Multi-scene anti-explosion and anti-impact protection device based on door grid sponge fractal structure

Abstract

The invention belongs to the field of engineering structure protection, and particularly relates to a multi-scene anti-explosion and anti-impact protection device based on a door grid sponge fractal structure, and the protection device is detachably connected to the surface of a protected structure in a modular assembly mode. Each protection device comprises a surface plate, a back plate and a core layer bonded between the surface plate and the back plate; the surface plate and the back plate are both designed to be high-strength metal plates and serve as a framework of the protection device. The core layer is formed by periodically arranging a plurality of same door grid sponge fractal structures at equal intervals; each door grid sponge fractal structure absorbs energy through compression of the core layer under the explosion impact load, the initial peak value of the explosion load applied to the protected structure is reduced, the impact duration is prolonged, and therefore the impact resistance of the structure is greatly improved. The protection device can be applied to multi-scene anti-explosion and anti-impact protection. When the protection device is installed on a wall body, the functions of heat preservation, heat insulation, sound insulation and noise reduction of the door grid sponge fractal structure can be fully played.

Description

Technical Field

[0001] The present invention belongs to the field of engineering structure protection, and in particular relates to an anti-explosion and anti-impact protection device for an engineering structure, and specifically relates to a multi-scenario anti-explosion and anti-impact protection device based on a Menger sponge fractal structure. Background Art

[0002] The threat of explosions to human life and property cannot be underestimated, so how to improve the protection performance of structures under explosion impact loads has received widespread attention from the engineering and academic communities. With the continuous development of science and technology, people's design requirements for engineering structures are constantly increasing. Important engineering structures should not only meet the requirements of normal service performance, but also have superior protection performance under extreme loads (explosion or impact).

[0003] Traditional engineering protection mainly includes two design concepts: one is the "rigid protection" design concept, which is to use high-strength structural components to improve the bearing capacity of engineering structures, or to build explosion-proof barriers to prevent terrorist attacks by car bombs; the other is the "flexible protection" design concept, which is to install flexible energy-absorbing devices on the outside of the building structure to reduce the load input to the structure by absorbing energy, thereby reducing damage to the engineering structure, such as sandwich structures or sacrificial hanging panels.

[0004] The "rigid protection" design has good explosion and impact resistance, but sometimes the protection structure itself, as a part of the structural component, may have a great impact on the integrity of the structure after damage. Sometimes it is necessary to use the reinforcement method of rebuilding the damaged component, which has high maintenance costs and a long construction period.

[0005] Protective devices that use "flexible protection" designs, such as lightweight flexible sacrificial cladding, are easy to install and use the large plastic deformation of the core layer at relatively low stress levels to absorb large amounts of energy while transferring controlled forces to the main structure. There are many different types of core layer structures, such as negative Poisson's ratio structures, tubular structures, corrugated plate structures, etc.

[0006] Fractals are entities that are self-similar at different length scales and follow natural hierarchical patterns, and the Menger sponge structure is a characteristic fractal topology. Menger sponge fractals have been used in different engineering fields, including energy, architecture, biomedicine, manufacturing, and urban design, due to their large surface area and small volume. However, there is no application of Menger sponge fractals in the field of explosion and impact resistance. Summary of the invention

[0007] In view of the defects of the prior art, the present invention proposes a multi-scenario explosion-proof and impact-proof protective device based on the Menger sponge fractal structure, which can be used to improve the protective performance of engineering structures under explosion or impact loads. It is known that natural structures with potential layered microstructures, such as human bones and wood, have excellent mechanical properties. Therefore, the protective device proposed in the present invention is bionic human bone tissue structure. Bone tissue includes cortical bone and cancellous bone. Its main protective principle is that the cortical bone is hard and dense, has high pressure resistance, is distributed on the surface of the bone, and provides bone hardness; while the cancellous bone is loose and porous sponge-like, and is interwoven by many reticular trabeculae, which are distributed inside the bone, so that the bone has compressive tension and elasticity. This structure enables the bone to withstand pressure and maintain a certain elasticity, thereby effectively absorbing and dispersing impact force. Trabeculae have a highly complex structure and a multi-level layered structure, and they show excellent performance whether as a supporting structure of the human body or as impact protection. The present invention designs a protective device based on the impact resistance principle of human bones. The device has excellent energy absorption and explosion resistance, and is easy to install and replace, which can significantly reduce economic and time costs.

[0008] The present invention is achieved in that: A multi-scenario explosion-proof and impact-proof protective device based on a Menger sponge fractal structure, wherein the protective device is detachably connected to the surface of the protected structure in a modular assembly form; Each guard includes a surface plate, a core layer and a back plate; The core layer is bonded between the surface plate and the back plate by epoxy resin; the core layer is composed of a number of identical Menger sponge fractal structures arranged periodically at equal intervals, and the fractal structure is generated by replicating the structure of the same shape again or by continuously removing the structure of the same shape, and has periodicity and self-similarity; each Menger sponge fractal structure is regarded as a self-healing toughness unit of the protective device; The front plate and the back plate are both high-strength metal plates; the back plate is detachably connected to the protected structure.

[0009] Furthermore, the pores of the Menger sponge fractal structure are square, circular, diamond, cross, or a mixed arrangement of pores of different shapes.

[0010] Furthermore, the materials used for the surface plate and the back plate are low-carbon steel plates, stainless steel plates, alloy steels and plastic steels.

[0011] Furthermore, the material of the Menger sponge fractal structure is one of polylactic acid material, shape memory alloy, and melamine foam.

[0012] Furthermore, the Menger sponge fractal structure is any fractal level.

[0013] Furthermore, all components of the protective device are prefabricated components, prepared by 3D printing technology, and each component is connected by modular assembly.

[0014] The present invention also discloses a method for installing the multi-scenario explosion-proof and impact-proof protective device based on the Menger sponge fractal structure, comprising the following steps: Step 1: clean the outer surface of the engineering structure wall, and set bolt holes at the four corners of the back plate surface; Step 2, modeling the Menger sponge fractal structure in 3D modeling software, wherein the fractal structure is generated by replicating the same shape structure again or by continuously removing the same shape structure; Step 3: Import the designed Menger sponge fractal structure model into the 3D printing slicing software, set appropriate printing parameters according to the selected 3D printing material and printer type, and transfer the print file generated by the slicing software to the 3D printer to complete the printing; Step 4: evenly apply the polyurethane coating on the front and back surfaces of the front plate and back plate to form an anti-corrosion protective layer; Step 5: prepare a plurality of Menger sponge fractal structures according to the geometric dimensions of the surface plate or the back plate, arrange the Menger sponge fractal structures periodically at equal intervals and bond them between the surface plate and the back plate respectively.

[0015] Furthermore, the modeling analysis method in step 2 includes: creating an initial cube unit, and then subdividing the cube into 3 n equal small cubes, and remove the small cubes in the center and six surfaces of the cube, leaving 3 n -7 small cubes, place the remaining 3 n -7 small cubes are divided according to the above operations; the side length of each small cube is 1 / n of the size of the previous cube, so after k iterations, the side length of the cube is 1 / n of the side length of the initial cube k ; According to the recursive rule of Menger sponge, multiple iterations are performed to finally form a Menger sponge fractal structure of the nth fractal level.

[0016] The technical effects of the present invention are as follows: (1) The protective device proposed in the present invention is composed of a surface plate, a core layer, and a back plate, and its structural features are designed to imitate the human skeleton. The surface plate and the back plate are similar to the cortical bone in the bone tissue, and use the hard, dense, and high pressure-resistant material properties to provide "rigid protection", providing the required rigidity for the protective device. Several Menger sponge fractal structures serve as the core layer to perform "flexible protection" by absorbing energy through compression. The protective device proposed in the present invention is a "rigid and flexible" protective device that can achieve hierarchical protection of the protected structure, and the protective effect is better than single rigid protection or flexible protection.

[0017] (2) The protective device proposed in the present invention can not only be used for explosion and impact protection of above-ground engineering structures, but can also be used as an energy sink in underground engineering structures to suppress and absorb ground impact. In addition, the core layer of the protective device proposed in the present invention has the characteristics of elastic wave band gap, which can prevent elastic waves within a specific frequency range from propagating, thereby reducing the vibration of people or equipment inside the underground structure.

[0018] (3) The present invention can change the energy consumption performance of the protective device by adjusting various parameters of the protective device, such as the geometric parameters, relative density, pore shape and size, and fractal grade of the Menger sponge fractal structure. Therefore, the protective device can be optimized and designed considering the actual engineering conditions, thereby maximizing practicality and economy.

[0019] (4) The material used for the core layer of the present invention is light in weight, energy-saving and environmentally friendly, and simple to manufacture. When the protective device is installed on the wall, the thermal insulation material properties of the Menger sponge fractal structure can be fully utilized, and the Menger sponge fractal structure can form multiple adjustable phonon band gaps, thereby providing the function of sound insulation and noise reduction.

[0020] (5) The protective device of the present invention adopts modular assembly connection, which makes installation and maintenance and reinforcement more convenient, greatly reducing time and economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the protective device of the present invention; Figure 2 This is a schematic diagram of the fractal structure of Menger sponge of the present invention; Figure 3 This is the front view of the Menger sponge fractal structure; Figure 4 It is a schematic cross-sectional view of the protective device structure of the present invention; Figure 5 Schematic diagram of the process of creating the Menger sponge fractal structure; Figure 6 Schematic diagram of different pore shapes in the fractal structure of Menger sponge; Figure 7 Schematic diagram of the different pore sizes in the fractal structure of Menger sponge.

[0022] In the figure: 1, surface plate; 2, core layer; 21, Menger sponge fractal structure; 211, pores; 3, back plate; 4, bolt holes; 5, high-strength bolts. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] like Figure 1-7 As shown, the present invention discloses a multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure, including a surface plate 1, a core layer 2 and a back plate 3; the core layer 2 is bonded between the surface plate 1 and the back plate 3 by epoxy resin, and the back plate 3 is connected to the protected structure by bolts. This structure can not only reduce the explosion load transmitted from the core layer to the protected structure, but also realize the modular installation of the protective device. The key parts of the protective device are all connected by modular assembly, which makes the installation, maintenance and reinforcement of the protective device more convenient, greatly reducing time and economic costs. Therefore, the toughness protection purpose of local damage and local replacement is achieved through modular design.

[0025] All parts of the protective device are prefabricated components, among which the core layer 2 can be prepared by 3D printing technology, and each part is connected by a modular assembly method so that the protective structure can be assembled on site.

[0026] The surface plate 1 and the back plate 3 are both designed to be high-strength metal plates, serving as the skeleton of the protective device, thereby achieving the purpose of "rigid protection"; preferably, the materials used for the surface plate 1 and the back plate 3 can be low-carbon steel plates, stainless steel plates, alloy steels, plastic steels and other materials. The surface plate 1 can apply the explosion load more evenly to the core layer 2, and at the same time reduce the impact energy input to the core layer 2. The back plate 3 can not only fix the protective device to the protected structure, but also reduce the explosion load transmitted from the core layer 2 to the protected structure.

[0027] The core layer 2 preferably uses a material with a longer stress platform, which can absorb more energy during the compression process of the core layer, further improving the protective performance of the structure. The core layer has the characteristics of an elastic wave band gap, which can prevent elastic waves within a specific frequency range from propagating, thereby reducing the vibration of people or equipment inside the underground structure. In addition, the core layer substrate should also have the advantages of easy molding, convenient construction, light weight and environmental protection.

[0028] Furthermore, the core layer 2 consumes the explosion energy through the deformation of the Menger sponge fractal structure 21, so the protective device can protect the above-ground engineering structure; the core layer 2 is composed of a number of identical Menger sponge fractal structures, each of which can be regarded as a self-healing toughness unit of the protective device, and utilizes the compression of the core layer under the explosion impact load to absorb energy, thereby reducing the initial peak value of the explosion load applied to the protected structure and prolonging the duration of the impact, thereby greatly improving the impact resistance of the structure.

[0029] The structural characteristics of the Menger sponge fractal structure give it good energy absorption and shock absorption. Each Menger sponge fractal structure is like a trabecula in the human skeleton, which consumes impact energy through deformation. Therefore, the protective device can be used to protect ground engineering structures. The fractal structure is generated by replicating the same shape structure again or by continuously removing the same shape structure. Therefore, the fractal structure is a multi-level complex structure with self-similarity at different scales. Therefore, the Menger sponge fractal structure can be regarded as a periodic and self-similar structure with wave velocity tuning ability, which can realize wave regulation. The protective device with the Menger sponge fractal structure as the core layer can act as an energy sink to reduce the propagation of ground shock waves, thereby effectively protecting underground engineering structures.

[0030] Preferably, the structural parameters of the Menger sponge fractal structure have different degrees of influence on the impact resistance of the core layer. The energy absorption capacity and wave propagation performance of the Menger sponge fractal structure can be changed by adjusting the spacing, geometric dimensions, pore size, shape and fractal grade of the Menger sponge fractal structure. The size of the pores 211 of the Menger sponge fractal structure can be precisely adjusted by additive manufacturing technology. Preferably, the pores 211 of the Menger sponge fractal structure can be arranged in a square, circular, diamond, cross or mixed shapes.

[0031] Preferably, the material of the Menger sponge fractal structure 21 can be polylactic acid material, shape memory alloy, melamine foam and other materials. Due to the controllability of its physical parameters, in actual engineering, the core layer can be reasonably adjusted according to different working conditions, thereby improving the performance of the protective device in resisting explosion impact. The Menger sponge fractal structure 21 can form multiple adjustable phonon band gaps, thereby providing the function of sound insulation and noise reduction.

[0032] The installation steps are described as an example of setting up a multi-scenario explosion-proof and impact-resistant protection device based on the Menger sponge fractal structure for the walls of engineering structures.

[0033] Step 1: clean the outer surface of the engineering structure wall, set bolt holes 4 at the four corners of the back plate 3, and the center of the bolt hole 4 is 40 mm away from the two adjacent sides of the back plate 3. A CNC high-speed drilling machine can be used to complete the precise layout of the bolt hole 4.

[0034] According to the degree of fractal iteration, the Menger sponge fractal structure 21 can be divided into 1, 2, 3...n levels. This embodiment will take the third fractal level as an example to describe the detailed process of making the Menger sponge fractal structure 21. Other levels of Menger sponge fractal structures 21 can be obtained by the same production method, and the difference lies in the number of fractal iterations. The rapid development and continuous improvement of additive manufacturing technology in terms of resolution and molding quality make complex printing architectures possible, so this patent will use 3D printing technology to manufacture the Menger sponge fractal structure 21.

[0035] Step 2: Select appropriate 3D modeling software to model the Menger sponge fractal structure 21. The fractal structure is generated by replicating the structure of the same shape again or by continuously removing the structure of the same shape. Therefore, in the modeling software, first create an initial cube unit (90 mm × 90 mm × 90 mm), then subdivide the cube into 27 equal small cubes, and remove the small cubes at the center of the cube and the centers of the six surfaces, leaving 20 small cubes, and divide the remaining 20 small cubes according to the above operations. The side length of each small cube is 1 / 3 of the size of the previous divided cube, so after k iterations, the side length of the cube is (1 / 3) of the side length of the initial cube. k According to the recursive rule of Menger sponge, multiple iterations are performed, and finally a Menger sponge fractal structure 21 of the third fractal level with a relative density of 0.4 is formed.

[0036] Fractal topology causes the volume of the cubic structure to decrease continuously, while the total surface area increases continuously. As the number of iterative segmentation increases, the surface area of ​​the Menger sponge fractal structure 21 approaches infinity, while its volume approaches zero. Obviously, the Menger sponge fractal structure 21 is a partially complete three-dimensional structure, and its geometric dimension is a non-integer between 2 and 3. The dimension of the third fractal level Menger sponge fractal structure 21 is 2.73. When the geometric dimension approaches 2, the pores 211 of the Menger sponge fractal structure tend to be smoother. The closer the geometric dimension is to 3, the greater the complexity of the pore space distribution, which also means that the ability of the Menger sponge fractal structure pores 211 to occupy space has been enhanced.

[0037] Step 3: Import the designed Menger sponge fractal structure 21 model into the 3D printing slicing software, and set appropriate printing parameters including printing speed, temperature, etc. according to the selected 3D printing material (such as polylactic acid material, shape memory alloy, melamine foam, etc.) and printer type. Transfer the print file generated by the slicing software to the 3D printer to complete the printing.

[0038] Step 4: evenly apply the polyurethane coating on the front and back surfaces of the surface plate 1 and the back plate 3 to form an anti-corrosion protective layer to block the contact between the external environment and the surface plate 1 and the back plate 3, thereby reducing the occurrence of corrosion.

[0039] Step 5: Prepare a plurality of Menger sponge fractal structures 21 according to the geometric dimensions of the surface plate 1 or the back plate 3, and arrange the Menger sponge fractal structures 21 periodically at equal intervals. Each Menger sponge fractal structure 21 can be regarded as a unit cell, and the distance between adjacent unit cells is 150 mm. Use epoxy resin to bond each Menger sponge fractal structure 21 between the surface plate 1 and the back plate 3.

[0040] Step six, fix the 1 mm thick back plate 3 to the outer surface of the wall with high-strength bolts 5. The number of back plates 3 needs to be determined according to the surface area of ​​the wall, thereby completing the modular installation of the protective device.

[0041] 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 and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-scenario explosion and impact protection device based on Menger sponge fractal structure, characterized by: The protective device is detachably connected to the surface of the protected structure in a modular assembly form; Each guard includes a surface plate, a core layer and a back plate; The core layer is bonded between the surface plate and the back plate by epoxy resin; the core layer is composed of a number of identical Menger sponge fractal structures arranged periodically at equal intervals, and the fractal structure is generated by replicating the structure of the same shape again or by continuously removing the structure of the same shape, and has periodicity and self-similarity; each Menger sponge fractal structure is regarded as a self-healing toughness unit of the protective device; The front plate and the back plate are both high-strength metal plates; the back plate is detachably connected to the protected structure.

2. The multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure according to claim 1 is characterized in that: The pores of the Menger sponge fractal structure are square, circular, diamond, cross, or a mixture of pores of different shapes.

3. The multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure according to claim 1 is characterized in that: The materials used for the surface plate and the back plate are low-carbon steel plates, stainless steel plates, alloy steels and plastic steels.

4. The multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure according to claim 1 is characterized in that: The material of the Menger sponge fractal structure is one of polylactic acid material, shape memory alloy, and melamine foam.

5. The multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure according to claim 1 is characterized in that: The Menger sponge fractal structure can be any fractal level from 1 to n, where n is a positive integer.

6. The multi-scenario explosion-proof and impact-proof protective device based on Menger sponge fractal structure according to claim 1 is characterized in that: All components of the protective device are prefabricated components, prepared by 3D printing technology, and each component is connected by modular assembly.

7. The installation method of the multi-scenario explosion-proof and impact-proof protective device based on the Menger sponge fractal structure according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: clean the outer surface of the engineering structure wall, and set bolt holes at the four corners of the back plate surface; Step 2, modeling the Menger sponge fractal structure in 3D modeling software, where the fractal structure is generated by replicating the same shape structure again or by continuously removing the same shape structure; Step 3: Import the designed Menger sponge fractal structure model into the 3D printing slicing software, set appropriate printing parameters according to the selected 3D printing material and printer type, and transfer the print file generated by the slicing software to the 3D printer to complete the printing; Step 4: evenly apply the polyurethane coating on the front and back surfaces of the front plate and back plate to form an anti-corrosion protective layer; Step 5: prepare a plurality of Menger sponge fractal structures according to the geometric dimensions of the surface plate or the back plate, arrange the Menger sponge fractal structures periodically at equal intervals and bond them between the surface plate and the back plate respectively.

8. The installation method of the multi-scenario explosion-proof and impact-proof protective device based on the Menger sponge fractal structure according to claim 7 is characterized in that: The modeling analysis method in step 2 includes: creating an initial cube unit, and then subdividing the cube into 3 n equal small cubes, n is a positive integer; remove the small cubes at the center and six surfaces of the cube, leaving 3 n -7 small cubes, place the remaining 3 n -7 small cubes are divided according to the above operations; the side length of each small cube is 1 / n of the size of the previous cube, so after k iterations, the side length of the cube is 1 / n of the side length of the initial cube k ; According to the recursive rule of Menger sponge, multiple iterations are performed to finally form a Menger sponge fractal structure of the nth fractal level.

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