脆性聚甲基丙烯酸甲酯板动态裂纹传播有限元模拟

Finite Element Simulation of Dynamic Crack Propagation in Brittle PMMA Plates

开发了包含内聚力单元模型的用户材料子程序,嵌入商用有限元软件ABAQUS,采用显式求解模块模拟预加载的脆性聚甲基丙烯酸甲酯(PMMA)板中动态裂纹传播行为。在模拟过程中采用了刚性线性衰减的内聚力准则,分别考虑了率无关和率相关两种情况。模拟结果表明:在相同的预加载荷下,采用率无关内聚力模型计算的裂纹传播速度在绝大部分情况下大于实验测试值,只在高速时二者基本一致;采用率相关内聚力模型,所得到的模拟结果与实验结果基本吻合,这说明率相关内聚力模型可以反映快速裂纹传播时的裂纹尖端复杂率过程。

A user-defined material mechanical behavior subroutine （VUMAT） is developed to incorporate it into ABAQUS for numerically simulating the propagation of dynamic cracks in the preloaded brittle PMMA plates. The initial-rigid, linear decay, and irreversible cohesive rule, rate-independence or rate-de- pendence, are adopted in the subroutine. The simulation results are compared with the experimental observations. It is shown that, in most cases, the crack propagation velocities simulated using a rate-inde- pendent cohesive law are greater than the experimental values under the prescribed preloading, except in the high crack velocity regime, when the numerical results are similar to the experimental data. A ratedependent cohesive law is proposed. The numerical simulation results obtained by the rate-dependent cohesive law agree well with the experimental data in all test velocity range. It also confirmed that the utilization of a rate-dependent cohesive law is necessary for the simulations of brittle crack propagation, because it better describes the complex fracture process occurring in the tip zone of the fast propagating cracks.