含半圆形埋藏裂纹金属构件脉冲放电时应力场分析

对纯弯曲载荷作用下含半圆形埋藏裂纹的金属构件在脉冲放电瞬间的应力场进行了理论分析，运用热传导、非定常热应力及汉克尔变换等理论，推导出应力场分布理论公式。由公式可知,在脉冲放电瞬间，电磁热在裂纹尖端形成热压应力场，压应力场能有效地抑制裂纹的扩展。对脉冲放电前后的含半圆形埋藏裂纹构件进行了超声波检测实验,利用超声波对比法测得脉冲放电后构件裂尖应力值,该应力值有所增大。

Analysis of Stress Field at Time of Pulse Discharge in Metal Structurewith Semicircle Embedding Crack

Stress field at the time of pulse discharge in metal structure with a semicircle embedding crack under pure bending was  analyzed theoretically. The stress field distribution of the crack tip was derived by using heat conduction, the unsteady thermal stress and the Hankel transform theory. The theoretical analysis results show that the thermal compressive stress field which can inhibit the crack propagation effectively is formed around the crack tip. The thermal stress of components was detected before and after the pulse discharge using  ultrasonic contrast method. The thermal stress around the crack tip increases after the pulse discharge.