Determination of non-uniform residual stresses in laminated composites using integral hole drilling method: Experimental evaluation

In this article, the integral hole drilling method, developed in the first part of this research, has been employed to calculate the non-uniform residual stresses trapped within various composite laminates. Test specimens were fabricated using hand layup assisted with vacuum bagging technique. In order to study the capability of the model in predicting the residual stresses in different layups, three different ply configurations are used in this article as: symmetric cross-ply ([0° 2 /90° 2 ] S ), unsymmetric cross-ply ([0° 4 /90° 4 ]), and symmetric quasi-isotropic ([0°/±45°/90°] S ) specimens. Using the developed method in the present research, calculated residual stresses in each layer of the laminates showed good agreements in comparison with the theoretical values.