爆炸荷载作用下动态裂纹扩展试验研究

应用爆炸加载的透射式动焦散线测试系统,分析了爆炸裂纹的扩展规律。用有机玻璃试样直观、形象地研究了爆炸加载和卸载过程破裂时的应力(应变)场、成核区(阴影区)的动态特征变化,分析了爆炸裂纹发展、止裂及破坏模式、动态应力强度因子的变化规律,精确得到了材料在爆炸荷载作用下的止裂韧性值。确认了早期爆炸裂纹是在爆轰压力作用下产生快速扩展裂纹,裂纹尖端形成应力集中和积聚较大的应变能,爆炸裂纹中后期的焦散形式与一般动态焦散接近相同。初步提出了爆炸裂纹的大部分扩展是应变能释放的动态卸载破坏的结论。

EXPERIMENTAL STUDY ON PROPAGATION OF DYNAMIC CRACKS UNDER BLASTING LOADING

It is an effective new method to make further analysis of crack propagation for blasting fracture with dynamic caustics. Using a plexiglass sample and by means of shadow optical method of caustics,the different features of dynamic variation in stress (or strain) field,plastic area,and nucleation zone (shadow area) during loading and unloading are studied. The propagation,termination,and mode of blasting cracks are presented. An accurate termination tenacity value is achieved;and preliminary cracks are extended rapidly under blasting stress wave. A full of strain energy accumulates in the top of blasting crack;and the mode of caustics of latter crack is close to the common dynamic caustics. The majority of blasting cracks is a process of unloading fracture.