Three-dimensional finite element analyses of microvoid growth in X80 pipeline steel

摘要

Three-dimensional cell models were developed to study the damage by void growth in X80 pipeline steel.Periodical void arrays are investigated by analyzing representative unit cells.The isotropic behavior of the matrix material is modeled using v.Mises plasticity.The cell models are analyzed by the large strain finite element method under monotonic loading while keeping the stress triaxiality constant.The analysis results imply that the representative unit cells with void shape deviated from sphere responses a lower flow stress,meanwhile shows mesoscopic mechanics anisotropy,in spite of the nearly void volume percentage.At the stress triaxiality higher than 2,the interface stress of MA/Matrix in the cells isn’t higher to nucleate micro voids by decohesion of the particle-matrix interface.At the stress triaxiality lower than 1,the condition of nucleating micro voids is satisfied.%本文开发了三维体胞模型研究X80管线钢中因孔洞扩展造成的损伤.采用代表性体胞模型对周期性孔洞点阵进行了分析.基体材料采用v.Mises塑性流动理论和各项同性假设进行建模.在保持恒定的应力三轴度单调加载条件下,采用大变形有限单元方法对体胞模型进行了分析.结果显示在体积率相近时,孔洞形态越偏离球形,造成的各向异性越明显,体胞的抵抗变形能力也越低.在应力三轴度大于等于2时,体胞中MA岛/基体界面应力达不到使之脱离的程度,而在应力三轴度降低至1时具有使MA岛/基体界面分离的充分条件.