Introduction Honeycomb structures with negative Poisson's ratio effect and functional gradient variation have unique mechanical properties and good energy absorption capacity, which can effectively reduce the initial peak stress (PCF) caused by impact and improve the energy absorption rate of structures, and have been widely used in the field of impact protection. Therefore, it is of great significance to study the energy absorption characteristics of honeycomb structures. However, most of the existing researches focus on the gradient design of traditional honeycomb structures, and the gradient design of new structures needs to be further studied. Compared with the traditional honeycomb, the sinusoidal negative Poisson's ratio honeycomb structure has better energy absorption capacity, compressive strength and bending strength, and also has excellent performance in sound insulation and shock absorption. Therefore, this paper takes the sinusoidal negative Poisson's ratio honeycomb structure as the research object. Materials and Methods In order to further improve the dynamic response of honeycomb structures under in-plane impact, numerical simulation, experimental verification and multi-objective optimization design are adopted in this paper. Firstly, the sine curve is introduced into the negative Poisson's ratio honeycomb structure. The gradient layer number of the cellular structure was fixed, and the sinusoidal negative Poisson ratio cellular structure was established with the amplitude, period and cell wall thickness of the sinusoidal curve as the gradient. Under multivelocit conditions, the sinusoidal negative Poisson's ratio cell structures of the non-gradient (NG-CM), amplitude gradient (AG-CM), periodic gradient (PG-CM), and wall thickness gradient (WTG-CM) was simulated and analyzed for comparison. Secondly, according to the theory of multicellular materials, a formula for calculating the relative density of honeycomb structures with negative Poisson's ratio of sinusoidal curves is established. The relationship between cell parameters, elastic modulus and Poisson's ratio is derived by taking a single cell with sinusoidal negative Poisson's ratio as the analysis target. Thirdly, the NG-CM specimen was made by metal 3D printer and the quasi-static compression test was carried out. The test results were compared with the simulation results, and the reliability of the finite element simulation results was verified. Forthly, the number of gradient layers of the honeycomb structure is changed. AG-CM, PG-CM and WTG-CM with two gradient layers, four gradient layers and six gradient layers were established respectively, and their buffering energy absorption characteristics were simulated by ABAQUS under multi-velocity conditions. Finally, NSGA-II algorithm based on random forest is used to optimize the gradient sinusoidal honeycomb structure. The amplitude gradient value and wall thickness gradient value of the honeycomb structure are taken as design variables, and the PCF and SEA generated by the honeycomb structure in the face of impact are taken as optimization targets. In order to verify the accuracy of the optimization results, a simulation model was established and the impact simulation was carried out through the gradient values corresponding to the two groups of optimization values. The error between the optimization results and the simulation results was within 5%, which met the requirements of the optimization design. The innovation of this paper is that the AG-CM, PG-CM, WTG-CM honeycomb structure based on sine curve is proposed, and then the negative Poisson's ratio honeycomb structure is proposed with layer gradient. The research in this paper revealed the relationship between gradient setting, impact mode, gradient layer number, PCF and SEA of sinusoidal gradient negative Poisson’s ratio honeycomb structure, which provided a prerequisite for quantitative analysis when considering the specific application situation. It will provide a new design idea for the multi-objective optimization of the impact dynamic performance of honeycomb structures. Conclusion The results show that WTG-CM has the lowest PCF and the highest specific absorption energy (SEA) under low velocity (7 m/s) impact. In the face of positive gradient impact (PGI) at medium and high speed (35 m/s, 70 m/s), the buffering and energy absorption characteristics of AG-CM are better than other honeycomb structures. WTG-CM has the lowest PCF and the highest SEA when facing the inverse gradient shock (NGI). The smaller the number of gradient layers, the more obvious the densification is. The honeycomb structure produces plastic deformation in regions with low relative density. The difference of compaction strain between gradient layers decreases with the increase of the number of gradient layers. According to the actual demand, two groups of optimization values are selected from a series of optimization solutions. The PCF of optimization value 1 is reduced by 64.9% compared with NG-CM, and the SEA of optimization value 2 is increased by 22.2% compared with NG-CM, showing obvious optimization effect.

In-Plane Impact Performance of a Gradient Sinusoidal Negative Poisson-Ratio Honeycomb Structure

期刊论文
发表日期：

2025年2月18日

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Yuhua Song,
Sen Jiang,
Baoqing Zhang,
Hui Liu,
Fengde Liu

摘要

Introduction

Honeycomb structures with negative Poisson's ratio effect and functional gradient variation have unique mechanical properties and good energy absorption capacity, which can effectively reduce the initial peak stress (PCF) caused by impact and improve the energy absorption rate of structures, and have been widely used in the field of impact protection. Therefore, it is of great significance to study the energy absorption characteristics of honeycomb structures. However, most of the existing researches focus on the gradient design of traditional honeycomb structures, and the gradient design of new structures needs to be further studied. Compared with the traditional honeycomb, the sinusoidal negative Poisson's ratio honeycomb structure has better energy absorption capacity, compressive strength and bending strength, and also has excellent performance in sound insulation and shock absorption. Therefore, this paper takes the sinusoidal negative Poisson's ratio honeycomb structure as the research object.

Materials and Methods

In order to further improve the dynamic response of honeycomb structures under in-plane impact, numerical simulation, experimental verification and multi-objective optimization design are adopted in this paper. Firstly, the sine curve is introduced into the negative Poisson's ratio honeycomb structure. The gradient layer number of the cellular structure was fixed, and the sinusoidal negative Poisson ratio cellular structure was established with the amplitude, period and cell wall thickness of the sinusoidal curve as the gradient. Under multivelocit conditions, the sinusoidal negative Poisson's ratio cell structures of the non-gradient (NG-CM), amplitude gradient (AG-CM), periodic gradient (PG-CM), and wall thickness gradient (WTG-CM) was simulated and analyzed for comparison. Secondly, according to the theory of multicellular materials, a formula for calculating the relative density of honeycomb structures with negative Poisson's ratio of sinusoidal curves is established. The relationship between cell parameters, elastic modulus and Poisson's ratio is derived by taking a single cell with sinusoidal negative Poisson's ratio as the analysis target. Thirdly, the NG-CM specimen was made by metal 3D printer and the quasi-static compression test was carried out. The test results were compared with the simulation results, and the reliability of the finite element simulation results was verified. Forthly, the number of gradient layers of the honeycomb structure is changed. AG-CM, PG-CM and WTG-CM with two gradient layers, four gradient layers and six gradient layers were established respectively, and their buffering energy absorption characteristics were simulated by ABAQUS under multi-velocity conditions. Finally, NSGA-II algorithm based on random forest is used to optimize the gradient sinusoidal honeycomb structure. The amplitude gradient value and wall thickness gradient value of the honeycomb structure are taken as design variables, and the PCF and SEA generated by the honeycomb structure in the face of impact are taken as optimization targets. In order to verify the accuracy of the optimization results, a simulation model was established and the impact simulation was carried out through the gradient values corresponding to the two groups of optimization values. The error between the optimization results and the simulation results was within 5%, which met the requirements of the optimization design. The innovation of this paper is that the AG-CM, PG-CM, WTG-CM honeycomb structure based on sine curve is proposed, and then the negative Poisson's ratio honeycomb structure is proposed with layer gradient. The research in this paper revealed the relationship between gradient setting, impact mode, gradient layer number, PCF and SEA of sinusoidal gradient negative Poisson’s ratio honeycomb structure, which provided a prerequisite for quantitative analysis when considering the specific application situation. It will provide a new design idea for the multi-objective optimization of the impact dynamic performance of honeycomb structures.

Conclusion

The results show that WTG-CM has the lowest PCF and the highest specific absorption energy (SEA) under low velocity (7 m/s) impact. In the face of positive gradient impact (PGI) at medium and high speed (35 m/s, 70 m/s), the buffering and energy absorption characteristics of AG-CM are better than other honeycomb structures. WTG-CM has the lowest PCF and the highest SEA when facing the inverse gradient shock (NGI). The smaller the number of gradient layers, the more obvious the densification is. The honeycomb structure produces plastic deformation in regions with low relative density. The difference of compaction strain between gradient layers decreases with the increase of the number of gradient layers. According to the actual demand, two groups of optimization values are selected from a series of optimization solutions. The PCF of optimization value 1 is reduced by 64.9% compared with NG-CM, and the SEA of optimization value 2 is increased by 22.2% compared with NG-CM, showing obvious optimization effect.