A high-strength and high-toughness layered gradient structure and its preparation method

Abstract

The present invention proposes an impact-resistant high-strength and tough layered gradient structure, which belongs to the field of new materials, including two first hard phase layers arranged at intervals; two soft phase layers sandwiched between the two first hard phase layers and arranged at intervals; a second hard phase layer sandwiched between the two soft phase layers; the first hard phase layer includes a soft phase structure and a hard phase structure, the soft phase structure is a mesh structure and a plurality of mesh holes are opened on the surface, and the hard phase structure fills all the mesh holes. The present invention adopts a pearl layer structure combined with an interlayer sandwich structure, introduces a layer of hard phase between the interlayer soft phases of the traditional pearl layer structure, so that a "soft-hard-soft" sandwich structure is formed between the brick layers, and the hard phase bricks in the "brick-mud" structure provide strength, and the soft phase mortar has excellent deformation ability. The arrangement of the hard phase and the soft phase can evenly distribute the stress and avoid stress concentration. The interlayer sandwich structure introduces an interlayer "soft-hard-soft" synergistic mode to ensure the strength and toughness of the overall structure.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and in particular to an impact-resistant high-strength and tough layered gradient structure and a preparation method thereof. Background Art

[0002] In many fields such as aerospace and automotive engineering, extreme loads such as impact can cause serious damage to protective equipment, and the demand for the development of composite materials and structures with high strength, high toughness and high energy absorption is increasing. However, the traditional design concept has a single material and low energy absorption performance, which makes it difficult to meet the needs of high strength and high toughness at the same time. The nacre of shells in nature shows a perfect balance between stiffness, strength and toughness. Due to its unique structure, its toughness is several orders of magnitude higher than its component (aragonite). The nacre structure is mainly composed of 95% calcium carbonate (aragonite) by volume and 5% organic matrix (protein) by volume. The hard phase aragonite (brick) is embedded in the soft phase organic matrix (mud) in a parallel and staggered pattern, forming a unique "brick-mud" structure.

[0003] Functional gradient materials are composed of two or more materials. Through the material preparation process, the composition and structure are gradually changed in space, which can complement the advantages of materials with different properties. Inspired by the natural nacre structure, the nacre-like composite material prepared by structural design has the gradient characteristics of the hard phase and soft phase composition and arrangement. The nacre-like structure has been proven to improve the energy absorption and impact resistance of the material, but most of them show excellent impact resistance at lower impact speeds (<5m / s), while the impact resistance is limited under high-speed impact. Therefore, a new type of high-strength and high-toughness impact-resistant layered gradient structure is designed, which can have high impact resistance at higher impact speeds (13m / s), so that the new material can be used in explosion-proof, protection and energy absorption fields. Summary of the invention

[0004] In view of this, the present invention proposes an impact-resistant high-strength and tough layered gradient structure and a preparation method thereof, which are used to solve the problem that the current imitation pearl layer material has poor high impact resistance at a higher impact speed (13m / s).

[0005] The technical solution of the present invention is implemented as follows: the present invention provides an impact-resistant and high-toughness layered gradient structure, including two first hard phase layers, which are arranged at intervals; two soft phase layers, which are sandwiched between the two first hard phase layers and are arranged at intervals; and a second hard phase layer, which is sandwiched between the two soft phase layers, wherein the first hard phase layer includes a soft phase structure and a hard phase structure, the soft phase structure is a mesh structure with a plurality of mesh holes opened on the surface, and the hard phase structure fills all the mesh holes.

[0006] On the basis of the above technical solution, preferably, the hard phase structure and the second hard phase layer are made of the same hard phase material, and the soft phase layer and the soft phase structure are made of the same soft phase material.

[0007] More preferably, the hard phase material is polylactic acid material, and the soft phase material is thermoplastic polyurethane material.

[0008] On the basis of the above technical solution, preferably, the soft phase structure is a honeycomb structure, and the shape of the mesh is hexagonal.

[0009] More preferably, the average side length of the mesh is 4-7 mm.

[0010] On the basis of the above technical solution, preferably, the thickness of the first hard phase layer is greater than the sum of the thicknesses of the two soft phase layers and the second hard phase layer.

[0011] More preferably, the soft phase layer and the second hard phase layer have the same thickness.

[0012] More preferably, the meshes of two upper and lower adjacent soft phase structures are staggered.

[0013] More preferably, one of the soft phase structures of the adjacent layers is translated along the extension direction of one side length of the mesh by a distance of 50% of the side length, so that the meshes of the adjacent soft phase structures are staggered.

[0014] On the other hand, the present invention also provides a method for preparing an impact-resistant and high-strength and tough layered gradient structure, which is used to prepare the above-mentioned impact-resistant and high-strength and tough layered gradient structure, comprising the following steps: step 1, using 3D modeling software to establish a 3D model of the impact-resistant and high-strength and tough layered gradient structure, dividing the hard phase material and the soft phase material in the established 3D model, and saving them as hard phase model files and soft phase model files respectively; step 2, importing the hard phase model file and the soft phase model file into the slicing software, setting the slice layer thickness to 0.2 mm, and exporting the print file after slicing processing; step 3, using a fused deposition 3D printer to print according to the print file, setting the hard phase material to polylactic acid material, the polylactic acid material nozzle temperature to 205-210°C, setting the soft phase material to thermoplastic polyurethane material, the thermoplastic polyurethane material nozzle temperature to 215-220°C, setting the printing platform temperature to 50-60°C, setting the printing speed to 20-40mm / s, and printing to obtain an impact-resistant and high-strength and tough layered gradient structure.

[0015] The impact-resistant high-toughness layered gradient structure and its preparation method of the present invention have the following beneficial effects compared with the prior art:

[0016] The present invention adopts an imitation nacre structure combined with an interlayer sandwich structure, and introduces a layer of hard phase between the interlayer soft phases of the traditional imitation nacre structure, so that a "soft-hard-soft" sandwich structure is formed between the brick layers. In the "brick-mud" structure, the hard phase bricks provide strength, and the soft phase mortar has excellent plastic deformation ability. Combined with its unique hard phase and soft phase arrangement mode, a gradient change in composition and arrangement mode is achieved, and stress can be evenly distributed. When subjected to high-speed impact, a large amount of impact energy can be dissipated, avoiding stress concentration and catastrophic damage to the structure. The interlayer sandwich structure introduces an interlayer "soft-hard-soft" synergistic mode, which further ensures the overall strength and toughness of the structure, so that the new imitation nacre-interlayer sandwich structure has excellent strength, toughness and impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a three-dimensional diagram of the impact-resistant high-toughness layered gradient structure of the present invention;

[0019] Figure 2 An exploded perspective view of the impact-resistant high-toughness layered gradient structure of the present invention;

[0020] Figure 3 It is an exploded side view of the impact-resistant high-toughness layered gradient structure of the present invention;

[0021] Figure 4 is a three-dimensional diagram of the first hard phase layer of the present invention;

[0022] Figure 5 It is a top view of the first hard phase layer of the present invention.

[0023] In the figure: 1, first hard phase layer; 11, soft phase structure; 12, hard phase structure; 101, mesh; 2, soft phase layer; 3, second hard phase layer. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, combined Figure 2 The impact-resistant and high-toughness layered gradient structure of the present invention comprises a first hard phase layer 1, a soft phase layer 2 and a second hard phase layer 3.

[0026] The two first hard phase layers 1 are arranged at intervals. The first hard phase layer 1 comprises a soft phase structure 11 and a hard phase structure 12 . The soft phase structure 11 is a mesh structure with a plurality of mesh holes 101 on the surface. The hard phase structure 12 fills the mesh holes 101 .

[0027] The two soft phase layers 2 are sandwiched between the two first hard phase layers 1 and are arranged at intervals.

[0028] The second hard phase layer 3 is sandwiched between the two soft phase layers 2 .

[0029] The principle of the present invention is to combine the imitation pearl layer structure with the interlayer sandwich structure, and introduce a hard phase between the soft phases of the traditional imitation pearl layer structure, so that a "soft-hard-soft" sandwich structure is formed between the brick layers. In the "brick-mud" structure, the hard phase bricks provide strength, and the soft phase mortar has excellent plastic deformation ability, which can dissipate a large amount of impact energy when subjected to high-speed impact. Its unique hard phase and soft phase arrangement can evenly distribute stress and avoid stress concentration leading to catastrophic damage to the structure; the interlayer sandwich structure introduces the "soft-hard-soft" synergistic mode between the layers, which further ensures the overall strength and toughness of the structure, so that the new imitation pearl layer-interlayer sandwich structure has excellent strength, toughness and impact resistance. .

[0030] exist Figure 2 In a preferred embodiment shown, the hard phase structure 12 and the second hard phase layer 3 are made of the same hard phase material, and the soft phase layer 2 and the soft phase structure 11 are made of the same soft phase material, so that the soft phase layer 2 and the soft phase structure 11 can be combined into a soft phase as a whole, and the hard phase structure 12 as a "brick" is wrapped in the soft phase as a whole, forming a "brick-mud" structure, which helps to improve the impact resistance of the structure, while reducing the types of materials required to produce the impact-resistant and high-strength and tough layered gradient structure of this application, thereby reducing production difficulty and cost.

[0031] exist Figure 2In a preferred embodiment shown, the hard phase material is a polylactic acid material, and the soft phase material is a thermoplastic polyurethane material. Polylactic acid, also known as polylactide, is a polyester polymer obtained by polymerization with lactic acid as the main raw material. Thermoplastic polyurethane elastomer, also known as thermoplastic polyurethane rubber, abbreviated as TPU, is a (AB)n type block linear polymer, A is a high molecular weight (1000~6000) polyester or polyether, B is a diol containing 2~12 straight-chain carbon atoms, and the chemical structure between the AB segments is diisocyanate; it has excellent comprehensive properties such as high toughness, wear resistance, and oil resistance. The present application can also use other types of hard phase materials and soft phase materials, and the preparation method of the structure will also change accordingly.

[0032] exist Figure 3 In a preferred embodiment shown, the soft phase structure 11 is a honeycomb structure, and the mesh 101 is in the shape of a hexagon, and the hexagonal shape of the mesh 101 is preferably an irregular hexagon. The hexagon is the best filling shape on a plane, and can achieve the densest arrangement in space, thereby improving the use efficiency of the material and the stability of the structure. The mesh 101 can also be in other shapes, and changes in its shape will change the performance of the structure.

[0033] exist Figure 4 In a preferred embodiment shown, the average side length of the mesh 101 is 4-7 mm. Limiting the size of the mesh 101 can effectively balance the lightweight and strength of the material. Within this range, the strength and stiffness of the mesh 101 can be optimized, so that the stress is evenly distributed. This improves the structural strength of the impact-resistant high-toughness layered gradient structure, which can not only optimize the lightweight and energy absorption capacity of the material, but also provide reliable protection and support in a variety of applications.

[0034] exist Figure 3 In a preferred embodiment shown, the thickness of the first hard phase layer 1 is greater than the sum of the thicknesses of the two soft phase layers 2 and the second hard phase layer 3, ensuring that the main part of the imitation pearl layer has high strength and high impact resistance. The change in the proportional relationship between the thickness of the first hard phase layer 1 and the sum of the thicknesses of the two soft phase layers 2 and the second hard phase layer 3 will change the volume ratio of the soft phase to the hard phase, which will affect the strength and impact resistance of the structure.

[0035] exist Figure 3 In a preferred embodiment shown, the soft phase layer 2 and the second hard phase layer 3 have the same thickness to ensure that the interlayer sandwich structure has the ability to enhance the impact resistance of the layered structure of the present application.

[0036] exist Figure 5 In a preferred embodiment shown, the meshes 101 of two upper and lower adjacent soft phase structures 11 are staggered, which helps to improve the structural strength of the impact-resistant and high-toughness layered gradient structure.

[0037] exist Figure 5 In a preferred embodiment shown, one of the soft phase structures 11 of adjacent layers is translated along the extension direction of one of the sides of the mesh 101 by a distance of 50% of the side length, so that the meshes 101 of the adjacent soft phase structures 11 are staggered and the polygons of adjacent layers do not overlap, which helps to improve the structural strength of the impact-resistant and high-toughness layered gradient structure.

[0038] A method for preparing an impact-resistant high-strength and tough layered gradient structure of the present invention is used to prepare the impact-resistant high-strength and tough layered gradient structure of any of the above-mentioned embodiments, comprising the following steps: step 1, using 3D modeling software to establish a 3D model of the impact-resistant high-strength and tough layered gradient structure, dividing the hard phase material and the soft phase material in the established 3D model, and saving them as a hard phase model file and a soft phase model file, respectively, the model file is an STL file; step 2, importing the hard phase model file and the soft phase model file into a slicing software, setting the slice layer thickness to 0.2 mm, and exporting the print file after slicing processing, the print file is a g-code file; step 3, using a fused deposition 3D printer to print according to the print file, setting the hard phase material to a polylactic acid material, the polylactic acid material nozzle temperature to 205-210°C, setting the soft phase material to a thermoplastic polyurethane material, the thermoplastic polyurethane material nozzle temperature to 215-220°C, setting the printing platform temperature to 50-60°C, setting the printing speed to 20-40mm / s, and printing to obtain the impact-resistant high-strength and tough layered gradient structure.

[0039] The impact-resistant high-strength and tough layered gradient structure of the present invention and the traditional imitation pearl layer structure were compared by a split Hopkinson pressure bar loading test, with an impact speed of 13m / s, and the impact resistance data of the two were respectively detected, including structural strength and total structural energy absorption, and the test data were obtained as shown in Table 1. Among them, the impact-resistant high-strength and tough layered gradient structure of the present invention adopts an imitation pearl layer-interlayer sandwich structure, and embodiments 1 to 6 are designed, namely N33L, N43L, N53L, N63L, N73L and N83L in Table 1; the average side length of the mesh holes 101 on the first hard phase layer 1 in each embodiment is 3mm, 4mm, 5mm, 6mm, 7mm and 8mm respectively. Correspondingly, comparative examples 1 to 6 of imitation pearl layer structures are designed, namely N3, N4, N5, N6, N7 and N8 in Table 1; the average side length of the holes in the mesh structure of each comparative example is 3mm, 4mm, 5mm, 6mm, 7mm and 8mm respectively.

[0040] Table 1

[0041]

[0042] By comparing the data of each embodiment with the corresponding comparative example with the same number of layers, it can be found that when the impact speed of the test is 13m / s, the impact-resistant high-strength and tough layered gradient structure of the present invention adopts an imitation pearl layer-interlayer sandwich structure, and its structural strength and total energy absorption performance are significantly improved compared with a simple imitation pearl layer structure. Therefore, the impact-resistant high-strength and tough layered gradient structure of the present invention has higher impact resistance at a higher impact speed (13m / s). However, according to Example 1 and its corresponding comparative data, it can be found that when the side length of the mesh 101 is too small, the size of the mesh 101 is extremely small and the arrangement is extremely dense, resulting in the hard phase structure 12 as a "brick" having a smaller distribution area in the plane, which in turn has limited improvement in the structural strength of the structure, but at the same time, the soft phase material in the structure accounts for a large proportion, so the total energy absorption effect is still significant; correspondingly, according to Example 6 and its corresponding comparative data, it can be found that when the side length of the mesh 101 is too large, the size of the mesh 101 is extremely large and the arrangement is relatively sparse, so the hard phase structure 12 as a "brick" has a larger distribution area in the plane, thereby significantly improving the structural strength of the structure, but at the same time, the proportion of the soft phase material in the structure is reduced, resulting in a significant weakening of the effect of improving the total energy absorption.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An impact-resistant, high-toughness layered gradient structure, characterized in that: include: Two first hard phase layers (1) are arranged at intervals; Two soft phase layers (2) are sandwiched between the two first hard phase layers (1) and are arranged at intervals; A second hard phase layer (3) is sandwiched between the two soft phase layers (2); The first hard phase layer (1) comprises a soft phase structure (11) and a hard phase structure (12); the soft phase structure (11) is a mesh structure with a plurality of mesh holes (101) formed on its surface; and the hard phase structure (12) fills up the mesh holes (101); The hard phase structure (12) and the second hard phase layer (3) are made of the same hard phase material, and the hard phase material is polylactic acid material; The soft phase layer (2) and the soft phase structure (11) are made of the same soft phase material, and the soft phase material is a thermoplastic polyurethane material; the soft phase structure (11) is a honeycomb structure, and the mesh (101) is in the shape of a hexagon, and the average side length of the mesh (101) is 4-7 mm; the meshes (101) of two upper and lower adjacent soft phase structures (11) are staggered, and one of the soft phase structures (11) of the adjacent layer is translated along the extension direction of one side length of the mesh (101) by a distance of 50% of the side length, so that the meshes (101) of the adjacent soft phase structures (11) are staggered; The layer thickness of the first hard phase layer (1) is greater than the sum of the layer thicknesses of the two soft phase layers (2) and the second hard phase layer (3), and the layer thicknesses of the soft phase layer (2) and the second hard phase layer (3) are the same; The method for preparing the impact-resistant high-toughness layered gradient structure comprises the following steps: Step 1: Use 3D modeling software to establish a 3D model of an impact-resistant, high-strength and tough layered gradient structure, divide the hard phase material and the soft phase material in the established 3D model, and save them as a hard phase model file and a soft phase model file respectively; Step 2: Import the hard phase model file and the soft phase model file into the slicing software, set the slice thickness to 0.2 mm, and export the print file after slicing; Step three, use a fused deposition modeling 3D printer to print according to the print file, set the hard phase material to polylactic acid material, set the polylactic acid material nozzle temperature to 205-210°C, set the soft phase material to thermoplastic polyurethane material, set the thermoplastic polyurethane material nozzle temperature to 215-220°C, set the printing platform temperature to 50-60°C, set the printing speed to 20-40mm / s, and print to obtain an impact-resistant, high-strength and tough layered gradient structure.

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