Deformation State Evaluation Around Deep Drilled Hole After Three-Dimensional Stress Release

Deep hole drilling technique (DHD) has received much attention as a method for measurements of thorough thickness residual stresses in recent years. In the past, however, the measurements of residual stresses by DHD technique have been limited to evaluation for in-plane stress and stress in through thickness direction. In the present study, the effect of shear stresses in through thickness direction on deformation states around the through thickness hole after stress release is discussed by theoretical approaches. In addition, the method for evaluating shear stresses in cutting direction is proposed from the result obtained by the previous theoretical investigation. Then, an unequal three-dimensional residual stress field is evaluated by DHD (or iDHD) technique and the proposed method using measurement changes obtained by numerical analysis. Finally, the reasons why the differences between the evaluation results and the stress distributions on the center line of the trepanned core are exits are clarified for high-accuracy evaluation.