CN114485271B - An anti-shock structure and anti-shock equipment - Google Patents

Abstract

The invention provides an impact-resistant structure and impact-resistant equipment, wherein the porosity of the impact-resistant structure is gradually increased inwards along the outer surface; the impact resistant structure has a porosity-location distribution function gradient at an intermediate location that is greater than a porosity-location distribution function gradient at a beginning and ending location in an inward direction along the outer surface. The application shock resistance structure, the outer porosity that has lower and higher elastic modulus, can bear bigger stress, the inlayer has higher porosity, can have bigger deformation space, can bear bigger strain, is favorable to the effect of inlayer buffering, guarantees the bulk strength of the protective equipment that shocks resistance.

Description

An anti-shock structure and anti-shock equipment

technical field

The invention belongs to the field of anti-shock structures, in particular to an anti-shock structure and anti-shock equipment used in the design field of cushioning structures such as safety helmets, bulletproof vests, and sports shoe soles.

Background technique

In daily production and life and practical engineering applications, impact damage has caused huge losses to the safety of people's lives and properties. In aerospace, railway transportation, sports and other fields, the impact load acting on the body is an important factor of human injury. With the development of people's needs for daily life and engineering technology, the body has higher and higher requirements for the ability to withstand high loads. Therefore, the demand for high-strength, impact-resistant human body equipment is facing a trend of rapid growth.

The impact-resistant structures in the prior art usually utilize the energy-absorbing properties of the equipment configuration itself to achieve a cushioning effect. Disclosed as Chinese patent literature CN107328302A is a kind of energy-absorbing cushioning bulletproof helmet lining, and it comprises multi-layer perforated ceramic layer, also comprises foamed metal layer and elastic airgel layer; , apply it to the body of the bulletproof helmet, and realize the absorption of the impact force when the body of the bulletproof helmet is impacted by bullets. In addition, Chinese patent document CN110145967A discloses a hollowed-out inner liner for bulletproof helmets, which includes a triangular structure composed of a cross-shaped skeleton, a rigid ring and reinforcing ribs; The main parts form a triangular stable structure, which further strengthens the anti-deformation ability of the helmet.

The above-mentioned anti-shock equipment designed for the configuration of the equipment has the effect of optimizing the anti-shock performance. However, the existing impact-resistant structures often have the problems of low material utilization rate and small deformation space, which urgently need to be solved by those skilled in the art.

Contents of the invention

This application solves the problem of low material utilization rate and small deformation space in the impact-resistant structure in the prior art, and further provides a structure with high material utilization rate, improved deformation space, and overall improvement of the protective equipment to withstand compressive loads. Impact-resistant structures and impact-resistant equipment that improve the performance of the outer surface, such as puncture resistance and wear resistance.

The technical solution adopted by the application to solve the above-mentioned technical problems is:

An anti-shock structure, the porosity of the anti-shock structure gradually increases along the outer surface; in the inward direction along the outer surface, the porosity-position distribution function gradient of the middle position of the anti-shock structure Greater than the gradient of the porosity-position distribution function at the start and end segment locations.

The porosity of the impact resistant structure is in the range of 18-70%.

The impact-resistant structure includes a dense area and a porous area arranged in sequence along the outer surface inwardly, wherein the porosity of the dense area is less than or equal to 30%; the porosity of the porous area is greater than 30%; the The ratio of the thickness of the dense layer to the overall thickness of the impact-resistant structure is 30-40%.

The position distribution function of the porosity Pw (Z) of the impact-resistant structure is:

Wherein, Z is a normalized depth coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure, and Z=1 indicates that the position is on the inner surface of the impact-resistant structure.

The impact-resistant structure is configured as a single layer or multiple layers.

The position distribution function of the modulus of elasticity of the impact-resistant structure is:

Wherein, Z is a normalized depth coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure, and Z=1 indicates that the position is on the inner surface of the impact-resistant structure.

The impact-resistant structure is made of high-performance fiber-reinforced composite materials.

The anti-shock equipment provided with the anti-shock structure.

The anti-shock equipment is any one of helmets, bulletproof vests, and soles of sports shoes.

The advantages of the anti-shock structure and anti-shock equipment described in this application are:

In the anti-shock structure described in the present application, the porosity of the anti-shock structure gradually increases along the outer surface; in the direction inward along the outer surface, the porosity-position distribution of the middle position of the anti-shock structure The gradient of the function is greater than the gradient of the porosity-position distribution function at the initial and final positions. This setting method with a larger gradient of the middle part of the function and a smaller gradient of the two ends of the function makes the porosity distribution function of the impact-resistant structure It presents an approximately S-shaped distribution. This porosity setting method of approximately S-shaped distribution can make the outer layer of the impact-resistant structure have lower porosity and higher elastic modulus, which can withstand greater stress, and the inner layer of walnut shell has higher porosity. , can have a larger deformation space, can withstand greater strain, is conducive to the buffering effect of the inner layer, and ensures the overall strength of the impact-resistant protective equipment, and the porous design of the inner layer is conducive to reducing the weight of the impact-resistant equipment. Moreover, the inventors of the present application have found through research that the impact-resistant structure in which the porosity is approximately distributed in an S-shaped gradient in the present application has a relatively small inner layer stress, and the high tensile stress area is distributed in the contact area of the outer layer of the shell. The high tensile stress on the inner surface is transferred to the outer surface, and the high tensile stress is eliminated by using the structural characteristics of the outer surface that can withstand greater stress, so as to improve the impact resistance of the structure as a whole, thereby improving the utilization rate of materials.

The impact-resistant structure in the present application can be applied to impact-resistant protective equipment with different designs and configurations, such as helmets, body armor, and soles of sports shoes. The anti-shock equipment of the anti-shock structure in this application is set, combined with the different protection area functions of the anti-shock equipment in practical applications (the outer layer is the part that is vulnerable to impact and the impact is stronger, and the inner layer is the area that absorbs collision energy), and proposes an anti-shock The porosity distribution of the impact structure is designed to increase in an S-shaped gradient, so that the outer layer of the impact-resistant equipment has a lower porosity and a higher elastic modulus, which improves the performance of the outer surface against puncture and wear resistance; the porosity of the inner layer of the impact-resistant equipment Larger, improve the compression deformation capacity, play a role in absorbing collision energy, meet different impact requirements from the outside to the inside, and improve the mechanical structure strength of the impact-resistant equipment as a whole.

As a preferred embodiment, the porosity of the impact-resistant structure is in the range of 18-70%, and the impact-resistant structure includes a dense area on the outside and a porous area on the inside, wherein the porosity of the dense area is less than or equal to 30%. %; the porosity of the porous region is greater than 30%; the ratio of the thickness of the dense region to the overall thickness of the impact-resistant structure is 30-40%. The advantage of this setting is that the proportion of the dense layer is positively related to the stiffness and strength of the material, and negatively related to the plastic strain of the material. The greater the proportion of dense layer, the greater the elastic modulus and yield strength of the material, but the weaker the ability of the material to withstand plastic strain. In order to meet different impact requirements from the outside to the inside, the ratio of 30-40% of the dense layer can improve the overall mechanical strength of the material from the perspective of performance compromise.

The impact-resistant structure described in this application is preferably made of high-performance fiber-reinforced composite materials. The material makes the material have excellent properties such as light weight, compression resistance, low-speed impact resistance, cold resistance and heat resistance.

In order to make the technical solution of the impact-resistant structure and the impact-resistant equipment described in the present invention more clear, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

As shown in Figure 1, it is a partial schematic diagram of the impact-resistant structure of the present invention;

As shown in Figure 2 is the position distribution function figure of the porosity Pw (Z) of anti-shock equipment of the present invention;

As shown in Figure 3 is a schematic structural view of the anti-shock equipment of the present invention;

As shown in Figure 4, it is a schematic diagram of the experimental device structure of the three-point bending experiment of the 3D printed specimen;

Wherein, reference sign is:

1-shock-resistant structure; 2-helmet; 3-indenter of the three-point bending experimental apparatus; 4-supporting cylinder of the three-point bending experimental apparatus; 5-specimen.

Detailed ways

In the following embodiments, "outside" and "inside" in the design direction are relative to the direction of the impact force. When in use, the side of the impact-resistant structure facing the impact force, that is, the side directly bearing the impact force is the outer side, and vice versa for the inner side.

This embodiment provides an anti-shock structure 1, and the anti-shock structure 1 is made of carbon fiber material. A partial schematic diagram of the impact-resistant structure 1 is shown in FIG. 1 . As a preferred embodiment, the impact-resistant structure 1 can be made of high-performance fiber-reinforced composite materials. A composite material made of this kind, thereby further improving the performance of the impact-resistant structure 1.

The porosity of the impact-resistant structure 1 gradually increases inward along the outer surface; in the inward direction along the outer surface, the gradient of the porosity-position distribution function at the middle position of the impact-resistant structure 1 is greater than the initial and Gradient of the porosity-position distribution function at the end-section position. The porosity range of the impact-resistant structure 1 in this embodiment is 18-70%.

In this embodiment, the impact-resistant structure 1 is set as a single-layer structure, and the position distribution function of the porosity Pw(Z) of the impact-resistant structure 1 is:

Wherein, Z is the normalized depth coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure 1, Z=1 indicates that the position is on the inner surface of the impact-resistant structure 1, and the position of Pw(Z) The distribution function curve is approximately S-shaped, as shown in Figure 2. As an optional embodiment, the impact-resistant structure 1 can also be configured as a double-layer or at least three-layer structure, as long as the position distribution function of the overall porosity Pw(Z) of the impact-resistant structure complies with the above-mentioned function law.

Reconstruct the geometric structure of the impact-resistant structure 1 to complete the finite element model. Then use Abaqus to simulate the finite element model, and calculate the elastic modulus of each layer by simulating quasi-static compression. By fitting the elastic modulus of each layer with the position depth, the change law of the elastic modulus of the impact-resistant structure 1 in the thickness direction can be obtained. The position distribution function of the modulus of elasticity of the impact-resistant structure 1 is:

Wherein, Z is a normalized position coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure 1 , and Z=1 indicates that the position is on the inner surface of the impact-resistant structure 1 .

The impact-resistant structure 1 can be divided into an outer dense area and an inner porous area, wherein the porosity of the dense area is less than or equal to 30%; the porosity of the porous area is greater than 30%, and the thickness of the dense area is The value of the ratio to the overall thickness of the impact-resistant structure lies between 30-40%. The porosity of the impact resistant structure is in the range of 18-70%.

The impact-resistant equipment provided with the impact-resistant structure described in this embodiment is shown in Figure 3, the impact-resistant structure 1 is used for the outer layer of the helmet shell of the helmet 2, and the thickness of the impact-resistant structure 1 in the outer layer of the helmet shell The density is 9.2mm, the density is 969.63kg/m ³ , the elastic modulus has an S-shaped gradient distribution, the average value is 0.55Gpa, and the Poisson's ratio is 0.4.

Experimental comparison

In order to prove the technical effect of the impact-resistant structure and the impact-resistant equipment described in this application, experiments are specially set up to detect the performance of the impact-resistant structure and equipment in this application and comparative examples.

3D printing test piece three-point bending experiment

There are three groups of 3D printing specimens in this experiment. The first group of specimens adopts the impact-resistant structure prepared by the above implementation method of this application, and the second group of specimens adopts a structure with a uniform distribution of elastic modulus, and its porosity is evenly distributed. , is 32%; the third group of specimens adopts the structure with linear gradient distribution of elastic modulus, and its porosity ranges from 18 to 70%. The dimensions of the three groups of test pieces are all 98.6×22.8×5㎜.

Use material mechanics testing machine to carry out three-point bending experiment to three groups of test pieces, three groups of test pieces are placed on the supporting cylinder 4 of experimental apparatus, as shown in Fig. The pressure is applied at the middle position, and the displacement loading control method is adopted. The loading speed of the indenter is 2mm/s. The upper surface of the specimen 5 is subjected to compression, and the lower surface is subjected to tension. The fracture process of the specimen was photographed by a high-speed camera, and the stress state of the three groups of specimens under the same external force was analyzed. The experimental results confirmed that the specimens of the second group and the third group all fractured, and the moment of fracture all started from the lower surface directly below the specimens. However, the cracks in the impact-resistant structure in this application start from the support contact position between the lower surface and the lower end, and extend obliquely upward to the upper surface. Obviously, the crack distribution is longer, and higher energy is required for fracture.

Simplified spherical shell simulation experiment

There are also three sets of spherical shells in this experiment. The first set of spherical shells adopts the impact-resistant structure prepared by the embodiment of the application; the second set of spherical shells adopts a structure whose elastic modulus is evenly distributed; A structure in which the modulus is distributed along a linear gradient. The diameters of the three groups of spherical shells are all 20mm, and the thickness of the spherical shell layer is 1mm.

The software Abaqus is used to simulate and analyze the stress state of the three groups of spherical shells under the same external force. The results show that the spherical shell made of the impact-resistant structure of the present application has less stress in the inner layer, and the high tensile stress area is distributed in the contact area of the outer layer of the shell. This distribution transfers the original high tensile stress on the inner surface to the outer surface, the inner layer is in a low stress state, and the shell damage starts from the outer layer. But for the second and third groups of spherical shells, the damage of the shell starts from the inner surface first. This is consistent with the results of the above three-point bending experiments on 3D printed specimens.

Helmet comparison experiment

The structure of the outer layer of the ordinary helmet used for comparison is the same as that of the helmet in the embodiment of the present application, but the material adopts linear elastic constitutive structure, and its elastic modulus is 0.55Gpa.

Using the software Abaqus to simulate, when the forehead of the helmet collides with the flat anvil at a speed of 6.2m/s, the Mises stress on the head surface wearing the helmet of this application is significantly smaller than that of wearing a normal helmet. The highest Mises stress in the comparative helmet model is about 1.6 times that of the improved model. This proves that the impact-resistant equipment adopting the impact-resistant structure of the present application has better impact resistance.

The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be determined by the claims.

Claims (7)

1. An anti-shock structure, characterized in that, the porosity of the anti-shock structure increases gradually along the outer surface; on the inward direction along the outer surface, the porosity of the anti-shock structure at the middle position - the gradient of the position distribution function is greater than the gradient of the porosity-position distribution function at the initial and final segment positions; The position distribution function of the porosity Pw (Z) of the impact-resistant structure is: ; Wherein, Z is the normalized depth coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure, and Z=1 indicates that the position is on the inner surface of the impact-resistant structure; The position distribution function of the modulus of elasticity of the impact-resistant structure is: ; Wherein, Z is a normalized depth coordinate, Z=0 indicates that the position is on the outer surface of the impact-resistant structure, and Z=1 indicates that the position is on the inner surface of the impact-resistant structure. 2. The impact-resistant structure according to claim 1, characterized in that, the porosity of the impact-resistant structure is in the range of 18-70%. 3. The anti-shock structure according to claim 2, characterized in that, the anti-shock structure comprises a dense area and a porous area sequentially arranged along the inner direction of the outer surface, wherein the porosity of the dense area is less than or equal to 30%; the porosity of the porous region is greater than 30%; the ratio of the thickness of the dense layer to the overall thickness of the impact-resistant structure is 30-40%. 4. The impact-resistant structure according to claim 3, characterized in that, the impact-resistant structure is configured as a single layer or multiple layers. 5. The impact-resistant structure according to claim 4, characterized in that, the impact-resistant structure is made of high-performance fiber reinforced materials. 6. An anti-shock device provided with the anti-shock structure according to any one of claims 1-5. 7. The anti-shock equipment according to claim 6, characterized in that, the anti-shock equipment is any one of helmets, body armor, and soles of sports shoes.

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