Thin-wall energy absorption tube and energy absorption method

Abstract

The invention relates to a thin-wall energy absorption tube and an energy absorption method. The thin-wall energy absorption tube comprises an overturning part, a transition part and a restraining part which are sequentially connected in the axial direction to form a reducing hollow thin-wall tubular structure. The overturning part and the transition part are fixedly connected through an annular connecting piece, the annular connecting piece is of a plane annular or truncated cone annular structure, and the transition part and the restraining part are fixedly connected on an interface perpendicular to the central axis; in the connecting area of the overturning part and the transition part, the boundary of the projection of the connecting end of the overturning part on the horizontal plane is completely contained or completely contained in the boundary of the projection of the connecting end of the transition part on the horizontal plane, and the horizontal plane is any plane perpendicular to the central axis. According to the invention, the load curve is stable, the stroke efficiency is high, the load curve platform is improved, and the bearing average collision force performance can exceed that of the same gradually folded thin-walled tube.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy absorption structure, in particular to a thin-walled energy absorption tube and an energy absorption method. BACKGROUND

[0002] With the increasing speed and light weight of vehicles such as automobiles, rail vehicles and aerospace vehicles, higher and higher requirements are put forward for energy dissipation when accidents occur.

[0003] The energy absorption efficiency of axial deformation of a thin-walled structure is about one order of magnitude higher than that of transverse deformation. The deformation modes of the axial deformation thin-walled energy absorption device include axial progressive folding, free flipping, mold flipping, expansion, contraction, splitting, etc.

[0004] In one energy dissipation structure, an energy absorption device such as a front energy absorption box or a front longitudinal beam is made by using axial progressive stable folding deformation of a thin-walled structure. This axial progressive folding deformation of a thin-walled tube has the advantages of high energy absorption efficiency, compact structure after deformation, and high effective stroke efficiency, and is most widely used. Figure 1 Fig. 2 shows a structural schematic diagram of the axial progressive folding thin-walled tube after deformation under axial load, Figure 2 Fig. 3 shows an axial load force-displacement curve diagram of the axial progressive folding thin-walled tube. As can be seen from the diagram, this kind of tube has a very high initial peak force and a relatively high periodic folding trigger load in deformation, and the deformation load is relatively low after triggering. In each folding deformation process, the load fluctuates greatly, which is not conducive to load and member protection in vehicles. Therefore, in this structure, although the initial peak force and periodic fluctuation can be reduced by introducing an initial deformation trigger mechanism and introducing periodic defects or folds, indentations axially on the folding wavelength, respectively, the load fluctuation problem cannot be fundamentally solved.

[0005] In another energy dissipation structure, an energy absorption device using a free flipping form of a thin-walled tube has the advantages of almost constant deformation load and long effective stroke. Figure 4 Fig. 4 shows a structural schematic diagram of the free flipping thin-walled tube after deformation under axial load, Figure 3 Fig. 5 shows an axial load force-displacement curve diagram of the free flipping thin-walled tube. As can be seen from the diagram, the average load of the free flipping thin-walled tube is lower than that of the progressive stable folding tube of the same specification.

[0006] An ideal energy absorption device should have constant deformation load, high energy absorption efficiency and complete deformation stroke efficiency (100%). Therefore, it is urgent to propose a thin-walled energy absorption tube which has both high energy absorption efficiency and almost constant deformation load and high effective stroke efficiency, so as to realize more reliable application in automobiles, rail vehicles and aerospace vehicles. SUMMARY

[0007] In view of the defects of the prior art, the thin-wall energy absorption tube and the energy absorption method provided by the application overcome the defects of the prior art, are reasonable in design, and are compact in structure.

[0008] To achieve the above object, the application is implemented by the following technical scheme: The application provides a thin-wall energy absorption tube, which comprises a turnover part, a transition part and a constraint part which are sequentially connected in an axial direction to form a variable-diameter hollow thin-wall tubular structure; the turnover part and the transition part are fixedly connected through an annular connecting piece; the annular connecting piece is a planar annular structure or a truncated cone annular structure; the transition part and the constraint part are fixedly connected at an interface perpendicular to a central axis; in a connecting area of the turnover part and the transition part, a boundary of a horizontal plane projection of a connecting end of the turnover part is completely contained in a boundary of a horizontal plane projection of a connecting end of the transition part, and the horizontal plane is any plane perpendicular to the central axis.

[0009] Preferably, the turnover part is a cylindrical tube, a prism tube, a conical tube or a pyramid tube.

[0010] Preferably, the turnover part is made of metal or non-metal or composite material with good plastic deformation capacity.

[0011] Preferably, a wall surface of the transition part coincides with a motion track formed by a generatrix around the central axis in a circumferential direction; the generatrix is an inclined straight line with a constant included angle with the central axis, or a smooth convex curve or concave curve.

[0012] Preferably, at the interface perpendicular to the central axis, the constraint part is arranged in a circumferential direction as a ring-shaped integral structure continuously connected to the transition part, or the constraint part is arranged in the circumferential direction as a plurality of sheet-shaped structures spaced from each other and connected to the constraint part.

[0013] The application further provides an energy absorption method of the thin-wall energy absorption tube, which is implemented by the thin-wall energy absorption tube and comprises the following steps: S1, triggering turnover: under the action of an axial load, the turnover part is guided by the transition part to plastically lose stability and deform, and inward turning or outward turning occurs; S2, forming a double-layer tube: the transition part continuously guides the plastic deformation of the turnover part, so that the turnover part is pushed into the inside of the constraint part to form an inward turning double-layer structure, or is pushed to the outside of the constraint part to form an outward turning double-layer structure; S3. Constraint and friction: The axial load is continued to be applied, and the constraint portion applies a radial contraction constraint to the turning portion of the inward-turned double-layer structure, or applies a radial expansion constraint to the turning portion of the outward-turned double-layer structure; at the same time, the double-layer tube wall formed by the inward-turned or outward-turned turning portion and the constraint portion dissipates energy through contact friction during axial relative movement, thereby enhancing deformation bearing capacity.

[0014] Wherein, when executing step S1, the restraining portion is fixed, and an axial load is applied to the top end of the flipping portion through the rigid plate.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a thin-walled energy absorption tube and energy absorption method. Energy is absorbed by plastic deformation of a folding portion, which is either turned outward or inward. A restraining portion constrains contraction outside the inward-turning folding portion or expansion inside the outward-turning folding portion. The inward or outward-turning folding portion forms a double-walled tube structure. The contact and compression between the two walls generate friction, which further absorbs axial load energy and improves deformation bearing capacity.

[0016] Compared to traditional progressively folding thin-walled tubes, the energy absorption process features a smoother load curve, avoiding periodic and violent fluctuations. Initial peak forces are significantly reduced, effective stroke efficiency is high, and the effective working stroke is longer for the same tube length. Compared to free-tumbling thin-walled tubes, the energy absorption process features a higher plateau force and higher energy absorption efficiency. This invention maintains the smooth load curve and high stroke efficiency of free-tumbling tubes while also improving the load curve plateau, resulting in an average collision force performance superior to comparable progressively folding thin-walled tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the axially progressively folded thin-walled tube after deformation under axial load; Figure 2 The axial load-displacement curve of the axial progressively folded thin-walled tube (the horizontal axis is the displacement, in mm; the vertical axis is the axial load, in N); Figure 3 The axial load-displacement curve of the free-turning thin-walled tube (the horizontal axis is the displacement, in mm; the vertical axis is the axial load, in N); Figure 4 It is a schematic diagram of the structure of the free-turning thin-walled tube after deformation under axial load; Figure 5 Schematic diagrams of the three-dimensional structures of two embodiments of the thin-walled energy absorption tube proposed in the present invention; Figure 6 for Figure 5 Front views of two embodiments of medium-thin-wall energy absorbing tubes; Figure 7Cross-sectional view of another embodiment of the thin-walled energy absorption tube; Figure 8 Cross-sectional view of another embodiment of the thin-walled energy absorption tube; Figure 5 Axial load force-displacement curve of the thin-walled energy absorption tube proposed in the present application; Figure 9 Structure diagram of the thin-walled energy absorption tube after deformation under axial load; Figure 10 Axial load force-displacement curve of the axial progressive collapse thin-walled tube, the free-folding thin-walled tube, and the thin-walled energy absorption tube proposed in the present application (wherein the blue line is the axial progressive collapse thin-walled tube, the black line is the free-folding thin-walled tube, and the red line is the thin-walled energy absorption tube proposed in the present application; the horizontal coordinate is displacement, in mm; and the vertical coordinate is axial load force, in N); Figure 11 Energy absorption amount-displacement curve of the axial progressive collapse thin-walled tube, the free-folding thin-walled tube, and the thin-walled energy absorption tube proposed in the present application (wherein the blue line is the axial progressive collapse thin-walled tube, the black line is the free-folding thin-walled tube, and the red line is the thin-walled energy absorption tube proposed in the present application; the horizontal coordinate is displacement, in mm; and the vertical coordinate is energy absorption amount, in J); Figure 12 Structure diagram of another embodiment of the thin-walled energy absorption tube proposed in the present application; In the figure: 1, folding part; 2, transition part; 3, constraint part; 4, annular connecting piece. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0019] Embodiment 1

[0020] Please refer to Figure 5 a, 6a, a thin-walled energy absorption tube, comprising a folding part 1, a transition part 2 and a constraint part 3 connected in sequence in the axial direction to form a variable-diameter hollow thin-walled tubular structure; the folding part 1 and the transition part 2 are fixedly connected by an annular connecting piece 4, and the annular connecting piece 4 is a planar annular structure.

[0021] Among them, the transition part 2 and the constraint part 3 are fixedly connected on an interface perpendicular to the central axis. On the interface perpendicular to the central axis, such as Figure 5As shown in a, the constraint portion 3 is provided as an annular integral structure continuously connected to the transition portion 2 in the circumferential direction. Figure 12 As shown, the constraint portion 3 is provided as a plurality of sheet-like structures connected to the constraint portion 3 at intervals in the circumferential direction.

[0022] In the connection area between the flip part 1 and the transition part 2 (i.e., the planar area including the inner and outer edges of the annular connector 4), the boundary of the connection end of the flip part 1 projected on the horizontal plane is completely contained in the boundary of the connection end of the transition part 2 projected on the horizontal plane, wherein the connection end is the end where the flip part 1 or the transition part 2 is connected to the annular connector 4, and the horizontal plane is any plane perpendicular to the central axis of the thin-walled energy absorption tube.

[0023] In this embodiment, the turning portion 1 is an axially load-bearing tubular structure having a central axis, such as a cylindrical tube, a prismatic tube, a conical tube, or a pyramidal tube. The turning portion 1 is made of metal, non-metal, or composite material with good plastic deformation ability.

[0024] like Figure 8 As shown, when the turning portion 1 is subjected to an axial load, it undergoes axial displacement under pressure, causing it to turn and deform to absorb energy. The transition portion 2 guides the turning portion 1 inward and causes it to contract into the interior of the constraint portion 3, ensuring that the turning portion 1 does not experience Euler instability, progressively stable folding, or tearing failure. The constraint portion 3 constrains the turning portion 1 that has contracted and deformed and turned inward. The deformed turning portion 1 and the constraint portion 3 form a double-layer tube wall that is in contact and compressed, generating frictional energy absorption and improving the deformation load-bearing capacity. In the present invention, the inward turning of the turning portion 1 and the restraining friction combine to form a double-layer energy absorption mechanism.

[0025] The following table is a comparison table of energy absorption performance indicators of axially progressively folded thin-walled tubes (deformation mode is folding), free-flipping thin-walled tubes (deformation mode is free flipping), and thin-walled energy absorption tubes in this embodiment (deformation mode is constrained flipping) with the same size and material specifications. In the table, the energy absorption performance indicators are as follows: (1) Initial Peak Crushing Force (IPCF) refers to the peak force that occurs when a Class II structure collides (an initial peak force that is too high will cause serious injuries to the personnel in the vehicle). Unit: kN.

[0026] (2) Energy Absorption (EA), defined as the total energy dissipated by the structure during the collision. The higher the value, the stronger the structure's ability to absorb energy. Unit: J. Its calculation formula is as follows:

[0027] Where: The load received by the thin-walled structure, is the crushing displacement.

[0028] (3) Specific Energy Absorption (SEA), defined as the energy absorbed by unit mass of the structure during the crushing process, and the calculation formula is as follows:

[0029] In the formula, is the mass of the thin-walled structure.

[0030] Mean Crushing Force (MCF), defined as the average value of the load curve during the total crushing process, can reflect the basic situation of energy absorption of the structure, and the calculation formula is as follows:

[0031] In the formula, is the total compression displacement.

[0032] (5) Crushing Force Efficiency (CFE), defined as the ratio of the average impact force to the initial peak force (the higher the impact force efficiency, the stronger the deformation bearing capacity and energy absorption capacity, and the ideal energy absorption structure impact force efficiency is 1, and its impact force-displacement curve is a horizontal straight line). The calculation formula is as follows:

[0033] From the above table, under the free flip deformation mode, the load of the free flip thin-walled tube is very stable, the impact force efficiency reaches 83.56%, and has excellent load consistency, but the average impact force is lower, about 29% lower than that of the folding deformation mode. And because the effective stroke efficiency of the free flip deformation mode is longer, close to the length of the tube of the flip part 1, its specific energy absorption is only 14% lower than that of the folding deformation mode.

[0034] The average impact force of the thin-walled energy absorption tube proposed in the present application is significantly improved compared with the free flip deformation mode, and the average impact force reaches 74.63kN, which is increased by 64% compared with the free flip deformation mode, and is also increased by about 17% compared with the folding deformation mode. Therefore, compared with the traditional progressive folding thin-walled tube, the load curve during the energy absorption process is more stable and avoids periodic violent fluctuations, the initial peak force is significantly reduced, the effective stroke efficiency is high, and the effective working stroke is longer with the same tube length; compared with the free flip thin-walled tube, the platform force during the energy absorption process is higher, and the energy absorption efficiency is higher.

[0035] Embodiment 2

[0036] Referring to Figure 5 b, a thin-walled energy absorption tube, comprising a turnover portion 1, a transition portion 2 and a constraint portion 3 connected in sequence in the axial direction to form a variable-diameter hollow thin-walled tubular structure; the turnover portion 1 and the transition portion 2 are fixedly connected through an annular connecting piece 4, and the transition portion 2 and the constraint portion 3 are fixedly connected at an interface perpendicular to the central axis, and the annular connecting piece 4 is a planar annular structure.

[0037] In the connecting area of the turnover portion 1 and the transition portion 2 (i.e. the planar area containing the inner and outer side edges of the annular connecting piece 4), the boundary of the horizontal plane projection of the connecting end of the turnover portion 1 completely contains the boundary of the horizontal plane projection of the connecting end of the transition portion 2. Wherein, the connecting end is one end at the connection of the turnover portion 1 or the transition portion 2 and the annular connecting piece 4, and the horizontal plane is any plane perpendicular to the central axis of the thin-walled energy absorption tube.

[0038] In this embodiment, when the turnover portion 1 is subjected to axial load, the turnover portion 1 is deformed by axial displacement under pressure, the transition portion 2 guides the turnover portion 1 to turn outward, and the turnover portion 1 is expanded to wrap outside the constraint portion 3; the constraint portion 3 constrains the turnover portion 1 which is expanded and wrapped outside to turn outward.

[0039] Embodiment 3

[0040] Referring to Figure 7 c, a thin-walled energy absorption tube, comprising a turnover portion 1, a transition portion 2 and a constraint portion 3 connected in sequence in the axial direction to form a variable-diameter hollow thin-walled tubular structure; the turnover portion 1 and the transition portion 2 are fixedly connected through an annular connecting piece 4, and the transition portion 2 and the constraint portion 3 are fixedly connected at an interface perpendicular to the central axis, and the annular connecting piece 4 is a truncated cone annular structure.

[0041] In the connecting area of the turnover portion 1 and the transition portion 2 (i.e. the three-dimensional area containing the upper and lower edges of the truncated cone annular structure of the annular connecting piece 4), the boundary of the horizontal plane projection of the connecting end of the turnover portion 1 is completely contained in the boundary of the horizontal plane projection of the connecting end of the transition portion 2, wherein the connecting end is one end at the connection of the turnover portion 1 or the transition portion 2 and the annular connecting piece 4, and the horizontal plane is any plane perpendicular to the central axis of the thin-walled energy absorption tube.

[0042] In this embodiment, when the turnover portion 1 is subjected to axial load, the transition portion 2 guides the turnover portion 1 to turn inward, and the turnover portion 1 is contracted into the inside of the constraint portion 3. The constraint portion 3 constrains the turnover portion 1 which is contracted and turned inward into it.

[0043] Embodiment 4

[0044] Referring to Figure 7d. A thin-walled energy absorption tube, comprising a turning portion 1, a transition portion 2 and a restraining portion 3, which are sequentially connected in the axial direction to form a hollow thin-walled tubular structure with a variable diameter; the turning portion 1 and the transition portion 2 are fixedly connected by an annular connector 4, and the transition portion 2 and the restraining portion 3 are fixedly connected at an interface perpendicular to the central axis, and the annular connector 4 is a truncated cone annular structure.

[0045] Within the connection region between the flip portion 1 and the transition portion 2 (i.e., the three-dimensional region encompassing the upper and lower edges of the truncated cone-shaped ring structure of the annular connector 4), the horizontal projection of the connection end of the flip portion 1 completely encompasses the horizontal projection of the connection end of the transition portion 2. The connection end is defined as the end where the flip portion 1 or transition portion 2 connects to the annular connector 4, and the horizontal plane is defined as any plane perpendicular to the central axis of the thin-walled energy absorber tube.

[0046] In this embodiment, when the turnover portion 1 is subjected to an axial load, the transition portion 2 guides the turnover portion 1 to flip outward, and causes the turnover portion 1 to expand and wrap around the outside of the constraint portion 3; the constraint portion 3 constrains the expansion and deformation of the turnover portion 1 that is wrapped around it.

[0047] In Examples 3 and 4, the transition portion 2 is a truncated cone-shaped annular structure with different cross-sectional sizes at its two ends in the axial direction. Specifically, the wall surface of the truncated cone-shaped transition portion 2 coincides with the motion trajectory formed by a generatrix circumferentially around the central axis; the generatrix is ​​an inclined straight line with a constant angle to the central axis, or a smooth convex or concave curve.

[0048] In the present invention, the inversion portion 1 is the primary energy absorber, absorbing energy through plastic deformation, either by everting or turning inward. The constraint portion 3 constrains contraction outside the inverted portion 1 or expansion inside the inverted portion 1. After the inverted or outverted portion 1 forms a double-walled structure, the contact between the two walls generates friction under pressure, further absorbing axial load energy and improving deformation bearing capacity.

[0049] In addition, the present invention also provides an energy absorption method of a thin-walled energy absorption tube, which is implemented by a thin-walled energy absorption tube and includes the following steps: S1. Triggering flip: Under the action of axial load, the flip part 1 is guided by the transition part 2, causing the tube wall to plastically deform and turn inward or outward; S2. Forming and guiding the double-layer tube: The transition portion 2 continuously guides the turnover portion 1 to plastically deform, so that the turnover portion 1 is pushed into the interior of the constraint portion 3 to form an inverted double-layer structure, or is pushed to the outside of the constraint portion 3 to form an outward-turned double-layer structure; S3. Constraint and friction: The axial load is continued to be applied, and the constraint portion 3 applies a radial contraction constraint to the turnover portion 1 of the inverted double-layer structure, or applies a radial expansion constraint to the turnover portion 1 of the outverted double-layer structure; at the same time, the double-layer tube wall formed by the inverted or outverted turnover portion 1 and the constraint portion 3 dissipates energy through contact friction during axial relative movement, thereby enhancing deformation bearing capacity.

[0050] Wherein, when executing step S1, the restraining portion is fixed, and an axial load is applied to the top end of the flip portion through the rigid plate to ensure that the axial load on the top end of the flip portion is uniform.

[0051] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A thin-walled energy absorbing tube, characterized in that: It includes a flip part, a transition part and a constraint part that are connected in sequence in the axial direction to form a variable diameter hollow thin-walled tubular structure; the flip part and the transition part are fixedly connected by an annular connector, and the annular connector is a planar annular or truncated cone annular structure, and the transition part and the constraint part are fixedly connected at an interface perpendicular to the central axis; in the connection area between the flip part and the transition part, the boundary of the projection of the connection end of the flip part on the horizontal plane is completely accommodated in, or completely accommodates, the boundary of the projection of the connection end of the transition part on the horizontal plane, and the horizontal plane is any plane perpendicular to the central axis.

2. The thin-walled energy absorbing tube according to claim 1, characterized in that: The turning portion is a cylindrical tube, a prismatic tube, a conical tube or a pyramidal tube.

3. The thin-walled energy absorbing tube according to claim 1, characterized in that: The turning portion is made of metal, non-metal or composite material with good plastic deformation ability.

4. The thin-walled energy absorbing tube according to claim 1, characterized in that: The wall surface of the transition portion coincides with the motion trajectory formed by the busbar circumferentially around the central axis; the busbar is an inclined straight line with a constant angle to the central axis, or a smooth convex curve or concave curve.

5. The thin-walled energy absorbing tube according to claim 1, characterized in that: On an interface perpendicular to the central axis, the constraint portion is circumferentially configured as an annular integral structure continuously connected to the transition portion, or the constraint portion is circumferentially configured as a plurality of sheet structures connected to the constraint portion at intervals.

6. An energy absorption method for a thin-walled energy absorption tube, implemented by the thin-walled energy absorption tube according to any one of claims 1 to 4, characterized in that: The steps include: S1. Triggering flipping: Under the action of axial load, the flipping portion is guided by the transition portion and the tube wall plastically loses its stability and deforms, causing inversion or eversion; S2. Forming and guiding the double-layer tube: The transition portion continuously guides the turnover portion to plastically deform, so that the turnover portion is pushed into the interior of the constraint portion to form an inverted double-layer structure, or is pushed outside the constraint portion to form an outward-turned double-layer structure; S3. Constraint and friction: The axial load is continued to be applied, and the constraint portion applies a radial contraction constraint to the turning portion of the inward-turned double-layer structure, or applies a radial expansion constraint to the turning portion of the outward-turned double-layer structure; at the same time, the double-layer tube wall formed by the inward-turned or outward-turned turning portion and the constraint portion dissipates energy through contact friction during axial relative movement, thereby enhancing deformation bearing capacity.

7. The energy absorbing method of a thin-walled energy absorbing tube according to claim 6, characterized in that: When executing step S1, the restraining portion is fixed, and an axial load is applied to the top end of the flipping portion through the rigid plate.

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