V型缺口冲击试样缺口根部三维弹性应力场分析

通过三维有限元计算来研究V型缺口冲击试样缺口根部三维弹性应力场，分析了不同厚度含有V型缺口冲击度校缺口根部的应力集中系数、离面约束系数以及相对离面应力σz/σz0。结果表明：中面缺口根部附近的应力集中系数是B／α的函数，当B／α值较小时，随着B／α值的增加，界面缺口根部应力集中系数Kt增加，在B/α＝0.5附近达到最大值；一，界面缺口根部应力集中系数Kt随着B/α值的增加反而减小，沿厚度方向界面缺口根部附近应力集中系数Kt均小于相应中面的应力集中系数，缺口根部的应力集中系数Kt是z/B和B／α的函数。沿厚度方向界面缺口根部附近的离面约束系数Tz也是z/B和B／α的函数，随着厚度的增加离面约束系数Tz增大，离中面越近离面约束系数Tz越大。根据上述结果分析了高强度管线钢在冲击试验中断口产生分层裂纹的原因。

Three-Dimensional Elastic Stress Fields Near V Notches of the Impact Test Sample

The problems considered here are the V notches of the impact test sample subjected to a 3-point bending load. Detailed three-dimensional finite element computations are performed to investigate the stress field near the notches. The effects of B/a and z/B on stress concentration factor (SCF) and out-of-plane stress constraint factor are analyzed. The stress concentration factor (SCF) at notch root in the middle plane is the function of B/a . The thickness of test samples has obvious effects on the stress concentration factor K t . The stress concentration factors K t from the middle plane to the free plane are less than the ones ( K t ) m-p in the middle plane at notch root, and they are functions of B/a and z/B . The out-of-plane stress constraint factors are functions of B/a and z/B . The T z increases with increasing B and closing to the middle plane. The reasons for the fracture separation are analyzed according to the results of three-dimensional finite element computations of the impact test sample subjected to a 3-point bending load.