Strong-impact-resistant three-layer composite honeycomb aluminum negative poisson ratio filling front longitudinal beam protection structure

Abstract

The invention discloses a strong-impact-resistant three-layer composite honeycomb aluminum negative poisson ratio filling front longitudinal beam protection structure, and belongs to the technical field of vehicle passive safety and protection structures. The protection structure comprises a protection base body and a filling functional layer arranged in the protection base body. The protection base body is used for providing the main body bearing capacity of the front longitudinal beam, and the filling functional layer is of a multi-layer filling structure with different stress mechanisms, so that the front longitudinal beam achieves graded dispersion of impact loads in the collision process, loads are stably transmitted, and structure invasion is restrained; the protection capacity of the front structure of the vehicle under the strong impact working condition is improved through the protection base body and the filling functional layer. By arranging the multiple layers of filling structures with different stress characteristics, the front longitudinal beam can rapidly reduce the acceleration peak value in the initial stage of collision, achieve stable energy absorption in the middle stage, keep the acceleration stable, effectively inhibit the structure from invading into a passenger compartment in the later stage, and improve the overall protection effect when a vehicle is in head-on collision.

Description

Technical Field

[0001] This invention belongs to the field of vehicle passive safety and protection structure technology, specifically relating to a three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protection structure that resists strong impacts. Background Technology

[0002] During vehicle operation, collisions are a major cause of vehicle structural damage and occupant injuries or fatalities, especially in frontal collisions where the front structure must withstand high-amplitude impact loads in a very short time. These strong impact loads are characterized by short duration, high peak load, and concentrated energy, easily causing large deformations in the front structure and even intrusion into the passenger compartment, posing a serious threat to the safety of occupants. During a collision, the deformation mode, acceleration response, and load transfer process of the front structure significantly influence the impact injuries suffered by occupants. Therefore, a protective structure capable of withstanding strong impacts, stably absorbing energy, and providing reliable intrusion resistance is crucial for improving the passive safety performance of vehicles.

[0003] Currently, most vehicle front protection structures follow the traditional design approach of thin-walled metal components, forming energy-absorbing components such as front longitudinal beams through methods such as steel plate bending and welding. However, this type of front protection structure still has the following shortcomings under strong impact conditions:

[0004] (1) Limited protection capability. Existing front longitudinal beams mostly use a single material or a single structural form, which are prone to problems such as excessively high initial acceleration peak and unstable energy absorption process under strong frontal collision conditions; although the load-bearing capacity can be improved by simply increasing the thickness of the plate, it will significantly increase the overall vehicle weight and cost, and it is difficult to achieve stable buffer energy absorption, which is not conducive to the lightweight design requirements of the vehicle;

[0005] (2) Adverse secondary effects after collision. Under strong impact, traditional thin-walled metal structures are prone to local buckling, tearing or fracture. After the damage, the passenger compartment is intruded in an uncontrolled direction, causing secondary damage to the passenger compartment and the people inside the vehicle.

[0006] In summary, during a frontal collision, the front longitudinal beam structure is prone to severe acceleration response, concentrated load transfer, and insufficient resistance to intrusion under strong impact loads, making it difficult to provide effective protection for the vehicle structure and occupant safety at different stages of the collision. Summary of the Invention

[0007] In response to the problems pointed out in the background art, the present invention proposes a three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure that resists strong impacts. The front longitudinal beam is provided with a multi-layer functional filling structure. Each filling layer is fixed to the inner wall of the cap-shaped beam by a stop structure and adhesive method. During the collision process, they cooperate to participate in the force and realize the graded dispersion and transmission of strong impact loads.

[0008] Technical Solution: To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure with strong impact resistance includes a protective substrate and a filling functional layer disposed within the protective substrate. The protective substrate provides the main load-bearing capacity of the front longitudinal beam, and the filling functional layer is a multi-layer filling structure with different stress mechanisms, enabling the front longitudinal beam to achieve graded dispersion of impact loads, stable load transfer, and suppression of structural intrusion during a collision. The protective substrate and the filling functional layer improve the protection capability of the vehicle's front structure under strong impact conditions.

[0010] Preferably, the protective substrate includes a cap-shaped component and a cover plate disposed at the lower end of the cap-shaped component; the cap-shaped component and the cover plate are welded together to form a cap-shaped beam.

[0011] Preferably, a multi-layered stop structure is provided on the inner wall of the cap-shaped part along the longitudinal direction; structural adhesive is distributed and arranged on the inner walls of both the cap-shaped part and the cover plate.

[0012] Preferably, the cap-shaped component has three layers of stop structures, and the thickness of the cap-shaped component's cross-section is the same as the thickness of each layer of stop structures, with each thickness set to a value of [missing value]. The dimensions of each layer of the stop structure satisfy the following formula:

[0013] ;

[0014] ;

[0015] in, , , These represent the widths of the three-layer stop structure; , , These represent the heights of the three-layer stop structure; Indicates the width of the cross-section of the hat-shaped component; This indicates the height of the cross-section of the hat-shaped component.

[0016] Preferably, the filling functional layer includes a honeycomb aluminum I layer, a honeycomb aluminum II layer, and a negative Poisson's ratio layer arranged sequentially along the longitudinal direction of the hat-shaped beam; the honeycomb aluminum I layer is located in the front end region of the front longitudinal beam; the honeycomb aluminum II layer is located in the middle region of the front longitudinal beam; and the negative Poisson's ratio layer is located in the rear end region of the front longitudinal beam and is close to the passenger compartment.

[0017] Preferably, both the honeycomb aluminum layer I and the honeycomb aluminum layer II are composed of regularly arranged hexagonal honeycomb cells, with the axial direction of the honeycomb cells aligned with the longitudinal direction of the vehicle; the negative Poisson's ratio layer is composed of an array of re-entry negative Poisson's ratio cells, with the cells containing concave connecting rod structures that generate a lateral contraction effect during longitudinal compression; the honeycomb aluminum layer I, the honeycomb aluminum layer II, the negative Poisson's ratio layer, the cap-shaped component, and the cover plate are connected by adhesive.

[0018] Preferably, the cap-shaped component and the cover plate have the same length, and their length values ​​are both set to... The lengths of the longitudinally arranged honeycomb aluminum I layer, honeycomb aluminum II layer, and negative Poisson's ratio layer are respectively , , The honeycomb aluminum layer I, honeycomb aluminum layer II, and negative Poisson's ratio layer have the same width, and their width values ​​are all set to... The heights of the honeycomb aluminum layer I, honeycomb aluminum layer II, and negative Poisson's ratio layer are all the same, and their height values ​​are all set to... Specifically, it must meet the following size requirements:

[0019] ;

[0020] ;

[0021] ;

[0022] ;

[0023] in, This indicates the thickness value of the cross-section of the hat-shaped component; Indicates the width of the cross-section of the hat-shaped component; This indicates the height of the cross-section of the hat-shaped component.

[0024] Preferably, the out-of-plane equivalent compressive yield strength of the honeycomb aluminum is: The out-of-plane crushing platform stress is The yield strength of the base aluminum alloy is The equivalent density of honeycomb aluminum is The density of the base aluminum alloy is It meets the following strength requirements:

[0025] ;

[0026] ;

[0027] 1;

[0028] Where π represents the plastic hinge rotation constant, h1 represents the height of the honeycomb cell in the loading direction, and l1 represents the length of the honeycomb cell wall. Indicates the angle of inclination of the cell wall; The geometric correction factor representing the load-bearing capacity of honeycomb aluminum at the yield stage. This represents the relative density scaling index during the yielding stage; Geometric correction factor representing the load-bearing capacity of aluminum cellular batteries during the platform phase; This represents the relative density scaling index for the platform phase.

[0029] As a preferred option, the cap-shaped parts and cover plates are made of high-strength steel; the base materials for both the honeycomb aluminum I layer and the honeycomb aluminum II layer are made of aluminum alloy.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0031] (1) The present invention provides a three-layer composite honeycomb aluminum negative Poisson ratio filled front longitudinal beam protective structure that resists strong impact. By setting a multi-layer filling structure with different stress characteristics in the longitudinal direction inside the front longitudinal beam, the front longitudinal beam exhibits a segmented response in the early, middle and late stages of the collision. It can quickly reduce the peak acceleration in the early stage of the collision, achieve stable energy absorption in the middle stage and maintain stable acceleration, and effectively suppress the structure from intruding into the passenger compartment in the later stage, thereby improving the overall protection effect during the frontal collision of the vehicle.

[0032] (2) The present invention provides a three-layer composite honeycomb aluminum negative Poisson ratio filled front longitudinal beam protective structure that resists strong impact. By setting an in-plane pressure honeycomb aluminum filling layer in the middle of the front longitudinal beam, the structure has the ability to actively constrain the in-plane deformation direction under strong impact. It can guide the front longitudinal beam to undergo controlled compression deformation mainly along the longitudinal direction, avoid uncontrolled deformation caused by excessive bending and tearing in the middle area of ​​the front longitudinal beam and intrusion into the passenger compartment, thereby effectively reducing the risk of adverse secondary effects during the collision. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure of the present invention, wherein (a) is a schematic diagram of the structure of the protective substrate; (b) is a front view of the protective structure; (c) is a front view of the filling functional layer; and (d) is a top view of the filling functional layer.

[0034] Figure 2 This is a schematic diagram of the honeycomb aluminum layer of the present invention, wherein (a) is a three-dimensional view of the honeycomb aluminum layer, (b) is a unit schematic diagram of the honeycomb aluminum layer, and (c) is a front view of the honeycomb aluminum layer;

[0035] Figure 3 This is a schematic diagram of the negative Poisson's ratio layer of the present invention, wherein (a) is a three-dimensional view of the negative Poisson's ratio layer, (b) is a unit schematic diagram of the negative Poisson's ratio layer, and (c) is a front view of the negative Poisson's ratio layer;

[0036] The components are: 1. Honeycomb aluminum layer I; 2. Honeycomb aluminum layer II; 3. Negative Poisson's ratio layer; 4. Hat-shaped component; 5. Cover plate. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0038] Example 1

[0039] The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure provided in this embodiment mainly includes a protective substrate and a filling functional layer disposed within the protective substrate.

[0040] like Figure 1 As shown, the protective substrate includes a cap-shaped component 4 and a cover plate 5; the cap-shaped component 4 and the cover plate 5 are welded to form a cap-shaped beam, thereby forming an outer shell protective structure; the cap-shaped component 4 is used to provide the main load-bearing capacity of the front longitudinal beam, and the cover plate 5 is used to cooperate with the cap-shaped component 4 to form a closed section.

[0041] Multiple stop structures are provided longitudinally on the inner wall of the cap-shaped part 4 to limit the multi-layer filling structure inside the cap-shaped part 4; structural adhesive is distributed on the inner walls of the cap-shaped part 4 and the cover plate 5; the multi-layer filling structure is fixed on the cap-shaped part 4 and the cover plate 5 by the structural adhesive.

[0042] In this embodiment, both the cap-shaped component 4 and the cover plate 5 are made of high-strength steel.

[0043] The cap-shaped component 4 and the cover plate 5 have the same length, and their length values ​​are both set to... The height of section 4 of the hat-shaped component is The width of section 4 of the hat-shaped component is The thickness of the 4-section of the hat-shaped component is the same as the thickness of each layer of the stop structure, and its thickness value is set to... And not less than 1.6mm, the thickness of cover plate 5 is And not less than 1.2mm, the widths of the three layers of the stop structure from the impact layer inward are respectively , , The heights of the three-layer stop structure are respectively , , The cap-shaped beam, formed by welding the cap-shaped component 4 and the cover plate 5, is made of high-strength steel with a yield strength of not less than 500 MPa and a tensile strength of not less than 780 MPa. The dimensions of each layer of the stop structure satisfy the following formula:

[0044] ;

[0045] ;

[0046] In this embodiment, the length of both the cap-shaped component 4 and the cover plate 5 is 1000mm. The thickness of the cap-shaped component 4 is 1.8mm, and the thickness of the cover plate 5 is 1.5mm. The height of the cap-shaped component 4 is 100mm, and the width is 80mm. Stop structures with a thickness of 1.8mm are distributed at distances of 248.65mm, 747.75mm, and 998.2mm from the front end, respectively. The heights of the stops are 49.1mm, 73.65mm, and 98.2mm, respectively. The cap-shaped component 4 and the cover plate 5 are welded to form a hollow cap-shaped beam structure, which serves as the load-bearing shell of the entire protective structure and is used to withstand and transmit longitudinal impact loads during collisions.

[0047] The filling functional layer includes a honeycomb aluminum layer I 1 subjected to out-of-plane impact, a honeycomb aluminum layer II 2 subjected to in-plane impact, and a negative Poisson's ratio layer 3; the honeycomb aluminum layer I 1, the honeycomb aluminum layer II 2, and the negative Poisson's ratio layer 3 are arranged sequentially along the longitudinal direction of the cap-shaped beam; and are connected to the cap-shaped component 4 and the cover plate 5 by adhesive bonding, and the honeycomb aluminum layer I 1, the honeycomb aluminum layer II 2, and the negative Poisson's ratio layer 3 are separated and limited by the stop structure provided on the cap-shaped component 4.

[0048] The honeycomb aluminum layer I 1 is located at the front end of the front longitudinal beam and serves as the impact-bearing layer of the entire protective structure. It is used to withstand out-of-plane impact loads and disperse impact forces in the early stages of a collision. The honeycomb aluminum layer II 2 is located after the honeycomb aluminum layer I 1 and serves as an intermediate transition layer. It is used to withstand in-plane compressive loads during a collision, stabilize the deformation mode in the middle of the front longitudinal beam, and guide the impact load to be transmitted rearward. The negative Poisson's ratio layer 3 is located near the passenger compartment and serves as the rear protective layer of the entire protective structure. It is used to provide enhanced load-bearing capacity in the later stages of a collision and suppress the intrusion of the front longitudinal beam toward the passenger compartment.

[0049] like Figure 2 As shown, both honeycomb aluminum layer I 1 and honeycomb aluminum layer II 2 are composed of regularly arranged hexagonal honeycomb cells, and the axial direction of the honeycomb cells is consistent with the longitudinal direction of the vehicle; negative Poisson's ratio layer 3 is composed of a reentry negative Poisson's ratio cell array, and the cell includes a concave connecting rod structure inside.

[0050] The honeycomb aluminum layer I 1, which is subjected to out-of-plane impact, serves to reinforce the front end of the front longitudinal beam and disperse the impact load. The axial direction of the honeycomb unit is consistent with the longitudinal direction of the vehicle. The honeycomb aluminum layer II 2, which is subjected to in-plane impact, serves to bear and constrain the honeycomb unit in the in-plane direction and to buffer and absorb energy to maintain stable acceleration, so that the deformation direction of the middle structure of the front longitudinal beam is effectively controlled.

[0051] In this embodiment, the base material of both the honeycomb aluminum layer I 1 and the honeycomb aluminum layer II 2 is aluminum alloy, preferably 3003 aluminum alloy. The cell side length is not less than 3mm, the honeycomb wall thickness is not less than 0.03mm, the honeycomb core thickness is not less than 20mm, the apparent density of the honeycomb aluminum core material is not less than 40kg / m³, the equivalent compressive yield strength in the out-of-plane compression direction of the honeycomb aluminum layer I 1 is not less than 0.8MPa, and the crushing plateau stress is not less than 1.2MPa.

[0052] like Figure 1 As shown, the lengths of the longitudinally arranged honeycomb aluminum layer I, honeycomb aluminum layer II, and negative Poisson's ratio layer 3 are respectively... , , The honeycomb aluminum layer I, honeycomb aluminum layer II, and negative Poisson's ratio layer 3 have the same width, and their width values ​​are all set to... The heights of honeycomb aluminum layer I, honeycomb aluminum layer II, and negative Poisson's ratio layer 3 are all the same, and their height values ​​are all set to... It must meet the following size requirements:

[0053] ;

[0054] ;

[0055] ;

[0056] ;

[0057] in, This indicates the length of the hat-shaped component 4; This indicates the thickness value of section 4 of the hat-shaped component; This indicates the width of section 4 of the hat-shaped component; This indicates the height of section 4 of the hat-shaped component.

[0058] The out-of-plane equivalent compressive yield strength of honeycomb aluminum is The out-of-plane crushing platform stress is The yield strength of the base aluminum alloy is The equivalent density of honeycomb aluminum is The density of the base aluminum alloy is It meets the following strength requirements:

[0059] ;

[0060] ;

[0061] 1;

[0062] Where π represents the plastic hinge rotation constant, h1 represents the height of the honeycomb cell in the loading direction, and l1 represents the length of the honeycomb cell wall. Indicates the angle of inclination of the cell wall; The geometric correction factor representing the load-bearing capacity of honeycomb aluminum at the yield stage. This represents the relative density scaling index during the yielding stage; Geometric correction factor representing the load-bearing capacity of aluminum cellular batteries during the platform phase; This represents the relative density scaling index for the platform phase.

[0063] For regular hexagonal aluminum honeycomb with uniform thickness, when the material is dominated by plastic buckling, C1 is taken as 4.41 and n1 as 5 / 3 based on the energy balance principle and geometric similarity analysis. C2 is the geometric correction coefficient for the bearing capacity of the aluminum honeycomb in the out-of-plane stable crushing stage. Its value is determined by the geometric configuration and collapse deformation mode of the honeycomb unit, reflecting the proportion of the effective area of ​​the honeycomb wall participating in the bearing during the stable crushing process, and is taken as 0.4-0.8. n2 is the relative density scaling index of the plateau stage. Since the equivalent bearing capacity of the stable crushing plateau stage is approximately proportional to the effective bearing area, and the effective bearing area is linearly related to the relative density of the honeycomb, the plateau stress is approximately linearly related to the relative density, and the index n2 is taken as 1.

[0064] The negative Poisson's ratio layer 3 is located near the passenger compartment and serves as the end-end protection layer for the front longitudinal beam under strong impact conditions. The negative Poisson's ratio layer 3 is composed of an array of reentry-type negative Poisson's ratio units, each containing a concave connecting rod structure. During longitudinal compression, this structure generates a lateral contraction effect, gradually strengthening the contact and constraint between the negative Poisson's ratio layer 3 and the inner wall of the cap-shaped beam. This results in a higher end-end load-bearing capacity, suppressing the intrusion of the front longitudinal beam towards the passenger compartment in the later stages of the collision.

[0065] like Figure 3 As shown, the length of the diagonal member of the structural unit is Cell length is The cell height is z, and the length of the vertical connecting rod is... The next angle is The thickness of the unit member is The cell width is The equivalent yield strength of layer 3 with negative Poisson's ratio is The equivalent density of the negative Poisson's ratio layer 3 structure is The density of the base aluminum alloy is The yield strength of the base aluminum alloy is The equivalent yield strength is not less than 2MPa, the base aluminum alloy material is 5052 aluminum alloy, and it meets the following requirements:

[0066] ;

[0067] ;

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] ;

[0073] ;

[0074] ;

[0075] in, Geometric correction factor representing the bearing capacity of a negative Poisson's ratio layer; is the efficiency coefficient of the plastic collapse mechanism, with a value of 0.5-0.8; n is the scaling exponent of the equivalent yield strength as a function of the relative density of the negative Poisson's ratio structure, with a value of 2.

[0076] The honeycomb aluminum I layer 1, honeycomb aluminum II layer 2, and negative Poisson's ratio layer 3 arranged longitudinally are all connected to the inner wall of the cap-shaped beam by adhesive. The structural adhesive is applied at the contact point between the outer surface of each filling layer and the inner wall of the cap-shaped beam, and is distributed continuously or intermittently along the longitudinal direction of the cap-shaped beam. This ensures reliable positioning of the filling layers during assembly and provides uniform lateral constraint to the filling layers during collisions.

[0077] In this embodiment, the overall dimensions of the honeycomb aluminum layer I 1 are 248mm in length, 76mm in width, and 98mm in height. The substrate of the honeycomb aluminum layer I 1 is made of aluminum alloy, specifically 3003 aluminum alloy, with a yield strength of 150MPa, a cell side length of 5mm, a honeycomb wall thickness of 0.05mm, a honeycomb core thickness of 20mm, and an apparent density of 40kg / m³. The equivalent compressive yield strength in the out-of-plane compression direction of the honeycomb aluminum layer I 1 is approximately 2.2MPa, and the crushing plateau stress is approximately 1.4MPa. The honeycomb aluminum layer I 1 is composed of regularly arranged hexagonal honeycomb cells, with the axial direction of the cells aligned with the longitudinal direction of the vehicle. Under impact load, the gradual collapse of the honeycomb cells achieves stable energy absorption, thereby rapidly reducing the peak acceleration at the initial stage of the collision. The honeycomb aluminum layer I 1 is positioned longitudinally along the front longitudinal beam and is connected to the inner wall of the cap-shaped beam by adhesive bonding, ensuring stable compressive deformation of the honeycomb aluminum layer I 1 under impact.

[0078] The overall dimensions of the second layer of the honeycomb aluminum alloy are 497mm in length, 76mm in width, and 98mm in height. The substrate of the second layer is also made of aluminum alloy, specifically 3003 aluminum alloy, with a yield strength of 150MPa, a cell side length of 5mm, a honeycomb wall thickness of 0.05mm, a honeycomb core thickness of 20mm, and an apparent density of 40kg / m³. The second layer is also composed of regular honeycomb units, but it is primarily subjected to in-plane impact. During the process, the in-plane load-bearing and stabilizing effect of the honeycomb units causes controlled compressive deformation preferentially to occur longitudinally in the middle of the front longitudinal beam. Through the in-plane compressive characteristics of the second layer, uncontrolled failure modes such as localized tearing in the middle area of ​​the front longitudinal beam can be effectively avoided, thereby stabilizing the impact load transmission path and reducing the risk of adverse secondary effects during collision. The second layer is also fixed to the inner wall of the cap-shaped beam by adhesive bonding, and is limited in the longitudinal direction by a stop structure set on the inner wall.

[0079] The overall dimensions of the negative Poisson's ratio layer 3 are 248 mm in length, 76 mm in width, and 98 mm in height. The length of the structural unit diagonal rod is 6 mm, the length of the vertical connecting rod is 4 mm, the cell length is 14.39 mm, the cell height is 10 mm, the reentry angle is 60°, the thickness of the unit rod is 0.2 mm, the cell width is 6 mm, the base aluminum alloy material is 5052 aluminum alloy, the yield strength is 195 MPa, and the equivalent yield strength is approximately 7 MPa.

[0080] Under the same operating conditions, the length of the infill layer in the optimized structure was varied to test the impact of different infill layers on the overall structure's performance. The optimized group was formed by taking the main component of the honeycomb aluminum layer I as its total length. 211 The honeycomb aluminum II layer 2, which accounts for the main component of the total length, forms the optimized group. 121 The negative Poisson ratio layer 3, which constitutes the main component of the entire length, forms the optimized group. 112 A comparative analysis of the main performance indicators of the front longitudinal beam, including the energy absorption EA at 40ms, was conducted. 40 Energy absorption EA at 70ms 70 Specific energy absorption area (SEA), mean crushing force (MCF), and peak crushing force (PCF); simultaneously supplemented with mid-section displacement mean acceleration (Mid-A). avg and the mean acceleration of the latter part of the displacement Rear-A avg As auxiliary indicators, the details are shown in Table 1 below.

[0081] Table 1. Comparison of front longitudinal beam performance under different optimization schemes

[0082]

[0083] Analysis results show that the optimized group 211 In the internal filling structure, the honeycomb aluminum I layer 1, which is subjected to out-of-plane impact, accounts for the majority and exhibits stronger resistance to strong impacts in the initial and middle stages of impact. During plastic compression deformation, this structure can continuously absorb more impact energy, demonstrating a high EA (exponential energy absorption). 40 EA 70 And in terms of specific energy absorption level, the overall energy absorption efficiency is optimal.

[0084] Optimized group 121 In the middle, the honeycomb aluminum layer II 2, which is subjected to in-plane impact, accounts for the majority, and its ability to reduce acceleration in the early stage is relatively stronger than that of the optimized group. 211 Slightly weaker, but with a smoother acceleration response; the average acceleration during mid-range displacement is slightly higher than that of the Optimized group. 211 It can maintain a stable energy absorption state for a relatively long period of time. Since the structure mainly experiences in-plane compressive deformation in the middle section, its plastic deformation energy absorption capacity is slightly lower than that under out-of-plane compression. Therefore, its overall energy absorption level is slightly lower than that of the optimized group. 211 However, the structural deformation process is more stable.

[0085] Optimized group 112 In the structure, the negative Poisson's ratio layer constitutes the majority, and its energy absorption capacity at the front end is at a moderate level, but its active constraint capacity in the in-plane deformation direction in the middle section is insufficient. Approximately 40 ms after impact, the structure begins to exhibit significant bending deformation, resulting in a significantly lower energy absorption efficiency and total energy absorption compared to the optimized group. 211 and Optimized group 121 Since the latter part of the structure loses its positive controlled compressive deformation characteristics, its average acceleration in the latter part no longer has effective comparative analysis significance.

[0086] In the later stages of the impact, the optimization group... 211 With the Optimized group 121 The average acceleration of the rear section displacement increased to a high level, indicating that under longitudinal impact, the rear negative Poisson's ratio layer enhanced the contact and constraint capacity with the inner wall of the cap beam through lateral contraction, effectively resisting the intrusion of the front longitudinal beam towards the crew compartment. The optimized group... 112 Since the middle section has already experienced bending instability, the subsequent structure is unable to form an effective longitudinal load-bearing path, and its acceleration response loses its engineering significance.

[0087] A comprehensive comparison reveals that the honeycomb aluminum layer I 1, subjected to out-of-plane impact, exhibits the strongest impact resistance and energy absorption capacity, rapidly reducing the impact response in the early stages of impact. However, its acceleration variation is significant, potentially leading to a higher risk of transient loads. The honeycomb aluminum layer II 2, subjected to in-plane impact, primarily demonstrates stable energy absorption and deformation restraint capabilities, continuously absorbing energy while maintaining relatively stable acceleration. However, its energy absorption capacity per unit deformation is relatively low. The negative Poisson's ratio layer 3 exhibits strong resistance to intrusion in the later stages of impact, gradually enhancing its restraint effect with the inner wall of the front longitudinal beam during compression. However, when its proportion is too high, it weakens the honeycomb aluminum layer II's ability to guide structural deformation, reducing the overall energy absorption efficiency and stability of the structure.

[0088] The negative Poisson's ratio layer 3 is composed of an array of reentry-type negative Poisson's ratio units. Each unit includes a concave connecting rod structure, which generates a lateral contraction effect during longitudinal compression. This gradually strengthens the contact and constraint between the negative Poisson's ratio layer 3 and the inner wall of the cap-shaped beam during compression deformation. Through the deformation characteristics of the negative Poisson's ratio units, the negative Poisson's ratio layer 3 provides high load-bearing capacity and intrusion resistance in the later stages of the collision, suppressing further deformation of the front longitudinal beam towards the passenger compartment. The negative Poisson's ratio layer 3 is adhesively fixed to the inner wall of the cap-shaped beam body and is limited in the longitudinal direction by a stop structure to ensure that it participates in force distribution according to a predetermined sequence during the collision.

[0089] The impact-resistant composite multi-layer filled front longitudinal beam structure of this invention is used in conjunction with the vehicle body longitudinal beam frame. A closed structure is formed by welding the cap-shaped component 4 to the cover plate 5, and then it is connected and fixed to the vehicle body longitudinal beam frame. The front longitudinal beam has a multi-layered functional filling structure inside. Each filling layer is fixed to the inner wall of the cap-shaped beam by a stop structure and adhesive bonding. During a collision, they work together to bear the force, achieving graded dispersion and transmission of strong impact loads.

[0090] This invention uses Hypermesh and dyna finite element software to complete simulation experiments. It adopts a protective structure that uses an equivalent heavy hammer to impact the front longitudinal beam. The experiment is compared with the traditional front longitudinal beam under the same working conditions. In this experiment, the protective structure of the three-layer front longitudinal beam consists of two layers. The first layer (layer 1) corresponds to a cap-shaped component 4 with a length of 280mm, a height of 60mm, a width of 80mm, and a thickness of 1.4mm. It is made of high-strength steel. The filling layer uses equivalent honeycomb aluminum with a thickness of 0.03mm, made of 3003 aluminum alloy, with a yield strength of 150MPa, a cell side length of 5mm, a honeycomb core thickness of 10mm, and an apparent density of 40kg / m³. It is subjected to out-of-plane compression. The second layer (layer 2) corresponds to a cap-shaped component 4 with a length of 550mm, a height of 60mm, a width of 80mm, and a thickness of 1.8mm. It is also made of high-strength steel. The filling layer uses equivalent honeycomb aluminum with a thickness of 0.03mm, made of 3003 aluminum alloy, with a yield strength of 150MPa and a cell side length of 5mm. The honeycomb core is 10mm thick, and the apparent density of the honeycomb aluminum core material is 40kg / m³, subject to in-plane compression. The hat-shaped part 4 corresponding to the negative Poisson's ratio layer 3 is 290mm long, 60mm high, 80mm wide, and 2.4mm thick. The filling layer adopts an equivalent negative Poisson's ratio structure. The structural unit diagonal rod is 6mm long, the vertical connecting rod is 4mm long, the cell length is 14.39mm, the cell height is 10mm, the reentry angle is 60°, the unit rod thickness is 0.2mm, the cell width is 6mm, the base aluminum alloy material is 5052 aluminum alloy, and the yield strength is 210MPa. The cover plate 5 is 1120mm long, 100mm wide, and 1.2mm thick, and the material is high-strength steel. Except for the absence of a filling structure, the parameters of the front longitudinal beam are the same.

[0091] Based on the comprehensive analysis of experimental data (the analysis here compares the results of the optimized group and the traditional front longitudinal beam), in the initial stage of impact, the peak crushing force of the control group was approximately 58.22 kN, while that of the optimized group was approximately 81.75 kN, an increase of approximately 40.41%. The average crushing force of the control group was approximately 46.62 kN, while that of the optimized group was approximately 68.05 kN, an increase of approximately 45.99%. Furthermore, analyzing the corresponding acceleration trend, the acceleration decrease rate of the control group was approximately 1.42 g / ms, while that of the optimized group was approximately 3.44 g / ms, an increase of approximately 142.25%. This indicates that the optimized group can more rapidly reduce the acceleration level after the peak value appears in the initial stage of impact, thereby effectively shortening the high acceleration duration and achieving rapid peak reduction. During the mid-impact phase, the control group absorbed approximately 1.33e7J of energy in the mid-section, while the optimized group absorbed approximately 2.92e7J, representing an increase in energy absorption capacity of approximately 119.55%. Based on this, analysis of the acceleration trend showed that the average acceleration difference in the control group was approximately 0.78g, while the average acceleration difference in the optimized group was approximately 0.50g, representing a stability improvement of approximately 35.60%. This indicates that the optimized group maintained more stable acceleration and sustained energy absorption during the mid-impact phase. In the late-impact phase, the lateral displacement fluctuation at the rear end of the control group was approximately ±2.50mm, with a peak value of approximately 2.68mm, while the lateral displacement fluctuation at the rear end of the optimized group was approximately ±1.50mm, with a peak value of approximately 1.52mm. Under the same working conditions, after increasing the impact strength, the control group experienced tearing and bending approximately 40ms after impact, while the optimized group maintained stable longitudinal deformation. This indicates that the optimized structure has the ability to actively constrain the inward deformation direction under strong impact, and can guide the front longitudinal beam to undergo controlled compression deformation mainly along the longitudinal direction, avoiding uncontrolled deformation and intrusion into the passenger compartment caused by excessive bending and tearing of the front longitudinal beam in the middle region, thereby effectively reducing the risk of adverse secondary effects during the collision.

[0092] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure with strong impact resistance, characterized in that: It includes a protective substrate and a filling functional layer set in the protective substrate; the protective substrate is used to provide the main bearing capacity of the front longitudinal beam, and the filling functional layer is a multi-layer filling structure with different stress mechanisms, so that the front longitudinal beam can achieve graded dispersion of impact load, stable transfer of load and suppression of structural intrusion during the collision; the protective substrate and the filling functional layer improve the protection capability of the front structure of the vehicle under strong impact conditions.

2. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 1, characterized in that: The protective substrate includes a cap-shaped component (4) and a cover plate (5) located at the lower end of the cap-shaped component (4); the cap-shaped component (4) and the cover plate (5) are welded together to form a cap-shaped beam.

3. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 2, characterized in that: A multi-layered stop structure is provided longitudinally on the inner wall of the cap-shaped part (4); structural adhesive is distributed on the inner walls of both the cap-shaped part (4) and the cover plate (5).

4. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 3, characterized in that: The cap-shaped component (4) is provided with a three-layer stop structure. The thickness of the cross section of the cap-shaped component (4) is the same as the thickness of each layer of the stop structure, and the thickness value is set to 1. The dimensions of each layer of the stop structure satisfy the following formula: ； ； in, , , These represent the widths of the three-layer stop structure; , , These represent the heights of the three-layer stop structure; Indicates the width of the cross section of the hat-shaped component (4); This indicates the height of the section of the hat-shaped component (4).

5. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 1, characterized in that: The filling functional layer includes honeycomb aluminum layer I (1), honeycomb aluminum layer II (2), and negative Poisson's ratio layer (3) arranged sequentially along the longitudinal direction of the hat-shaped beam; honeycomb aluminum layer I (1) is located in the front end area of ​​the front longitudinal beam; The honeycomb aluminum II layer (2) is located in the middle area of ​​the front longitudinal beam; the negative Poisson's ratio layer (3) is located in the rear area of ​​the front longitudinal beam and is close to the crew compartment.

6. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 5, characterized in that: The honeycomb aluminum I layer (1) and the honeycomb aluminum II layer (2) are both composed of regularly arranged hexagonal honeycomb units, and the axial direction of the honeycomb units is consistent with the longitudinal direction of the vehicle; the negative Poisson's ratio layer (3) is composed of a re-entry negative Poisson's ratio unit array, and the unit includes a concave connecting rod structure, which generates a lateral contraction effect during longitudinal compression. The honeycomb aluminum I layer (1), the honeycomb aluminum II layer (2), the negative Poisson's ratio layer (3), the cap-shaped part (4), and the cover plate (5) are connected by adhesive.

7. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 5, characterized in that: The cap-shaped part (4) and the cover plate (5) have the same length, and their length values ​​are both set to The lengths of the longitudinally arranged honeycomb aluminum I layer (1), honeycomb aluminum II layer (2), and negative Poisson's ratio layer (3) are respectively , , The widths of the honeycomb aluminum I layer (1), the honeycomb aluminum II layer (2), and the negative Poisson's ratio layer (3) are the same, and their width values ​​are all set to 1. The heights of the honeycomb aluminum I layer (1), the honeycomb aluminum II layer (2), and the negative Poisson's ratio layer (3) are the same, and their height values ​​are all set to... Specifically, it must meet the following size requirements: ； ； ； ； in, This indicates the thickness value of the cross section of the hat-shaped component (4); Indicates the width of the cross section of the hat-shaped component (4); This indicates the height of the section of the hat-shaped component (4).

8. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 5, characterized in that: The out-of-plane equivalent compressive yield strength of honeycomb aluminum is The out-of-plane crushing platform stress is The yield strength of the base aluminum alloy is The equivalent density of honeycomb aluminum is The density of the base aluminum alloy is It meets the following strength requirements: ； ； 1； Where π represents the plastic hinge rotation constant, and h1 represents the height of the cellular element in the loading direction. Indicates the length of the cell wall. Indicates the angle of inclination of the cell wall; The geometric correction factor representing the load-bearing capacity of honeycomb aluminum at the yield stage. This represents the relative density scaling index during the yielding stage; Geometric correction factor representing the load-bearing capacity of aluminum cellular batteries during the platform phase; This represents the relative density scaling index for the platform phase.

9. The impact-resistant three-layer composite honeycomb aluminum negative Poisson's ratio filled front longitudinal beam protective structure according to claim 1, characterized in that: The cap-shaped part (4) and the cover plate (5) are both made of high-strength steel; the base material of the honeycomb aluminum I layer (1) and the honeycomb aluminum II layer (2) is aluminum alloy.

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