CN114547947A - Multi-scale hierarchical triangular shock-resistant system and application thereof - Google Patents
Multi-scale hierarchical triangular shock-resistant system and application thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of impact-resistant structures, and discloses a multi-scale hierarchical triangular impact-resistant system and application thereof, wherein the multi-scale hierarchical triangular impact-resistant system comprises a plurality of hierarchical periodic units; the hierarchical periodic unit comprises a plurality of macroscale triangles, mesoscale triangles and microscale triangles with different geometric dimensions; the macroscale triangles are periodically arranged, the mesoscale triangles are nested in the macroscale triangles, and the three microscale triangles are embedded outside the middle mesoscale triangle. According to the invention, a plurality of mesoscopic and microscale triangles are nested in the macroscale triangle, and due to the existence of the microstructure, the local rigidity of the structure is enhanced, and the deformation mode of the structure is changed, so that the structure has better compression resistance and dynamic impact energy absorption characteristics. Under high-speed impact, the stress fluctuation value of the multi-scale triangular hierarchical structure is relatively gentle, secondary damage of the protective structure to the protected structure can be effectively reduced, and the protective effect is improved.
Description
Technical Field
The invention belongs to the technical field of impact-resistant structures, and particularly relates to a multi-scale hierarchical triangular impact-resistant system and application thereof.
Background
At present, the impact resistance is a key technical index of equipment such as large armored vehicles, ships, aircraft carriers and the like, and the battlefield viability is concerned. It is a common technical means at present to absorb the energy of the blast impact by applying a sacrificial layer on the outer side of the equipment in the area subject to the blow, and by plastic deformation and destruction of the sacrificial layer. In consideration of the overall performance and actual working conditions of large equipment, the design of the light-weight high-strength impact-resistant energy-absorbing structure has important significance for improving the armor protection capability and ensuring the armor safety.
The honeycomb material has the characteristics of good mechanical property and light weight, and is widely applied to the related engineering field at present. For a honeycomb structure, the topological form of the minimum periodic unit has a great influence on the mechanical properties of a macroscopic structure, such as the mechanical properties of triangular, quadrilateral and kagome honeycombs are quite different. The purpose of improving the performance of the honeycomb structure is achieved by designing the topological structure of a single cell, and the method is a key focus field of researchers. With the high requirements on quality, strength, rigidity and the like in modern equipment, the common honeycomb structure is difficult to meet the engineering application requirements, and a hierarchical structure design thought with macro-micro multi-scale provides a technical approach for improving the static and dynamic mechanical properties of the honeycomb structure.
A hierarchical structure is a structure having macro-micro multi-scale features where the micro-structures have macrostructurally similar topological features that are assembled into a new structure in addition to or in place of a side or corner of the macro-structure. The introduction of the microstructure can obviously enhance the mechanical property of the structure on the premise of keeping the structure quality and the volume meeting the application requirements, and is applied to the fields of aerospace, engineering construction and the like at present.
The existing single-scale triangular grid structure has the conditions of poor compression resistance, insufficient energy absorption property under quasi-static compression and dynamic impact, and is difficult to effectively protect a protected structure under certain mass constraint; and the stress fluctuation is large during high-speed impact, and secondary damage to the structure is easy to occur.
Through the above analysis, the problems and defects of the prior art are as follows:
the existing single-scale triangular grid structure has the conditions of poor compression resistance, insufficient energy absorption property under quasi-static compression and dynamic impact, and is difficult to effectively protect a protected structure under certain mass constraint; and the stress fluctuation is large during high-speed impact, and secondary damage to the structure is easy to occur.
The difficulty in solving the above problems and defects is: under the condition of meeting the quality constraint, the energy absorption characteristic of the structure is improved to meet the engineering application requirement, and the energy absorption characteristic is a key technical bottleneck of the current impact-resistant structure design. At present, researchers have conducted a series of structural design studies, but key technical structures and design guidance schemes have not yet been obtained. In addition, under the high-speed impact working condition, the fluctuation situation of the internal stress of the structure is influenced by various factors, and the relevant influence mechanism is not clear. Therefore, on the premise of meeting the mass constraint, certain technical difficulty exists in improving the compression resistance characteristic and the energy absorption characteristic; on the premise of guaranteeing the energy absorption characteristic, the purpose of regulating and controlling stress fluctuation under impact load is achieved by designing the structural topology, and certain technical difficulty exists. The significance of solving the problems and the defects is as follows: under explosive impact loads, insufficient energy absorption characteristics of the protective structure can cause the protected structure to suffer excessive transient loads, which in turn leads to structural failure. The energy absorption characteristic is a key evaluation index of the protective structure. On the premise of meeting the quality constraint, the energy absorption characteristic is obviously improved, the important significance is achieved for guaranteeing the safety of the protected structure, the failure probability of the structure can be effectively reduced, and the anti-explosion capability of the structure is improved. Meanwhile, the stress fluctuation of the protective structure under the impact load can also damage the structure to a certain extent, and the relatively gentle stress fluctuation can reduce the impact from the protective structure, so that the structure safety is guaranteed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a multi-scale hierarchical triangular shock-resistant system and application thereof.
The invention is realized in such a way that a multi-scale hierarchical triangular anti-impact system comprises:
a number of hierarchical periodic units;
the hierarchical periodic unit comprises a plurality of macroscale triangles, mesoscale triangles and microscale triangles with different geometric dimensions;
the macroscale triangles are periodically arranged, the mesoscale triangles are nested in the macroscale triangles, the three microscale triangles are embedded outside the mesoscale triangle, and the outer ends of the microscale triangles are in contact with the inner wall of the macroscale triangle.
Furthermore, the side length of the mesoscale triangle is half of that of the macroscale triangle, and the side length of the microscale triangle is half of that of the mesoscale triangle.
Furthermore, the macro-scale triangle, the meso-scale triangle and the micro-scale triangle are in contact without gaps in the assembling process.
Further, a single said hierarchical periodic unit is obtained by translation and rotation of a macro-scale triangle.
Further, the multi-scale hierarchical triangular shock-resistant system is composed of m multiplied by n hierarchical periodic units, wherein m is the number of transverse unit cells, n is the number of longitudinal layers, m is greater than or equal to 1, and n is greater than or equal to 1.
Further, a single-level periodic unit is filled with a mesoscale triangle and three microscale triangles in the macroscale triangle.
By combining all the technical schemes, the invention has the advantages and positive effects that: the invention provides a multi-scale triangle hierarchical structure by nesting a plurality of mesoscopic and microscale triangles in a macroscale triangle. Due to the existence of the microstructure, the local rigidity of the structure is enhanced, the deformation mode of the structure is changed, and the structure has better compression resistance and dynamic impact energy absorption. According to the graph in fig. 3 and the table 1, under quasi-static compression, the compression resistance of the multi-scale triangular hierarchical structure is improved by about 35% compared with that of a single-scale triangular hierarchical structure, and the energy absorption property is improved by about 204%. According to the graph 4 and the table 2, under the low speed of 5m/s and the high speed impact of 100m/s, the multi-scale triangular layer structure has the characteristic of obvious smaller stress fluctuation compared with the triangular grating structure, the secondary damage of the protective structure to the protected structure can be effectively reduced, and the protective effect is improved.
Compared with a triangular grid structure, the energy-absorbing triangular grid structure has higher compression resistance and energy absorption characteristics. Under static compression, the energy absorption characteristic of the multi-scale level triangle is increased by nearly two times compared with that of a single-scale triangular grid structure, the energy absorption characteristic is partially improved under dynamic impact, and the multi-scale level triangle can be used for structural design of compression-resistant and impact-resistant sandwich plates and has good engineering application value.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a hierarchical periodic unit provided in an embodiment of the present invention, which may be translated and rotated to obtain a multi-scale triangular-level impact-resistant structure. The mesoscopic triangles are embedded in the macroscopic triangles, and the microscopic triangles are embedded at the periphery of the mesoscopic triangles and are in mutual contact without gaps.
Fig. 2 is a schematic diagram of a single-scale triangular grid structure and a multi-scale triangular-level anti-impact structure according to an embodiment of the present invention. The multi-scale triangular-level shock-resistant structure can be obtained by periodic unit translation and rotation as shown in fig. 1. It is critical to ensure that the structural joint is seamless.
Fig. 3 is a graph comparing quasi-static compressive stress strain of a multi-scale hierarchical structure and a single-scale triangular grating structure at the same equivalent density according to an embodiment of the present invention.
Fig. 4(a) is a stress-strain diagram and a partial enlarged view of a single-scale triangular grid structure provided by the embodiment of the invention at impact velocities of 5m/s and 100 m/s.
Fig. 4(b) is a stress-strain diagram and a partial enlarged view of the multi-scale triangular-level impact-resistant structure provided by the embodiment of the invention at impact velocities of 5m/s and 100 m/s.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Aiming at the problems in the prior art, the invention provides a multi-scale hierarchical triangular anti-impact system and an application thereof, and the invention is described in detail below with reference to the accompanying drawings.
As shown in fig. 1, a basic unit level periodic unit of a multi-scale level triangular anti-shock system is provided for the embodiment of the present invention.
Fig. 2 shows a multi-scale hierarchical triangular sandwich panel and a single-scale triangular grid structure sandwich panel. Establishing a simulation model in LS-DYNA finite element software according to the designed triangular hierarchical structure, wherein the formed material is TPU, and the material parameters are as follows: density 1168kg/cm3Poisson's ratio is 0.48, elastic modulus is 72.25MPa, tangent modulus is 10.74MPa, yield modulus is 2.747MPa, and stress limit is 25.5417 MPa. The side length of the macroscale triangle is 2cm, and the side lengths of the mesoscopic triangle and the microscale triangle are 1cm and 0.5cm respectively.
In order to prove the excellent performance of the multi-scale triangular hierarchical structure provided by the invention, a single-scale triangle and a multi-scale triangle are established for comparison, and in order to ensure that the three structures have the same equivalent density, the wall thicknesses of the macroscopic structure, the mesoscopic structure and the multi-scale triangle are respectively 0.3cm, 0.15cm and 0.088 cm.
The stress-strain curves of the three structures under quasi-static compression and at different impact velocities were extracted, as shown in fig. 3. To evaluate the energy absorption characteristics of the structure, the energy absorption characteristics of the structure were calculated from the stress-strain curves of the structure under compression and impact:
in the formula, EA is the structural energy-absorbing characteristic, deltaDFor the densification stroke of the structure under the compression condition,f (x) is a compressive force.
And extracting the densification strain, initial peak stress, energy absorption characteristic and platform area average stress of the structure according to the simulated stress-strain curve for evaluating the structure performance. The densification strain is the stroke required by the structure in the stage of compressing to be incompressible, the initial peak stress is the compressive force required by the structure in the stage of yielding, the plateau area average stress is the average stress after the structure enters the stage of yielding until densification, and the energy absorption characteristic is the energy required by the structure in the stage of compressing from the initial state to densification.
Table 1 gives the data relating to the three structures under quasi-static compression and table 2 gives the data relating to the structures at different impact velocities. It can be seen that under quasi-static compression, the multi-scale triangular hierarchical structure has better compression resistance and energy absorption characteristics. Under the condition of the same mass and volume, the compression resistance characteristic of the multi-scale triangular hierarchical structure is improved by 34.2% compared with that of a single-scale triangular grid structure, and the energy absorption characteristic is improved by about twice.
Table 1: comparison of energy absorption characteristics of multi-scale hierarchical structure and single-scale triangular grid structure under quasi-static compression
Table 2: comparison of energy absorption characteristics of multi-scale hierarchical structure and single-scale triangular grid structure under different impact speeds
FIG. 4 shows stress-strain curves of a multi-scale triangular hierarchical structure and a single-scale triangular grating structure at low speed (5m/s) and high speed (100 m/s). It can be seen from the figure that under low-speed and high-speed impact, the multi-scale triangular hierarchical structure has better energy absorption characteristic, and in the impact process, the stress value fluctuation is smoother, so that the protection of a protected structure is more facilitated.
The invention has good compression resistance and energy absorption. Compared with the traditional single-scale triangular grid structure, the multi-scale triangular hierarchical structure can obviously improve the energy absorption characteristic under the premise of the same quality, the energy absorption characteristic of the structure is improved by nearly three times in quasi-static compression, and the energy absorption characteristic of the multi-scale triangular hierarchical structure is slightly higher than that of the single-scale triangular grid structure in dynamic impact. Under dynamic impact working conditions, stress-strain curves of the multi-scale triangular hierarchical structure are more gentle, fluctuation is smaller, and the multi-scale triangular hierarchical structure is more uniform in deformation under the impact working conditions, so that transient impact of the protective structure on the protected structure is reduced, and the protective structure can be more effective.
According to the effect description, the multi-scale triangular hierarchical structure provided by the invention has excellent energy absorption characteristic, and can be applied to structures and equipment which are easy to suffer from explosion impact working conditions, such as armored vehicle chassis protection, ship board side lightning protection cabin design, explosion-proof tank lining, automobile protection structures, explosion-proof workers, buildings and the like.
The multi-scale triangular hierarchical structure provided by the invention has the characteristic of highly adjustable and controllable materials and geometric dimensions, can be adjusted according to actual application working conditions, and has good engineering application value.
The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A multi-scale, hierarchical, triangular impact resistant system, comprising:
a number of hierarchical periodic units;
the hierarchical periodic unit comprises a plurality of macroscale triangles, mesoscale triangles and microscale triangles with different geometric dimensions;
the macroscale triangles are periodically arranged, the mesoscale triangles are nested in the macroscale triangles, and the three microscale triangles are embedded outside the mesoscale triangles.
2. The multi-scale, hierarchical triangular impact-resistant system of claim 1, wherein the side length of the meso-scale triangle is half of the macro-scale triangle and the side length of the micro-scale triangle is half of the meso-scale triangle.
3. The multi-scale, hierarchical triangular impact-resistant system of claim 1, wherein the macro-scale triangles, meso-scale triangles, and micro-scale triangles contact each other without gaps during assembly.
4. The multi-scale, hierarchical triangular impact-resistant system according to claim 1, wherein a single said hierarchical periodic unit is obtained by translation and rotation of a macro-scale triangle.
5. The multi-scale hierarchical triangular impact-resistant system of claim 1, consisting of m x n hierarchical periodic units, where m is the number of transverse cells, n is the number of longitudinal layers, m is greater than or equal to 1, and n is greater than or equal to 1.
6. The multi-scale, hierarchical triangular impact resistance system of claim 1, wherein the micro-scale triangular outer ends are in contact with the macro-scale triangular inner walls.
7. The multi-scale, hierarchical triangular impact-resistant system of claim 1, wherein four multi-scale, hierarchical triangles are symmetrically arranged in a single hierarchical periodic unit.
8. The multi-scale, hierarchical triangular impact-resistant system of claim 1, wherein a single hierarchical periodic unit fills a macro-scale triangle with one meso-scale triangle and three micro-scale triangles.
9. A sandwich beam provided with a multi-scale, hierarchical triangular impact-resistant system according to any one of claims 1 to 8.
10. A sandwich panel provided with a multi-scale, hierarchical triangular impact-resistant system according to any one of claims 1 to 8.
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| CN117367808A (en) * | 2023-04-24 | 2024-01-09 | 中国人民解放军国防科技大学 | Welding-free self-similar protective structure for engine static test |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117367808A (en) * | 2023-04-24 | 2024-01-09 | 中国人民解放军国防科技大学 | Welding-free self-similar protective structure for engine static test |
| CN117367808B (en) * | 2023-04-24 | 2024-04-30 | 中国人民解放军国防科技大学 | Welding-free self-similar protective structure for engine static test |
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