Honeycomb zero-Poisson-ratio forward gradient protection plate

Abstract

The invention relates to a honeycomb zero-Poisson-ratio forward gradient protection plate, belongs to the technical field of protection structures, and particularly relates to a honeycomb zero-Poisson-ratio forward gradient protection plate structure with an annular reinforcing structure and a gradient strategy. According to the honeycomb zero-Poisson-ratio forward gradient protection plate structure, a circular ring structure is introduced on the basis of a traditional zero-Poisson-ratio honeycomb, and stress distribution and deformation coordination in the structure are further optimized by adding circular rings. Deformation of the unit cells under stress in different directions can be better coordinated, and optimization of the zero Poisson's ratio characteristic is achieved. According to the honeycomb zero-Poisson-ratio forward gradient protection plate structure, the inclined ribs in different areas have different buckling threshold values through gradient thickness arrangement of the circular rings. During compression, all the areas are bent in sequence, staged energy absorption is achieved, sudden reduction of the energy absorption capacity is avoided, and the stability of the shape of the structure is maintained.

Description

Technical Field

[0001] The invention relates to a honeycomb zero Poisson's ratio positive gradient protection plate, belonging to the technical field of protection structures, and in particular to a honeycomb zero Poisson's ratio positive gradient protection plate structure with an annular reinforcement structure and a gradient strategy. Background Art

[0002] At present, impact accidents are showing a high-frequency outbreak trend in many industries. Vehicle collisions, fragment impacts and explosion shock waves have become very common safety risks in modern human production and life, which not only cause significant casualties and economic losses, but also pose a severe challenge to public safety. In response to the application needs of controlling lateral deformation under complex external force impacts, efficient protective structures with negative Poisson's ratio and multi-gradient energy absorption characteristics are constantly developing. However, the current negative Poisson's ratio structure has problems of stress concentration and fatigue failure, which can easily lead to structural stiffness degradation and reduced energy absorption efficiency. With its unique grid shape, the zero Poisson's ratio honeycomb will not expand or contract in the lateral direction when compressed or stretched, and can maintain a stable shape and achieve efficient energy absorption. However, it is prone to deformation or damage when subjected to large tensile or compressive loads, and its bearing capacity is relatively low. Summary of the invention

[0003] The technical solution of the present invention is: to overcome the shortcomings of the prior art and propose a honeycomb zero Poisson's ratio positive gradient protective plate. Through geometric configuration improvement, enhanced component design and gradient design, a honeycomb zero Poisson's ratio positive gradient protective plate structure that meets the wide-area strain rate bearing requirements and structural stability is provided, which is expected to improve the bearing capacity and impact resistance of the protective plate structure. By reasonably improving the configuration, adding a circular ring structure inside, splicing into a circular ring to enhance the zero Poisson's ratio cell, the overall strength and energy absorption performance of the structure are improved. Along the load direction, a gradient design is formed by adjusting the wall thickness of the internal circular ring structure. When the structure is subjected to in-plane compression, the structure is directional induced to undergo orderly buckling in the load direction, achieving directional and orderly plastic deformation energy absorption of the structure, and avoiding asymmetric stacking of the structure. Compared with other zero Poisson's ratio structures, this new honeycomb zero Poisson's ratio positive gradient protective plate structure can further improve stability and energy absorption efficiency, providing a more reliable and efficient protective structure option for related engineering applications.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A honeycomb zero Poisson's ratio positive gradient protection plate, the protection plate comprising a plurality of horizontal ribs 3, a plurality of circular rings 2 and a plurality of oblique ribs 1;

[0006] The protective plate is made of 316L stainless steel material through 3D printing technology;

[0007] There are several circular rings 2 evenly distributed from left to right between two adjacent horizontal ribs 3. Each circular ring 2 is connected to the upper and lower horizontal ribs 3 by four inclined ribs 1, and the horizontal ribs 3, circular rings 2 and inclined ribs 1 are integrally formed.

[0008] When each circular ring 2 is connected to the upper and lower horizontal ribs 3 by four inclined ribs 1, the four inclined ribs 1 are defined as the first inclined rib 11, the second inclined rib 12, the third inclined rib 13, and the fourth inclined rib 14 respectively, and the upper and lower horizontal ribs 3 are the first horizontal rib 31 and the second horizontal rib 32 respectively.

[0009] One end of the first inclined rib 11 is connected to the first horizontal rib 31, and the other end of the first inclined rib 11 is connected to the circular ring 2.

[0010] One end of the second inclined rib 12 is connected to the second horizontal rib 32, and the other end of the second inclined rib 12 is connected to the circular ring 2.

[0011] The included angle between the extension line of the end of the first inclined rib 11 connected to the circular ring 2 and the extension line of the end of the second inclined rib 12 connected to the circular ring 2 is α, and the value of α is 60 - 120°.

[0012] One end of the third inclined rib 13 is connected to the first horizontal rib 31, and the other end of the third inclined rib 13 is connected to the circular ring 2.

[0013] One end of the fourth inclined rib 14 is connected to the second horizontal rib 32, and the other end of the fourth inclined rib 14 is connected to the circular ring 2.

[0014] The included angle between the extension line of the end of the third inclined rib 13 connected to the circular ring 2 and the extension line of the end of the fourth inclined rib 14 connected to the circular ring 2 is also α.

[0015] It is defined that two horizontal ribs 3, one circular ring 2 and four inclined ribs 1 form a single cell.

[0016] The single cell has shape symmetry, and the horizontal rib does not bend under the action of symmetric force, avoiding its bending deformation and being able to maintain the zero Poisson's ratio characteristic of the structure.

[0017] The single cell is extended through a two-dimensional plane array to form a single-layer honeycomb structure with a periodic topological configuration.

[0018] It is defined that the circular ring between the topmost horizontal rib and the adjacent horizontal rib is the first-level circular ring 4, the circular rings below the first-level circular ring 4 are the second-level circular rings 5, and so on, and the remaining circular rings are the third-level circular rings 6 and the fourth-level circular rings 7 respectively.

[0019] The circular ring structures in the zero Poisson's ratio cells of different layers have a unidirectional increasing gradient change in the load direction, with a total of four circular ring gradients, namely:

[0020] The thickness of the first-stage ring 4 (i.e., the difference between the inner diameter and the outer diameter of the first-stage ring 4) is 0.3-0.5 mm;

[0021] The thickness of the second-stage ring 5 is 0.05mm-0.15mm thicker than that of the first-stage ring 4;

[0022] The thickness of the third-stage circular ring 6 is 0.05mm-0.15mm greater than that of the second-stage circular ring 5;

[0023] The thickness of the fourth-stage circular ring 7 is 0.05 mm to 0.15 mm greater than that of the third-stage circular ring 6;

[0024] The wall thickness of the first three layers of rings is t r1 ~t r3 The critical buckling stress of the ring is lower than the instability threshold of the overall structure. The wall thickness of the fourth ring is t r4 The same as the horizontal rib wall thickness. Based on the elastic mechanics equivalent model, the geometric parameters of the rib ring are optimized so that the in-plane equivalent elastic modulus meets the preset load conditions. That is, the thickness of the fourth-level ring 7, the thickness of the horizontal rib and the thickness of the oblique rib are all the same;

[0025] The hierarchical structure is further described as realizing a close-packed array of cells through translation transformation in the x-axis direction to construct a single-layer supporting substrate.

[0026] The hierarchical structure is further implemented by stacking four layers of plate structures in the y-axis direction to form a composite sandwich structure with a three-dimensional mechanical gradient.

[0027] The critical buckling stress of the first three layers of circular rings is lower than the instability threshold of the overall structure, which preferentially triggers local buckling energy dissipation rather than overall collapse.

[0028] The wall thickness of the fourth circular ring is the same as that of the horizontal ribs and the oblique ribs of the structure, which can avoid stress concentration caused by thickness difference and prevent the structure from being damaged or deformed prematurely at this position.

[0029] When the honeycomb structure is compressed by external force, the first layer of circular cells is preferentially buckled, and then each layer collapses according to a gradient, forming a regular layer-by-layer deformation mode, extending the platform stress stage of the structure, achieving phased energy absorption, and avoiding a sudden drop in energy absorption capacity.

[0030] Beneficial Effects

[0031] The honeycomb zero Poisson's ratio positive gradient protection plate structure of the present invention introduces a ring structure based on the traditional zero Poisson's ratio honeycomb. The addition of the ring further optimizes the stress distribution and deformation coordination inside the structure. It can better coordinate the deformation of the unit cells when they are subjected to forces in different directions, and achieve the optimization of zero Poisson's ratio characteristics.

[0032] The honeycomb zero Poisson's ratio positive gradient protection plate structure of the present invention sets the gradient thickness of the circular ring, so that the diagonal ribs in different regions have different buckling thresholds. During compression, the buckling occurs in each region in turn, realizing staged energy absorption, avoiding a sudden drop in the energy absorption capacity, and maintaining the stability of the shape of the structure itself.

[0033] The honeycomb zero Poisson's ratio positive gradient protection plate structure of the present invention is prepared by a 3D printing mechanism, which is conducive to the precise manufacturing of complex structures and can flexibly adjust the structural parameters according to the design requirements. At the same time, suitable materials can be selected according to the actual application scenarios to meet different performance requirements, and it has a certain material adaptability. Brief Description of the Drawings

[0034] Figure 1 is a circular ring reinforced zero Poisson's ratio cell;

[0035] Figure 2 is the front view of the protection plate;

[0036] Figure 3 is the schematic diagram of the overall structure of the protection plate;

[0037] Figure 4 Unidirectional positive gradient: experimental / simulation compression strain - Poisson's ratio curve;

[0038] Figure 5 Unidirectional positive gradient: experimental / simulation compression stress - compression strain curve;

[0039] Figure 6 Schematic diagram of compression experiment - simulation of universal testing machine;

[0040] Among them, 1 - diagonal rib, 11 - first diagonal rib, 12 - second diagonal rib, 13 - third diagonal rib, 14 - fourth diagonal rib, 2 - circular ring structure, 3 - horizontal rib, 31 - first horizontal rib, 32 - second horizontal rib, 4 - first - stage circular ring, 5 - second - stage circular ring, 6 - third - stage circular ring, 7 - fourth - stage circular ring. Detailed Embodiment

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] The designed size of the unit cell structure is 24mm×14.66mm, and the unit cells are extended in a two - dimensional array in the X - Y plane to form a 4×4 honeycomb structure with a periodic topological configuration.

[0043] The structure includes a gradient ring design, with four rings 4-7 arranged along the y-axis direction, and their wall thicknesses t r1 ~t r4 forming a unidirectional increasing gradient.

[0044] For the first three rings of the gradient, the buckling critical stress values of the rings with wall thicknesses t r1 ~t r3 are lower than the instability threshold of the overall structure, and the local buckling energy dissipation mechanism is preferentially triggered.

[0045] Embodiment

[0046] As Figures 1 - 3 shown, a honeycomb zero Poisson's ratio positive gradient protection plate, which includes 5 horizontal ribs 3, 16 rings 2 and 64 inclined ribs 1;

[0047] The protection plate is manufactured by 3D printing technology using 316L stainless steel material. According to the constitutive experiment, the density of the material can be obtained as 7830 kg / m 3 , the Young's modulus E is 158.45 GPa, and the Poisson's ratio is 0.3v;

[0048] Between two adjacent horizontal ribs 3, 4 rings 2 are evenly distributed from left to right. Each ring 2 is connected to the upper and lower horizontal ribs 3 through four inclined ribs 1, and the horizontal ribs 3, rings 2 and inclined ribs 1 are integrally formed;

[0049] When each ring 2 is connected to the upper and lower horizontal ribs 3 through four inclined ribs 1, the four inclined ribs 1 are respectively defined as the first inclined rib 11, the second inclined rib 12, the third inclined rib 13, and the fourth inclined rib 14, and the upper and lower horizontal ribs 3 are respectively the first horizontal rib 31 and the second horizontal rib 32;

[0050] One end of the first inclined rib 11 is connected to the first horizontal rib 31, and the other end of the first inclined rib 11 is connected to the ring 2;

[0051] One end of the second inclined rib 12 is connected to the second horizontal rib 32, and the other end of the second inclined rib 12 is connected to the ring 2;

[0052] The included angle between the extension line of the end of the first inclined rib 11 connected to the ring 2 and the extension line of the end of the second inclined rib 12 connected to the ring 2 is α, and the value of α is 120°;

[0053] One end of the third inclined rib 13 is connected to the first horizontal rib 31, and the other end of the third inclined rib 13 is connected to the ring 2;

[0054] One end of the fourth inclined rib 14 is connected to the second horizontal rib 32, and the other end of the fourth inclined rib 14 is connected to the ring 2;

[0055] The included angle between the extension line of one end where the third diagonal rib 13 is connected to the ring 2 and the extension line of one end where the fourth diagonal rib 14 is connected is also α;

[0056] Define that two horizontal ribs 3, one ring 2 and four diagonal ribs 1 form a single cell;

[0057] The single cell is extended through a two-dimensional plane array to form a single-layer honeycomb structure with a periodic topological configuration;

[0058] The single cell has shape symmetry. Under the action of symmetric forces, the horizontal ribs do not bend, avoiding their bending deformation and being able to maintain the zero Poisson's ratio characteristic of the structure;

[0059] The length of the horizontal rib 3 is 96.00 mm, the width of the horizontal rib 3 is 20.00 mm, and the distance between the topmost horizontal rib and the lowermost horizontal rib is 56.24 mm;

[0060] Define the ring between the topmost horizontal rib and the adjacent horizontal rib as the first-level ring 4, the ring below the first-level ring 4 as the second-level ring 5, and so on. The remaining rings are the third-level ring 6 and the fourth-level ring 7 respectively;

[0061] The ring structures in the zero Poisson's ratio cells of different layers have a unidirectional increasing gradient change in the load direction. There are a total of four ring gradients, namely:

[0062] The thickness of the first-level ring 4 (i.e., the difference between the inner diameter and the outer diameter of the first-level ring 4) is 0.5 mm;

[0063] The thickness of the second-level ring 5 is 0.1 mm more than the thickness of the first-level ring 4;

[0064] The thickness of the third-level ring 6 is 0.1 mm more than the thickness of the second-level ring 5;

[0065] The thickness of the fourth-level ring 7 is 0.1 mm more than the thickness of the third-level ring 6;

[0066] The wall thickness of the first three layers of rings is t r1 ~t r3 The buckling critical stress value of the ring is lower than the overall structure instability threshold. The wall thickness t r4 of the fourth layer of the ring is the same as the wall thickness of the horizontal rib. Based on the equivalent elastic model of elasticity, the geometric parameters of the rib and ring are optimized to make the in-plane equivalent elastic modulus meet the preset load conditions. That is, the thicknesses of the fourth-level ring 7, the horizontal rib, and the diagonal rib are the same;

[0067] The present invention uses parametric slicing and multi-level support strategies in 3D printing to complete complex geometry manufacturing, achieving one-piece molding of a hierarchical structure arranged in a 4×4 array, and combining nested gradient circular rings to form a three-dimensional multi-scale structure. The step compensation in 3D printing is used to achieve snap-fit fixation, so that the outer diameter of the upper circular ring is slightly smaller than the inner diameter of the lower circular ring (such as an outer diameter difference of 0.1 mm), avoiding mechanical failure caused by gaps.

[0068] Quasi-static mechanical property tests and simulation simulations were carried out on the above honeycomb zero Poisson's ratio positive gradient protection plate. When conducting quasi-static mechanical property tests, an MTS Criterion Model 44 universal testing machine was used, and the obtained Poisson's ratio-compressive strain curve is as Figure 4 shown, and the compressive stress-compressive strain curve is as Figure 5 shown. From Figure 4 and Figure 5 , it can be seen that the experimental results of the quasi-static mechanical property tests and the experimental results of the simulation simulations are consistent in the change trends at each stage, and the results are consistent and can be mutually verified. From Figure 5 , it can be seen that the energy absorption process of the structure is smoother and the energy release is more stable. The introduced circular ring structure significantly improves the mechanical properties of the structure.

[0069] For the quasi-static compression test carried out by simulation simulation and a universal testing machine, the obtained structural deformation process is as Figure 6 shown. The circular ring with the wall thickness t r1 of the first layer buckles first, and then is triggered layer by layer in the order of the wall thickness t r2 -t r3 -t r4 to form a progressive folding deformation band. At the initial stage of compression, the structure maintains a relatively regular shape, and then the structure begins to deform. The unit cells in the circular ring-reinforced zero Poisson's ratio structure gradually undergo compressive deformation, and the circular rings and other parts such as the rods deform in coordination. There is no slip or fracture at the connection of the horizontal ribs. Under the compressive load, the honeycomb structure can undergo three stages of deformation: cell compression → delamination collapse → overall densification, and no local instability occurs.

[0070] In summary, the above is only a preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Honeycomb zero Poisson's ratio positive gradient protection plate, characterized in that: The protection plate includes a plurality of horizontal ribs, a plurality of circular rings and a plurality of inclined ribs; A plurality of circular rings are evenly distributed between two adjacent horizontal ribs from left to right; Each circular ring is connected to the upper and lower horizontal ribs by four inclined ribs.

2. The honeycomb zero Poisson's ratio positive gradient protection plate according to claim 1, characterized in that: When each circular ring is connected to the upper and lower horizontal ribs by four inclined ribs, the four inclined ribs are defined as the first inclined rib, the second inclined rib, the third inclined rib, and the fourth inclined rib respectively, and the upper and lower horizontal ribs are the first horizontal rib and the second horizontal rib respectively; One end of the first inclined rib is connected to the first horizontal rib, and the other end of the first inclined rib is connected to the circular ring; One end of the second inclined rib is connected to the second horizontal rib, and the other end of the second inclined rib is connected to the circular ring; The included angle between the extension line of the end of the first inclined rib connected to the circular ring and the extension line of the end of the second inclined rib connected to the circular ring is α, and the value of α is 60-120°; One end of the third inclined rib is connected to the first horizontal rib, and the other end of the third inclined rib is connected to the circular ring; One end of the fourth inclined rib is connected to the second horizontal rib, and the other end of the fourth inclined rib is connected to the circular ring; The included angle between the extension line of the end of the third inclined rib connected to the circular ring and the extension line of the end of the fourth inclined rib connected to the circular ring is also α.

3. The honeycomb zero Poisson's ratio positive gradient protection plate according to claim 2, characterized in that: The circular ring between the topmost horizontal rib and the adjacent horizontal rib is defined as the first-level circular ring, the circular ring below the first-level circular ring is the second-level circular ring, and so on. The remaining circular rings are the third-level circular ring, the fourth-level circular ring,..., the nth-level circular ring; n is the number of layers of the circular rings; The thickness of the first-level circular ring is 0.3-0.5mm; The thickness of the nth-level circular ring is 0.05mm-0.15mm larger than the thickness of the (n-1)th-level circular ring.

4. The honeycomb zero Poisson's ratio positive gradient protection plate according to claim 3, characterized in that: The thickness of the nth-level circular ring, the thickness of the horizontal rib and the thickness of the inclined rib are the same.

5. The honeycomb zero Poisson's ratio positive gradient protection plate according to claim 1, characterized in that: The protection plate is manufactured by 3D printing technology using 316L stainless steel material.

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