Thermal Residual Stresses in Single-sided Bonded Composite Patching

Thermal residual strains/stresses in the single-sided bonded specimens, resulting from the mismatch in coefficients of thermal expansion between the carbon/epoxy composite patch and the aluminum alloy substrate, were experimentally and numerically investigated. A two-dimensional plane-stress finite element model was developed to predict the thermal residual stresses. The finite element analysis (FEA) results agree well with the experimental results, which indicates the FEA is an efficient method to estimate the residual stresses in the single-sided patched structures. The FEA results show that the residual stress in the substrate near the adhesive interface and the peak shear stress in the adhesive layer can be efficiently reduced by increasing the adhesive layer thickness, and as the patch to substrate stiffness ratio increases, the residual stress decreases and the peak shear stress increases.