A torsional negative Poisson's ratio energy absorption device based on boundary curve and its design method

Abstract

The present invention relates to the technical field of mechanical negative Poisson's ratio metamaterial energy absorption technology, and in particular to a torsional negative Poisson's ratio energy absorption device based on a boundary curve and a design method thereof. The device improves specific energy absorption. The introduced curve-designed torsional boundary can absorb more energy through torsion when subjected to the impact of a load. Moreover, the boundary drives a central rotating block while torsioning. The rotation direction of the central rotating block is opposite to the torsion direction of the boundary, which can better absorb the energy brought by the load. The pillars designed with the boundary curve are adjustable. The strength and angle of the pillars can be further changed by changing the curve type and parameters, thereby changing the torsional capacity and energy absorption capacity. The stiffness can be adjusted by adjusting factors such as the period and amplitude of the boundary curve. The arc-shaped rod connecting the disk and the ring can greatly guide the torsion between the ring and the disk, thereby increasing the stiffness and energy absorption capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical negative Poisson's ratio metamaterial energy absorption technology, and in particular to a torsional negative Poisson's ratio energy absorption device based on a boundary curve and a design method thereof. Background Art

[0002] Artificially designed negative Poisson's ratio metamaterials originated from the pioneering work of Lakes et al. in 1987. Since then, through the continuous research of numerous scholars, the development of existing negative Poisson's ratio metamaterials has been unprecedented. However, it is undeniable that existing three-dimensional compression-torsion NPR structures are mostly isotropic, rather than using multi-deformation mechanisms to achieve the unique NPR effect. Notably, negative Poisson's ratio structures that achieve lateral rotation through axial compression have attracted much attention due to their excellent mechanical properties. In existing technologies, compression-torsion negative Poisson's ratio structures are mostly chiral.

[0003] Compared with positive Poisson's ratio materials or structures, negative Poisson's ratio materials or structures have better impact resistance and energy absorption performance. Applying negative Poisson's ratio materials or honeycomb structures to energy absorption devices will greatly improve the safety performance of automobiles in accidents. However, most existing energy absorption devices remain at the traditional thin-walled boxes or thin-walled tubes, and their energy absorption effect is still largely lacking. The compression-torsion negative Poisson's ratio has better energy absorption and mechanical effects than the traditional negative Poisson's ratio, but its design is relatively difficult. In response to the above shortcomings, the present invention provides a compression-torsion negative Poisson's ratio energy absorption device and a design method thereof, and in particular relates to a torsional negative Poisson's ratio energy absorption device based on a boundary curve and a design method thereof. Summary of the Invention

[0004] Negative Poisson's ratio metamaterials have many advantages, such as good energy absorption effect, low relative density, and light weight. However, negative Poisson's ratio metamaterials have the disadvantage of low stiffness, which limits their application. The negative Poisson's ratio structures / devices designed based on the existing foundation are mostly traditional structures, and some are chiral structures. However, the chiral structure is only designed based on circular pillars, and the actual torsional effect is not outstanding. Moreover, there is only a torsional effect, and there is no outstanding negative Poisson's ratio effect, so the unique advantages of the negative Poisson's ratio cannot be applied. The purpose of the present invention is to provide a torsional negative Poisson's ratio energy absorption device based on a boundary curve and a design method thereof, which solves the problems described in the above background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a torsional negative Poisson's ratio energy absorption device based on a boundary curve, comprising an upper ring (1), a support (6) hinged at the bottom of the upper ring (1), a disk (2) connected to the middle section of the support (6), an arc-shaped rod (5) hinged on the inner wall of the disk (2), a rotating block (4) hinged at one inner end of the arc-shaped rod (5), and a lower ring (3) hinged at the bottom of the support (6).

[0006] A torsional negative Poisson's ratio energy absorption design method based on a boundary curve comprises the following steps:

[0007] S1: By introducing a curve to design the boundary of the torsional pillar, the pillar can induce the device to twist, which has a better torsional effect than traditional circular pillars. At the same time, the curve shape can be changed to adjust the torsional effect. Changing the thickness of the pillar can also change the structural stiffness and increase the energy absorption effect.

[0008] S2: By adjusting the period, amplitude, curvature and other conditions of the boundary curve, variable stiffness adjustment is performed to achieve application on different vehicle models.

[0009] S3: Design boundary conditions based on the curved foundation and then design the curved support pillars to avoid stress concentration.

[0010] S4: The rotating block in the middle of the torsion support rotates, thereby driving the structure to rotate; a part of the energy can be converted into kinetic energy of rotation, which drives the middle rotating block to rotate, thereby driving the structure to rotate, increasing the energy absorption capacity.

[0011] S5: A rotating block is designed in the middle of the device; it can twist in the opposite direction of the outer ring during deformation, which can increase its stiffness and energy absorption effect.

[0012] S6: Arrange the single torsion structure up and down and left and right to obtain a multi-cellular honeycomb structure, thereby increasing the energy absorption capacity of the device, i.e., specific energy absorption.

[0013] S7: The obtained honeycomb structure is filled into a box in an orderly manner to obtain the energy absorbing device of the present invention, and it is helpful to fix it in a place where it is needed.

[0014] Preferably, in said S1, the curved torsion boundary is composed of two curves and the boundary of a disk, and has a better energy absorption effect than the traditional negative Poisson's ratio device. The introduced curved design torsion boundary can absorb more energy by twisting when subjected to the impact of the load, and the boundary drives the middle rotating block while twisting. The rotation direction of the middle rotating block is opposite to the torsion direction of the boundary, which can better absorb the energy brought by the load and increase the stiffness of the energy absorption device to a certain extent. It can cope with deformation during large impacts and ensure people's life safety.

[0015] Preferably, in said S2, the boundary curve is variable and can be a trigonometric function boundary curve, a B-spline curve, a curve deformed from a minimal surface formula, a boundary curve of an approximate function, and a curve derived from a Taylor expansion. By changing the curve type and parameters, the strength and angle of the pillar can be further changed, and the torsional capacity and energy absorption capacity can be changed; by adjusting the period and amplitude factors of the boundary curve, the stiffness can be adjusted.

[0016] Preferably, in said S3, there is a certain gap between the pillars, and there is blank space between the disc and the upper and lower rings, which reduces the weight of the device to a certain extent and can also be applied to some precision occasions.

[0017] Preferably, in S4, the arc-shaped rod connecting the disk and the ring can guide the torsion between the ring and the disk to a great extent, thereby increasing the rigidity and energy absorption capacity.

[0018] The present invention provides the following beneficial effects:

[0019] (1) Improve specific energy absorption. Compared with the traditional negative Poisson's ratio device, it has a better energy absorption effect. The introduced curved design torsion boundary can absorb more energy by twisting when it is subjected to the impact of the load. Moreover, the boundary drives the rotating block in the middle while twisting. The rotation direction of the rotating block in the middle is opposite to the twisting direction of the boundary, which can better absorb the energy brought by the load. At the same time, it increases the stiffness of the energy absorption device to a certain extent, can cope with the deformation during large impact, and ensure people's life safety.

[0020] (2) It can be processed and manufactured using existing technologies. The curved torsion boundary is composed of two curves and the boundary of the disk, which is easier to manufacture.

[0021] (3) The boundary curve is variable. It can be a trigonometric function boundary curve, a B-spline curve, a curve derived from a minimal surface formula, a boundary curve of an approximate function, a curve derived from a Taylor expansion, and so on. Therefore, the pillar designed with the boundary curve is adjustable. By changing the curve type and parameters, the strength and angle of the pillar can be further changed, thereby changing the torsional capacity and energy absorption capacity. It can adapt to the needs of various occasions. At the same time, by adjusting factors such as the period and amplitude of the boundary curve, the stiffness can be adjusted.

[0022] (4) There is a certain gap between the pillars, and the space between the disc and the upper and lower rings is filled with blanks, which reduces the weight of the device to a certain extent and can also be used in some precision occasions.

[0023] (5) The arc-shaped rod connecting the disk and the ring can guide the torsion between the ring and the disk to a great extent, thereby increasing the stiffness and energy absorption capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is an isometric view of the part;

[0025] Figure 2 It is the front view of the part;

[0026] Figure 3 It is the top view of the part;

[0027] Figure 4 is an isometric view of component 6 with the array removed;

[0028] Figure 5 is a sketch of the relevant curve on component 1;

[0029] Figure 6 is a sketch of the relevant curve on component 2;

[0030] Figure 7 A sketch of the relevant curves on component 3;

[0031] Figure 8 Schematic diagram of the stacked array structure;

[0032] Figure 9 It is a structural diagram of the lattice structure;

[0033] Figure 10 This is an isometric view of the energy absorption box structure. DETAILED DESCRIPTION

[0034] like Figure 1-10As shown, the present invention provides a technical solution: a torsional negative Poisson's ratio energy absorption device based on a boundary curve, comprising an upper ring 1, a pillar 6 hinged at the bottom of the upper ring 1, a disk 2 connected to the middle section of the pillar 6, an arc-shaped rod 5 hinged on the inner wall of the disk 2, a rotating block 4 hinged at one end of the inner side of the arc-shaped rod 5, and a lower ring 3 hinged at the bottom of the pillar 6; a torsional negative Poisson's ratio energy absorption design method based on a boundary curve, comprising the following steps: by introducing a curve to design a torsional pillar boundary, the pillar can induce the device to torsion, which has a better torsional effect than traditional circular columns, and the curve shape can be changed to adjust the torsional effect, and changing the pillar thickness can also change the structural stiffness and increase the energy absorption effect; the curve torsion boundary is The composition of two curves and the boundary of the disk has better energy absorption effect than the traditional negative Poisson's ratio device. The introduced curve design torsion boundary can absorb more energy by twisting when it is subjected to the impact of the load, and the boundary drives the rotating block in the middle while twisting. The rotation direction of the rotating block in the middle is opposite to the torsion direction of the boundary, which can better absorb the energy brought by the load. At the same time, it increases the stiffness of the energy absorption device to a certain extent, can cope with deformation during large impacts, and ensure people's life safety; by adjusting the period, amplitude, curvature and other conditions of the boundary curve, variable stiffness adjustment is performed to achieve application on different models; the boundary curve is variable and can be a trigonometric function boundary curve Lines, B-spline curves, curves deformed from minimal surface formulas, boundary curves of approximate functions, and curves derived from Taylor expansions can further change the strength and angle of the pillars by changing the curve type and parameters, and change the torsional capacity and energy absorption capacity; by adjusting the period and amplitude factors of the boundary curves, the stiffness can be adjusted; based on the curve basic design boundary conditions, and then the curved surface pillars are designed to avoid stress concentration. There are certain gaps between the pillars, and the gaps between the disk and the upper and lower rings are filled with blanks, which reduces the weight of the device to a certain extent and can also be used in some precision occasions; the rotating block in the middle of the torsion pillar rotates, thereby driving the structure to rotate; the A portion of the energy is converted into rotational kinetic energy, which drives the middle rotating block to rotate, and then drives the structure to rotate, thereby increasing the energy absorption capacity. The arc-shaped rod connecting the disk and the ring can guide the torsion between the ring and the disk to a great extent, thereby increasing the stiffness and energy absorption capacity. A rotating block is designed in the middle of the device, which can twist in the opposite direction of the outer ring during deformation, thereby increasing its stiffness and energy absorption effect. The single torsion structure is arrayed up and down and left and right to obtain a multi-cellular honeycomb structure, thereby increasing the energy absorption capacity of the device, that is, specific energy absorption. The obtained honeycomb structure is filled into a box in an orderly manner to obtain the energy absorption device of the present invention, which is helpful for fixing it in occasions where it is needed.

[0035] The present invention is further described in detail below by way of examples, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods.

[0036] The torsional negative Poisson's ratio energy absorption design method based on the boundary curve provides a new torsional negative Poisson's ratio energy absorption device. The negative Poisson's ratio energy absorption device provided by the present invention has a better energy absorption effect than the traditional negative Poisson's ratio, can adapt to the energy absorption under large load impact, and ensure people's life safety in accidents. By introducing the curve design to torsion pillar boundary, the pillar can induce the device to torsion, which has a better torsion effect than the traditional circular column. At the same time, the curve shape can be changed to adjust the torsion effect. Changing the pillar thickness can also change the structural stiffness and increase the energy absorption effect. By adjusting the period, amplitude, curvature and other conditions of the boundary curve, The device can be adjusted for variable stiffness to achieve application on different vehicle models. The curved pillar design based on the boundary conditions can avoid stress concentration. The torsional pillar not only contracts inward when impacted, but also rotates, converting a portion of the energy into rotational kinetic energy, driving the middle rotating block to rotate, thereby driving the structure to rotate and increase the energy absorption capacity. A rotating block is designed in the middle of the device, which can twist in the opposite direction of the outer ring during deformation, increasing its stiffness and energy absorption effect. The single torsional structure is arrayed up and down, left and right, to obtain a multi-cellular honeycomb structure. This increases the energy absorption capacity of the device, that is, the specific energy absorption. The honeycomb structure is orderly filled into a box to obtain the energy absorption device of the present invention, which is helpful for fixing it in places where it is needed.

Claims

1. A torsional negative Poisson's ratio energy absorption design method based on boundary curve, characterized by: The torsion structure comprises an upper ring (1), a support (6) is hingedly connected to the bottom of the upper ring (1), a disc (2) is connected to the middle section of the support (6), an arc-shaped rod (5) is hingedly connected to the inner wall of the disc (2), a rotating block (4) is hingedly connected to one inner end of the arc-shaped rod (5), and a lower ring (3) is hingedly connected to the bottom of the support (6); return The following steps are involved: S1: twisting the pillar boundary by introducing a curved design; S2: Variable stiffness adjustment is performed by adjusting the period, amplitude, and curvature conditions of the boundary curve; S3: Design boundary conditions based on the curved foundation, and then design the curved support pillars; S4: A rotating block is designed in the middle of the torsion structure. The rotating block in the middle of the torsion support can rotate, thereby driving the structure to rotate. The rotation direction of the rotating block in the middle is opposite to the boundary torsion direction. S5: Arraying two or more twisted structures in the up, down, left, and right directions to obtain a multi-cellular honeycomb structure; S6: The obtained honeycomb structure is orderly filled into a box to obtain a torsional negative Poisson's ratio energy absorption device based on the boundary curve.

2. The torsional negative Poisson's ratio energy absorption design method based on boundary curve according to claim 1, characterized in that: In the S2, the boundary curve is one of the trigonometric function boundary curve, the B-spline curve, the curve transformed from the minimal surface formula, the boundary curve of the approximate function, and the curve derived from the Taylor expansion. By changing the curve type and parameters, the strength and angle of the pillar are further changed, and the torsional capacity and energy absorption capacity are changed; by adjusting the period and amplitude factors of the boundary curve, the stiffness is adjustable.

3. The torsional negative Poisson's ratio energy absorption design method based on boundary curve according to claim 1 is characterized in that: In the S3, there is a certain gap between the pillars, and the space between the disc and the upper and lower rings is filled with blanks.

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