Structure beneficial to collision force transmission of non-bearing cross-country vehicle girder and design method

Abstract

The invention discloses a structure beneficial to collision force transmission of a non-bearing cross-country automobile girder and a design method, and belongs to the technical field of automobile frames. A front anti-collision beam and an energy absorption box form a first-section energy absorption area, a second-section energy absorption area is arranged behind a first suspension mounting plate, and a third-section energy absorption area is arranged below a front shock absorption tower bag; a reinforcing rectangular pipe is arranged on the front longitudinal beam, a multi-cavity reinforcing structure is arranged at the turning position of the rear section of the front longitudinal beam, and lap joints of reinforcing plates are arranged in a staggered mode in the X direction. A local reinforcing piece is arranged at the corner of the middle-rear section longitudinal beam; and an extension sleeve structure is arranged between the girder side vehicle body suspension and the vehicle body side vehicle body suspension. According to the non-bearing cross-country vehicle, ordered absorption of collision energy is achieved through the multi-stage gradient energy absorption area, the small-offset collision bearing capacity is improved through the reinforcing structure, force transmission interruption is avoided through the staggered design of the lap joints, the problem that a vehicle body is separated from a girder during collision is solved through the extending sleeve structure, and the collision safety performance of the non-bearing cross-country vehicle is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of vehicle body structure technology, specifically to a structure and design method that facilitates the transmission of collision forces in the frame of a non-load-bearing off-road vehicle. Background Technology

[0002] With the rapid development of the automotive industry and the social economy, vehicle safety has become a crucial research topic. As the most critical passive safety structure in a non-load-bearing vehicle body, the frame's structural strength during a collision is paramount. However, vehicles with frame structures are multi-functional and significantly heavier than typical sedans and SUVs. This results in frame vehicles experiencing far greater impact energy in crash tests compared to unibody vehicles, making it difficult for them to achieve the same safety ratings as unibody models. Furthermore, the body structure and frame structure in these vehicles use a flexible (body mount) connection, fixing the body mounts to the frame and connecting them with long bolts through the center of the body mount to the side mounting points. The body and frame structures are essentially independent. During a collision, the upper body experiences significant inertial forces that shear and break the connecting bolts of the second, third, and fourth mounts, the most critical points of the flexible connection between the body and the frame. This causes all the impact energy to be transferred and absorbed by the frame, and the separation of the upper body results in significant secondary injuries to the vehicle occupants. Meanwhile, in frontal collisions, the frame-mounted vehicle, compared to a traditional unibody structure, has two fewer force transmission paths. Because the body doesn't directly face the impacts of the chassis on various harsh road conditions, and the chassis and engine are mounted on the frame, eliminating the front longitudinal beams and upper side beams, energy cannot be effectively transferred to the cage-like body structure during a collision. This makes the development of frame-mounted vehicles far more challenging than that of traditional unibody structures. Furthermore, as safety requirements increase year by year, passenger vehicle collision safety technologies are constantly iterating and optimizing, necessitating continuous improvement of frame-mounted vehicle structural solutions. Summary of the Invention

[0003] The purpose of this invention is to provide a structure and design method that facilitates the transmission of collision forces in the frame of a non-load-bearing off-road vehicle, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a collision force transmission structure beneficial to the beam of a non-load-bearing off-road vehicle, characterized in that it comprises: The front bumper beam and the energy-absorbing box are provided with the force transmission structure of the front bumper beam corresponding to the force transmission structure of the energy-absorbing box. The energy-absorbing box is provided with a collapse structure to form the first energy-absorbing zone. The second energy absorption zone is located behind the first suspension mounting plate on the side of the main beam, and a weakening structure is provided on the main beam where the second energy absorption zone is located. The third energy absorption zone is located below the front shock absorber tower on the side of the main beam; A reinforcing member is provided on the front longitudinal beam of the main beam and is connected to the front longitudinal beam and the mounting end plate of the anti-collision beam. A reinforcing plate is provided at the bend of the rear section of the front longitudinal beam of the main beam, forming a multi-cavity cross-section at the bend. The lap joints of the reinforcing plates are staggered in the X direction; Local reinforcement members are provided at the bends of the longitudinal beam structure in the middle and rear sections of the main beam, and the lap joints of the local reinforcement members are staggered in the X direction. The force transmission reinforcement structure is located between the body mount on the side of the main beam and the body mount mounting structure on the side of the body, and is used to maintain the connection between the body and the main beam during a collision.

[0005] Preferably, the reinforcing ribs of the front anti-collision beam are aligned with the force-transmitting reinforcing ribs inside the energy-absorbing box, and the center of the energy-absorbing box is aligned with the center of the front longitudinal beam of the main beam.

[0006] Preferably, the second energy-absorbing zone is formed by the damper's envelope avoidance feature, and the deformation resistance of the second energy-absorbing zone is greater than that of the first energy-absorbing zone; the deformation resistance of the third energy-absorbing zone is greater than that of the second energy-absorbing zone.

[0007] Preferably, the reinforcing member is a reinforcing rectangular tube, and the reinforcing rectangular tube is connected to the front longitudinal beam and the anti-collision beam mounting end plate by eight welds on both sides.

[0008] Preferably, the reinforcing plate includes inner and outer double reinforcing plates, forming a four-cavity cross-section at the bend of the rear section of the front longitudinal beam of the main beam, and the inner and outer double reinforcing plates are made by thermoforming process.

[0009] Preferably, the reinforcing plate includes an outer reinforcing plate, which is a double-reinforcing plate structure. Its length completely covers the bend of the longitudinal beam, forming a four-cavity cross-section. The outwardly convex force-transmitting structure of the outer reinforcing plate extends beyond the wheel arch of the front bulkhead in the X direction.

[0010] Preferably, the force transmission enhancement structure is an extended sleeve structure, which includes a sleeve welded to the vehicle body frame. The protruding part of the sleeve and the inner tube of the vehicle body suspension cooperate with each other through a tapered structure to form a double sleeve combination structure.

[0011] Preferably, the taper of the tapered structure is 15 degrees.

[0012] This invention also discloses a design method for a collision force transmission structure that is beneficial to the frame of a non-load-bearing off-road vehicle, comprising: The force transmission structure of the front bumper beam is set to correspond with the force transmission structure of the energy absorption box, and a crumple structure is set on the energy absorption box to form the first energy absorption zone. A weakening structure is set on the main beam behind the first suspension mounting plate to form a second energy absorption zone; A third energy absorption zone is formed below the front shock absorber tower. A reinforcing member is installed on the front longitudinal beam, and the reinforcing member is connected to the front longitudinal beam and the mounting end plate of the anti-collision beam; A reinforcing plate is installed at the bend of the rear section of the front longitudinal beam to form a multi-cavity cross-section; The lap joints of the reinforcing plates are staggered in the X direction; Local reinforcement members are installed at the bends of the middle and rear longitudinal beam structure, and the lap joints of the local reinforcement members are staggered in the X direction. A force-transfer reinforcement structure is installed between the frame-side body mount and the body-side body mount mounting structure to maintain the connection between the body and the frame during a collision.

[0013] Preferably, the force transmission enhancement structure is an extended sleeve structure, which includes a sleeve welded to the vehicle body frame. The protruding part of the sleeve and the inner tube of the vehicle body suspension cooperate with each other through a tapered structure to form a double sleeve combination structure.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: By setting a three-segment gradient energy absorption zone, this invention achieves orderly absorption of collision energy, avoids unexpected buckling of the longitudinal beams, and significantly improves energy absorption efficiency. Through the combined design of reinforced rectangular tubes and multi-cavity reinforced structures, the structural load-bearing capacity under 25% small offset collision conditions is effectively enhanced, significantly reducing passenger compartment intrusion. The staggered design of the reinforced plate lap joints avoids stress concentration on the force transmission path, ensuring continuous transmission of collision force. The extended sleeve structure solves the technical problems of bolt shearing fracture and body-beam separation in traditional non-load-bearing bodies during collisions, allowing the upper body frame to effectively participate in force transmission and increasing the force transmission path of the entire vehicle. This invention significantly improves the collision safety performance of non-load-bearing off-road vehicles while achieving lightweight design. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the first energy-absorbing region of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of the second energy-absorbing region of the present invention.

[0017] Figure 3 This is a schematic diagram of the third energy-absorbing region of the present invention.

[0018] Figure 4 for Figure 3 Cross-sectional schematic diagram of the structure shown Figure 5 This is a schematic diagram of the 25% small offset collision reinforcement structure of the present invention.

[0019] Figure 6 This is a schematic diagram of the inner and outer double reinforcing plates at the bend of the front longitudinal beam 3 of the present invention.

[0020] Figure 7 This is a schematic diagram of the structure of the double reinforcing plate covering the bend of the front longitudinal beam 3 of the present invention.

[0021] Figure 8 This is a schematic diagram of the external reinforcing plate protrusion force transmission structure 12 of the present invention.

[0022] Figure 9 This is a schematic diagram of the staggered design of the inner and outer reinforcing plate lap joints of the present invention.

[0023] Figure 10 This is a schematic diagram of the structure of the local reinforcing plate 13 at the bend of the rear longitudinal beam in this invention.

[0024] Figure 11 This is a schematic diagram of the structure of the suspension extension sleeve 161 of the present invention.

[0025] Figure 12 This is a schematic diagram of the cross-section connecting the body frame 18, body mount 16, and main beam 15.

[0026] Figure 13 This is a schematic diagram showing the matching of the side extension sleeve 161 of the vehicle frame 18 with the vehicle suspension 16. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Equivalent substitutions, formal modifications, or parameter adjustments made by those skilled in the art to the following embodiments based on their understanding of the technical solutions of the present invention all fall within the scope of protection of the present invention.

[0028] This invention provides a collision force transmission structure and design method for a non-load-bearing off-road vehicle frame 15, aiming to solve problems in existing non-load-bearing body structures, such as bolt shearing fracture, missing force transmission paths, and low energy absorption efficiency during collisions due to the flexible connection between the frame 15 and the body. Through systematic design, this invention divides the frame 15 structure into multiple energy absorption zones, deformation-resistant zones, and force transmission zones, and combines this with an innovative suspension extension sleeve 161 structure to achieve orderly absorption and efficient transmission of collision energy, significantly improving the overall vehicle's collision safety performance.

[0029] like Figures 1 to 12 As shown, the non-load-bearing off-road vehicle frame 15 involved in this invention mainly includes a front anti-collision beam 1, an energy-absorbing box 2, a front longitudinal beam 3, a middle and rear longitudinal beam, various energy-absorbing zones, a reinforced rectangular tube 7, inner and outer reinforcing plates, a local reinforcing plate 13, and body suspension 16 extension sleeves 161, among other core components. These components are connected by welding, bolts, and other methods to form an integrated force-transfer frame, ensuring that under various conditions such as frontal collisions and small offset collisions, the structure can collapse in an orderly manner according to a preset deformation pattern and transfer the remaining energy to the rear structure, preventing serious intrusion into the passenger compartment.

[0030] like Figure 1 As shown, this invention sets a first collision energy-absorbing zone at the front end of the vehicle frame, mainly composed of a front bumper beam 1 and an energy-absorbing box 2. The front bumper beam 1 is made of 6-series aerospace aluminum alloy and is stamped with internal reinforcing ribs. These reinforcing ribs are fully aligned with the force-transmitting reinforcing ribs inside the energy-absorbing box 2 in the X-direction (vehicle driving direction). The energy-absorbing box 2 adopts a rectangular cross-section design, with its center position coinciding with the center of the front longitudinal beam 3 of the main beam 15. This ensures that the collision force is directly and stably transmitted from the bumper beam 1 to the energy-absorbing box 2, and then to the front longitudinal beam 3, avoiding structural instability or bending deformation due to misalignment of the force transmission path. CAE simulation verification shows that when the center offset exceeds 5mm, the crushing efficiency of the energy-absorbing box 2 will decrease by more than 15%, and asymmetric buckling is likely to occur. Therefore, this embodiment strictly controls the center alignment deviation to within 2mm.

[0031] The energy-absorbing box 2 and the front bumper beam 1 are connected by full welding, and the welding strength must be sufficient to prevent weld cracking during a collision. Crushing notches 21 are provided on the sides and upper and lower surfaces of the energy-absorbing box 2. The shape, number, and depth of the crushing notches 21 are determined through CAE simulation optimization based on the vehicle's collision energy target. In this embodiment, the crushing notches are square notches, symmetrically arranged on the four sides of the energy-absorbing box 2, with a notch depth of 15%~25% of the height of the energy-absorbing box 2 and a notch angle of 60°~90°. Through simulation iteration, it is ensured that the energy-absorbing box 2 can stably crush under axial impact, and that the crushing mode is progressive folding deformation rather than overall buckling. By setting the crushing notches, the structural strength of the first energy-absorbing zone is lower than that of the second energy-absorbing zone behind it. Specifically, the average crushing load of the first energy-absorbing zone is set to 80kN~120kN, thereby ensuring that the collision energy is preferentially absorbed by the energy-absorbing box 2, avoiding irreversible deformation of the longitudinal beam during low-speed collisions, and reducing maintenance costs.

[0032] Regarding material selection, the energy-absorbing box 2 is preferably made of 6-series aerospace aluminum alloy with a thickness of 1.2mm to 2.0mm. The specific value is determined through simulation iteration based on the vehicle weight and collision energy target. The front bumper beam 1 is made of ultra-high strength steel with a tensile strength of over 800MPa, preferably HC820 / 1180DP or higher strength hot-formed steel, to provide sufficient resistance to deformation and ensure that energy is effectively transferred to the energy-absorbing box 2 in the initial stage of the collision.

[0033] like Figure 2 As shown, the present invention provides a second collision energy absorption zone behind the first suspension mounting plate 4. This zone is located in the middle-front section of the front longitudinal beam 3, i.e., between the first suspension mounting plate 4 and the front shock absorber tower 6. This section of the longitudinal beam has no reinforcing plate and is an exposed longitudinal beam body. Within this zone, the present invention provides a weakening structure on the internally high-pressure formed rectangular plane. This weakening structure can be a circular or elliptical process hole, or a local crushing groove or a stepped variable cross-section structure.

[0034] In this embodiment, the weakening feature of the second energy-absorbing zone is achieved using elliptical process holes, which are arranged in an array along the X-direction on the upper and lower surfaces and inner and outer sides of the longitudinal beam. The major axis of the process holes is parallel to the X-direction, with a major axis dimension of 30mm~50mm, a minor axis dimension of 15mm~25mm, and a hole spacing of 50mm~80mm. By setting the process holes, while ensuring axial collapse capacity, a certain degree of bending stiffness is retained to prevent premature bending under non-frontal collision conditions. Through CAE simulation analysis, the axial compressive strength of the second energy-absorbing zone is defined as the energy-absorbing structure participating in the energy absorption after the first energy-absorbing zone is completely crushed, that is, its crushing load is higher than the crushing load of energy-absorbing box 2. In this embodiment, the average crushing load of the second energy-absorbing zone is set to 150kN~200kN, which is lower than the crushing load of the subsequent third energy-absorbing zone (220kN~280kN), thereby ensuring that the collapse sequence is: energy-absorbing box 2 → second energy-absorbing zone → third energy-absorbing zone.

[0035] The length, cross-sectional dimensions, and distribution density of weakening features of the second energy-absorbing zone are all optimized based on the vehicle's collision energy absorption curve. In this embodiment, the length of this zone is designed to be 200mm to 350mm, capable of absorbing approximately 15% to 25% of the vehicle's collision energy. The specific energy absorption value is determined after vehicle collision analysis using simulation software such as LS-DYNA.

[0036] like Figure 3 and Figure 4As shown, this invention includes a third collision energy absorption zone below the front shock absorber tower 6. This zone utilizes the installation envelope space of the front shock absorber to form a variable cross-section structure on the front longitudinal beam 3. Specifically, the longitudinal beam gradually transitions from a rectangular cross-section to a trapezoidal or locally narrowed cross-section at this point to accommodate the arrangement requirements of the shock absorber assembly. This variable cross-section structure itself is a natural weakening zone, with a structural strength lower than the rear longitudinal beam body, thus serving as the final energy absorption zone.

[0037] The deformation resistance strength of the third energy-absorbing zone is defined as the energy absorption capacity after the second energy-absorbing zone collapses, meaning its collapse load is higher than that of the second energy-absorbing zone. In this embodiment, the strength gradient is precisely controlled by adjusting the transition fillet radius (R50~R100) at the variable cross-section, the presence or absence of local reinforcing plates, and the gradual change in material thickness (from 2.0mm to 2.5mm). Specifically, this area does not have additional reinforcing plates and relies solely on the deformation energy absorption of the longitudinal beam body material. Its collapse load is approximately 10% to 20% higher than that of the second energy-absorbing zone, ensuring that under extreme collision conditions, the front longitudinal beam 3 can achieve complete axial collapse, maximizing the absorption of collision energy and reducing the residual energy transferred to the passenger compartment. According to simulation analysis, after adopting this three-section energy-absorbing structure, the axial collapse energy absorption efficiency of the front longitudinal beam 3 is improved by approximately 25% compared to the traditional structure.

[0038] In addition, the third energy absorption zone is connected to the front shock absorber tower 6 by welding. The tower itself serves as the connection point between the frame and the body, and also plays a role in distributing loads and enhancing local stiffness, thus preventing the longitudinal beam from becoming unstable or punctured at the end of the collapse.

[0039] like Figure 5 As shown, for the stringent condition of a 25% small offset collision, this invention includes a reinforcing rectangular tube 7 located below the first suspension mounting plate 4 near the front longitudinal beam 3. This reinforcing rectangular tube 7 is made of high-strength steel rectangular tubing, with a cross-sectional dimension matching that of the front longitudinal beam 3, extending its length to the mounting end plate of the anti-collision beam 1. The reinforcing rectangular tube 7 is connected to the front longitudinal beam 3 and the end plate of the anti-collision beam 1 by eight welds, forming a double-sided connection structure. That is, the reinforcing rectangular tube 7 is simultaneously welded to the side and bottom surfaces of the longitudinal beam, with evenly distributed welds to ensure sufficient connection strength to withstand the enormous bending moment and shear force generated in a small offset collision. Each weld is at least 50mm long, and the weld penetration depth is at least 80% of the base material thickness.

[0040] The outer end face of the reinforced rectangular tube 7 is aligned with the outer extension of the anti-collision beam 1, ensuring that under a 25% overlap collision condition, the collision load first acts on the reinforced rectangular tube 7 and then is transferred to the front longitudinal beam 3 body, thereby preventing the front longitudinal beam 3 from bending and failing due to not being directly stressed. By introducing this reinforced rectangular tube 7, the present invention effectively disperses the small offset collision load, which was originally borne by only one side of the longitudinal beam, to the longitudinal beam body and the reinforcement structure, significantly improving the local load-bearing capacity of the frame. C-IASI small offset collision simulation verification shows that, with this structure, the passenger compartment intrusion is reduced by approximately 40% compared to the traditional structure, enabling the vehicle to meet more stringent collision safety regulations.

[0041] like Figure 6 As shown, this invention incorporates inner and outer double reinforcing plates at the structural bend of the rear section of the front longitudinal beam 3. This bend is a critical area for the transition from the front longitudinal beam 3 to the middle and rear longitudinal beams, and also a turning point in the collision force transmission path. During a collision, it is highly susceptible to bending or crushing, leading to interruption of force transmission. To address this issue, this invention employs an inner and outer double reinforcing plate structure in this area, transforming the original single-cavity longitudinal beam cross-section into a four-cavity cross-section.

[0042] Specifically, the inner reinforcing plate is attached to the inner wall of the longitudinal beam, and the outer reinforcing plate is attached to the outer wall of the longitudinal beam. Together with the longitudinal beam body, they form multiple closed cavities. The inner and outer double reinforcing plates are preferably manufactured using a thermoforming process, and the material is ultra-high strength boron steel with a tensile strength of 1500MPa or higher, specifically 22MnB5, with a thickness of 1.5mm to 2.5mm. The thermoforming process ensures that the reinforcing plate has extremely high yield strength (up to 1200MPa or higher), while achieving complex geometric shapes at bends to ensure a tight fit with the longitudinal beam body. By forming a four-cavity cross-section, the section modulus of this area is increased by approximately three times compared to a single-cavity structure, significantly enhancing bending and torsional resistance. Even after complete energy absorption in a high-speed collision (such as a 64km / h frontal collision), the structure at this point does not bend, ensuring that the impact force can be smoothly transferred to the middle and rear longitudinal beams.

[0043] like Figure 7 As shown, this invention further employs an outer double-reinforcing plate structure at the bend of the front longitudinal beam 3, with its length completely covering the bend. Unlike the aforementioned inner and outer double-reinforcing plates, the outer double-reinforcing plate refers to a double-layered reinforcing plate on the outer side, i.e., an outer and inner reinforcing plate stacked together to form a four-cavity cross-section. This structure further enhances the deformation resistance of the bend area, ensuring the continuity of the force transmission path.

[0044] The outer double reinforcing plates extend to both ends of the bend area and are connected to the main longitudinal beam via continuous welds to avoid stress concentration areas. In this embodiment, the outer double reinforcing plates adopt a progressive thickness design, with the thickness being greatest near the center of the bend (2.5mm) and gradually decreasing to 1.5mm towards both ends to smoothly transition the stiffness difference and prevent local instability caused by abrupt changes in stiffness. This structure ensures smooth force transmission while also meeting the requirements for lightweight design, reducing weight by approximately 8% compared to a uniform thickness scheme.

[0045] like Figure 8 As shown, the present invention further includes a raised force-transmitting structure 12 on the outer reinforcing plate located at the bend of the rear section of the front longitudinal beam 3. This raised structure extends in the X direction, with its front end extending beyond the wheel arch 11 of the front bulkhead. The core purpose of this design is that, in the event of a collision, this raised structure can preferentially contact and participate in the force-bearing process with the deformation-resistant outer reinforcing plate of the main beam 15, directly transferring the collision load to the reinforcing plate, thereby bypassing the weak area of ​​the front bulkhead wheel arch 11 and reducing the intrusion into the passenger compartment.

[0046] In this embodiment, the raised force-transmitting structure 12 is a reinforcing rib stamped on the outer reinforcing plate. Its cross-section is U-shaped, with a rib height of 15mm to 25mm and an extension length of approximately 80mm to 150mm along the X direction. A gap of 3mm to 5mm is reserved between the front end face of the raised structure and the wheel arch 11 of the front bulkhead of the vehicle body. Under normal driving conditions, there is no contact. However, under collision conditions, as the longitudinal beam deforms and displaces, the raised structure quickly contacts the wheel arch 11, forming an auxiliary force-transmitting path. Simulation analysis shows that this raised structure can share approximately 20% to 30% of the front bulkhead load, effectively reducing the intrusion into the passenger compartment and significantly improving the integrity of the passenger compartment.

[0047] like Figure 9 As shown, this invention employs a staggered lap joint design at the bend of the inner and outer reinforcing plates at the rear section of the front longitudinal beam 3. Specifically, the front lap position of the inner reinforcing plate does not coincide with the front lap position of the outer reinforcing plate in the X-direction, with a staggered distance of 50mm to 100mm between them. Similarly, the rear ends of the inner and outer reinforcing plates are also staggered. The purpose of this design is to avoid stress concentration at the lap joint during collision force transmission. If the lap joints of the inner and outer reinforcing plates are located at the same X-direction position, this section will bear extremely high concentrated stress under collision loads, easily leading to weld tearing or base material cracking, causing interruption of force transmission. By staggering the lap joints, the stress distribution is more uniform, the force transmission path is smoother, and the structural reliability is significantly improved. Finite element analysis shows that the peak stress in the joint area is reduced by approximately 35% after the staggered design, and the safety factor is increased to over 1.5.

[0048] like Figure 10As shown, this invention adds a local reinforcing plate 13 at the bend in the structure of the longitudinal beam 14 in the middle and rear section of the main beam 15. The middle and rear section of the longitudinal beam 14 is a key transition area connecting the front energy-absorbing zone and the rear structure, and its bend also faces the problem of stress concentration. The reinforcing plate is made of a material that matches the longitudinal beam body and is fixed to the inner or outer side of the longitudinal beam by welding, forming a reinforced cavity together with the longitudinal beam.

[0049] Similar to the aforementioned inner and outer reinforcing plates, the lap joints of this reinforcing plate also adopt a staggered design in the X direction, with a staggered distance of 60mm~100mm, to avoid overlapping with the welds or structural abrupt changes of the longitudinal beam itself. By setting up the local reinforcing plate 13, it is ensured that the collision energy can be effectively transferred from the front of the frame to the rear longitudinal beam, avoiding bending or tearing in the middle and rear sections, and ensuring the structural integrity of the entire vehicle.

[0050] like Figure 11 , Figure 12 and Figure 13 As shown, this invention features an innovative design in the body mount 16 connection structure to address the problem of separation between the body and the frame 15 caused by bolt shearing failure during a collision in traditional non-load-bearing body structures. In the traditional body mount 16 structure, the body and frame 15 are connected by a flexible mount element, with a long bolt at the center of the mount. This bolt bears both axial tensile force and lateral shear force. During a severe collision, due to the enormous inertial force on the body, the bolt is easily sheared, causing the body to separate from the frame 15. This not only disrupts the force transmission path of the upper body but may also cause secondary damage.

[0051] This invention incorporates an extension sleeve 161 in the vehicle body side mount 16 mounting structure. This extension sleeve 161 is welded to the vehicle body frame 18, extending downwards and protruding from the lower surface of the vehicle body frame 18. The protruding portion of the extension sleeve 161 matches the inner tube 162 of the vehicle body mount 16, with a tapered fit structure 163 between them. The tapered angle is 15 degrees, ensuring both guiding function during assembly and rapid contact during a collision. This tapered fit allows for an assembly tolerance of ±2mm, reducing manufacturing and assembly difficulty.

[0052] The side suspension 16 of the main beam 15 is fixedly connected to the main beam 15 by bolts 17. The inner tube 162 and the extension sleeve 161 of the body suspension 16 form a parallel double-sleeve combination structure. Under normal driving conditions, a small gap of 0.5mm to 1.5mm is maintained between the extension sleeve 161 and the inner tube 162 of the suspension, and it does not bear any load. When a collision occurs, the body moves relative to the main beam 15 under the action of inertial force. The extension sleeve 161 quickly comes into contact with the inner tube 162 of the suspension, and the two form a rigid support. This changes the connection between the body and the main beam 15 from a single bolt shear bearing to the axial compression and radial support of the double sleeves, effectively avoiding bolt shear breakage.

[0053] Meanwhile, since the extension sleeve 161 is directly welded to the vehicle frame 18, the collision force can be directly transmitted from the main beam 15 to the upper cage-like body through this sleeve structure, allowing the vehicle frame 18 to also participate in the collision force transmission, significantly increasing the force transmission path of the entire vehicle and improving energy absorption efficiency. In this embodiment, the extension sleeve 161 is made of high-strength steel pipe, with the material grade being QSTE500 or higher strength, and a wall thickness of 3mm to 5mm. A gap of 1mm to 2mm is left between its inner diameter and the outer diameter of the suspension inner tube 162 to ensure smooth alignment during assembly and rapid contact during a collision.

[0054] In a preferred embodiment of the present invention, the main beam 15 is manufactured using an internal high-pressure forming process. This process enables the integral forming of complex cross-sections, reduces the number of welds, and improves structural consistency and fatigue life. Key components such as the front longitudinal beam 3, the middle longitudinal beam 10, the rear longitudinal beam 13, and the energy-absorbing box 2 are all manufactured using internal high-pressure forming. The cross-sectional shape can be optimized according to load requirements, and the forming pressure is controlled between 80MPa and 120MPa.

[0055] The reinforcing structures, such as the inner and outer reinforcing plates and the supplementary reinforcing plates, are made of high-strength boron steel such as 22MnB5. After being heated to an austenitizing temperature of 930℃~950℃, they are rapidly formed and quenched to obtain a martensitic structure. Their tensile strength can reach more than 1500MPa and their yield strength can reach more than 1200MPa, which can provide extremely high structural strength without significantly increasing the weight.

[0056] In terms of welding technology, this invention mainly adopts a combination of carbon dioxide gas shielded welding and laser welding. Key stress-bearing parts, such as the connection between the reinforced rectangular tube 7 and the front longitudinal beam 3, and the connection between the inner and outer reinforcing plates and the longitudinal beam, employ continuous full welding. The welding current is controlled at 180A~240A, and the welding voltage at 20V~26V to ensure that the weld strength is not lower than that of the base material. The connection between the energy-absorbing box 2 and the front anti-collision beam 1 also adopts a full welding design to avoid connection failure due to insufficient weld strength. All welds undergo visual inspection and ultrasonic testing to ensure the absence of defects such as cracks and lack of fusion.

[0057] The force transmission structure design method of this invention is based on a combination of computer simulation analysis and experimental verification. The specific steps are as follows: First, based on the target vehicle weight, collision safety regulations (such as C-NCAP, C-IASI, etc.), and the vehicle body structure layout, the overall structural form and initial geometric parameters of the main beam 15 are determined. The target vehicle weight is typically set to 2.0t~3.5t, corresponding to a collision energy of 80kJ~150kJ.

[0058] Secondly, a finite element model of the entire vehicle was established, and CAE simulation analyses were performed for frontal collisions and 25% small offset collisions. Explicit dynamic solvers such as LS-DYNA were used, with mesh sizes controlled between 5mm and 10mm. The material model adopted an elastoplastic constitutive model, considering strain rate effects. Based on the simulation results, the intensity gradient of each energy-absorbing zone was adjusted to ensure the collapse sequence met design requirements. The intensity gradient was mainly defined by adjusting the material thickness (1.2mm~3.0mm), setting weakening features, and adding or removing reinforcing plates.

[0059] Secondly, multi-cavity cross-section design is implemented for key force transmission areas such as bends. Through section modulus calculation and topology optimization, the shape, thickness, and overlap position of the reinforcing plate are determined. By staggering the overlap joints, stress concentration is avoided, and the stress distribution along the force transmission path is made more uniform.

[0060] Finally, real-vehicle crash tests are conducted for verification, and the structural parameters are optimized by comparing them with the simulation results. Through the above iterative process, typically 2-3 rounds of simulation optimization and 1-2 rounds of real-vehicle verification are required to ultimately form the beam-15 structure that meets performance requirements and has lightweight advantages.

[0061] By employing the above structure and design method, the present invention achieves the following technical effects: The three-section energy absorption zone design achieves gradient and orderly absorption of collision energy, avoiding overall buckling or unexpected deformation of the longitudinal beam. The energy absorption efficiency is improved by about 20% to 25% compared with the traditional structure, and the energy absorption curve is smoother.

[0062] By strengthening the rectangular tube 7 and the multi-cavity reinforcement structure, the structural load-bearing capacity under the 25% small offset collision condition is significantly improved, and the passenger compartment intrusion is reduced by about 40%, meeting the stringent safety regulations.

[0063] By staggering the lap joints of the reinforcing plates, stress concentration is avoided, the peak stress in the force transmission path is reduced by about 35%, the structural safety factor is increased to over 1.5, the continuity of the force transmission path is ensured, and the reliability of the structure is improved.

[0064] By using the suspension extension sleeve 161 structure, the technical problems of bolt shearing and breakage and separation of the body and the main beam 15 during the collision of traditional non-load-bearing body are solved. This allows the upper body frame 18 to effectively participate in force transmission, increases the force transmission path of the whole vehicle, improves the force transmission efficiency of the whole vehicle by about 30%, and significantly improves the collision safety performance.

[0065] The structure of this invention is based on internal high-pressure forming and thermoforming processes, achieving a balance between lightweight and high strength. Compared with traditional welded structures, it reduces weight by about 10% to 15%, and is applicable to a variety of non-load-bearing off-road vehicles, with good versatility and scalability.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A collision force transmission structure beneficial to the frame of a non-load-bearing off-road vehicle, characterized in that, include: The front bumper beam and the energy-absorbing box are provided with the force transmission structure of the front bumper beam corresponding to the force transmission structure of the energy-absorbing box. The energy-absorbing box is provided with a collapse structure to form the first energy-absorbing zone. The second energy absorption zone is located behind the first suspension mounting plate on the side of the main beam, and a weakening structure is provided on the main beam where the second energy absorption zone is located. The third energy absorption zone is located below the front shock absorber tower on the side of the main beam; A reinforcing member is provided on the front longitudinal beam of the main beam and is connected to the front longitudinal beam and the mounting end plate of the anti-collision beam. A reinforcing plate is provided at the bend of the rear section of the front longitudinal beam of the main beam, forming a multi-cavity cross-section at the bend. The lap joints of the reinforcing plates are staggered in the X direction; Local reinforcement members are provided at the bends of the longitudinal beam structure in the middle and rear sections of the main beam, and the lap joints of the local reinforcement members are staggered in the X direction. The force transmission reinforcement structure is located between the body mount on the side of the main beam and the body mount mounting structure on the side of the body, and is used to maintain the connection between the body and the main beam during a collision.

2. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The reinforcing ribs of the front anti-collision beam are aligned with the force-transmitting reinforcing ribs inside the energy-absorbing box, and the center of the energy-absorbing box is aligned with the center of the front longitudinal beam of the main beam.

3. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The second energy-absorbing zone is formed by the damper's envelope avoidance feature, and the deformation resistance of the second energy-absorbing zone is greater than that of the first energy-absorbing zone; the deformation resistance of the third energy-absorbing zone is greater than that of the second energy-absorbing zone.

4. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The reinforcing member is a reinforced rectangular tube, and the reinforced rectangular tube is connected to the front longitudinal beam and the anti-collision beam mounting end plate by eight welds on both sides.

5. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The reinforcing plate includes inner and outer double reinforcing plates, forming a four-cavity cross-section at the bend of the rear section of the front longitudinal beam of the main beam. The inner and outer double reinforcing plates are made by thermoforming process.

6. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The reinforcing plate includes an outer reinforcing plate, which is a double-reinforcing plate structure. Its length completely covers the bend of the longitudinal beam, forming a four-cavity cross-section. The outwardly convex force-transmitting structure of the outer reinforcing plate extends beyond the wheel arch of the front bulkhead in the X direction.

7. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 1, characterized in that, The force transmission enhancement structure is an extended sleeve structure, which includes a sleeve welded to the vehicle body frame. The protruding part of the sleeve and the inner tube of the vehicle body suspension cooperate with the tapered structure to form a double sleeve combination structure.

8. The collision force transmission structure for non-load-bearing off-road vehicle beams according to claim 7, characterized in that, The taper of the tapered structure is 15 degrees.

9. A design method for a collision force transmission structure that is beneficial to the main beam of a non-load-bearing off-road vehicle, characterized in that, include: The force transmission structure of the front bumper beam is set to correspond with the force transmission structure of the energy absorption box, and a crumple structure is set on the energy absorption box to form the first energy absorption zone. A weakening structure is set on the main beam behind the first suspension mounting plate to form a second energy absorption zone; A third energy absorption zone is formed below the front shock absorber tower. A reinforcing member is installed on the front longitudinal beam, and the reinforcing member is connected to the front longitudinal beam and the mounting end plate of the anti-collision beam; A reinforcing plate is installed at the bend of the rear section of the front longitudinal beam to form a multi-cavity cross-section; The lap joints of the reinforcing plates are staggered in the X direction; Local reinforcement members are installed at the bends of the middle and rear longitudinal beam structure, and the lap joints of the local reinforcement members are staggered in the X direction. A force-transfer reinforcement structure is installed between the frame-side body mount and the body-side body mount mounting structure to maintain the connection between the body and the frame during a collision.

10. The design method according to claim 9, characterized in that, The force transmission enhancement structure is an extended sleeve structure, which includes a sleeve welded to the vehicle body frame. The protruding part of the sleeve and the inner tube of the vehicle body suspension cooperate with the tapered structure to form a double sleeve combination structure.

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