Abstract: 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-dependence, 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-independent 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 rate-dependent 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.

Key words: solid mechanics, cohesive element, dynamic fracture, ABAQUS, PMMA, rate-dependent cohesive law