Abstract: The method of characteristics was used to analyze the stress wave propagations in the brittle materials. The random nucleation and the growth of the cracks in the brittle materials were described by using the cohesive fracture model. A practical simulation tool, ExpRing was developed for simulating the fracture and fragmentation in an expanding brittle ring. The ExpRing code was briefly explained. By using this code, the fragmentations of the rings with different intrinsic defects were simulated. The calculation results show: (1) within a certain strainrate range, the equally-spaced point defects will control the final fracture sites and the fragment sizes and it can induce a defect-controlled-fragmentation (DCF) platform in the relation curve between the fragment size and the strain rate; (2) the spacing and the magnitude of the defects will alter the width and the location of the DCF platform; (3) the strength of the brittle materials with initial defects exhibit an apparent strain-rate effect. And further study displays that the materials with sinuouslydistributed defects exhibit similar fragmentation behaviors to the materials with equally-spaced point defects.