冲击载荷下分支交错层状仿生复合材料动态断裂行为的实验研究和数值模拟

Experimental Study and Numerical Simulation of Dynamic Fracture Behavior of Branch Staggered Laminated Biomimetic Composites under Impact Loading

通过三点弯动态冲击实验和数值模拟方法,研究了分支交错层状仿生复合材料的动态断裂韧性。首先设计并制备了分支交错层状仿贝壳复合材料试样,即将一种脆性刚性材料和一种橡胶类材料分别作为复合材料的硬质层和软胶层;随后采用改进的分离式Hopkinson压杆装置进行了三点弯冲击实验;接着讨论了初始冲击速度、硬质材料长宽比、软质材料层厚度对复合材料试样动态断裂行为的影响;最后采用ABAQUS有限元数值模拟,研究了不同宽度和不同冲击方向对复合材料试样动态断裂韧性和裂纹扩展的影响。结果表明:随着冲击速度和硬质材料长宽比增加、软胶层厚度减小,裂纹越倾向于沿直线扩展,反之,裂纹越倾向于绕过硬质材料沿着软胶层呈折线扩展;试样的峰值动载荷和起裂时间也随之增大。有限元模拟结果表明:随着结构总宽度的增大,试样断裂韧性增加,裂纹倾向于绕过硬质材料沿着软胶层扩展;采用实验设计的冲击方向时,试样的断裂韧性高于其他方向。

The dynamic fracture toughness of branch staggered laminated biomimetic composites was studied by three-point bending dynamic impact experiments and numerical simulations.Firstly,the branched staggered laminated shell-like composite specimens were designed and prepared.A brittle rigid material and a rubber material were selected as the hard and soft phases of the composite,respectively.Next,the threepoint bending impact experiments were carried out by the improved split Hopkinson bar device,then the effects of initial impact velocity,hard material aspect ratio and soft material layer thickness on the dynamic fracture behavior of composite specimens were discussed.Finally,the effects of different widths and impact directions on the dynamic fracture toughness and crack propagation of composite specimens were studied by numerical simulation using finite element software ABAQUS.The experimental results show that with the increase of the impact velocity and the ratio of length to width of hard material,the thickness of the soft rubber layer decreases,the crack tends to propagate along a straight line,and vice versa.With the increase of the impact velocity,the peak dynamic load and initiation time of the specimen also increase.The finite element simulation results show that the fracture toughness of the specimen increases with the increase of the width,and the crack tends to bypass the hard material and propagate along the soft rubber layer;using the impact direction designed by the experiment,the fracture toughness of the sample is higher than that in other directions.