Composite buffer structure based on metal-liquid crystal elastomer and preparation method thereof

Abstract

The invention discloses a composite buffer structure based on a metal-liquid crystal elastomer, which comprises a liquid crystal elastomer and a plurality of star-shaped negative Poisson's ratio structural plates embedded in the liquid crystal elastomer, and the plurality of star-shaped negative Poisson's ratio structural plates are sequentially arranged in parallel; the star-shaped negative Poisson's ratio structural plate comprises a plurality of unit cell structures arranged in the same plane in an array mode, each unit cell structure comprises two connecting rods and a quadrangular star structure formed by sequentially connecting eight cell walls end to end, and four outwards-convex nodes and four inwards-concave nodes are formed in the connecting positions of the eight cell walls. The first ends of the two connecting rods are respectively connected with the two concave nodes in the opposite directions; the second ends of the two connecting rods of the two unit cell structures adjacent in the transverse direction are in butt joint with each other, the two unit cell structures adjacent in the longitudinal direction are connected with each other at the two convex nodes, the scheme can show a more stable progressive deformation mode and higher energy absorption capacity under the dynamic impact condition, and then a better protection effect on a device is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of buffering and energy absorption, and in particular to a composite buffering structure based on metal-liquid crystal elastomer and a preparation method thereof. Background Art

[0002] In the field of impact, research is increasingly turning to high-speed impacts, with inter-object collisions being the most common phenomenon. These impacts often release enormous amounts of energy, a direct cause of damage to critical internal components, requiring absorption and control. However, due to the limited space available for many internal components requiring protection, effective absorption and dissipation of impact energy, minimizing damage to components, has become a hot topic in the field of impact protection and energy absorption. Designing cushioning structures that combine lightweight design with superior energy absorption within limited space has become a hot topic in current research.

[0003] Due to their high fracture toughness, shear modulus, energy absorption, and indentation resistance, negative Poisson's ratio structures are widely used in healthcare, aerospace, automotive, marine, and defense and military applications. They not only meet lightweighting requirements but also absorb and dissipate impact energy through structural deformation and damage, mitigating the impact load's potential for damage to personnel and equipment. Therefore, negative Poisson's ratio structures hold great promise for application in the energy absorption field.

[0004] The existing star-shaped concave negative Poisson's ratio structure has a uniform structure that deforms as a whole and exhibits a negative Poisson's ratio effect under low-speed impact, and turns into local deformation at the impact end during high-speed impact, and the higher the speed, the more significant the local deformation; under high-speed impact, it is often accompanied by uneven force; and the typical characteristics of the high-speed impact process are short action time and large energy release, and a large amount of energy release will cause serious damage to the structure; the star-shaped concave negative Poisson's ratio structure has more significant local deformation due to uneven force under high-speed impact conditions, thereby exhibiting premature local failure and unstable deformation mode; at the same time, when bearing loads, stress concentration is also prone to form at sharp corners and connecting rod connections, causing the star-shaped concave negative Poisson's ratio structure to produce an unstable deformation mode, premature failure of the buffering and energy absorption capacity, and reduced energy absorption efficiency, which in turn leads to device damage. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a composite buffer structure based on metal-liquid crystal elastomer and a preparation method thereof, which solves the problem of poor buffering and energy absorption effect of the existing star-shaped concave negative Poisson's ratio structure.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A composite buffer structure based on a metal-liquid crystal elastomer is provided, comprising a liquid crystal elastomer and a plurality of star-shaped negative Poisson's ratio structural plates embedded in the liquid crystal elastomer, wherein the plurality of star-shaped negative Poisson's ratio structural plates are arranged in parallel in sequence; the star-shaped negative Poisson's ratio structural plates comprise a plurality of unit cell structures arranged in an array in the same plane, the unit cell structure comprising two connecting rods and a four-pointed star structure formed by eight cell walls connected end to end in sequence, the connections between the eight cell walls forming a total of four convex nodes and four concave nodes, the first ends of the two connecting rods being respectively connected to two concave nodes located in opposite directions; the second ends of the two connecting rods of two unit cell structures adjacent in the transverse direction are butted against each other, and the two unit cell structures adjacent in the longitudinal direction are connected to each other at the two convex nodes.

[0007] Furthermore, the outer sides of the four convex nodes are all convex fillets after rounding, and the outer sides of the two concave nodes not connected to the connecting rod are all first concave fillets after rounding.

[0008] Furthermore, the two connecting rods in the unit cell structure are located on the same straight line.

[0009] Furthermore, the two connecting rods in the unit cell structure form four concave corners with the four cell walls connected thereto, two of which are second concave rounded corners after rounding, and the two second concave rounded corners are located on the same side of the straight line where the connecting rods are located.

[0010] In a second aspect, a method for preparing a composite buffer structure based on a metal-liquid crystal elastomer is provided, which comprises the following steps: S1: Prepare a number of star-shaped negative Poisson's ratio structural plates by 3D printing, and arrange the star-shaped negative Poisson's ratio structural plates in parallel in a mold; S2: synthesizing an unpolymerized liquid crystal elastomer and pouring it into a mold arranged with a plurality of star-shaped negative Poisson's ratio structural plates; S3: Irradiating the mold with ultraviolet light until the liquid crystal elastomer is polymerized and solidified, and then demolding is performed to obtain a composite buffer structure of metal-liquid crystal elastomer.

[0011] Furthermore, the preparation method of the liquid crystal elastomer is: S21: mixing liquid crystal monomer RM257 and n-butylamine n-BA at a molar ratio of 1.1:1, and adding 0.2 wt % of photoinitiator I651 to obtain a mixture; S22: stirring the mixture at a preset temperature for a certain period of time, dissolving the mixture in tetrahydrofuran, and performing ultrasonic dispersion to obtain an unpolymerized liquid crystal elastomer.

[0012] Furthermore, the material of the star-shaped negative Poisson's ratio structural plate is one of stainless steel, die steel, titanium alloy and aluminum alloy.

[0013] The beneficial effects of the present invention are: 1. This solution combines a liquid crystal elastomer with a star-shaped negative Poisson's ratio structural plate, fully leveraging the advantages of both materials. The star-shaped negative Poisson's ratio structural plate provides a load-bearing framework and initial stiffness, while the liquid crystal elastomer delays the fracture process of the composite buffer structure through large deformation and viscoelastic dissipation mechanisms, allowing the composite buffer structure to maintain a certain load-bearing capacity after fracture failure. As a result, the composite buffer structure exhibits a more stable progressive deformation mode and stronger energy absorption capacity under dynamic impact conditions, thereby providing better protection for the device.

[0014] 2. This solution rounds off the outer sides of the convex nodes and arranges concave fillets at the connections between the connecting rods and the cell walls. This alleviates the stress concentration phenomenon of the star-shaped negative Poisson's ratio structural plate when it is subjected to impact loads, avoids unstable deformation of the unit cell structure caused by stress concentration, thereby preventing the premature failure of the buffering energy absorption capacity and improving the buffering energy absorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of a star-shaped negative Poisson's ratio structural plate.

[0016] Figure 2 Schematic diagram of the unit cell structure.

[0017] Among them, 1. Single cell structure, 2. Connecting rod, 3. Cell wall, 4. Convex node, 5. Concave node, 6. Convex fillet, 7. First concave fillet, 8. Concave corner, 9. Second concave fillet. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0019] like Figure 1 and Figure 2 As shown, the composite buffer structure based on metal-liquid crystal elastomer in this solution includes a liquid crystal elastomer and a plurality of star-shaped negative Poisson's ratio structural plates embedded in the liquid crystal elastomer, and the plurality of star-shaped negative Poisson's ratio structural plates are arranged in parallel in sequence.

[0020] The star-shaped negative Poisson's ratio structural plate includes several unit cell structures 1 arranged in an array in the same plane. The unit cell structure 1 includes two connecting rods 2 and a four-pointed star structure formed by eight cell walls 3 connected end to end in sequence. The connections between the eight cell walls 3 form four convex nodes 4 and four concave nodes 5. The first ends of the two connecting rods 2 are respectively connected to two concave nodes 5 located in opposite directions; the second ends of the two connecting rods 2 of two adjacent unit cell structures 1 in the transverse direction are butt-jointed with each other, and the two adjacent unit cell structures 1 in the longitudinal direction are connected to each other at two convex nodes 4, thereby realizing the array arrangement of several unit cell structures 1.

[0021] Specifically, the outer sides of the four convex nodes 4 are all convex fillets 6 after rounding treatment, and the outer sides of the two concave nodes 5 that are not connected to the connecting rod 2 are all first concave fillets 7 after rounding treatment; the two connecting rods 2 in the single cell structure 1 are located on the same straight line, and the four cell walls 3 connected to the two connecting rods 2 respectively form a total of four concave corners 8, of which two concave corners 8 are second concave fillets 9 after rounding treatment, and the two second concave fillets 9 are located on the same side of the straight line where the connecting rod 2 is located; this arrangement enables the star-shaped negative Poisson's ratio structural plate to effectively alleviate the stress concentration phenomenon when it is subjected to an impact load parallel to the plate surface and perpendicular to the connecting rod 2, thereby avoiding unstable deformation of the single cell structure 1 caused by stress concentration, thereby preventing premature failure of the buffering energy absorption capacity, and is conducive to improving the buffering energy absorption effect.

[0022] This solution also provides a method for preparing a composite buffer structure based on a metal-liquid crystal elastomer, which comprises the following steps: S1: A plurality of star-shaped negative Poisson's ratio structural plates are prepared by 3D printing; specifically, the material of the star-shaped negative Poisson's ratio structural plates is one of stainless steel, die steel, titanium alloy and aluminum alloy; the star-shaped negative Poisson's ratio structural plates can be designed and drawn using 3D drawing software, and then printed layer by layer using the laser melting process of a metal 3D printer. After printing is completed, the star-shaped negative Poisson's ratio structural plates can be powder cleaned, annealed, support material removed, polished and sandblasted; finally, the plurality of star-shaped negative Poisson's ratio structural plates are arranged in parallel in a mold; wherein, the mold can be made of polycarbonate to achieve light transmittance of the mold.

[0023] S2: Synthesizing an unpolymerized liquid crystal elastomer and pouring it into a mold having a plurality of star-shaped negative Poisson's ratio structural plates arranged thereon; wherein the preparation method of the liquid crystal elastomer is: S21: mixing a liquid crystal monomer RM257 and n-butylamine n-BA at a molar ratio of 1.1:1, and adding 0.2 wt % of a photoinitiator I651 to obtain a mixture; wherein the chemical name of the liquid crystal monomer RM257 is 1,4-bis[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, and the chemical name of the photoinitiator I651 is 2,2-dimethoxy-2-phenylacetophenone of butylated hydroxytoluene; S22: The mixture is stirred at 80° C. for 20 hours, and then dissolved in tetrahydrofuran. Finally, the mixture is dispersed by ultrasonication to obtain an unpolymerized liquid crystal elastomer.

[0024] S3: Irradiating the mold with ultraviolet light until the liquid crystal elastomer is polymerized and solidified, and then demolding is performed to obtain a composite buffer structure of metal-liquid crystal elastomer.

[0025] In summary, this scheme combines liquid crystal elastomer with star-shaped negative Poisson's ratio structural plate, which can give full play to the advantages of both materials. The star-shaped negative Poisson's ratio structural plate provides the load-bearing skeleton and initial stiffness, while the liquid crystal elastomer delays the fracture process of the composite buffer structure through large deformation and viscoelastic dissipation mechanism, so that the composite buffer structure exhibits a more stable progressive deformation mode and stronger energy absorption capacity under dynamic impact conditions, thereby providing better protection for the device.

Claims

1. A composite buffer structure based on metal-liquid crystal elastomer, characterized in that: It comprises a liquid crystal elastomer and a plurality of star-shaped negative Poisson's ratio structural plates embedded in the liquid crystal elastomer, wherein the plurality of star-shaped negative Poisson's ratio structural plates are arranged in parallel in sequence; The star-shaped negative Poisson's ratio structural plate includes a plurality of unit cell structures arranged in an array in the same plane. The unit cell structure includes two connecting rods and a four-pointed star structure formed by connecting eight cell walls end to end. The connections between the eight cell walls form four convex nodes and four concave nodes. The first ends of the two connecting rods are respectively connected to two concave nodes located in opposite directions. The second ends of the two connecting rods of two unit cell structures adjacent in the transverse direction are butted against each other, and the two unit cell structures adjacent in the longitudinal direction are connected to each other at two convex nodes.

2. The composite buffer structure based on metal-liquid crystal elastomer according to claim 1, characterized in that: The outer sides of the four convex nodes are all convex fillets after rounding, and the outer sides of the two concave nodes not connected to the connecting rod are all first concave fillets after rounding.

3. The composite buffer structure based on metal-liquid crystal elastomer according to claim 2, characterized in that: The two connecting rods in the unit cell structure are located on the same straight line.

4. The composite buffer structure based on metal-liquid crystal elastomer according to claim 3, characterized in that: The two connecting rods in the unit cell structure and the four cell walls connected thereto form four concave corners in total, two of which are second concave rounded corners after rounding, and the two second concave rounded corners are located on the same side of the straight line where the connecting rods are located.

5. A method for preparing a composite buffer structure based on metal-liquid crystal elastomer according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Prepare a number of star-shaped negative Poisson's ratio structural plates by 3D printing, and arrange the star-shaped negative Poisson's ratio structural plates in parallel in a mold; S2: synthesizing an unpolymerized liquid crystal elastomer and pouring it into a mold arranged with a plurality of star-shaped negative Poisson's ratio structural plates; S3: Irradiating the mold with ultraviolet light until the liquid crystal elastomer is polymerized and solidified, and then demolding is performed to obtain a composite buffer structure of metal-liquid crystal elastomer.

6. The method for preparing a composite buffer structure based on metal-liquid crystal elastomer according to claim 5, characterized in that: The preparation method of the liquid crystal elastomer is as follows: S21: mixing liquid crystal monomer RM257 and n-butylamine n-BA at a molar ratio of 1.1:1, and adding 0.2 wt % of photoinitiator I651 to obtain a mixture; S22: stirring the mixture at a preset temperature for a certain period of time, dissolving the mixture in tetrahydrofuran, and performing ultrasonic dispersion to obtain an unpolymerized liquid crystal elastomer.

7. The method for preparing a composite buffer structure based on metal-liquid crystal elastomer according to claim 5, characterized in that: The material of the star-shaped negative Poisson's ratio structural plate is one of stainless steel, die steel, titanium alloy and aluminum alloy.

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