Incremental Hole Drilling for Residual Stress Analysis of Thin Walled Components with Regard to Plasticity Effects

The incremental hole-drilling method is widely used in residual stress depth distribution analysis. However, two specific difficulties with the generalization of the incremental method exist, including the consideration of the sample thickness and residual stress states close to the local material’s yield strength. The stress concentration effect of the hole can lead to plastic deformation in the vicinity of the hole, which results in an overestimation of residual stresses. Typically, the effect of the component’s thickness and the plasticity effects are analyzed separately and correction approaches are proposed. In the current paper, we analyze the combined effects of plasticity and thickness on residual stress analysis using the incremental hole-drilling method. A systematic study was performed on steel samples with (i) isotropic and (ii) anisotropic elastic and elasto-plastic material behavior with varying thicknesses ranging between 1 mm and 4 mm. Electronic speckle pattern interferometry (ESPI) hole-drilling experiments were conducted on beam samples loaded using a 4-point bending fixture. Finite element simulations were conducted to gain insight into the effects of incremental hole-drilling. The results indicate that reducing the component’s thickness increases the plastic deformation in the vicinity of the hole and results in significant stress deviations. Thin components bend during hole-drilling as a result of the loss of stiffness, which amplifies the plasticity effect.