3mm, respectively;

[0149] Multi-objective optimization of the biomimetic anti-collision beam and aluminum alloy energy-absorbing box was performed by setting a population size of 40, an evolutionary number of 200, and a crossover probability of 0.9. After 8000 iterations, the Pareto solution set for multi-objective optimization was obtained. While ensuring that the intrusion amount does not exceed that of the steel structure, the mass of the anti-collision beam and energy-absorbing box was minimized. A compromise solution was selected from the Pareto front, and the compromise solution was determined and rounded to:

[0150] [x1,x2,x3,x4,x5,x6] = [1.5,1.4,2.2,1.4,1.4,1]

[0151] The response values ​​for maximum energy absorption E, peak impact force F, maximum intrusion of the crash beam D, crash beam mass M1, and energy absorption box mass M2 are:

[0152] [E,F,D,M1,M2]=[776.3,21.605,-62.562,0.84488,0.12467]

[0153] Based on the optimized anti-collision beam and energy-absorbing box cross-sectional thickness, a low-speed collision model was established for simulation to obtain the collision results. The collision simulation results and the optimization results obtained in HyperStudy were used to verify the error between the performance index values ​​obtained after the optimization of the approximate model and the collision simulation values, and to verify the accuracy of the approximate model and the compromise solution obtained by the NSGA-Ⅱ genetic algorithm.

[0154] In practical implementation, a biomimetic automotive crash beam and aluminum alloy energy-absorbing box were used to replace the original steel crash beam and energy-absorbing box. The thickness of the energy-absorbing box was the same as that of the original steel energy-absorbing box. Low-speed collision simulations were conducted. The parameters of the two structures are as follows: the mass of the new crash beam, the mass of the energy-absorbing box, the intrusion amount, the absorbed energy, and the collision force are 1.613 kg, 0.1317 kg, -29.3955 mm, 789.961 J, and 48.881 kN, respectively. The mass of the ordinary crash beam, the mass of the energy-absorbing box, the intrusion amount, the absorbed energy, and the collision force are 2.321 kg, 0.5846 kg, -67.6731 mm, 782.427 J, and 15.827 kN, respectively. From the perspective of collision performance, the maximum absorbed energy is not significantly different, the intrusion amount is reduced by nearly 2.3 times compared to the original structure, and the peak collision force is increased by 3.8 times. Due to the greater stiffness of the biomimetic structure, the intrusion amount is smaller, but the peak collision force is excessively large. The performance indicators of a car's front end should be appropriate; excessive stiffness will render it ineffective in protecting the vehicle during low-speed collisions. Therefore, using the performance parameters of a steel front-end structure as a reference, we conduct multi-objective optimization of the biomimetic automotive crash beam and aluminum alloy energy-absorbing box to meet usage requirements.

[0155] Furthermore, the optimal cross-sectional thickness of the aforementioned anti-collision beam and energy-absorbing box is determined by using the ply thickness of the anti-collision beam and the cross-sectional thickness of the energy-absorbing box as design variables, such as... Figure 29 As shown. The thickness of each component is taken as discrete values, with a value interval of 0.5mm. The value ranges of each design variable are as follows:

[0156] x1,x2,x3,x4,x5,x6∈[1,1.5,2,2.5,3]

[0157] In the formula: x1 is the thickness of the front plate of the anti-collision beam (19); x2 is the thickness of the upper plate of the anti-collision beam (20); x3 is the thickness of the rear plate of the anti-collision beam (21); x4 is the thickness of the reinforcing rib plate of the anti-collision beam (22); x5 is the thickness of the lower plate of the anti-collision beam (23); x6 is the thickness of the energy-absorbing box (24).

[0158] Furthermore, the Kriging modeling method is an efficient approximation model that easily yields good fitting results when applied to highly nonlinear situations. The optimal Latin hypersolution method was used to randomly sample 65 data points for each design variable, and response values ​​were obtained from these data points. Fifty sets of data were used to fit the Kriging approximation model for maximum energy absorption, peak collision force, maximum intrusion of the crash beam, and the mass of the crash beam and energy-absorbing box. The prediction accuracy of the obtained Kriging approximation model was tested using another 15 sets of data.

[0159] Furthermore, the aforementioned accuracy requirement is achieved using the coefficient of determination (R²). 2Error analysis was performed, with a value range of [0,1]. If the approximate model has high accuracy, its value should be close to 1. The determination coefficients for the maximum energy absorption, peak collision force, maximum intrusion of the anti-collision beam, mass of the anti-collision beam, and mass of the energy absorption box are 96.61%, 96.65%, 98.70%, 95.66%, and 96.74%, respectively, all greater than 90%, meeting the accuracy requirements.

[0160] Furthermore, the biomimetic anti-collision beam and energy-absorbing box undergo multi-objective optimization. The maximum energy absorption, the peak collision force at the energy-absorbing box cross-section, and various design variables are used as constraint functions, while the maximum intrusion of the anti-collision beam and the mass of the anti-collision beam and energy-absorbing box are used as objective functions. The NSGA-II genetic algorithm is employed to perform multi-objective optimization on the response surface approximation model. The optimized mathematical model is as follows:

[0161]

[0162] In the formula: m1(x) is the mass of the crash beam; m2(x) is the mass of the energy-absorbing box; D(x) is the maximum intrusion amount; E(x) is the maximum energy absorbed, E L E U Its upper and lower limits are 770J and 800J respectively; F(x) is the peak collision force, F L F U Its upper and lower limits are set to 15kN and 25kN respectively; x i For the thickness of the anti-collision beam and energy-absorbing box, x L and x U The upper and lower limits for its value are 1mm and 3mm, respectively.

[0163] Furthermore, the biomimetic anti-collision beam and energy-absorbing box underwent multi-objective optimization by setting the population size to 40, the number of generations to 200, and the crossover probability to 0.9. After 8000 iterations, the Pareto solution set for multi-objective optimization was obtained, as shown below. Figure 30 As shown. Reducing the mass of the crash beam and energy-absorbing box will lead to an increase in the intrusion of the crash beam. Excessive intrusion will reduce collision safety. The primary goal of this paper is to achieve lightweighting. Therefore, the mass of the crash beam and energy-absorbing box should be reduced as much as possible while ensuring that the intrusion does not exceed that of the steel structure. A compromise solution 25 is selected in the Pareto front, and the compromise solution 25 is determined and rounded to:

[0164] [x1,x2,x3,x4,x5,x6] = [1.5,1.4,2.2,1.4,1.4,1]

[0165] The response values ​​for maximum energy absorption E, peak impact force F, maximum intrusion of the crash beam D, crash beam mass M1, and energy absorption box mass M2 are:

[0166] [E,F,D,M1,M2]=[776.3,21.605,-62.562,0.84488,0.12467]

[0167] Furthermore, based on the optimized cross-sectional thicknesses of the anti-collision beam and energy-absorbing box, a low-speed collision model was established for simulation to obtain the collision results. The collision simulation results and the optimization results obtained in HyperStudy were used to verify the errors between the performance index values ​​obtained after the optimization of the approximate model and the collision simulation values, and to verify the accuracy of the approximate model and the compromise solution 25 obtained by the NSGA-II genetic algorithm.

[0168] Furthermore, the multi-objective optimization results of the biomimetic anti-collision beam and energy-absorbing box were analyzed. Before optimization, the total mass of the anti-collision beam and energy-absorbing box was 1.7447 kg, and after optimization, it was 0.9537 kg, a reduction of 45.34%. Before optimization, the maximum absorbed energy was 789.961 J, and after optimization, it was 787.993 J, a decrease of 0.25%, a relatively small change. Before optimization, the peak impact force of the energy-absorbing box section was 48.8811 kN, and after optimization, it was 20.2085 kN, a reduction of 58.67%. Before optimization, the maximum intrusion was -29.3955 mm, and after optimization, it was -64.2847 mm, an increase of 118.69%, a significant increase, but still within the allowable value. The results show that after optimization, the stiffness decreased, the maximum intrusion increased, and the peak impact force of the energy-absorbing box section decreased. The performance indicators after optimization tend to be reasonable and meet the usage requirements. The original steel anti-collision beam and energy-absorbing box structure had a total weight of 2.9056 kg. Compared with the original steel structure, the bionic structure of the car anti-collision beam and aluminum alloy energy-absorbing box designed and optimized by this patent has a weight reduction of 1.9519 kg, which is 67.2%.

[0169] Step 9: The structure of the biomimetic anti-collision beam is relatively complex. Using integrated molding technology can more completely reproduce the superior performance of the biomimetic automotive anti-collision beam design. A method is proposed to use photopolymerization molding technology to mold a microstructure automotive anti-collision beam with a biomimetic structure, and to apply this technology to traditional investment casting. For the molding of the biomimetic automotive anti-collision beam wax model, according to the designed 3D model of the biomimetic automotive anti-collision beam, the casting is 3D modeled in CATIA according to the gating system scheme, such as the gating system model of the biomimetic automotive anti-collision beam casting. The 3D model is imported into the computer, photosensitive resin is used as the molding material, and SLA (Stereo lithography Appearance) molding equipment is used with process parameters set to 350mw laser power, 3500mm / s scanning speed, and 0.1mm layer thickness to print the gating system model structure of the biomimetic automotive anti-collision beam casting, resulting in the biomimetic automotive anti-collision beam casting assembly wax model.

[0170] In practical implementation, the structure of biomimetic anti-collision beams is quite complex. Using integrated molding technology can completely replicate the superior performance of the biomimetic automotive anti-collision beam design. This invention proposes applying photopolymerization molding technology to an integrated molding technology for a biomimetic automotive anti-collision beam. First, based on the structural parameters of the anti-collision beam, a model tree of the biomimetic automotive anti-collision beam casting system is designed. Figure 31 Then, an SLA photopolymerization molding machine is used to print the casting tree to obtain a well-shaped biomimetic automotive anti-collision beam casting system model tree.

[0171] Furthermore, the molding of the aforementioned biomimetic automotive crash beam wax model involves, based on the designed structural parameters of the biomimetic automotive crash beam, performing a 3D modeling of the biomimetic automotive crash beam casting in CATIA according to the gating system scheme, such as the biomimetic automotive crash beam casting gating system model tree. Figure 31 The 3D model is imported into the computer, and the SLA photopolymerization molding equipment prints the biomimetic automotive anti-collision beam casting system model structure with a laser power of 350mw, a scanning speed of 3500mm / s, and a layer thickness of 0.1mm. This produces a well-shaped casting system model tree, which is used to prepare for lost-wax investment casting.

[0172] Step 10: The wax model of the casting is wrapped and covered with shell-making slurry. After the slurry solidifies, it is baked and heated in a dewaxing kettle. The wax model inside will slowly melt and flow out, and be completely removed at 750-850℃. In practice, it is preferred to completely remove it at 800℃. Since the casting pouring temperature affects the solidification time, it is necessary to control the pouring time, pouring temperature, shell temperature, and solidification temperature of the casting to ensure that the casting is successfully stamped. Then, the semi-finished product is modified and processed according to the process requirements.

[0173] In practice, the manufacturing method of the wax model of the biomimetic automotive anti-collision beam casting assembly specifically includes the following steps:

[0174] A. 3D modeling of the biomimetic automotive crash beam casting according to the gating system scheme: 3D modeling of the biomimetic automotive crash beam according to the gating system scheme is performed using CATIA to obtain the casting model tree;

[0175] B. Printing pattern: Using casting photosensitive resin as raw material, the tree pattern of the casting model is printed using photocuring molding technology;

[0176] C. Preparation of slurry: When preparing the slurry for shell making, first close the slurry tank and put in silica sol, wetting agent and refractory quartz sand. Then open the "L"-shaped slurry mixing tank and stir continuously until the slurry is completely mixed and well wetted. Then add defoamer and continue stirring until fully mixed. Prepare a specific slurry according to the characteristics and performance requirements of the resin and alloy.

[0177] D. The pre-prepared slurry is repeatedly dipped and sanded to standardize the shell of the biomimetic structure of the anti-collision beam. The shell is made of five and a half layers and covered with short carbon fiber to enhance the pull-out and fracture effect during the shell fracture process.

[0178] E. Dewaxing: Dewaxing is used to obtain the mold shell. The resin is completely removed by heating a steam dewaxing kettle to obtain the mold shell of the biomimetic car anti-collision beam structure tree. First, the steam dewaxing kettle is heated to 150°C, and then the mold shell is placed in it. The steam dewaxing kettle is then rapidly heated to 380°C and held for 0.5 hours. Then, it is heated to 800°C and held at that temperature. Finally, it is heated to 1000°C for calcination. Most of the resin has been removed at 380°C and completely removed at 800°C to obtain the wax model shell.

[0179] F. Casting: Wrap the thin-walled area of ​​the wax model shell with two layers, especially in the thin-walled area where the temperature field is low and there is a tendency to loosen, add an extra layer of heat insulation felt to control its too fast solidification. The casting time is 10 seconds, the casting temperature is 1480℃, and the mold shell temperature is 1200℃ to ensure that the wax model shell is successfully punched.

[0180] G. Cleaning the shell: Clean the casting shell with a high pressure and high speed water flow of 70-120Mpa at a cleaning efficiency of 20-30 sets / h.

[0181] H. Cleaning the casting: Separate the casting from the gating system. After separation, use a grinding wheel to grind the riser residue of the casting. Trim the edges according to the process requirements to obtain the prepared biomimetic automotive anti-collision beam.

[0182] During implementation, the wax model of the casting is wrapped and covered with a specially formulated shell-forming slurry. After the slurry solidifies, the entire casting is baked and heated in a dewaxing kettle, causing the wax model inside to slowly melt and flow out, and be completely removed at 800℃. The influence of casting pouring temperature on solidification time requires control of pouring time, pouring temperature, shell temperature, and casting solidification temperature to ensure smooth casting. Then, the semi-finished product is modified and processed according to process requirements.

[0183] Furthermore, a wax model of the biomimetic automotive crash beam casting was prepared. The biomimetic crash beam uses high-strength steel, and the casting temperature is often very high. Therefore, the selected refractory material needs to have a high melting point, strong heat resistance, stable composition, and appropriate particle size. Quartz sand and silica sol binder were used for melting and casting to create the wax model shell. When preparing the shell-making slurry, the slurry tank was first closed, and silica sol, wetting agent, and refractory material were added. The "L"-shaped slurry mixing tank was then opened, and the slurry was continuously stirred until it was completely mixed and well-wetted. Then, an antifoaming agent was added, and stirring continued until fully mixed. For shell preparation, the surface dirt of the biomimetic structural model of the crash beam was first removed with a cleaning agent and then air-dried to ensure good coating properties. The pre-prepared slurry was repeatedly applied for dipping and sanding. A standardized shell-making process was used for the biomimetic structural model of the crash beam, with five and a half layers of shell made and covered with short-cut carbon fiber to enhance the pull-out and fracture effects during the shell breakage process.

[0184] Furthermore, the preparation of the wax model requires dewaxing. First, the steam dewaxing kettle is heated to 150°C, then the biomimetic structural model of the microstructured automotive anti-collision beam is placed inside. The steam dewaxing kettle is then rapidly heated to 380°C and held for 0.5 hours, followed by heating to 800°C and holding at that temperature, and finally heating to 1000°C for calcination. Most of the resin is removed at 380°C and completely removed at 800°C.

[0185] Furthermore, to investigate the effect of casting pouring temperature on solidification time, the surface of the wax model shell was treated with insulating felt, which has a good heat insulation effect. Two layers of insulating felt were applied to the thin-walled areas of the wax model, with an additional layer added to areas where the temperature field is lower and there is a tendency for loosening, to control excessively rapid solidification. The pouring time was 10 seconds, the pouring temperature was 1500℃, and the shell temperature was controlled at 1200℃. This resulted in a favorable solidification temperature field for the casting, ensuring successful molding of the wax model shell.

[0186] Furthermore, the preparation of the wax model shell for successful molding requires further trimming and processing. The semi-finished product is modified and processed according to process requirements. A hydraulic shell removal method is used, employing high-pressure water cleaning equipment. The module is fixed on a frame, and the wax model shell is cleaned with a cleaning efficiency of 20-30 sets / hour and a high-pressure, high-speed water flow of 70-120 MPa. Next, the casting is cleaned. First, a band saw is used to separate the casting from the gating system. Second, after separation, a grinding wheel is used to grind any remaining riser in the casting. Finally, edge trimming is performed. After demolding, the casting is placed on a positioning fixture and trimmed according to process requirements to obtain the prepared biomimetic automotive anti-collision beam.

[0187] This invention aims to overcome the limitations of current automotive crash beam designs, which primarily focus on improving mechanical performance and crashworthiness by simply increasing material thickness or replacing materials with high-strength ones. This approach fails to achieve a balance between strength, material cost, manufacturing cost, and lightweighting, and often results in poor energy absorption while enhancing crashworthiness, leading to numerous design flaws and safety hazards. The invention provides a biomimetic automotive crash beam design and optimization method. The crash beam designed using this method exhibits superior crashworthiness and energy absorption compared to traditional crash beams. By designing a biomimetic curved surface feature and an internal biomimetic reinforcing rib structure, the appropriate combination of these two elements avoids the current limitations of simply increasing material thickness or replacing materials with high-strength ones. This approach achieves a balance between strength, material cost, manufacturing cost, and lightweighting, while simultaneously enhancing crashworthiness and minimizing energy absorption.

[0188] This invention combines photopolymerization molding technology with lost-wax casting to process and manufacture the outer shell and internal reinforcing supports of the crash beam, thereby improving the crash beam's impact resistance, energy absorption capacity, and lightweight level, maximizing passenger safety and achieving energy conservation and emission reduction.

[0189] Compared with the prior art, the present invention has the following advantages:

[0190] 1. The application of structural bionics, rarely used in the traditional field of automotive anti-collision beam design, is explored in this invention. By studying the unique curved surface structure of the tortoise shell and the mechanical properties of the diaphragm structure between the carapace and plastron, the invention integrates the distinctive structural form of the tortoise shell using bionics, forming an anti-collision beam structure that is aesthetically pleasing, has excellent mechanical properties, and is lightweight.

[0191] 2. Currently, automotive crash beams are mainly designed using traditional methods, focusing solely on increasing structural mass to improve crashworthiness. While traditional designs meet the deformation requirements during a collision, there is significant room for improvement in structural strength and weight reduction. The peak impact force during a collision is also relatively large, easily causing injury to occupants and pedestrians. The biomimetic structure of the automotive crash beam described in this invention overcomes the drawbacks of traditional designs, such as poor lightweighting results caused by simply increasing structural mass and material thickness to improve crashworthiness.

[0192] 3. Compared with traditional automotive crash beam structures, the biomimetic structure of the automotive crash beam described in this invention has excellent impact resistance and energy absorption capacity, thus effectively ensuring the safety of occupants. Traditional automotive front and rear crash beams are almost all stamped shell structures without internal reinforcing ribs, or have ordinary reinforcing ribs with solid cross-sections in the shape of a square, a sun, an eye, or a grid, resulting in poor energy absorption and limited crash resistance. This invention, however, designs a crossbeam with a biomimetic reinforcing rib structure. The number and spacing of the biomimetic reinforcing ribs inside the biomimetic automotive crash beam can be adjusted according to the design requirements of different automotive application environments, efficiently achieving the required strength and collision energy absorption performance of the crash beam.

[0193] 4. Currently, most automotive crash beam designs primarily focus on improving mechanical performance and crashworthiness, simply increasing material thickness or replacing materials with high-strength ones. This fails to achieve a balance between strength, material cost, manufacturing costs, and lightweighting. Furthermore, while improving crashworthiness, it's difficult to simultaneously address collision energy absorption, leading to numerous design flaws and safety hazards. This paper proposes a biomimetic automotive crash beam design and manufacturing method. The crash beam designed using this method exhibits superior crashworthiness and energy absorption compared to traditional crash beams. By designing a curved surface structure and internal biomimetic reinforcing ribs, and adjusting the thickness, spacing, and number of these ribs, the method avoids the current limitations of simply increasing material thickness or replacing materials with high-strength ones. It achieves a balance between strength, material cost, manufacturing costs, and lightweighting, while simultaneously improving crashworthiness and absorbing collision energy.

[0194] The parts of this invention not described in detail are prior art.

[0195] The embodiments selected herein for the purpose of disclosing the inventive objectives are currently considered suitable; however, it should be understood that the invention is intended to include all variations and modifications of the embodiments that fall within the scope of this concept and invention.

Claims

1. A design and optimization method for a biomimetic automotive anti-collision beam, characterized by: The method specifically includes the following steps: The first step is to analyze the shape of the anti-collision beam and the actual working condition of the stiffeners, taking into account the curved surface characteristics of the tortoise shell, and extract the similarities between the two in terms of structure, load, and function, and regard the tortoise shell and the anti-collision beam as similar systems; then, similarity analysis is performed on the anti-collision beam and the tortoise shell using similarity theory to obtain the similarity. The second step is to use HANDYSCAN3D handheld 3D laser scanning to obtain a tortoise shell carapace with good surface condition. After reconstructing the tortoise shell surface using reverse engineering technology, a geometric model is established. The 3D geometric model is then imported into HyperWorks for preprocessing and then imported into Ls-Dyna for collision analysis to study the role of the tortoise shell surface and reinforcing ribs in its deformation resistance characteristics. The third step is to extract the structural features of the tortoise shell and conduct biomimetic design of the anti-collision beam. The curved surface features of the top of the tortoise shell are extracted as the curved surface structure of the shell of the biomimetic anti-collision beam, and the shell shape curved surface structure of the biomimetic anti-collision beam is obtained. Then, a diaphragm structure connecting the carapace and the plastron of the tortoise shell is used as a reinforcing rib. The tortoise shell reinforcing rib is applied to the anti-collision beam and simplified in engineering to obtain the outline curve of the reinforcing rib beam structure of the biomimetic anti-collision beam. Then, a three-dimensional model of the biomimetic automotive anti-collision beam is constructed based on the extracted structural feature parameters. Step 4: Import the geometric model of the front bumper beam into HyperMesh software, use shell elements to mesh the beam, establish a finite element model of the steel front bumper beam, use the OptiStruct solver to solve and calculate, analyze the performance of the front bumper beam, and use finite element analysis software to perform free modal simulation analysis on the bumper beam to solve for the natural frequency, damping and mode shape of the bumper beam. The fifth step involves importing the three-dimensional model of the biomimetic anti-collision beam into HyperMesh for three-point static pressure finite element modeling, and then performing simulation analysis in Nastran software. The strength of the biomimetic anti-collision beam is studied through three-point static pressure tests and simulation analysis. The static pressure-displacement curves obtained from the tests and simulation analysis verify the effectiveness and reliability of the biomimetic method and establish the evaluation index for the strength performance of the biomimetic anti-collision beam. Step 6: In HyperMesh, establish the geometric model of the front end of the car and the rigid wall, and simplify the whole vehicle connected to the front longitudinal beam as a rigid plate. In the pre-processing software HyperMesh, shell elements are used to mesh the established model. In Ls-Dyna software, according to the C-NCAP regulations of China Automotive Technology Research Center, the results of high-speed frontal collision simulation and test are compared and analyzed. Step 7: Using the established finite element model of the vehicle front end, in the low-speed frontal collision simulation, the collider is used to replace the rigid wall in the high-speed model. Solid elements are used to mesh it. The collision results are analyzed. After the collision simulation is completed, the energy change curves during the simulation calculation process are output in HyperGraph software. If each energy curve is smooth without abrupt changes, and the maximum hourglass energy is less than 4% to 6% of the total energy, then the low-speed frontal collision simulation calculation results are reliable. Step 8: Replace the original steel anti-collision beam and energy-absorbing box with a biomimetic automotive anti-collision beam and an aluminum alloy energy-absorbing box. The thickness of the energy-absorbing box is the same as that of the original steel energy-absorbing box. Perform low-speed collision simulation to obtain the anti-collision beam mass, energy-absorbing box mass, intrusion amount, energy absorption, and collision force parameters of the two structures. Using the performance parameters of the steel front-end structure as a reference, perform multi-objective optimization on the biomimetic automotive anti-collision beam and aluminum alloy energy-absorbing box. Step 9: According to the designed bionic structure car crash beam 3D model, the bionic structure car crash beam casting is 3D modeled in CATIA according to the gating system scheme. The gating system model structure of the bionic structure car crash beam casting is printed using SLA molding equipment to obtain the bionic structure car crash beam casting assembly wax model. Step 10: The wax model of the casting is wrapped and covered with shell-making slurry. After the slurry solidifies, it is baked and heated in a dewaxing kettle. The wax model inside will slowly melt and flow out. It is completely removed at 750-850℃. The pouring time, pouring temperature, shell temperature and solidification temperature of the casting are controlled to ensure that the casting is successfully stamped. Then, the semi-finished product is modified and processed according to the process requirements.

2. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: In the first step, when the tortoise shell and the crash beam are considered as similar systems, the similarity between the tortoise shell and the crash beam is denoted as... From the formula Confirmed, formula: ； In the formula The similarity of similar elements. For weighting coefficients, when ,and , Similarity of similar elements; Selecting coefficients The evaluation factor set is , , , The similarity elements between the two components in terms of structure, load, and function are extracted respectively. Based on the evaluation factor set and matrix scaling, the judgment matrix is ​​as follows: ； In matrix P, ; Furthermore, the similarity element serves as the judgment matrix P for evaluating similar systems, and the eigenvectors of matrix P are calculated as follows: Perform a consistency check on the judgment matrix P. The consistency formula for the matrix is ​​as follows: ； In the formula The random consistency ratio, As a consistency indicator, This is the average consistency index for random records; ； In the formula To determine the maximum value of the matrix, The order of the matrix; ； Similarity elements serve as the judgment matrix P for evaluating similar systems. The ratio is derived from the consistency calculation of matrix P. , The inconsistency of matrix P is considered acceptable and reasonable. The similarity of similarity elements between the tortoise shell and the anti-collision beam similar systems is: , The similarity between the tortoise shell and the anti-collision beam system is: , Scope between.

3. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: The bionic structure of the car anti-collision beam described in the third step is based on the parameters obtained by bionically mimicking the outer special curved surface structure of the tortoise shell shape. According to the principle of bionics, the evolution diagram of the tortoise shell curved surface structure is extracted. The curved surface structure of the anti-collision beam shell is the first step of the evolution of the tortoise shell curved surface structure characteristics by cutting the top of the tortoise shell (10) in the middle of the three-dimensional tortoise shell model diagram in the evolution diagram of the evolution of the tortoise shell curved surface structure. The top of the tortoise shell is cut with a width of 100mm to extract the curved surface characteristics of the top of the tortoise shell as the curved surface structure of the bionic anti-collision beam shell. The tail of the tortoise shell (9) plays the main role in transmitting stress. In the process of designing the bionic anti-collision beam, the second and third steps of the evolution of the evolution of the tortoise shell curved surface structure characteristics are symmetrically processed on the cut tail of the tortoise shell (9). In the fourth step of the evolution of the evolution of the tortoise shell curved surface structure characteristics, the curved surface at the connection between the anti-collision beam and the energy absorption box is changed to an arc with a radius of 2800mm to obtain the curved surface structure of the shell of the bionic anti-collision beam. In the design of the biomimetic structure car anti-collision beam, the internal reinforcing rib of the biomimetic anti-collision beam is designed to simulate the characteristics of a membrane structure connecting the carapace and the plastron of a tortoise. Through the principle of biomimetic engineering, the longitudinal simplified diagram of the reinforcing rib is obtained. The biomimetic reinforcing rib (17) of the anti-collision beam is a biomimetic simplification design of the internal structure of the tortoise shell model in the simplified design of the biomimetic reinforcing rib (12). The carapace (11) of the tortoise shell structure is simplified to the front collision side (14) of the original reinforcing rib beam. The plastron (13) of the tortoise shell structure is simplified to the rear side (16) of the original reinforcing rib beam. The reinforcing rib (12) connecting the carapace (11) and the plastron (13) of the tortoise shell in the exoskeleton structure of the tortoise shell is simplified to the original reinforcing rib beam reinforcing rib plate (15). The body of the biomimetic anti-collision beam reinforcing crossbeam is composed of arc-shaped curves. The inner boundary curve of the reinforcing crossbeam is two arches. The inner contour constraint curve is a simplified design of the cross-section of a diaphragm structure, which is a tortoise shell carapace and plastron. The contour curve is obtained from the evolution diagram of the biomimetic anti-collision beam reinforcing crossbeam structure.

4. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: In the sixth step, a geometric model of the front end of the car and the rigid wall is created in HyperMesh, and the strain rate is set when creating the steel material model in the pre-processing software HyperMesh.

5. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: In the seventh step, during the low-speed frontal collision simulation, a collider is used instead of the rigid wall in the high-speed model. Solid elements are used to mesh the collider, and an initial velocity of 1111.11 mm / s is given to the collider along the positive X-axis. All degrees of freedom except for translation in the X-axis direction are constrained. The mass of the actual vehicle is given to the collider, and all degrees of freedom of the simplified rigid plate are constrained. The remaining settings are the same as those in the high-speed collision in step six.

6. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: In the eighth step, using the performance parameters of the steel front-end structure as a reference, multi-objective optimization is performed on the biomimetic automotive anti-collision beam and the aluminum alloy energy-absorbing box. The optimal cross-sectional thickness of the anti-collision beam and the energy-absorbing box is determined. The thickness of the anti-collision beam and the cross-sectional thickness of the energy-absorbing box are used as design variables. The thickness of each component is taken discretely with a value interval of 0.5 mm. The value range of each design variable is as follows: ； in: The thickness of the front plate of the anti-collision beam is (19); The thickness of the upper plate of the anti-collision beam is (20). The thickness of the rear plate of the anti-collision beam is (21); The thickness of the stiffening plate for the anti-collision beam is (22); The thickness of the lower plate of the anti-collision beam is (23); The thickness of the energy-absorbing box is (24); The biomimetic anti-collision beam and aluminum alloy energy-absorbing box underwent multi-objective optimization. The maximum energy absorption, peak collision force at the energy-absorbing box cross-section, and various design variables were used as constraint functions, while the maximum intrusion of the anti-collision beam and the mass of the anti-collision beam and energy-absorbing box were used as objective functions. The NSGA-II genetic algorithm was employed to perform multi-objective optimization on the response surface approximation model. The optimized mathematical model is as follows: ； In the formula: For the quality of the anti-collision beam; For the mass of the energy-absorbing box; This represents the maximum amount of intrusion. To maximize energy absorption, , Its upper and lower limits are set to 770J and 800J, respectively; This represents the peak collision force. , Its upper and lower limits are set to 15kN and 25kN, respectively; For the thickness of the anti-collision beam and energy-absorbing box, and Its upper and lower limits are set to 1mm and 3mm, respectively; Multi-objective optimization of the biomimetic anti-collision beam and aluminum alloy energy-absorbing box was performed by setting a population size of 40, an evolutionary number of 200, and a crossover probability of 0.

9. After 8000 iterations, the Pareto solution set for multi-objective optimization was obtained. While ensuring that the intrusion amount does not exceed that of the steel structure, the mass of the anti-collision beam and energy-absorbing box was minimized. A compromise solution was selected from the Pareto front, and the compromise solution was determined and rounded to: ； The response values ​​for maximum energy absorption E, peak impact force F, maximum intrusion of the crash beam D, crash beam mass M1, and energy absorption box mass M2 are: ； The collision results were obtained by establishing a low-speed collision model based on the optimized anti-collision beam and energy-absorbing box cross-sectional thickness. The collision simulation results and the optimization results obtained in HyperStudy were used to verify the error between the performance index values ​​obtained after the optimization of the approximate model and the collision simulation values, and to verify the accuracy of the approximate model and the compromise solution obtained by the NSGA-II genetic algorithm.

7. The design and optimization method for the biomimetic automotive anti-collision beam according to claim 1, characterized in that: The manufacturing method of the wax model of the biomimetic automotive anti-collision beam casting in step ten specifically includes the following steps: A. 3D modeling of the biomimetic automotive crash beam casting according to the gating system scheme: 3D modeling of the biomimetic automotive crash beam according to the gating system scheme is performed using CATIA to obtain the casting model tree; B. Printing pattern: Using casting photosensitive resin as raw material, the tree pattern of the casting model is printed using photocuring molding technology; C. Preparation of slurry: When preparing the slurry for shell making, first close the slurry tank and put in silica sol, wetting agent and refractory quartz sand. Then open the "L"-shaped slurry mixing tank and stir continuously until the slurry is completely mixed and well wetted. Then add defoamer and continue stirring until fully mixed. Prepare a specific slurry according to the characteristics and performance requirements of the resin and alloy. D. The pre-prepared slurry is repeatedly dipped and sanded to standardize the shell of the biomimetic structure of the anti-collision beam. The shell is made of five and a half layers and covered with short carbon fiber to enhance the pull-out and fracture effect during the shell fracture process. E. Dewaxing: Dewaxing is used to obtain the mold shell. The resin is completely removed by heating a steam dewaxing kettle to obtain the mold shell of the biomimetic car anti-collision beam structure tree. First, the steam dewaxing kettle is heated to 150°C, and then the mold shell is placed in it. The steam dewaxing kettle is then rapidly heated to 380°C and held for 0.5 hours. Then, it is heated to 800°C and held at that temperature. Finally, it is heated to 1000°C for calcination. Most of the resin has been removed at 380°C and completely removed at 800°C to obtain the wax model shell. F. Casting: Wrap the thin-walled area of ​​the wax model shell with two layers, especially in the thin-walled area where the temperature field is low and there is a tendency to loosen, add an extra layer of heat insulation felt to control its too fast solidification. The casting time is 10 seconds, the casting temperature is 1480℃, and the mold shell temperature is 1200℃ to ensure that the wax model shell is successfully punched. G. Cleaning the shell: Clean the casting shell with a high pressure and high speed water flow of 70-120Mpa at a cleaning efficiency of 20-30 sets / h. H. Cleaning the casting: Separate the casting from the gating system. After separation, use a grinding wheel to grind the riser residue of the casting. Trim the edges according to the process requirements to obtain the prepared biomimetic automotive anti-collision beam.

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