残余应力对P91钢断裂行为的影响

Effect of residual stress on the fracture behavior of P91 steel

通过面外局部压缩法在CT试样中引入残余应力后进行了准静态断裂拉伸测试,以研究残余应力对试样断裂行为的影响机理;同时利用有限元方法建立了LOPC法引入的残余应力对不同裂纹深度试样断裂行为影响的评估模型,通过CT试样准静态断裂拉伸试验验证了模型的准确性。从数值模拟与试验结果中可以看出,残余拉应力降低了断裂时的载荷与位移,残余压应力的作用效果相反;随着初始裂纹深度的增加,残余应力对断裂载荷的作用效果并未产生明显变化,而对断裂位移的作用效果明显增强;两种类型的残余应力均增大了启裂J积分,但残余压应力对应的J积分大于残余拉应力对应的J积分;随着裂纹深度的增加,J积分逐渐增大。

After residual stress was introduced into CT samples by the local out-of-plane compression(LOPC)method,the quasistatic fracture tensile test was carried out to study the influencing mechanism of residual stress on the fracture behavior of CT samples.At the same time,the finite element method was used to establish the evaluation model for the influence of residual stress introduced by LOPC method on the fracture behavior of specimens with different crack depths.The accuracy of the model was verified by quasi-static fracture tensile test of CT specimens.It can be seen from the numerical simulation and test results that residual tensile stress reduces the load and displacement during fracture,whereas the effect of residual compressive stress is opposite;As the initial crack depth increases,there is no significant change in the effect of residual stress on the fracture load,but the effect on the fracture displacement is significantly enhanced;Both types of residual stresses increase the initiation J-integral,but the J-integral corresponding to residual compressive stress is greater than that corresponding to residual tensile stress;As the crack depth increases,the J-integral gradually increases.