含圆形埋藏裂纹金属构件电磁热止裂时应变能密度分析

对带有圆形埋藏裂纹金属构件在脉冲放电瞬间的应变能密度进行了理论分析。在求解过程中，以张开型裂纹为例，应用了热传导、非定常热应力及汉克尔变换等理论知识，得出了含埋藏圆片裂纹在脉冲放电瞬间的温度场理论公式、热应力场公式和应变能密度公式。由热应力场公式和应变能密度公式可知，放电瞬间电磁热在裂纹尖端形成热压应力场，热压应力对金属构件做负功，减小了拉应力对构件的破坏程度，放电后构件的应变能密度降低了。以Cr12MoV模具钢中埋藏圆裂纹止裂为例，具体计算了脉冲放电前后不同拉应力作用下的应变能密度变化情况，为空间裂纹电磁热止裂技术的实际应用提供了理论基础。

ANALYSIS ON STRAIN ENERGY DENSITY DURING CRACK ARRESTING USING ELECTROMAGNETIC HEATING IN METAL COMPONENT WITH CIRCULAR EMBEDDING CRACK

The strain energy density is studied theoretically during pulse current discharging in a metal component with a circular embedding crack.The theoretical formula for temperature field,the thermal stress and strain energy densities are obtained for an open type crack based on a heat transfer formula,theories of unsteady thermal stress and the Hankel transform formula during pulse current discharging in a metal component with a disc-shaped sheet embedding crack.The formula obtained shows that a thermal stress field is formed at the crack tip during pulse current discharging,the thermal stress do negative work which reduces the component damage under tensile stress and the strain energy density is reduced after pulse discharging.Also,the difference of strain energy before and after pulse discharge is studied for Cr12MoV die steel with a disc-shaped sheet embedding crack under different tensile stresses.The study provides a theoretic basis for the applications of crack arresting with electromagnetic heating.