含裂纹三点弯曲梁起始扩展的动态分析

Dynamic Analysis on Initial and Propagation of Three Point Bending Beam with Crack

本文利用高速摄影捕捉含裂纹三点弯曲梁在冲击下裂纹扩展过程，借助动态焦散线对裂纹尖端初始曲线范围内的应力第二不变量分布进行了试验研究，并通过Ｄｅｔ．－准则对动载下裂纹起始扩展的条件和方向进行了分析。结果表明：裂纹扩展的实际方向与理论预测相一致；Ｄｅｔ．

A high speed framing camera is used to seize the crack transient process of three point bending beam with crack under impact load. The second stress invariants within initial curve of the crack tip are studied by dynamic caustics. According to the Det. criterion of fracture, the direction and the critical condition of the crack initiation are analysed. It stated clearly that the directions of crack propagating are identical both in reality and in theory, uniting Det. Criterion with caustics has wide ranging use in the study of dynamic fracture mechanics.