Peak stress of composite multiple-hole laminates with and without patch

In repairing of composite structures, the damage in the composite laminate is usually removed in the form of circular cutouts. Then a patch laminate is adhesively bonded to the damaged composite laminate. The primary objective of this study is to investigate the high stress of the damaged laminate with different hole patterns and the effect of having single and double patches with various configurations on these hole different patterns.;Five different hole patterns of the parent laminate with [+/-45 0/003/900]s graphite/epoxy and five different patch configurations with [+/-450/0 0]s graphite/epoxy were used in this study. An ANSYS 3D finite element model was developed to study the peak stress of each ply in the parent and patch laminates. Experiments were conducted on the specimens without patch.;This thesis presents a detailed finite element study on various hole arrangements on the parent laminate and effect of different patch configurations on these hole arrangements. It will exhibit the peak stress concentrations for all cases and draw important conclusions by comparing the results of no patch, single patch and double patch. Among the different hole pattern laminates without patch, the peak stress of 00 ply is obtained in the following order TBH (Top & bottom hole)>SA (square array)>SSH (side by side hole)>DA (Diamond array)> FH (five hole). This sequence is in agreement with the test indication where TBH has the highest strength and FH has the least strength. Among the different patch configuration, the circular patch bonded on the both sides of the laminate exhibited the lowest peak stress. This study contributes to a better understanding in selecting patch configurations or geometries for both composite bonded repairs in order to restore the laminate structural integrity.