Improvement and validation of residual stress measurement in composite laminates using the incremental hole-drilling method

In this paper, the incremental hole-drilling (IHD) method has been improved by attaching strain gauge rosettes on both top and bottom surfaces, and changing the calculation algorithm for solving the ill-conditioned problem. In order to assess the feasibility and accuracy of the improved IHD method, an experiment of measuring the in-plane stress distribution in a composite laminate under bending was proposed. The composite laminate, which is bended by an external pure bending moment and fixed in a stable state, contains an in-plane stress distribution with obvious gradients in thickness direction, which is essentially similar to residual stresses. A plain woven T800H/803 specimen was tested in the proposed experiment with the improved IHD method. The results calculated using both top-surface and bottom-surface measured strains, and by iteration algorithm, showed good agreement with the finite element method (FEM) simulation and high calculation efficiency.

Automated summary

This paper enhances the incremental hole-drilling (IHD) method for calculating in-plane stress distribution in composite laminates. An experiment was conducted to validate the accuracy and efficiency of the improved IHD method, showing good agreement with finite element method (FEM) simulation results.