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

By the FEM numerical simulation, the stressstrain 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.