Numerical Simulation for Stress Analysis of Functionally Graded Adhesively Bonded Composite Patch Repair System

Abstract

Abstract Three-dimensional finite element analyses have been carried out for adhesively bonded composite patch repaired an aluminum alloy plate structure with centre circular notch. Presence of defect in the plate causes stress gradients in the bond region which results inreduction of the performance of the patched panel. The patterns of different stresses at different interfaces (plate-adhesive-patch) at different angular positions with reference to loading direction are evaluated for mono-modulus adhesive. In the present research, an attempt has been made to improve the strength of adhesively bonded composite patch repaired system by reducing stress concentration at the critical regions. This has been achieved by smoothening/relieving stresses over the entire bond region by introducing functionally graded adhesive (FGA) material in-lieu of conventional mono-modulus adhesive. Linear material gradation function profile has been used to tailor adhesive layer in the bond region. Effect of material gradation profile with different modulus ratios on out-of-plane stresses at different interfaces of composite patch repaired system have been studied. Numerical simulations based on FE analyses depicts significant reduction in out-of-plane stress levels by which strength of functionally graded composite patch repaired system will be enhanced.