V型缺口冲击试样缺口根部三维弹性应力场分析

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

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型缺口冲击试样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/a的函数 ,当 B/a值较小时 ,随着B/a值的增加 ,界面缺口根部应力集中系数 Kt增加 ,在 B/a=0 .5附近达到最大值 ;之后 ,界面缺口根部应力集中系数 Kt随着 B/a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/a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/a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。

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.