非稳态蠕变裂纹C(t)积分和J(t)积分的有限元分析

Analysis of C(t ) and J(t ) Integrals for Non-Steady Creep Crack by Finite Element Method

利用有限元法分析恒定载荷和非恒定载荷作用下的非稳态蠕变裂纹问题。数值结果显示，虽然J积分和C积分在非稳态蠕变条件下均是路径相关的，但它们与路径相关的强弱程度大不一样。J积分在短时蠕变和长时间蠕变条件下是路往无关的，而在过渡蠕变时期，其与路径也只是弱相关。C积分在长时间蠕变条件下是路径无关的，而在短时蠕变条件下，其与路径呈现一种强相关。根据J积分和C积分的路径相关程度，提出了确定裂纹尖端J积分和C积分的方法，并给出恒定载荷、线性载荷和指数载荷作用下的有关分析结果。

This paper analyzed the non-steady creep cracks subjected to the constant and variable loadings. The numerical results show that although both the J and C integrals are path-dependent under non -- steady creep condition, the strength of the path-dependence is quite different. The J integral is path-independent for the short time creep and long one, while in the transition period, it is weakly path-dependent. The C integral is also path-independent for the long time creep, while for the short time creep, its value depend on the integral path strongly. According to the difference of the path-dependence of J and C integrals, the approaches to determine the J and C integrals at the crack tip were proposed. The numerical results for the J and C integrals at the crack tip were given out for several kinds of the time -- dependent loadings.