考虑Lode参数影响的Q235B钢循环微孔扩展模型

Cyclic void growth model of Q235B steel considering influence of Lode parameter

基于微观机制的循环微孔扩展模型可以用来预测钢材的超低周疲劳断裂,但是该模型主要考虑应力三轴度的影响,而忽略了Lode参数对钢材超低周疲劳断裂的影响。在循环微孔扩展模型(CVGM模型)的基础上,提出了考虑Lode参数影响的断裂模型(LCVGM模型)。采用Q235B钢材设计并加工了一批可表征不同应力状态的试件,开展了试件的单调拉伸和超低周循环加载试验。根据试验和有限元计算结果,得到了Q235B钢材的LCVGM模型参数。最后,利用考虑Lode参数影响的Q235B钢材的LCVGM模型预测了平面应变试件的超低周疲劳断裂过程,预测结果与试验结果的吻合很好,并且比CVGM模型的预测精度更高。

The cyclic void growth model based on the micro-mechanism can be used to predict the ultra-low cycle fatigue fracture of steel, but the model mainly considers the influence of stress triaxiality, and ignores the influence of Lode parameters on the ultra-low cycle fatigue fracture of steel. A fracture model considering the influence of Lode parameters was proposed based on the cyclic void growth model(CVGM model), which was namely as LCVGM model. A batch of test pieces that could characterize different stress states were designed and processed using Q235 B steel, and monotonic tensile and ultra-low cycle loading tests of the test pieces were carried out. According to the test and finite element calculation results, the LCVGM model parameters of Q235 B steel were obtained. Finally, the LCVGM model of Q235 B steel considering the influence of Lode parameters was used to predict the ultra-low cycle fatigue fracture process of the plane strain specimen. The prediction results were in good agreement with the test results, and the prediction accuracy was higher than that of the CVGM model.