压痕应变法中压痕周围的应力应变分布规律

Stress-strain around an indentation in measuring residual stress by indentation-strain method

利用有限元数值模拟方法,对压痕应变法测量残余应力中球形压痕周围不同受力方向的应力应变分布规律进行了分析。结果表明,在单向应力场中,与主方向成62°的分界线两侧,应变增量与外加应变之间的关系曲线特征不同,并随夹角而变化。在特定范围内,应变增量与拉应力间的关系夹角小于45°时近似为线性关系,夹角大于45°为二次曲线关系。而应变增量与压应力间的关系在分界线两侧可用线性函数和二次函数分别描述。在双向应力场中,如果把乘以泊松比的垂直方向应力值叠加到主应力上,则得到的规律与单向应力场的相同。

By the FEM numerical simulation, the stress-strain distributions in different directions around an indentation were analyzed as measuring residual stress with indentation-strain method. It indicated that, in axial stress field, the relation of strain increment and loading strain varies with the angle with principle stress direction and shows different characteristic in both side of 62° boundary. In given range, the relation of strain increment and tensile stress is approximately linear when the angle is less than 45°, whereas the relation changes to conic as the angle great than 45°. As to the relation of strain increment and compressive stress, it may be respectively described with linear and conic at both side of 62° boundary. In biaxial stress filed, the similar relations can be obtained if the stress in vertical to principle stress multiplication by Poisson's ratio was superimposed to principle stress.