EXPERIMENTAL STUDY ON VELOCITY DESTRIBUTION OF FRAGMENTS PRODUCED BY CATASTROPHIC IMPACTS

采用单级火药枪和双级光气枪分别对球形和立方叶蜡石进行了冲击破碎实验。获得了17个实验的高速运动影像。得到的结果是：1。球形目标碎片的大小分布分为两种，而不是三种。Takagi等人（1984）指出的三种机制可能是靶形状的影响。对最大破片质量的标度分析表明，冲击波随距离的衰减比-2晚于-3.3。没有观察到碎片速度与碎片质量之间明显的负相关关系，如Nakamura等人（1991）的研究结果。碎片速度与从冲击点到碎片初始位置的距离的-0.6次方相关。破片速度与破片初始位置的冲击波压力有关。平均破片速度与无因次冲击应力相关。

Impact fragmentation experiments of spherical and cubic pyrophyllites were performed using a single-stage powder gun and a double-stage light gas gun. High speed motion movies of 17 experiments were obtained. The obtained results are :1. Size distribution of fragments from spherical targets are divided into two regimes, not three. The three regimes indicated by Takagi et al. (1984) may be an effect of target shape.2. The scaling on the largest fragment mass shows that the decay ratio of shock wave with distance is -2 later than -3.3. The clear negative dependence of fragment velocity on fragment mass, such as that by Nakamura et al. (1991), was not observed.4. Fragment velocities correlate with the -0.6-th power of the distance from the shock point to the initial position of fragment.5. Fragment velocities correlate with the shock wave pressure at the initial position of fragments.6. The average fragment velocities correlate with the nondimensional impact stress.