裂纹缺陷对结构动态断裂行为的影响效应研究

采用落锤冲击加载的方式,结合焦散线方法,研究了裂纹缺陷对有机玻璃(PMMA)板条试件动态断裂行为的影响效应。通过对试件断裂破坏过程的观测和分析,得到了裂纹尖端动态应力强度因子和裂纹扩展速度的变化规律。结果表明,该试验加载条件下,结构的断裂韧度约为1.00 MN/m~(3/2);裂纹缺陷的存在对运动裂纹扩展的总体效果是抑制的,含裂纹缺陷试件中运动裂纹的扩展时间约为不含裂纹缺陷的1.5倍;随着裂纹缺陷长度的增加,运动裂纹在缺陷处再次起裂更为困难。

Research on Structural Dynamic Fracture Behavior with Crack Defect

Using the loading method of drop-hammer impact, combining with caustics method, effects of crack defect in the polymethyl methacrylate (PMMA) specimens on structural dynamic fracture behavior are researched. Through observation and analysis on dynamic fractural processes of specimens, change rules of dynamic stress intensity factor and velocity at crack tip are obtained. Results show that the fracture toughness of the PMMA structure is about 1.00 MN/m3/2 in the loading condition. Crack defect has negative effects on crack propagation as a whole, and propagation time of running crack in the specimen with crack defect is 1.5 times as long as that without crack defect. With increasing of crack defect length, it is harder for running crack to initiate for a second time at the crack defect.