Application of the Incremental Hole-Drilling Method on Thick Film Systems—An Approximate Evaluation Approach

A new evaluation procedure is presented regarding the application of the incremental hole-drilling technique to determine in-depth residual stress distribution in thick film systems. Using a direct correction of the measured strain relaxation, obtained after each incremental depth, to take into account the effect of the layered structure of the material, the standard evaluation procedures can still be used without any further modification. For example, the standardized integral method uses specific geometrical calibration constants, which are only valid for isotropic, homogeneous and linear elastic materials. Using artificial neural networks, for the prediction of the correction function to be applied to the measured strain relaxation in thick layered systems, the standard integral method can still be applied. The validation of the proposed approach is shown using finite element (FE-) simulations. In addition, the new evaluation strategy is applied for residual stress determination in a thermally sprayed Aluminum oxide coating on a steel (S690QL) substrate.