Through-Thickness Residual Stress Variations after Double-sided Dimpling and Drilling

Abstract Fatigue failure in aerospace structures frequently initiates at fastener holes, where stress concentrations and unfavourable residual stress (RS) distributions reduce fatigue life. The study investigates the in-depth residual stress distribution after double-sided dimpling and evaluates its uniformity using a rational experimental–computational correlation (RECC) approach. Experiments were conducted on 2024-T4 aluminium alloy plates subjected to double-sided dimpling followed by drilling of a 4 mm diameter hole. Surface displacement fields were measured using Digital Image Correlation (DIC). A three-dimensional finite element model developed in Abaqus was validated against experimental displacement data, demonstrating good agreement and enabling reliable prediction of residual stresses through the thickness. The analysis shows that the maximum through-thickness variation of residual stress is observed within the pile-up zone and remains comparatively low near the hole edge. Unlike cold expansion, where peak unevenness is typically concentrated at the hole edge, the highest variation in the present study is observed near elastic-plastic boundary. These findings indicate that double-sided dimpling provides a more uniform compressive residual stress field distribution, highlighting its effectiveness for residual stress engineering.