A method for absorbing energy from a gradual gradient collision of a rail vehicle

Abstract

The present invention provides a method for absorbing energy in a gradual gradient collision for rail vehicles. In the energy absorption method, the impedance and effective deformation stroke curves of the rail vehicle include a gradient energy absorption zone curve, and the gradient energy absorption zone curve refers to a curve in which the impedance is gradually increased as the effective deformation stroke of the vehicle increases; the gradual gradient is a smooth gradient or a step gradient; and the energy absorption method is implemented by a corresponding energy absorption device. The energy dissipation calculation results of the two modes of traditional multi-stage energy absorption in the prior art and the gradual gradient energy absorption of the present invention show that under the same impact conditions, the high-speed train adopting the gradual gradient energy absorption mode has better energy absorption and impact deceleration on the main energy absorption interface than the traditional multi-stage energy absorption mode. The gradual gradient energy absorption mode provided by the present invention can reduce the risk of train structure damage during a collision to a greater extent, and better protect the personal safety of passengers and drivers and control personnel.

Description

Technical Field

[0001] The invention belongs to the field of rail transit safety, and in particular relates to a collision energy absorption method for rail vehicles. Background Art

[0002] Rail transit vehicle collision accidents are often difficult to predict and cause high damage, and severe collision impacts can lead to catastrophic consequences. In some collision accidents at home and abroad, the vehicle body has been disintegrated on a large scale, the living space has been severely reduced, and the intensity of the collision load has been significantly higher than the relevant provisions of the existing train safety assessment standards. How to ensure transportation safety and achieve a higher margin of rail transit equipment protection has practical scientific significance and engineering value.

[0003] Passive safety protection is one of the main technologies for vehicles to reduce losses from collision accidents. Its principle is that the energy absorption device dissipates the collision energy through its structural plastic deformation, thereby reducing the impact kinetic energy transmitted to the passenger protection area. Unlike other vehicles such as cars, rail transit vehicles have distinct multi-body characteristics. There are many energy absorption interfaces, strong linkage, strong correlation characteristics of damage, and each car affects each other. The occurrence site is scattered, protection is difficult, and the collision energy is high, especially for long trains. The above many characteristics have led to great challenges in the current passive safety protection of trains. To achieve train safety at higher speeds, it is necessary to solve the energy dissipation channel problem in the multi-body system, the load level parameter matching between different load-bearing systems, and the integrated design and preparation of lightweight materials and structures for high energy absorption carriers.

[0004] Anti-climbing devices and car body collision deformation energy absorption structures, namely energy absorption structures, are installed at the ends of the train. Among them, the anti-climbing structure is installed in front of the deformable area at the end of the vehicle to suppress climbing during the train collision. The design of the energy absorption structure usually adopts one or more combined energy absorption structures such as honeycomb structure, crushing energy absorption structure, cutting energy absorption structure, etc. Under the action of longitudinal impact force, the energy absorption structure installed at the end of the car body undergoes plastic buckling, tearing, flipping, bulging and cutting deformation modes. The force-displacement curve during the deformation process usually shows an oscillating waveform, often accompanied by a large initial peak force.

[0005] The design form of the special energy absorption structure is a modular anti-climbing energy absorption component integrated with the common energy absorption element and the anti-climbing device structure, which is assembled to the front end of the chassis structure through mechanical connections such as bolts. As a relatively independent module, the special energy absorption structure is less restricted by the static strength of the vehicle body during design, but it must ensure that the longitudinal stiffness of the energy absorption structure is lower than the longitudinal stiffness of the vehicle body end structure, so that it undergoes plastic deformation before the main structure of the vehicle body during the collision and absorbs most of the impact kinetic energy. At the same time, the design of the special energy absorption structure has greater flexibility and fewer constraints, and its geometric parameters can be optimized to have good energy absorption characteristics during the collision. The special energy absorption structure installed on the end chassis of the train is also easier to load and unload and replace after a collision accident. Even if a serious collision accident occurs, the damage to the vehicle body structure is limited after the energy absorption structure is crushed. For the special energy absorption structure with anti-climbing function, anti-climbing teeth are usually installed at its end, which requires it to be able to withstand specific vertical loads to prevent the anti-climbing device from bending and failing and losing the anti-climbing function when the vehicle has an eccentric collision. In some extreme collision scenarios, the proprietary energy-absorbing structure must also withstand a certain bending moment to ensure that it can undergo orderly plastic deformation.

[0006] Research on the energy absorption design and energy dissipation distribution of the end of high-speed trains shows that: 1. The energy absorption process during vehicle collision is not a simple superposition of the designed energy absorption of each part of the energy absorption structure. When the distribution of parameters is unreasonable, the deformation degree of some collision interfaces often exceeds the design value, while the energy absorption capacity of other collision interfaces is not fully utilized. During the train collision process, the collision interface of the head car and the second car of the train is the main energy absorption interface. 2. The crushing force value of the first and second main energy absorption structures of the head car cannot be too high or too low. When the first and second main energy absorption structures are too low, the strength of the head car will be too soft relative to the strength of the middle car, resulting in excessive concentration of energy dissipation on the head car interface, resulting in serious damage to the car body; at the same time, when the crushing load is too high, the structural strength of the head car will be too strong than that of the middle car, resulting in energy dissipation concentrated on the middle car interface, resulting in serious damage to the middle car body.

[0007] Therefore, there is a need in the art for a new collision energy absorption method for rail vehicles. Summary of the invention

[0008] Based on the above development status and needs, the present invention carries out research on gradual gradient reduction energy absorption technology on the basis of traditional multi-stage energy absorption technology, further improves the crash resistance index by optimizing the energy absorption mode and energy absorption structure, and forms an engineering technical solution to verify the effectiveness of the research results, providing technical support for the research and development and application of a new generation of high-speed train collision energy absorption structures.

[0009] Therefore, the present invention provides a method for absorbing collision energy with a gradual gradient for a rail vehicle. In the energy absorption method, a curve of the impedance and effective deformation stroke of the rail vehicle includes a gradient energy absorption zone curve, and the gradient energy absorption zone curve means that the impedance increases gradually with the increase of the effective deformation stroke of the vehicle; the gradual gradient is a smooth gradient or a step gradient;

[0010] The energy absorption method is realized by a corresponding energy absorption device, wherein the energy absorption device comprises more than two energy absorption structures, wherein the energy absorption structure (1) comprises a circular tube structure (11) and an energy absorption seat (12), wherein the circular tube structure comprises a main section (111) and a matching section (112), wherein the outer wall of the main section is cylindrical and the inner wall is truncated cone-shaped as a whole, so that the wall thickness of the main section is thick at one end and thin at the other end, and the wall thickness of the main section is in a smooth gradient or a step gradient from the thick end to the thin end, wherein the wall thickness of the thick end is 5 to 30 mm, the wall thickness of the thin end is 4 to 8 mm, and the difference between the wall thickness of the thick end and the thin end is within 1 mm. The thin end is connected to a matching section (112), the matching section is used to connect an energy absorbing seat (12), the energy absorbing seat is in an annular shape as a whole, and is arranged on the radial outer side of the matching section, the outer wall size of the matching section is smaller than the outer wall size of the main section, so that a step or a curve transition is formed at the connection between the outer walls of the two, the inner wall of the matching section (112) maintains the same and continuous gradient structure as the main section (111), the outer diameter of the energy absorbing seat (12) is larger than the outer diameter of the main section, and the energy absorbing seat covers part or all of the matching section (112) and covers a part of the thin end of the main section (111) in the axial direction.

[0011] In a specific embodiment, the energy absorbing structure is used for the lead car of a rail vehicle, the length of the circular tube structure (11) is 200 to 2000 mm, preferably 600 to 1200 mm, and the energy absorbing seat (12) and the thin end of the main section (111) of the lead car are arranged at a position away from the body of the lead car, while the thick end of the main section (111) of the lead car is arranged at a position close to the body of the lead car.

[0012] In a specific embodiment, the energy absorbing device includes 2 to 12 energy absorbing structures, preferably 4 to 6 energy absorbing structures.

[0013] In a specific embodiment, the energy absorbing structure is used for an intermediate car of a rail vehicle, the length of the circular tube structure (11) is 100 to 800 mm, preferably 200 to 400 mm, and the energy absorbing seat (12) and the thin end of the main section (111) of the intermediate car are arranged at a position close to the intermediate car body, while the thick end of the main section (111) of the intermediate car is arranged at a position away from the intermediate car body.

[0014] In the present invention, energy absorbing structures and anti-climbing structures are arranged at the head and tail of each train, and energy absorbing structures are arranged between the middle cars of each train.

[0015] In a specific embodiment, the energy absorbing device includes 2 or 4 energy absorbing structures distributed on the left and right.

[0016] In a specific embodiment, the circular tube structure of the energy absorbing structure is made of AL6061 seamless aluminum alloy.

[0017] In a specific embodiment, the gradient energy absorption zone curve is expressed by the following mathematical expression:

[0018] F=F e1 +(F e2 -F e1 )(d / d e ) n

[0019] Where F is the impedance, F e1 is the minimum value of impedance, F e2 is the maximum value of the impedance, d is the effective deformation stroke, d e is the total effective deformation stroke, d e =d max -d min , d max is the maximum value of the effective deformation stroke, d min is the minimum value of the effective deformation stroke, n is the gradient index, and n<1.

[0020] In a specific implementation manner, the value of n is 0.1-0.5.

[0021] In general, the present invention has at least the following beneficial effects:

[0022] 1) The present invention has developed a new gradual gradient energy absorption mode. Compared with the traditional multi-stage energy absorption mode, under the same impact conditions, the energy absorption and impact deceleration of the high-speed train using the gradual gradient energy absorption mode of the present invention on the main energy absorption interface are better than those of the traditional multi-stage energy absorption mode. The gradual gradient energy absorption mode can reduce the risk of structural damage to the train during a collision to a greater extent, and can better protect the personal safety of passengers and drivers.

[0023] 2) The present invention develops a new type of energy-absorbing element with a tapered wall thickness. The advantages of materials and geometric shapes are fully utilized to achieve the energy dissipation effect of light weight and high specific energy absorption. The influence mechanism of structural parameters on the crashworthiness of energy-absorbing elements with tapered wall thickness is revealed, and the sensitivity analysis of structural parameters of variable thickness and tapered energy-absorbing elements is carried out to match the effective stroke-impedance curve of the gradient energy absorption mode, providing a scientific basis and theoretical support for the design and optimization of the vehicle's gradient energy absorption zone structure.

[0024] 3) The present invention has designed and verified a set of energy absorption module devices for the end of high-speed trains. The main energy absorption structure in the energy absorption module is mainly composed of a support frame, a cover plate, a movable hook seat and an energy absorption element, which fully utilizes the performance advantages of the gradient wall thickness and reduced diameter energy absorption element, while also having engineering application advantages such as lightweight, flexible configuration, and easy disassembly and assembly. Through collision impact simulation analysis and experimental verification, it is shown that the gradient energy absorption module designed by the present invention has a stable and orderly energy absorption process during the entire collision process, a large effective energy absorption deformation stroke, a large energy dissipation, good collision resistance, and good engineering application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural design diagram of the functional gradient energy absorption zone at the end of the head car of a high-speed train according to the present invention.

[0026] Figure 2 This is a structural design diagram of the end functional gradient energy absorption zone of the middle car of a high-speed train according to the present invention.

[0027] Figure 3 It is a schematic diagram of the energy absorption device corresponding to the end gradient energy absorption zone of the high-speed train head car of the present invention.

[0028] Figure 4 for Figure 3 Schematic diagram of the energy absorption device containing four energy absorption structures.

[0029] Figure 5 for Figure 3 Schematic diagram of the energy absorption device containing 6 energy absorption structures.

[0030] Figure 6 It is a three-dimensional diagram of the energy absorption structure of the lead vehicle of the present invention.

[0031] Figure 7 It is a cross-sectional view of the energy absorption structure of the lead vehicle of the present invention.

[0032] Figure 8 for Figure 7 A magnified view of a partial cross-sectional view of the energy absorbing structure.

[0033] Fig. 9 It is a three-dimensional diagram of the energy absorption structure of the middle car of the present invention.

[0034] Fig.10 It is a cross-sectional view of the energy absorption structure of the middle car of the present invention.

[0035] Fig.11 It is the impact force-effective stroke curve of the energy absorption structure of the head vehicle of the present invention.

[0036] Fig.12 The following are photos of deformation sequence of the energy-absorbing structure of the lead vehicle of the present invention during the impact test.

[0037] Fig.13 It is the impact force-effective stroke curve of the energy absorption structure impact test of the head vehicle of the present invention.

[0038] Fig.14 For Fig.13 The corresponding energy absorption curve.

[0039] Fig.15 It is the impedance effective deformation stroke curve of the multi-stage energy absorption zone of the head car of the high-speed train in the prior art.

[0040] Fig.16 It is the effective deformation stroke curve of the impedance force of the middle car of the high-speed train in the prior art.

[0041] Fig.17 It is the effective deformation stroke curve of the impedance force of the gradually changing gradient energy absorption zone of the leading car of the high-speed train in the present invention.

[0042] Fig.18 It is the effective deformation stroke curve of the impedance force of the gradual gradient energy absorption zone of the middle car of the high-speed train in the present invention.

[0043] Fig.19 It is the impedance force displacement curve of the end gradual gradient energy absorption zone of the present invention. DETAILED DESCRIPTION

[0044] Example 1

[0045] This embodiment is a collision energy absorbing device for rail vehicles according to the present invention.

[0046] In order to design a high-speed train collision energy absorption structure that meets the EU collision standard EN15227, the present invention proposes a design scheme of a circular tube diameter reduction deformation main energy absorption structure suitable for a vehicle end gradient energy absorption zone of a high-speed train by utilizing the principle of metal tube diameter reduction. Figure 1 and Figure 2 The following are the structural design schemes of the end functional gradient energy absorption zone of the head car and the middle car of the high-speed train. The head energy absorption zone of the high-speed train vehicle is a key component designed to protect train passengers and reduce the impact of accidents. Figure 1As shown, this area is mainly composed of three parts: a coupler 2, an anti-climbing energy absorbing structure 3 and a main energy absorbing structure. The coupler is one of the key components for connecting trains and is mainly responsible for pulling and braking the train. In the event of a collision, the coupler can disperse energy, prevent serious damage to the vehicle, and protect the safety of passengers. The anti-climbing energy absorbing structure 3 is located above the coupler and is used to absorb the energy generated during a collision and disperse it to other parts of the vehicle, thereby reducing the impact force on the passengers. The main energy absorbing structure is located below the anti-climbing energy absorbing structure. It includes a plurality of functional gradient thickness circular tube reduced diameter energy absorbing structures 1, which can absorb the energy generated during a high-speed train collision and convert it into heat energy or other forms of energy, thereby reducing the damage caused by the accident to the train and passengers. Figure 2 The schematic diagram of the energy absorption structure of the middle car. The functional gradient zone of the middle car of the high-speed train is composed of a coupler (the coupler is not shown in the figure) and two functional gradient thickness circular tube reduced diameter energy absorption structures 1, including a circular tube structure 11 and an energy absorption seat 12. The coupler of the middle car connects the front and rear parts of the train, and also plays the role of absorbing and buffering collision energy. The two functional gradient thickness circular tube reduced diameter energy absorption structures 1 are respectively located on the left and right sides. The structure of the gradient thickness circular tube can make the thickness of the tube body different at different positions, so as to achieve different strain degrees and energy absorption capabilities. The inventor determines the parameters and materials of each component according to factors such as the train running speed, quality and operating environment, and conducts numerical simulation and experimental verification. In this way, it can be ensured that the energy absorption zone can play the best safety performance under various conditions to protect the safety of passengers and trains.

[0047] Figure 3 to Figure 5 The figure shows the design scheme of the main energy absorption structure of the round tube shrinking deformation in the gradient energy absorption zone at the end of the vehicle. The corresponding components of the head vehicle include a support seat 41, a coupler 2, a cover plate 42, a coupler seat 43, and a round tube structure 11. The overall frame material of the support seat is Al 6082 aluminum alloy plate, and the side panels are reinforced with ribs. The longitudinal length of the outer frame is 960mm, the maximum height is 680mm, the minimum height is 605mm, the maximum width is 1200mm, and the minimum width is 980mm. The inner frame is the installation area of ​​the functional gradient energy absorption structure 1, with a longitudinal length of 860mm and a lateral width of 740mm. In order to further improve the impact energy absorption characteristics of the structure, the present invention preferably uses two functional gradient thickness round tube shrinking energy absorption structures: Figure 4 The four functional gradient thickness circular tubes shown are symmetrically distributed on the left and right. Figure 5The 6 functional gradient thickness circular tubes shown are symmetrically distributed on the left and right. The symmetrical distribution scheme of 4 functional gradient thickness circular tubes has a smaller overall mass and occupies a smaller space, but the impact load borne by a single tube is larger, and buckling instability is prone to occur. The symmetrical distribution scheme of 6 functional gradient thickness circular tubes has a larger overall mass and occupies a larger space, but the impact load borne by a single tube is smaller, and the structural deformation is more stable. In both schemes, parameters such as the diameter and wall thickness of the circular tube, and the design of the reduced diameter part can be determined according to the operating conditions and safety performance requirements of the train. In addition, the specific structural design of the coupler seat 43 and the support seat 41 is to ensure the coordination and cooperation of the energy absorption structure with other vehicle components.

[0048] The present invention uses Al6061 aluminum alloy material as the main component of the energy absorbing structure to ensure that the energy absorbing structure can withstand high-intensity impact force and undergo large plastic deformation when a collision occurs. The geometric shape of the energy absorbing structure is also an important factor affecting its impact energy absorption characteristics. Generally speaking, the larger the diameter and wall thickness of the round tube, the stronger the energy absorption capacity; and the design of the reduced diameter part determines the impedance characteristics and effective deformation stroke of the energy absorbing structure.

[0049] Figures 6 to 8 The figure shows the three-dimensional schematic diagram and cross-sectional view of the functional gradient circular tube energy absorption structure of the head vehicle. Figure 6 This is a three-dimensional diagram of the energy absorption structure of the lead vehicle. Figure 7 This is a cross-sectional view of the energy absorption structure of the lead vehicle. Figure 8 It is an enlarged view of the partial cross-sectional view of the energy absorbing structure. In this embodiment, the length of the head vehicle's functional gradient thickness reduced diameter circular tube energy absorbing structure is 860mm, the thick end of the circular tube is fixedly connected to the support seat, the outer diameter is 88mm, and the outer diameter of the circular tube matching section 112 is 80mm, which is used to match and connect with the inner diameter of the energy absorbing seat 12. The thickness of the circular tube is a key parameter for controlling the impact force. The thickness of the circular tube in different length directions corresponds to different impact forces. The impedance design value of a single circular tube at the initial deformation stroke is 240kN, and the corresponding thickness t0=7.0mm; the impedance at the final effective deformation stroke of 800mm is 345kN, and the corresponding tube wall thickness t1=9.1mm; the impedance changes from 240kN in the initial stroke to 345kN in the final stroke, and the thickness t b Gradual, and t b =t0+(t1-t0)(d / 800)^0.172. The total length of the energy absorbing seat 12 is 25 mm, wherein the inner diameter of the small end is 80 mm and the length is 5 mm; the inner diameter of the large end is 89 mm and the length is 10 mm; and the length of the curved transition section is 10 mm.

[0050] Figures 9-10 The figure shows the three-dimensional schematic diagram and cross-sectional view of the functional gradient circular tube energy absorption structure of the intermediate vehicle. Fig. 9 This is a three-dimensional diagram of the energy absorption structure of the middle car. Fig.10This is a cross-sectional view of the energy absorption structure of the middle car. The length of the round tube is 260mm, the length of the functional gradient thickness zone is 200mm, the external structural dimensions of the round tube and the structural dimensions of the energy absorption seat are consistent with the structural dimensions of the head car, according to the impedance design value of the initial deformation stroke of a single round tube is 224kN, and its corresponding thickness t0 = 6.4mm; the impedance at the final effective deformation stroke of 200mm is 498kN, and the corresponding tube wall thickness t1 = 12.3mm; the impedance changes from 224kN in the initial stroke to 498kN in the final stroke, and the thickness t b Gradual, and t b =t0+(t1-t0)(d / 800)^0.172.

[0051] Example 2

[0052] This embodiment is a simulation analysis of a functionally gradient thickness circular tube with reduced diameter and energy absorption structure.

[0053] Under the finite element simulation conditions, the test specimen is installed on a collision trolley, which runs on a steel rail and hits a rigid wall at a certain initial speed. At this time, the circular tube structure is subjected to a large impact load, and its energy absorption performance becomes an important factor affecting the performance of the specimen. The correlation analysis is based on the explicit nonlinear finite element method and is carried out on the DYNA3D dynamic impact simulation analysis platform. The numerical solution equations for component impact dynamic simulation are established based on the three equations of mass conservation, momentum conservation, and energy conservation. The explicit integration algorithm is used to control the calculation time and time step in combination with the specimen geometry and the trolley impact test. The contact algorithm uses automatic single-sided contact.

[0054] The results show that under the impact load, the circular tube is bent and flattened, and shear and compression stresses are generated. These stresses are mainly concentrated in the contact area between the circular tube and the energy absorbing seat. As the load increases, the contact area between the circular tube and the energy absorbing seat begins to produce plastic deformation, and a plastic area is gradually formed. From the deformation process, it can be seen that both circular tube distribution methods have undergone stable deformation, have good energy absorption performance, and can protect the supporting structure from damage when impacted or hit.

[0055] Fig.11The impact force-effective stroke curve of the functional gradient thickness circular tube energy absorption structure. As can be seen from the figure, as the compression stroke of the circular tube continues to increase, the impact force gradually increases. At the same time, the slope of the curve decreases with the increase of stroke, indicating that the energy absorption capacity of the circular tube to the impact force gradually decreases. The starting point of the curve indicates that when the impact force is small, the initial deformation of the circular tube is also small, and the impact energy can be effectively absorbed. However, as the impact force increases, the circular tube begins to deform significantly, and the slope of the curve slows down, which means that the efficiency of the circular tube in absorbing energy is gradually decreasing. It is worth noting that since the circular tube structure adopts a functional gradient thickness design, it can achieve better energy absorption effect when it is subjected to impact force. Therefore, the area under the curve indicates that the energy absorbed by the circular tube is also greater than that of the ordinary structure. At the same time, the number of pipes has no effect on the impact force-stroke curve of the functional gradient thickness circular tube energy absorption structure. If the functional gradient circular tube reduction thickness is increased in the same proportion, the design scheme of four symmetrical arrangements can also achieve the impact force level of the six symmetrical arrangements. In this case, the impact force level of a single circular tube will be higher. Designers can choose a suitable design scheme based on the size of the structural space, quality requirements, and the distribution of the load borne by the coupler mounting seat.

[0056] Example 3

[0057] In order to verify the impact energy absorption characteristics and safety performance of the functionally gradient thickness circular tube reduced diameter energy absorption structure, a collision test is required.

[0058] In order to further verify the deformation stability and movement coordination of the designed high-speed train end energy absorption combined structure, a trolley test was carried out. The impact test was carried out using the Central South University collision test bench. The impact condition was that the counterweight trolley hit the stationary rigid wall at a certain speed under the drive of the air cannon. The test trolley can appropriately adjust the counterweight to meet the impact energy of different test pieces.

[0059] from Fig.12 The deformation sequence of the functional gradient thickness circular tube energy absorption structure in the impact test shows that the deformation mode of the component follows a stable and controllable deformation mode. Fig.12 a, the rigid hook head contacts the rigid wall mount, a collision occurs, and the energy-absorbing structure of the functional gradient thickness circular tube with reduced diameter begins to deform. As the collision continues, the energy-absorbing structure undergoes stable and controllable deformation, such as Fig.12 As shown in b, when the impact displacement is 100 mm, it can be clearly seen that there are obvious friction marks on the surface of the round tube after the shrinkage deformation. Fig.12 When the impact displacement shown in c is 200 mm, as the energy absorbing tube continues to shrink in diameter, the deformed energy absorbing tube does not interfere with the support seat. Fig.12When the impact displacement shown in d is 400mm, the shrinkage deformation of the functional gradient thickness tube continues to proceed steadily, and the deformed tube undergoes a slight bending deformation. The undeformed tube remains stable under the impact force and does not experience unstable buckling. The entire energy absorption process is stable and orderly until the impact ends and the trolley speed drops to 0. After that, the trolley retreats to a certain extent due to the release of elastic potential energy.

[0060] From the photos of the final deformation mode of the functional gradient thickness circular tube energy absorption structure in the impact test, it can be seen that the deformation degree of the energy absorption structure after the test is large, and stable deformation has occurred. Among them, the main deformation area is concentrated in the circular tube area of ​​the energy absorption structure. The deformation amount of these deformation areas is large, forming a more obvious shrinkage and contraction deformation. During the entire test process, the energy absorption structure can effectively absorb the impact energy and avoid serious damage to the rail vehicle, which proves the good energy absorption characteristics and safety performance of the functional gradient thickness circular tube energy absorption structure.

[0061] Fig.13 This is the impact force-effective stroke curve of the impact test of the functional gradient thickness circular tube with reduced diameter energy absorption structure. It can be seen from the figure that the change of the impact force during the entire structural compression process is relatively smooth: the initial peak force is 1454kN. This peak force appears because the specimen has just contacted the rigid wall. The impact force of the rigid hook rises rapidly after contacting the rigid wall, reaching the first peak at 14.2mm. At this time, the functional gradient thickness circular tube begins to shrink and deform to absorb energy. When it reaches 37mm, the impact force enters the platform stage, and the amplitude of the impact force changes very little. The whole process lasts for 469mm, the energy absorption process is stable and orderly, and the structure does not show obvious instability. The average force of the entire collision process is 1160.8kN, and the deformation process is smooth and orderly. The average force of the entire process obtained in the numerical simulation experiment is 1247.1kN. It can be seen that the experimental and simulation results are relatively close, with a relative error of 7.43%.

[0062] Will Fig.13 The impact force-effective stroke curve can be obtained by integrating Fig.14 From the energy dissipation curve, we can see that during the impact test, the total energy dissipation of the functional gradient thickness circular tube energy-absorbing structure within the effective deformation stroke is about 526kJ. According to the kinetic energy theorem, the initial kinetic energy carried by the entire vehicle during collision is about 558MJ, and the energy is almost completely dissipated by the energy-absorbing structure.

[0063] Example 4

[0064] This embodiment is a collision energy absorption method for rail vehicles according to the present invention.

[0065] In the traditional multi-stage energy absorption mode at the end of a high-speed train, the impedance of the energy absorption zone during the impact process is in a stable and unchanged state, such as Fig.15 and Fig.16 This paper proposes a new energy absorption mode, which makes the impedance of the energy absorption zone in the impact process in a gradual change state, called the gradual gradient energy absorption mode, as shown in Fig.17 and Fig.18 shown.

[0066] Specifically, in the prior art, the front energy absorption device of a high-speed train generally adopts a multi-stage energy absorption structure, which works step by step. The first stage is the compression of the coupler (gas-liquid buffer + crush tube); the second stage is the combined compression of the main energy absorption structure and the anti-climbing energy absorption device. In this mode, the impedance of the energy absorption area at the end of the head car and the middle car of the high-speed train during the collision is in a stable and unchanged state. Fig.15 As shown in the figure, during the collision, first, the coupler system of the leading car starts to work, including the reversible deformation of the buffer and the irreversible deformation of the crush tube to absorb the kinetic energy of the impact. Secondly, the connection between the coupler and the bottom of the car is sheared and broken, and the coupler system returns to the car under the impact force, and the energy-absorbing structure absorbs most of the kinetic energy of the impact. Finally, the remaining kinetic energy is absorbed by the non-passenger area of ​​the car body. Fig.16 As shown, only the coupler crush tube in the middle car absorbs energy, so the kinetic energy generated by the collision between the vehicles is dissipated by the plastic deformation of the coupler crush tube.

[0067] According to the collision energy dissipation process of the existing high-speed train, on the basis of the energy absorption mode of the end energy absorption zone of the high-speed train in the prior art, the present invention proposes a gradual gradient energy absorption mode, such as Fig.17 and Fig.18 shown.

[0068] Fig.17 and Fig.18 It can be seen that during the collision, the gradual gradient energy absorption mode ensures that the impact platform force is a gradual change process, and provides a variable platform force-displacement curve at different compression positions in the end energy absorption zone. In actual engineering applications, the energy absorption structure can achieve gradual gradient energy absorption through a circular tube with a gradual wall thickness.

[0069] The mathematical expression of the impedance of the gradual gradient energy absorption zone at the end of a high-speed train is:

[0070] F=F e1 +(F e2 -F e1 )(d / d e ) n

[0071] Where F is the impedance, F e1 is the minimum value of impedance, F e2 is the maximum value of the impedance, d is the effective deformation stroke, d e is the total effective deformation stroke, d e =dmax -d min , d max is the maximum value of the effective deformation stroke, d min is the minimum value of the effective deformation stroke, and n is the gradient index.

[0072] According to the above formula, in the gradient energy absorption zone at the end of the high-speed train, the impedance value changes from the minimum value F e1 Rise to maximum value F e2 , the corresponding minimum effective deformation stroke d min Rising to the maximum value d max , and for values ​​of gradient index n<1, the distribution function is Fig.19 In the present invention, n is preferably 0.1 to 0.5.

[0073] Energy dissipation calculations were performed on the two modes of conventional multi-stage energy absorption in the prior art and the gradual gradient energy absorption mode of the present invention. The calculation results show that under the same impact conditions, the energy absorption and impact deceleration of the high-speed train using the gradual gradient energy absorption mode on the main energy absorption interface are better than those of the traditional multi-stage energy absorption mode. Compared with the traditional multi-stage energy absorption mode, the high-speed train using the gradual gradient energy absorption mode has significantly improved the energy absorption at the end of the collision head car, and the overall balanced reduction in impact deceleration. The gradual gradient energy absorption mode proposed by the present invention reduces the risk of structural damage to the train during a collision, and better protects the personal safety of passengers and drivers and control personnel.

[0074] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for absorbing energy by gradual gradient collision of rail vehicles, characterized in that: In the energy absorption method, the impedance and effective deformation stroke curve of the rail vehicle includes a gradient energy absorption zone curve, and the gradient energy absorption zone curve means that the impedance increases gradually with the increase of the effective deformation stroke of the vehicle; the gradual gradient is a smooth gradient or a step gradient; The energy absorption method is realized by a corresponding energy absorption device, the energy absorption device comprising more than two energy absorption structures, the energy absorption structure (1) comprising a circular tube structure (11) and an energy absorption seat (12), the circular tube structure comprising a main body section (111) and a matching section (112), the outer wall of the main body section being cylindrical and the inner wall being truncated cone-shaped as a whole, so that the wall thickness of the main body section is thick at one end and thin at the other end, and the wall thickness of the main body section is in a smooth gradient or a step gradient from the thick end to the thin end, the wall thickness of the thick end is 5 to 30 mm, the wall thickness of the thin end is 4 to 8 mm, and the difference between the wall thickness of the thick end and the thin end is within 1 mm. The thin end is connected to a matching section (112), the matching section is used to connect to an energy absorbing seat (12), the energy absorbing seat is in an annular shape as a whole, and is arranged on the radially outer side of the matching section, the outer wall size of the matching section is smaller than the outer wall size of the main section, so that a step or a curve transition is formed at the connection between the outer walls of the two, the inner wall of the matching section (112) maintains the same and continuous gradient structure as the main section (111), the outer diameter of the energy absorbing seat (12) is larger than the outer diameter of the main section, and the energy absorbing seat covers part or all of the matching section (112) and covers a part of the thin end of the main section (111) in the axial direction.

2. The method according to claim 1, characterized in that The energy absorbing structure is used for a lead car of a rail vehicle, the length of the circular tube structure (11) is 600-1200 mm, the energy absorbing seat (12) of the lead car and the thin end of the main body section (111) are arranged at a position away from the body of the lead car, while the thick end of the main body section (111) of the lead car is arranged at a position close to the body of the lead car.

3. The method according to claim 2, characterized in that The energy absorbing device includes 4 to 6 energy absorbing structures.

4. The method according to claim 1, characterized in that: The energy absorbing structure is used for an intermediate car of a rail vehicle, the length of the circular tube structure (11) is 200-400 mm, and the energy absorbing seat (12) and the thin end of the main body section (111) of the intermediate car are arranged at a position close to the intermediate car body, while the thick end of the main body section (111) of the intermediate car is arranged at a position far from the intermediate car body.

5. The method according to claim 4, characterized in that The energy absorbing device comprises 2 or 4 energy absorbing structures distributed on the left and right.

6. The method according to claim 1, characterized in that The circular tube structure of the energy absorbing structure is made of AL6061 seamless aluminum alloy.

7. The method according to any one of claims 1 to 6, characterized in that: The gradient energy absorption zone curve is expressed by the following mathematical expression: In the formula, F is the impedance, F e1 is the minimum value of impedance, F e2 is the maximum value of the impedance, d is the effective deformation stroke, d e is the total effective deformation stroke, d e = d max - d min , d max is the maximum value of the effective deformation stroke, d min is the minimum value of the effective deformation stroke, n is the gradient index, and n <1.

8. The method according to claim 7, characterized in that n The value is 0.1~0.5.

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