Abstract：The finite element commercial code LS-DANA is used to study the deformation process of Brazilian disk with pre-existing crack under impact loading. According to the virtual crack closure technique(VCCT)，the calculation methods for energy release rate and stress intensity factor are developed for impact loading. The variations of energy release rate and stress intensity factor with time are obtained. The effects of impact velocities on energy release rate and stress intensity factor are also analyzed. A comparison between fracture parameters for model I and model II shows that the parameters of model II are much smaller than those of model I. The Brazilian disk with a pre-existing center crack could be regarded as model I crack problem.
