Energy absorption structure and design method thereof

Abstract

The invention discloses an energy absorption structure and a design method thereof. The energy absorption structure comprises an outer peripheral plate, an inner peripheral plate and an inner peripheral plate, the number of the rib plates is multiple, and at least part of the rib plates in the multiple rib plates are arranged in a crossed mode and form crossed points; the bionic unit comprises a first pipe and a second pipe, the first pipe is arranged at the intersection of the rib plates, a first flow channel is formed in the first pipe, the second pipe is arranged in the first flow channel, a second flow channel is formed in the second pipe, the first flow channel is communicated with the second flow channel, a through hole communicated with the outside is formed in the second flow channel, and the first flow channel is communicated with the second flow channel. The first flow channel and the second flow channel are filled with magnetorheological fluid. According to the energy absorption structure, controllable crashworthiness is achieved, the situation that a traditional thin-wall energy absorption structure is constant in rigidity and poor in environmental adaptability due to the fact that the crashworthiness is uncontrollable along with design completion is avoided, the total energy absorption capacity of the bionic unit and the specific energy absorption capacity of a solid structure part are improved, and the crashworthiness is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle manufacturing, and in particular to an energy absorbing structure and a design method thereof. Background Art

[0002] It is pointed out in the relevant technology that thin-walled tube structures have the advantages of light weight, easy processing, and high energy absorption efficiency. Therefore, they are often used as collision buffering and energy absorption devices in the fields of vehicles, aerospace, civil engineering, etc. With the increasing requirements for lightweight structures and crash resistance in various fields, a large number of new thin-walled tube structures have been designed and proposed. These thin-walled structures usually improve the crash resistance and energy absorption characteristics of thin-walled structures by designing and optimizing their cross-sectional shapes or filling them with lightweight energy-absorbing materials such as foam aluminum and lattice structures. In particular, based on bionics, many thin-walled multicellular tube structures with high specific energy absorption have been proposed. Although these structures have excellent energy absorption performance, their collision energy absorption performance remains constant after their design is completed, and it is difficult to have a certain environmental adaptability when facing unpredictable collisions of different intensities in daily life. In addition, traditional thin-walled energy absorption structures all use the deformation of solid structures to achieve energy absorption. In fact, a well-designed structure can also achieve buffering energy absorption by using the fluidity of liquids, such as hydraulic dampers. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an energy absorbing structure having high crash resistance.

[0004] The invention also provides a design method of the energy absorbing structure.

[0005] According to the first aspect of the present invention, the energy-absorbing structure includes: a peripheral plate, which encloses a containing space; a rib plate, which is located in the containing space, and the rib plate includes a plurality of rib plates, and at least some of the plurality of rib plates are cross-arranged to form an intersection; a bionic unit, which includes a first tube and a second tube, the first tube is arranged at the intersection of the plurality of rib plates, a first flow channel is formed in the first tube, the second tube is arranged in the first flow channel, the second tube forms a second flow channel, the first flow channel and the second flow channel are connected, the second flow channel forms a through hole connected to the outside, and the first flow channel and the second flow channel are both filled with magnetorheological fluid.

[0006] According to the energy-absorbing structure of the present invention, the damping force characteristics of the magnetorheological fluid can be controlled by the external magnetic field to change its energy absorption capacity when flowing in the first tube and the second tube, thereby achieving controllable crash resistance of the energy-absorbing structure, avoiding the poor environmental adaptability caused by the constant stiffness of traditional thin-walled energy-absorbing structures and the uncontrollable crash resistance as the design is completed, improving the total energy absorption of the bionic unit and the specific energy absorption of the solid structure part, and significantly improving the crash resistance.

[0007] In some embodiments, both ends of the first tube are closed, the first end of the second tube is located in the first flow channel, a connecting hole is formed on the peripheral wall of the first end of the second tube, the second tube is connected to the first tube through the connecting hole, the through hole is formed at the second end of the second tube, and the first flow channel is connected to the outside through the second flow channel.

[0008] In some embodiments, the length of the second tube is no greater than the length of the first tube, and the radius of the second tube is smaller than the radius of the first tube.

[0009] Furthermore, the radius of the second tube is not greater than 8 mm, and the ratio of the radius of the first tube to the radius of the second tube is 1.5 to 2.5.

[0010] In some embodiments, a weak area is formed at the first end of the second tube, the connecting hole is formed in the weak area, a sealing member is provided at the connecting hole, and the sealing member is openably provided at the connecting hole.

[0011] In some embodiments, the number of the ribs connected between the first tube and the second tube is no more than 6.

[0012] The design method of the energy absorbing structure according to the second aspect of the present invention is used to design the energy absorbing structure according to the first aspect of the present invention, and the design method comprises: step S2, designing the bionic unit;

[0013] Step S3, calculating the magnetic field strength applied outside the energy absorbing structure, and designing the controllability of the total energy absorption of the magnetorheological fluid;

[0014] Step S4: creating an energy absorption model of the bionic unit, and designing and verifying the controllability of the bionic unit.

[0015] According to the design method of the energy-absorbing structure of the present invention, the damping force characteristics of the magnetorheological fluid can be controlled by the external magnetic field to change its energy absorption capacity when flowing in the structure, thereby achieving controllable crash resistance of the energy-absorbing structure, avoiding the poor environmental adaptability caused by the constant stiffness of traditional thin-walled energy-absorbing structures and the uncontrollable crash resistance as the design is completed, improving the total energy absorption of the bionic unit and the specific energy absorption of the solid structure part, and significantly improving the crash resistance.

[0016] Furthermore, the step S3 comprises:

[0017] Step S3.1, control the magnetic induction intensity B by the current intensity I, the expression is:

[0018]

[0019] The magnetic field intensity H is calculated by the magnetic induction intensity B, and the expression is:

[0020]

[0021] Among them, μ 0 is the vacuum magnetic permeability, r is the distance from the magnetic field source to the magnetic field measurement point, and M is the magnetization intensity;

[0022] Step S3.2: Controlling the shear yield stress τ by means of the magnetic field strength H 0 , the expression is:

[0023]

[0024] Where, φ is the volume fraction of magnetic particles, M S is the saturation magnetization of the magnetic particles;

[0025] Step S3.3, the shear yield stress τ 0 , the shear stress τ and shear strain rate of the magnetorheological fluid The relationship between is expressed by the constitutive equation as follows:

[0026]

[0027] Where τ is the shear stress of the magnetorheological fluid, τ 0 is the shear yield stress controlled by the magnetic field intensity, η is the apparent viscosity of the magnetorheological fluid, v is the flow rate of the magnetorheological fluid, z is the radius of the set research point, is the shear strain rate of the magnetorheological fluid;

[0028] Step S3.4: Calculate the total energy E absorbed by the magnetorheological fluid during the compression process of the bionic unit. f , the expression is:

[0029]

[0030] Among them, t 0 is the time of compression stroke, Δp is the pressure drop, Q is the pipeline flow rate, v 1 is the average flow velocity of the magnetorheological fluid in the circular tube, Δp uc and Δp c are uncontrollable pressure drop and controllable pressure drop, E fuc is the uncontrollable energy absorbed by the magnetorheological fluid, E fc is the controllable energy absorbed by the magnetorheological fluid,

[0031] The uncontrollable pressure drop Δp of the magnetorheological fluid uc and controllable pressure drop Δp c The expression is:

[0032]

[0033] Where ρ is the fluid density, v 0 is the flow rate of the magnetorheological fluid in the first tube, v 1 is the flow rate of the magnetorheological fluid in the second tube, v 2 is the flow rate of the magnetorheological fluid flowing through the connecting hole, D is the hydraulic diameter of the non-circular cross section, L 0 is the initial tube length of the bionic unit, t is the compression time, ζ 1 , 2 , 3 , 4 is the local drag coefficient, and ζ 1 , 2 , 3 , 4 The empirical values ​​in this local state are taken as 0.5, 1, 0.06 and 1.2 respectively.

[0034] Furthermore, the step S4 comprises:

[0035] Step S4.1, calculate the effective crushing length L of the bionic unit v The effective crush energy absorption E s , the expression is:

[0036]

[0037] Among them, L v is the effective crush length, H is the half wavelength, E se is the total energy dissipated by deformation of the weak zone, E m is the film stretching energy, E b is the film bending energy,

[0038] The expression of the half wavelength H is:

[0039]

[0040] Where b is the thickness of the plate, M 0 is the plastic bending moment, L 1 is the length of the rib between the first tube and the second tube, L 2 α is the length of the rib on the radially outer side of the first tube; 1 , α 2 , and θ are the angles between the boundary of the plastic deformation area formed during the deformation process and the vertical lines of the upper and lower boundaries;

[0041] Step S4.2: Create an energy absorption model of the bionic unit, expressed as:

[0042] E=E s +Ef =∫Fd(v 0 t)

[0043] Step S4.3: Design the controllability of the bionic unit, and the theoretical controllability η c The expression is:

[0044] Its expression is:

[0045]

[0046] Among them, F m 、F uc 、F c The expressions of A, B, and C are:

[0047]

[0048] F uc =Δp uc ·NS cell

[0049] F c =Δp c ·NS cell

[0050]

[0051] The S cell is the cross-sectional area of ​​a single bionic unit;

[0052] Step S4.4, verifying the actual controllability of the bionic unit, and comparing the actual controllability with the theoretical controllability.

[0053] Furthermore, the designing of the bionic unit includes: calculating the local pressure loss Δp of the magnetorheological fluid during the flow process, and the expression of the local pressure loss Δp is:

[0054] Δp=Δp in +Δp out +Δp hole +Δp joint

[0055] Among them, Δp in is the pressure loss caused by the insufficient development of magnetorheological fluid, Δp out is the pressure loss caused by the magnetorheological fluid spraying from the through hole, Δp hole is the orifice flooding pressure loss caused by the magnetorheological fluid passing through the connecting hole of the second tube, Δp joint is the pressure loss caused by the confluence of multiple branches in the second pipe,

[0056] Δp in, Δp oyt , Δp hole , Δp joint The expressions are:

[0057]

[0058]

[0059] Where δ 1 , δ 2 , δ 3 , and δ 4 The drag coefficient under each local shape, v 0 is the flow rate of the magnetorheological fluid in the first tube, v 1 is the flow rate of the magnetorheological fluid in the second tube, v 2 is the flow rate of the magnetorheological fluid flowing through the connecting hole.

[0060] Further, a ratio between a radius R of the first tube and a radius r of the second tube is 1.5 to 2.5.

[0061] In some embodiments, the design method further includes: step S1, classifying the bionic units according to the number N of ribs.

[0062] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 is a schematic diagram of an energy absorbing structure according to an embodiment of the present invention;

[0064] Figure 2 yes Figure 1 Schematic diagram of the biomimetic unit shown in;

[0065] Figure 3 yes Figure 2 A schematic diagram of a lateral cross section of the biomimetic unit shown in ;

[0066] Figure 4 Yes Figure 3 Schematic diagram of applying magnetic field to the bionic unit shown in;

[0067] Figure 5 yes Figure 1 Schematic diagram of the verification of the energy absorbing structure shown in ;

[0068] Figure 6 yes Figure 2 Schematic diagram of theoretical derivation of the second tube of the bionic unit shown in;

[0069] Figure 7 yes Figure 6 Schematic diagram of further theoretical derivation of the second tube of the bionic unit shown in;

[0070] Figure 8 yes Figure 2 Schematic diagram of theoretical derivation of the first tube of the bionic unit shown in;

[0071] Fig. 9 yes Figure 8 Schematic diagram of further theoretical derivation of the first tube of the bionic unit shown in .

[0072] Reference numerals:

[0073] 100. Energy absorbing structure;

[0074] 1. Peripheral plate;

[0075] 2. Ribs;

[0076] 3. Bionic unit; 31. First tube; 32. Second tube; 321. Connecting hole;

[0077] 4. Through hole. DETAILED DESCRIPTION

[0078] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0079] First, refer to Figure 1-Figure 9 A design method for the energy absorbing structure 100 according to an embodiment of the second aspect of the present invention is described. The design method for the energy absorbing structure 100 is used to design the energy absorbing structure 100 according to an embodiment of the first aspect of the present invention.

[0080] The design method of the energy absorbing structure 100 according to the embodiment of the present invention includes:

[0081] Step S1, classifying the bionic units 3 according to the number of ribs N;

[0082] Step S2, designing the bionic unit 3;

[0083] Step S3, calculating the magnetic field strength applied outside the energy absorbing structure 100, and designing the controllability of the total energy absorption of the magnetorheological fluid;

[0084] Step S4: creating an energy absorption model of the bionic unit 3, and designing and verifying the controllability of the bionic unit 3.

[0085] According to the design method of the energy-absorbing structure 100 of the embodiment of the present invention, the damping force characteristics of the magnetorheological fluid can be controlled by the external magnetic field to change its energy absorption capacity when flowing in the structure, thereby achieving controllable crash resistance of the energy-absorbing structure 100, avoiding the poor environmental adaptability caused by the constant stiffness of traditional thin-walled energy-absorbing structures and the uncontrollable crash resistance as the design is completed, improving the total energy absorption of the bionic unit 3 and the specific energy absorption of the solid structure part, and significantly improving the crash resistance.

[0086] Specifically, step S1, classify the bionic units 3 according to the number of ribs N. The solid structure bionics has the characteristics of the multicellular structure of horsetail grass with extremely high load-bearing capacity. At the same time, drawing on the microstructure of the beetle elytra, hollow thin circular tubes are added at the intersection of the multicellular thin-walled tube ribs to form a bionic micro-circular structure with better energy absorption characteristics than the traditional thin-walled tube structure. According to the number N of ribs 2, the bionic units 3 are classified into N=3 bionic units, N=4 bionic units and N=5 bionic units, etc. Usually, the total number N of the ribs 2 cannot exceed 6. The inner radius of the second tube 32 is r, the inner radius of the first tube 31 is R, and the length is L. Based on the energy absorption effect of the magnetorheological fluid and the geometric size relationship of the bionic unit 3, the inner radius r of the second tube 32 is not greater than 8 mm. Figure 1 Shown are N=4 bionic units 3 .

[0087] Furthermore, based on the expression E in fluid mechanics f =V*ΔpIt can be seen that (E f = is the total energy absorption during the liquid flow, Δp is the fluid pressure drop generated during the flow, and V is the volume of the liquid flowing through): In the energy absorption structure 100, since the volume of the magnetorheological fluid stored is constant, the total energy absorption E of the magnetorheological fluid can only be increased by increasing the fluid pressure drop Δp generated during the flow of the magnetorheological fluid. f .

[0088] Therefore, a seal is provided at the through hole 4, and the seal can be opened at the through hole 4. When the energy absorbing structure 100 is crushed and deformed, the magnetorheological fluid enters the second tube 32 from the first tube 31 through the connecting hole 321, and after passing through the second tube 32, the seal is broken by pressure and flows out from the through hole 4.

[0089] The design of the bionic unit 3 includes: calculating the local pressure loss Δp of the magnetorheological fluid during the flow process, and the expression of the local pressure loss Δp is:

[0090] Δp=Δp in +Δp iut +Δp hole +Δp joint

[0091] Among them, Δp in is the pressure loss caused by the insufficient development of magnetorheological fluid, Δpout is the pressure loss caused by the magnetorheological fluid spraying from the through hole 4, Δp hole is the orifice flooding pressure loss caused by the magnetorheological fluid passing through the connecting hole 321 of the second tube 32, Δp joint The pressure loss caused by the merging of multiple branches in the second tube 32 is as follows: in , the pressure loss Δp caused by the magnetorheological fluid spraying from the through hole 4 out , the orifice flooding pressure loss Δp caused by the magnetorheological fluid passing through the connecting hole 321 of the second tube 32 hole and the pressure loss Δp caused by the merging of multiple branches in the second pipe 32 joint ,

[0092] Δp in , Δp out , Δp hole , Δp joint The expressions are:

[0093]

[0094] Where δ 1 , δ 2 , δ 3 , and δ 4 The drag coefficient under each local shape, v 0 is the flow rate of the magnetorheological fluid in the first tube 31, v 1 is the flow rate of the magnetorheological fluid in the second tube 32, v 2 is the flow rate of the magnetorheological fluid flowing through the connecting hole 321 .

[0095] As can be seen from the above, in order to improve the energy absorption capacity of the magnetorheological fluid during the flow process, it is necessary to design the ratio between the radius R of the first tube 31 and the radius r of the second tube 32 to be 1.5-2.5. It can be understood that the inner wall radius R of the first tube 31 is much larger than the inner wall radius r of the second tube 32, thereby increasing the flow velocity v of the magnetorheological fluid in the second tube 32. 1 and the flow rate v of the magnetorheological fluid flowing through the connecting hole 321 2 , thereby improving the energy absorption capacity of the magnetorheological fluid during the flow process.

[0096] Furthermore, a first tube 31 and a second tube 32 are provided at the intersection of the ribs 2, and the radius of the first tube 31 is much larger than the radius of the second tube 32 (the radius of the first tube 31 is at least 1.5-2.5 times the radius of the second tube 32). The radius of the first tube 31 is large enough to store more magnetorheological fluid and to make the magnetorheological fluid flow faster and achieve better energy absorption when the energy absorbing structure 100 is subjected to axial loading. Figure 1 and Figure 2 As shown, the first tube 31 and the rib plate 2 are combined to form an independent sealed cell, in which the magnetorheological fluid is arranged, and the sealed cells are independent of each other, thereby improving the safety of the sealed cells and avoiding the situation that an accident in one sealed cell may affect other sealed cells.

[0097] In some embodiments of the present invention, a controllable electromagnetic field is added outside the energy absorbing structure 100 to control the maximum shear yield stress and the minimum shear yield stress of the magnetorheological fluid. The energy dissipated by the magnetorheological fluid when flowing in the energy absorbing structure 100 can be divided into 0 The Coulomb damping and the flow velocity v i The shear yield stress τ of the magnetorheological fluid is 0 It can be changed by a magnetic field. Specifically, step S3 includes:

[0098] Step S3.1, control the magnetic induction intensity B by the current intensity I, the expression is:

[0099]

[0100] The magnetic field intensity H is calculated by the magnetic induction intensity B, and the expression is:

[0101]

[0102] Among them, μ 0 is the vacuum magnetic permeability, r is the distance from the magnetic field source to the magnetic field measurement point, and M is the magnetization intensity;

[0103] Step S3.2: Controlling the shear yield stress τ by means of the magnetic field strength H 0 , the expression is:

[0104]

[0105] Where, φ is the volume fraction of magnetic particles, M S is the saturation magnetization of the magnetic particles;

[0106] Step S3.3, shear yield stress τ 0 , shear stress τ and shear strain rate of magnetorheological fluid The relationship between is expressed by the constitutive equation as follows:

[0107]

[0108] Where τ is the shear stress of the magnetorheological fluid, v 0 is the shear yield stress controlled by the magnetic field intensity, η is the apparent viscosity of the magnetorheological fluid, v is the flow rate of the magnetorheological fluid, z is the radius of the set research point, is the shear strain rate of the magnetorheological fluid;

[0109] Step S3.4: Calculate the total energy E absorbed by the magnetorheological fluid during the compression process of the bionic unit 3 f , the expression is:

[0110]

[0111] Among them, t 0 is the time of compression stroke, Δp is the pressure drop, Q is the pipeline flow rate, v 1 is the average flow velocity of the magnetorheological fluid in the circular tube, Δp uc and Δp c are uncontrollable pressure drop and controllable pressure drop, E fuc is the uncontrollable energy absorbed by the magnetorheological fluid, E fc is the controllable energy absorbed by the magnetorheological fluid,

[0112] Uncontrollable pressure drop Δp of magnetorheological fluid uc and controllable pressure drop Δp c The expression is:

[0113]

[0114] Where p is the fluid density, v 0 is the flow rate of the magnetorheological fluid in the first tube 31, v 1 is the flow rate of the magnetorheological fluid in the second tube 32, v 2 is the flow rate of the magnetorheological fluid flowing through the connecting hole 321, D is the hydraulic diameter of the non-circular cross section, L 0 is the initial tube length of the bionic unit 3, t is the compression time, ζ 1 , 2 , 3 , 4 is the local drag coefficient, and ζ 1 , 2 , 3 , 4 The empirical values ​​in this local state are taken as 0.5, 1, 0.06 and 1.2 respectively.

[0115] In some embodiments of the present invention, it can be seen from the above that the total energy E absorbed by the magnetorheological fluid during the compression process of the bionic unit 3 is f The expression is:

[0116] E f =E fuc +E fc

[0117] That is, the total energy E absorbed by the magnetorheological fluid during the compression process of the bionic unit 3 is fUncontrollable energy E absorbed by the magnetorheological fluid fuc and the controllable energy E absorbed by the magnetorheological fluid fc Based on the super-folded unit theory of thin-walled tubes, assuming that the wavelength of a single crush deformation formed during the crushing of the energy-absorbing structure 100 is the same as the wall thickness, according to the principle of energy conservation, the energy consumed by a single crush deformation of the thin-walled tube is calculated from the film stretching energy E m and film bending energy E b composition.

[0118] Specifically, step S4 includes:

[0119] Step S4.1, calculate the effective crushing length L of the bionic unit 3 v The effective crush energy absorption E s , the expression is:

[0120]

[0121] Among them, L v is the effective crush length, H is the half wavelength, E se is the total energy dissipated by deformation of the weak zone, E m is the film stretching energy, E b is the film bending energy,

[0122] The expression of half wavelength H is:

[0123]

[0124] Where b is the thickness of the plate, M 0 is the plastic bending moment, L 1 is the length of the rib 2 between the first tube 31 and the second tube 32, L 2 α is the length of the rib 2 on the radially outer side of the first tube 31; 1 , α 2 , and θ is the angle between the boundary of the plastic deformation area formed during the deformation process and the vertical lines of the upper and lower boundaries, such as Figure 6-Figure 9 As shown;

[0125] Step S4.2, create an energy absorption model of the bionic unit 3, add the total energy absorption model of the magnetorheological fluid and the effective crushing energy absorption model of the solid structure to obtain the total energy absorption model of the magnetorheological bionic energy absorption unit, which can be calculated by the work done by the crushing force F of the magnetorheological bionic energy absorption unit during the crushing process ∫Fd(v 0 t) is described by:

[0126] E=E s +E f =∫Fd(v 0 t)

[0127] Step S4.3, design the controllability of the bionic unit 3. As can be seen from the above, the crushing force F generated during the crushing and energy absorption process of the bionic unit 3 is composed of the average crushing force F of the thin-walled solid structure. m , Coulomb damping force F during the flow of magnetorheological fluid c and the viscous damping force F of the magnetorheological fluid uc Composition, Coulomb damping force F generated by magnetorheological fluid c It can be controlled by changing the magnetic field strength, so the controllability of the bionic unit 3 is defined as the Coulomb damping force F c Ratio to crushing force F, theoretical controllability η c The expression is:

[0128]

[0129] Among them, F m 、F uc 、F c The expressions of A, B, and C are:

[0130]

[0131] F uc =Δp uc ·NS cell

[0132] F c =Δp c ·NS cell

[0133]

[0134]

[0135] S cell is the cross-sectional area of ​​a single bionic unit 3;

[0136] It can be understood that when the crushing speed of the energy absorbing structure 100 is constant, A, B and C are constants, so the controllability of the bionic unit 3 increases with the compression length v. 0 t increases and decreases.

[0137] Step S4.4, verify the actual controllability of the bionic unit 3, and compare the actual controllability with the theoretical controllability.

[0138] The following will refer to Figure 1-Figure 3 The verification of the actual controllability of the bionic unit 3 of the energy absorbing structure 100 according to a specific embodiment of the present invention is described.

[0139] Specifically, the controllability of N=4 bionic units 3 is checked.

[0140] Substitute the structural parameters and loading conditions of N=4 bionic unit 3 into the theoretical controllability η c In the expression of, the controllability η of the N=4 bionic unit 3 at a crushing speed of 3m / s can be obtained: c Theoretical value expression:

[0141]

[0142] The finite element model is used to calculate the compression distance v 0 Finite element simulation was performed on N=4 bionic unit 3 when t was different, and the E s , Δp uc and Δp c Substitute the controllability η c The controllability η of N = 4 bionic units 3 under different compression distances is obtained from the theoretical expression, and the simulation results are compared with the theoretical values ​​of the above formula, as shown in Figure 5 As shown, it can be seen that the theoretical value and simulation value of the controllability of N=4 bionic unit 3 have a good fit. The maximum theoretical controllability of bionic unit 3 at the beginning of compression is 27.73%. After being crushed to 200mm, the controllability drops to 12%.

[0143] The bionic unit 3 can be applied to a multi-cell energy absorbing structure 100, such as Figure 1 As shown, N=4 bionic units 3 are applied to a 9-cell thin-walled tube. The total energy absorption of the energy-absorbing structure 100 after the bionic unit 3 is set is increased by 293.7% compared with the traditional 9-cell thin-walled tube, and the total energy absorption of the thin-walled solid structure is increased by 62.54%. The maximum controllability at the initial moment is 22.44%. In an actual collision accident, the real-time collision intensity of the accident is combined with the controllability η c The energy absorption strength of the entire collision energy absorption structure 100 is adjusted using a theoretical value expression.

[0144] Reference below Figure 1-Figure 9 An energy absorbing structure 100 according to an embodiment of the first aspect of the present invention is described.

[0145] like Figure 1-Figure 9 As shown, the energy absorbing structure 100 according to the first embodiment of the present invention includes: a peripheral plate 1, a rib plate 2 and a bionic unit 3.

[0146] Specifically, the peripheral plate 1 encloses to form an accommodating space, the rib plate 2 is arranged in the accommodating space, the rib plate 2 includes a plurality of rib plates 2, and at least some of the plurality of rib plates 2 are cross-arranged to form an intersection, the bionic unit 3 includes a first tube 31 and a second tube 32, the first tube 31 is arranged at the intersection of the plurality of rib plates 2, a first flow channel is formed in the first tube 31, the second tube 32 is arranged in the first flow channel, a second flow channel is formed in the second tube 32, the first flow channel and the second flow channel are connected, the second flow channel is formed with a through hole 4 connected to the outside, and the first flow channel and the second flow channel are both filled with magnetorheological fluid.

[0147] According to the energy-absorbing structure 100 of the embodiment of the present invention, the damping force characteristics of the magnetorheological fluid can be controlled by the external magnetic field to change its energy absorption capacity when flowing in the first tube 31 and the second tube 32, thereby achieving controllable crash resistance of the energy-absorbing structure 100, avoiding the poor environmental adaptability caused by the constant stiffness of traditional thin-walled energy-absorbing structures and the uncontrollable crash resistance after the design is completed, improving the total energy absorption of the bionic unit 3 and the specific energy absorption of the solid structure part, and significantly improving the crash resistance.

[0148] In some embodiments of the present invention, both ends of the first tube 31 are closed, the first end of the second tube 32 is located in the first flow channel, a connecting hole 321 is formed on the peripheral wall of the first end of the second tube 32, the second tube 32 is connected to the first tube 31 through the connecting hole 321, the through hole 4 is formed at the second end of the second tube 32, the first flow channel is connected to the outside through the second flow channel, a weak area is formed at the first end of the second tube 32, the connecting hole 321 is formed in the weak area, a sealing member is provided at the connecting hole 321, and the sealing member is openably provided at the connecting hole 321. Therefore, the overall design of the energy absorbing structure 100 is ingenious, and the crash resistance is effectively improved.

[0149] Furthermore, the length of the second tube 32 is not greater than the length of the first tube 31, and the radius of the second tube 32 is smaller than the radius of the first tube 31. Preferably, the inner radius of the first tube 31 is much larger than the inner radius of the second tube 32, that is, the inner radius of the first tube 31 is at least 1.5 to 2.5 times the inner radius of the second tube 32, thereby effectively improving the energy absorption capacity of the magnetorheological fluid during the flow process.

[0150] Specifically, the radius of the second tube 32 is not greater than 8 mm, and the ratio of the radius of the first tube 31 to the radius of the second tube 32 may be 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5.

[0151] In order to ensure the energy absorbing effect of the energy absorbing structure 100 , preferably, the number of the ribs 2 connected between the first tube 31 and the second tube 32 is no more than six.

[0152] Reference Figure 3As shown, it is a comparison diagram of the bionic unit 3 before and after the collision. A collision force is applied to the illustrated left end of the bionic unit 3, and the bionic unit 3 is deformed. The deformation amount is the product of the compression stroke time and the flow rate of the magnetorheological fluid in the first tube 31. At this time, the magnetorheological fluid flows from left to right in the first tube 31. Since the volume in the first tube 31 is reduced, pressure is applied to the magnetorheological fluid, so that the magnetorheological fluid breaks through the seal of the connecting hole 321 at the weak area and flows into the second tube 32, and flows from right to left in the second tube 32.

[0153] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0154] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0155] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0156] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0157] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. An energy absorbing structure, characterized in that: include: Peripheral plates, the peripheral plates enclose and form a receiving space; A rib plate, wherein the rib plate is arranged in the accommodation space, and the rib plate comprises a plurality of rib plates, and at least some of the rib plates among the plurality of rib plates are cross-arranged to form a cross-point rib plate; A bionic unit, the bionic unit includes a first tube and a second tube, the first tube is arranged at the intersection of the ribs, a first flow channel is formed in the first tube, the second tube is arranged in the first flow channel, a second flow channel is formed in the second tube, the first flow channel and the second flow channel are connected, the second flow channel is formed with a through hole that can be connected to the outside, and the first flow channel and the second flow channel are both filled with magnetorheological fluid.

2. The energy absorbing structure according to claim 1, characterized in that: Both ends of the first tube are closed, the first end of the second tube is located in the first flow channel, a connecting hole is formed on the peripheral wall of the first end of the second tube, the second tube is connected to the first tube through the connecting hole, the through hole is formed at the second end of the second tube, and the first flow channel is connected to the outside through the second flow channel.

3. The energy absorbing structure according to claim 2, characterized in that: The length of the second tube is not greater than the length of the first tube, and the radius of the second tube is smaller than the radius of the first tube.

4. The energy absorbing structure according to claim 3, characterized in that: The radius of the second tube is not greater than 8 mm, and the ratio of the radius of the first tube to the radius of the second tube is 1.5 to 2.

5.

5. The energy absorbing structure according to claim 4, characterized in that: A weak area is formed at the first end of the second tube, the connecting hole is formed in the weak area, a sealing member is provided at the connecting hole, and the sealing member is openably provided at the connecting hole.

6. The energy absorbing structure according to any one of claims 1 to 5, characterized in that: The number of the ribs connected between the first tube and the second tube is no more than 6.

7. A design method for an energy absorbing structure, characterized in that: Used to design the energy absorbing structure according to any one of claims 1 to 6, the design method comprising: Step S2, designing the bionic unit; Step S3, calculating the magnetic field strength applied outside the energy absorbing structure, and designing the controllability of the total energy absorption of the magnetorheological fluid; Step S4: creating an energy absorption model of the bionic unit, and designing and verifying the controllability of the bionic unit.

8. The design method of the energy absorbing structure according to claim 7, characterized in that: The step S3 comprises: Step S3.1, control the magnetic induction intensity B by the current intensity I, the expression is: The magnetic field intensity H is calculated by the magnetic induction intensity B, and the expression is: Wherein, μ0 is the vacuum magnetic permeability, r is the distance from the magnetic field source to the magnetic field measurement point, and M is the magnetization intensity; Step S3.2, control the shear yield stress τ0 by the magnetic field intensity H, the expression is: Where, φ is the volume fraction of magnetic particles, M S is the saturation magnetization of the magnetic particles; Step S3.3, the shear yield stress τ0, the shear stress τ and the shear strain rate of the magnetorheological fluid The relationship between is expressed by the constitutive equation as follows: Wherein, τ is the shear stress of the magnetorheological fluid, τ0 is the shear yield stress controlled by the magnetic field intensity, η is the apparent viscosity of the magnetorheological fluid, v is the flow rate of the magnetorheological fluid, z is the set research point radius, is the shear strain rate of the magnetorheological fluid; Step S3.4: Calculate the total energy E absorbed by the magnetorheological fluid during the compression process of the bionic unit. f , the expression is: Among them, t0 is the time of compression stroke, Δp is the pressure drop, Q is the pipeline flow rate, v1 is the average flow velocity of magnetorheological fluid in the circular tube, Δp uc and Δp c are uncontrollable pressure drop and controllable pressure drop, E fuc is the uncontrollable energy absorbed by the magnetorheological fluid, E fc is the controllable energy absorbed by the magnetorheological fluid, The uncontrollable pressure drop Δp of the magnetorheological fluid uc and controllable pressure drop Δp c The expression is: Wherein, ρ is the fluid density, v0 is the flow rate of the magnetorheological fluid in the first tube, v1 is the flow rate of the magnetorheological fluid in the second tube, v2 is the flow rate of the magnetorheological fluid flowing through the connecting hole, D is the hydraulic diameter of the non-circular cross section, L0 is the initial tube length of the bionic unit, t is the compression time, ζ1, ζ2, ζ3, ζ4 are local resistance coefficients, and ζ1, ζ2, ζ3, ζ4 take the empirical values ​​of 0.5, 1, 0.06 and 1.2 in the local state respectively.

9. The design method of the energy absorbing structure according to claim 7, characterized in that: The step S4 comprises: Step S4.1, calculate the effective crushing length L of the bionic unit v The effective crush energy absorption E s , the expression is: Among them, L v is the effective crush length, H is the half wavelength, E se is the total energy dissipated by deformation of the weak zone, E m is the film stretching energy, E b is the film bending energy, The expression of the half wavelength H is: Wherein, b is the thickness of the thin plate, M0 is the plastic bending moment, L1 is the length of the rib between the first tube and the second tube, and L2 is the length of the rib on the radial outer side of the first tube; α1, α2, and θ are the angles between the boundary of the plastic deformation area formed during the deformation process and the vertical lines of the upper and lower boundaries; Step S4.2: Create an energy absorption model of the bionic unit, expressed as: And=And s +E f =∫Fd(v0t) Step S4.3: Design the controllability of the bionic unit, and the theoretical controllability η c The expression is: Its expression is: Among them, F m 、F uc 、F c The expressions of A, B, and C are: Fuc uc =Δp uc ·NS cell F c =Δp c ·NS cell The S cell is the cross-sectional area of ​​a single bionic unit; Step S4.4, verifying the actual controllability of the bionic unit, and comparing the actual controllability with the theoretical controllability.

10. The design method of the energy absorbing structure according to claim 7, characterized in that: The designing of the bionic unit includes: calculating the local pressure loss Δp of the magnetorheological fluid during the flow process, and the expression of the local pressure loss Δp is: Δp=Δp in +Δp out +Δp hole +Δp joint Among them, Δp in is the pressure loss caused by the insufficient development of magnetorheological fluid, Δp out is the pressure loss caused by the magnetorheological fluid spraying from the through hole, Δp hole is the orifice flooding pressure loss caused by the magnetorheological fluid passing through the connecting hole of the second tube, Δp joint is the pressure loss caused by the confluence of multiple branches in the second pipe, Δp in , Δp out , Δp hole , Δp joint The expressions are: Wherein δ1, δ2, δ3, and δ4 are the resistance coefficients under each local shape respectively, v0 is the flow rate of the magnetorheological fluid in the first tube, v1 is the flow rate of the magnetorheological fluid in the second tube, and v2 is the flow rate of the magnetorheological fluid flowing through the connecting hole.

11. The design method of the energy absorbing structure according to any one of claims 7 to 10, characterized in that: The method also includes: step S1, classifying the bionic units according to the number N of ribs.

12. The design method of the energy absorbing structure according to any one of claims 7 to 10, characterized in that: The ratio between the radius R of the first tube and the radius r of the second tube is 1.5 to 2.5.

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