Automobile energy absorption box and preparation method thereof

Abstract

The invention discloses an automobile energy absorption box and a preparation method thereof, and relates to the technical field of automobile collision safety, the automobile energy absorption box comprises a core body front end structure and a core body rear end structure, the core body front end structure is formed by core body front end structure cell element arrays, the core body rear end structure is formed by core body rear end structure cell element arrays, and the core body rear end structure is formed by core body rear end structure cell element arrays. Core body front end structure cell elements and core body rear end structure cell elements are all surrounded by outer side structures surrounding inner side structures, the outer side structures are negative Poisson's ratio structures, the inner side structures are positive Poisson's ratio structures, impact energy is resisted by means of multiple deformation characteristics of torsion, compression and expansion of positive and negative Poisson's ratio synergistic structures, kinetic energy brought by impact is fully absorbed, and the impact resistance is improved. And SLM integral forming is adopted, the defects caused by manufacturing and assembling of a traditional energy absorption box are overcome, and the reliability and durability of the energy absorption box are improved.

Description

Technical Field

[0001] This invention relates to the field of automotive collision safety technology, and more specifically, to an automotive energy-absorbing box and its manufacturing method. Background Technology

[0002] With the rapid development of the automotive industry and the continuous growth of vehicle ownership, collision accidents are frequent, making vehicle safety performance a core concern for consumers and industry regulators. As the first line of defense for absorbing collision energy, the performance of the energy absorption box directly determines the rationality of the energy transfer path during a collision, the control effect of peak impact force, and the degree of protection for key structures such as the vehicle's longitudinal beams. Simultaneously, it must also meet the requirements of vehicle lightweighting. Therefore, stringent requirements are placed on the comprehensive performance of the energy absorption box in terms of "lightweight design, high energy absorption efficiency, and structural stability."

[0003] However, existing energy-absorbing boxes generally have the following drawbacks: 1. Traditional energy-absorbing boxes generally adopt simple unit cell structures, such as hexagonal honeycomb, square, and circular structures. When subjected to impact, this structure only produces a single expansion deformation. The deformation mode is simple, and the impact resistance is insufficient. The energy-absorbing box has a poor effect on absorbing collision energy. It can only absorb a small amount of collision energy, and the rest of the energy will extend to the vehicle body, causing vehicle damage. More seriously, it can cause injury to the occupants. 2. In traditional processes, energy-absorbing boxes have manufacturing and assembly defects, which cause stress to concentrate at the connection points during collisions, easily leading to core detachment or shell cracking. Summary of the Invention

[0004] To address the problems of insufficient impact resistance, core structure deformation, limited energy absorption modes, and assembly defects inherent in existing energy-absorbing boxes, this invention aims to provide an automotive energy-absorbing box and its manufacturing method. Based on the biomimetic negative Poisson's ratio and hierarchical structure characteristics of the mantis shrimp's hard forelegs, a positive and negative Poisson's ratio synergistic structure is constructed to generate an embedded energy-absorbing core. The core is integrally molded using SLM technology. Leveraging the torsional, compression, and expansion deformation characteristics of the positive and negative Poisson's ratio synergistic structure and the advantages of additive manufacturing in reducing manufacturing defects, the impact resistance of the energy-absorbing box is improved, and excellent energy absorption performance is achieved.

[0005] The technical solution is as follows: This invention provides an automotive energy-absorbing box, comprising: two fixing plates and an energy-absorbing box shell, the two ends of which are fixedly connected to the two fixing plates respectively, and two kinds of biomimetic chiral energy-absorbing cores, which are filled into the interior of the energy-absorbing box shell, and the two kinds of biomimetic chiral energy-absorbing cores are a core front end structure and a core rear end structure respectively. The front end structure of the core is composed of a core front end structure cell array, and the rear end structure of the core is composed of a core rear end structure cell array. Both the front-end and rear-end structural cells of the core are surrounded by an outer structure, with the outer structure being a negative Poisson's ratio structure and the inner structure being a positive Poisson's ratio structure.

[0006] Furthermore, the outer structure of the core front end structural cell is composed of 6 connected outer chiral structures, which are connected in the shape of a cube. The center of the inner structure of the core front end structural cell is a cube frame, and the cube frame is fixedly connected to the outer chiral structures by a cylindrical rod.

[0007] Furthermore, the center of the outer chiral structure is a ring, and four rods are connected to the outside of the ring. The rods are tangent to the ring, and the angle between adjacent rods is the same. The end of the rod in each outer chiral structure is connected to the end of the rods of the other two adjacent outer chiral structures. The six faces of the cube are respectively aligned with the six outer chiral rings. Each ring is fixedly connected to the face of the cube it faces by four cylindrical rods, and the cylindrical rods are connected to the center of the edge of the cube.

[0008] Furthermore, each face of the cube is internally connected to a cross structure, which consists of two round rods, and the endpoints of the cross structure are connected to the center of each edge.

[0009] Furthermore, the outer structure of the core rear end structural cell is a negative Poisson's ratio honeycomb structure, and the inner structure is a positive Poisson's ratio honeycomb structure. The negative Poisson's ratio honeycomb structure and the positive Poisson's ratio honeycomb structure are connected by a chiral connection structure, which is a negative Poisson's ratio structure.

[0010] Furthermore, the negative Poisson's ratio honeycomb structure includes two symmetrical and parallel sides, with the same side of the two sides connected by two inclined planes, and the two inclined planes are inclined inward. The outer side of the positive Poisson's ratio honeycomb structure is a cylinder, and the center of the cylinder is a regular hexagonal cavity; The chiral connection structure consists of four plates. One end of each plate is tangent to the outer surface of the cylinder, and the angle between adjacent plates is the same. The other ends of the four plates are connected to the ends of the two sides of the negative Poisson's ratio honeycomb structure, respectively.

[0011] Furthermore, the intersection of adjacent core rear end structure cells within the core rear end structure forms a positive Poisson's ratio honeycomb structure.

[0012] Furthermore, the fixing plate, the energy-absorbing box shell, the front end structure of the core, and the rear end structure of the core are all made of aluminum alloy and coated with an anodized film.

[0013] The present invention also provides a method for preparing the automotive energy-absorbing box as described above, comprising the following steps: Step 1: Based on the characteristics of helical chirality, establish models of two biomimetic chiral energy-absorbing cores. The two biomimetic chiral energy-absorbing cores include the front end structure and the rear end structure of the core. Step 2: Import the models of the two biomimetic chiral energy-absorbing cores established in Step 1 into the 3D printing software, and use selective laser melting technology to complete the molding of the two biomimetic chiral energy-absorbing cores. Step 3: Fill the two biomimetic chiral energy-absorbing cores from Step 2 into the energy-absorbing box shell; Step four: Weld the fixing plate to the energy-absorbing box shell to complete the preparation of the automotive energy-absorbing box.

[0014] Furthermore, after the two biomimetic chiral energy-absorbing cores in step two are formed, they undergo annealing treatment.

[0015] The beneficial effects of this invention are as follows: The core of this automotive energy-absorbing box adopts an external negative Poisson's ratio structure surrounding an internal positive Poisson's ratio structure. Compared with the traditional honeycomb core energy-absorbing box, which undergoes a single expansion deformation when subjected to impact, the core structure of this automotive energy-absorbing box undergoes a coordinated deformation of positive and negative Poisson's ratio structures when subjected to impact load. This transforms the energy-absorbing box from a single expansion deformation into a torsional-compression-expansion coordinated deformation to resist impact energy, converting the impact energy into internal energy of the core and fully absorbing the kinetic energy brought by the impact. The core of this energy-absorbing box adopts a front and rear dual-core design, which has the advantages of multiple deformation modes, multiple force transmission paths and multiple energy absorption, greatly improving the stability of energy dissipation of the energy-absorbing box. This automotive energy-absorbing box is manufactured using SLM (Surface Mount Technology) in a single piece, avoiding the defects associated with traditional energy-absorbing box manufacturing and assembly. This improves the reliability and durability of the energy-absorbing box and ensures self-support during the 3D printing process. Furthermore, parameters such as the positive and negative Poisson's ratio structural dimensions and angles can be adjusted according to different vehicle models and operating conditions to cope with various impact conditions. This design approach is not only low-barrier to entry but also simple to manufacture and highly practical. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the biomimetic design of two biomimetic chiral energy-absorbing cores of the present invention.

[0017] Figure 2 This is a schematic diagram of the overall structure of the automotive energy-absorbing box of the present invention.

[0018] Figure 3 This is a schematic diagram of the structure of the two biomimetic chiral energy-absorbing cores of the present invention.

[0019] Figure 4 This is a schematic diagram of the front-end structure cell of the core of the present invention.

[0020] Figure 5 This is a schematic diagram of the core rear end structure cell of the present invention.

[0021] The reference numerals in the accompanying drawings of this invention are as follows: 1. Fixing plate; 2. Energy-absorbing box housing; 31. Core front end structure; 311. Outer chiral structure; 312. Cubic frame; 313. Cylindrical rod; 314. Core front end structure cell. 32. Core rear end structure; 321. Negative Poisson's ratio honeycomb structure; 322. Positive Poisson's ratio honeycomb structure; 323. Chiral connection structure; 324. Core rear end structure cell. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Example 1: Please refer to Figure 2 This embodiment discloses an automotive energy-absorbing box comprising: two fixing plates 1, an energy-absorbing box shell 2, and two biomimetic chiral energy-absorbing cores.

[0024] The fixing plate 1 is made of rectangular aluminum alloy plate by CNC milling. The plate thickness is designed to be 10mm. Bolt holes are provided at the four corners of the fixing plate 1. One fixing plate 1 is connected to the car bumper by bolts, and the other fixing plate 1 is connected to the longitudinal beam of the car body by bolts.

[0025] The energy-absorbing box shell 2 is made by extrusion molding and has a thickness of 10mm. Its two ends are connected to two fixing plates 1 by welding. The welded joints are sprayed with polyvinyl fluoride anti-corrosion coating with a thickness of 5μm to ensure corrosion resistance and connection reliability.

[0026] Please see Figure 1 Based on the scanning electron microscope image of the mantis shrimp's forelegs, it can be found that they exhibit helical chiral characteristics and hierarchical structural features in the front and rear structures. Therefore, based on the mantis shrimp's hard forelegs and the biomimetic negative Poisson's ratio and hierarchical structural features, two biomimetic chiral energy-absorbing cores were designed. The two biomimetic chiral energy-absorbing cores were filled into the front and rear ends of the energy-absorbing box shell 2, respectively, to form multi-level energy absorption.

[0027] Chirality refers to the property that an object cannot be superimposed on its mirror image. Due to their unique geometric configuration, chiral structures can achieve uniform energy dissipation through rotation and deformation when subjected to impact, thereby effectively reducing the initial peak force and avoiding stress concentration.

[0028] Please see Figure 3 The two types of biomimetic chiral energy-absorbing cores are the front-end structure 31 and the rear-end structure 32. The fixing plate 1, the energy-absorbing box shell 2, the front-end structure 31, and the rear-end structure 32 are all made of aluminum alloy and coated with an anodized film with a thickness of ≥10μm to extend their service life.

[0029] Please see Figure 2 and Figure 3 The front end structure 31 and the rear end structure 32 of the core are respectively filled into the front end and rear end of the energy absorption box shell 2.

[0030] Please see Figure 4 The core front end structure 31 is composed of an array of core front end structure cells 314, with the inner structure surrounded by an outer structure. The outer structure consists of six interconnected outer chiral structures 311, arranged in a cube shape, effectively replacing each of the six planes of the cube with an outer chiral structure 311. The center of each outer chiral structure 311 is a circular ring with an inner diameter of 9.6 mm and an outer diameter of 13.2 mm. Four rods are evenly connected to the outer side of the ring, tangent to the ring, with adjacent rods spaced at the same angle. The rods measure 29 mm × 1.8 mm × 2.2 mm. The end of each rod in each outer chiral structure 311 connects to the ends of the rods in the two adjacent outer chiral structures 311, with the connection point of every three rods forming the vertex of the outer chiral structure 311.

[0031] The center of the inner structure of the core front end structural cell 314 is a cube frame 312. The thickness of the edge of the cube frame 312 is 1.8mm. The six faces of the cube frame 312 are respectively aligned with the six rings of the outer chiral structure 311. Each ring is fixedly connected to the face of the cube frame 312 it is aligned with by four cylindrical rods 313. The cylindrical rods 313 are connected to the center point of the edge of the cube frame 312. The cylindrical rods 313 are perpendicular to the edge of the cube frame 312. The diameter of the cylindrical rods 313 is 1.8mm.

[0032] Each face of the cube frame 312 is internally connected by a cross structure, which consists of two round rods with a diameter of 1.8 mm. The endpoints of the cross structure are connected to the center of each edge of the cube frame 312.

[0033] For the core front-end structural cell 314, its outer chiral structure 311 has a negative Poisson's ratio characteristic, while the cubic frame 312 and the cylindrical rod 313 have a positive Poisson's ratio characteristic. When subjected to impact, the outer chiral structure 311 first undergoes contraction and torsional deformation, while the cylindrical rod 313 and the cubic frame 312 undergo expansion deformation, thereby achieving coordinated deformation of the positive and negative Poisson's ratio structures to absorb impact energy.

[0034] Please see Figure 5 The core rear structural cell 324 is entirely surrounded by an outer structure, which in turn encloses an inner structure. The outer structure of the core rear structural cell 324 is a negative Poisson's ratio honeycomb structure 321. This structure includes two symmetrical and parallel sides, connected on the same side by two inclined planes, which slope inwards. The two sides of the negative Poisson's ratio honeycomb structure 321 and their connected inclined planes form four vertices. The overall dimensions of the negative Poisson's ratio honeycomb structure 321 are 50mm × 50mm × 80mm, and the thickness of the sides and inclined planes is 3mm.

[0035] The inner structure of the core rear structural cell 324 is a positive Poisson ratio honeycomb structure 322. The outer side of the positive Poisson ratio honeycomb structure 322 is a cylinder with an outer diameter of 15mm. The center of the cylinder is a regular hexagonal cavity with a side length of 4mm.

[0036] The negative Poisson's ratio honeycomb structure 321 and the positive Poisson's ratio honeycomb structure 322 are connected by a chiral connection structure 323, which is a negative Poisson's ratio structure. Specifically, the chiral connection structure 323 consists of four plates, one end of which is tangent to the outer surface of the cylinder, and the angle between adjacent plates is the same. The other ends of the four plates are connected to the four vertices of the negative Poisson's ratio honeycomb structure 321, respectively.

[0037] The core rear end structure 32 is formed by an array of core rear end structure cells 324. Preferably, the intersection of adjacent core rear end structure cells 324 located inside forms a positive Poisson's ratio honeycomb structure. Specifically, the apex of the negative Poisson's ratio honeycomb structure 321 located inside is shaped like a quarter-cell honeycomb unit, and four quarter-cell honeycomb units are spliced ​​together to form a complete honeycomb structure. In this embodiment, a complete honeycomb structure is a regular hexagon with a side length of 5.4 mm. By designing a positive Poisson's ratio honeycomb structure at the intersection of core rear end structure cells 324, a positive and negative Poisson's ratio staggered structure is further formed. The positive and negative Poisson's ratio structures work together to deform and absorb impact energy, realizing energy dissipation in multiple deformation modes and improving the stability of energy dissipation.

[0038] For the core rear structural cell 324, the outer negative Poisson's ratio honeycomb structure 321 has negative Poisson's ratio characteristics, the inner positive Poisson's ratio honeycomb structure 322 has positive Poisson's ratio characteristics, and the chiral connection structure 323 has negative Poisson's ratio characteristics. When subjected to impact, the outer negative Poisson's ratio honeycomb structure 321 first contracts and deforms, which drives the chiral connection structure 323 to further contract. The positive Poisson's ratio honeycomb structure 322 undergoes torsional deformation. When it contracts to a certain extent, the positive Poisson's ratio honeycomb structure 322 begins to expand, ultimately achieving multiple energy dissipations.

[0039] The working principle of this automotive energy-absorbing box is as follows: When the car is impacted, the impact energy first acts on the front fixed plate 1. The fixed plate 1 transfers the energy to the front structure 31 of the core. The outer chiral structure 311 undergoes torsional contraction deformation along the central ring. The cylindrical rod 313 realizes the energy transfer. The cylindrical rod 313 and the cubic frame 312 are crushed under the action of the impact force, which squeezes the outer chiral structure 311 and realizes energy absorption.

[0040] When the front end structure 31 of the core is completely crushed, the impact force is transmitted to the rear end structure 32 of the core. First, the outer negative Poisson's ratio honeycomb structure 321 begins to shrink and deform, which drives the chiral connection structure 323 to undergo torsional deformation. The chiral connection structure 323 also has negative Poisson's ratio characteristics. When the two negative Poisson's ratio structures, negative Poisson's ratio honeycomb structure 321 and chiral connection structure 323, shrink, they will squeeze the positive Poisson's ratio honeycomb structure 322. The positive Poisson's ratio honeycomb structure 322 begins to expand, realizing multi-stage absorption of impact energy.

[0041] Ultimately, the residual impact force, after undergoing multiple deformations, multiple energy dissipations, and multiple force transmission paths, is smoothly transmitted to the vehicle longitudinal beams through the rear fixed plate 1, effectively reducing the peak collision force, preventing the passenger compartment from being subjected to severe impact, and achieving the goal of passive safety protection. Example

[0042] This embodiment discloses a method for preparing an automotive energy-absorbing box, used to prepare the automotive energy-absorbing box as described in Embodiment 1, including the following steps: Step 1: Based on the helical chiral characteristics of the mantis shrimp's forelegs, establish models of two biomimetic chiral energy-absorbing cores. The two biomimetic chiral energy-absorbing cores include a front end structure 31 and a rear end structure 32.

[0043] Step two involves importing the models of the two biomimetic chiral energy-absorbing cores created in Step one into the 3D printing software. Selective laser melting (SLM) is then used to form the two biomimetic chiral energy-absorbing cores. The laser power is 300W, the scanning speed is 1000mm / s, the layer thickness is 0.03mm, the preheating temperature is 200℃, and annealing is performed after forming.

[0044] Step 3: Fill the two biomimetic chiral energy-absorbing cores from Step 2 into the energy-absorbing box shell 2. The front end structure 31 of the core is filled into the front end of the energy-absorbing box shell 2, and the rear end structure 32 of the core is filled into the rear end of the energy-absorbing box shell 2.

[0045] Step four: Weld the two fixing plates 1 to the energy-absorbing box shell 2. Spray polyvinyl fluoride anti-corrosion coating on the weld joints. The coating thickness is 5μm. This completes the preparation of the automotive energy-absorbing box.

[0046] The biomimetic chiral energy-absorbing core in this energy-absorbing box is molded in one piece using SLM technology, avoiding defects caused by the manufacturing and assembly of the energy-absorbing box, improving the reliability and durability of the energy-absorbing box. Moreover, the structure of this energy-absorbing box is interconnected layer by layer, which can ensure self-support during the 3D printing process, reduce the need for support materials during printing, thereby improving efficiency, saving materials and improving surface quality.

[0047] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the present invention.

Claims

1. An energy-absorbing box for automobiles, comprising: Two fixed plates (1) and an energy-absorbing box shell (2), with the two ends of the energy-absorbing box shell (2) fixedly connected to the two fixed plates (1) respectively. The feature is that it also includes two kinds of biomimetic chiral energy-absorbing cores, which are filled into the interior of the energy-absorbing box shell (2). The two kinds of biomimetic chiral energy-absorbing cores are a core front end structure (31) and a core rear end structure (32). The front end structure (31) of the core is formed by an array of front end structure cells (314), and the rear end structure (32) of the core is formed by an array of rear end structure cells (324). Both the front end structural cell (314) and the rear end structural cell (324) of the core are surrounded by an outer structure, with the outer structure being a negative Poisson's ratio structure and the inner structure being a positive Poisson's ratio structure.

2. The automotive energy-absorbing box according to claim 1, characterized in that, The outer structure of the core front end structural cell (314) is composed of 6 outer chiral structures (311) connected together. The 6 outer chiral structures (311) are connected in the shape of a cube. The center of the inner structure of the core front end structural cell (314) is a cube frame (312). The cube frame (312) and the outer chiral structure (311) are fixedly connected by a cylindrical rod (313).

3. The automotive energy-absorbing box according to claim 2, characterized in that, The center of the outer chiral structure (311) is a ring, and four rods are connected to the outside of the ring. The rods are tangent to the ring, and the angle between adjacent rods is the same. The end of the rod in each outer chiral structure (311) is connected to the end of the rod of the other two adjacent outer chiral structures (311). The six faces of the cube (312) are respectively facing the six outer chiral structures (311) of the ring. Each ring is fixedly connected to the face of the cube (312) it faces by four cylindrical rods (313), and the cylindrical rods (313) are connected to the center of the edge of the cube (312).

4. The automotive energy-absorbing box according to claim 3, characterized in that, The cube (312) has a cross structure inside each face, which consists of two round rods and the endpoints of the cross structure are connected to the center of each edge.

5. The automotive energy-absorbing box according to claim 1, characterized in that, The outer structure of the core rear structural cell (324) is a negative Poisson's ratio honeycomb structure (321), and the inner structure is a positive Poisson's ratio honeycomb structure (322). The negative Poisson's ratio honeycomb structure (321) and the positive Poisson's ratio honeycomb structure (322) are connected by a chiral connection structure (323), which is a negative Poisson's ratio structure.

6. The automotive energy-absorbing box according to claim 5, characterized in that, The negative Poisson's ratio honeycomb structure (321) includes two symmetrical and parallel sides, with the same side of the two sides connected by two inclined planes, and the two inclined planes are inclined inward. The outer side of the positive Poisson's ratio honeycomb structure (322) is a cylinder, and the center of the cylinder is a regular hexagonal cavity; The chiral connection structure (323) consists of four plates. One end of each plate is tangent to the outer surface of the cylinder. The angle between adjacent plates is the same. The other ends of the four plates are connected to the ends of the two sides of the negative Poisson's ratio honeycomb structure (321).

7. The automotive energy-absorbing box according to claim 5, characterized in that, The intersection of adjacent core rear end structure cells (324) inside the core rear end structure (32) forms a positive Poisson's ratio honeycomb structure.

8. The automotive energy-absorbing box according to claim 1, characterized in that, The fixing plate (1), the energy-absorbing box shell (2), the core front end structure (31) and the core rear end structure (32) are all made of aluminum alloy and coated with an anodized film.

9. A method for preparing an automotive energy-absorbing box as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Based on the characteristics of helical chirality, establish models of two biomimetic chiral energy-absorbing cores. The two biomimetic chiral energy-absorbing cores include a front end structure (31) and a rear end structure (32). Step 2: Import the models of the two biomimetic chiral energy-absorbing cores established in Step 1 into the 3D printing software, and use selective laser melting technology to complete the molding of the two biomimetic chiral energy-absorbing cores. Step 3: Fill the two biomimetic chiral energy-absorbing cores from Step 2 into the energy-absorbing box shell (2); Step 4: Weld the fixing plate (1) to the energy-absorbing box shell (2) to complete the preparation of the automotive energy-absorbing box.

10. The method for preparing an automotive energy-absorbing box according to claim 9, characterized in that, After the two types of biomimetic chiral energy-absorbing cores in step two are formed, they undergo annealing.

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