Spherical Indentation, Part II: Experimental Validation for Measuring Equibiaxial Residual Stresses

Abstract

Abstract It is occasionally important or even inevitable to measure residual stresses without harming engineering components. Spherical indentation can be categorized as a nondestructive method to measure residual stresses, as it causes very little damage to the surface of the sample. Furthermore, it is cheap and quick. Spherical indentation has gained the interest of a number of researchers in recent years. Although, this technique has been used in the literature to measure residual stresses, it has mostly been employed to determine material characteristics. In the current study, the application of the spherical indentation to measure residual stresses was examined and verified experimentally. The instrumented indentation tests resulted in load-displacement curves for different materials with a variety of ranges of equibiaxial stresses, which were then used to train an artificial neural network (ANN). The stress measurements were carried out for both residual and applied stresses. A quenched sample and a cross-shaped bending sample were considered as a source of residual stresses and in-plane applied stresses, respectively. An important benefit of this method was that it could be used with no requirement for a reference stress-free sample. The results of stress measurements illustrated a reasonable success.