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 which results in holes in the laminate. Then a patch laminate is adhesively bonded to the damaged composite laminate. The presence of holes in any structures creates a high stress concentration at the edge of the hole which indeed reduces the life of the structure. 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. An ANSYS 3D finite element models are developed for the study. Five different hole patterns of the parent laminate with [±45⁰/0⁰₃/90⁰]s graphite/epoxy and five different patch configurations with ±45⁰/0⁰]s graphite/epoxy were used in this study. This thesis presents a detailed finite element study on various hole arrangements on the parent laminate and effect of different patch configuration 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. It is found that laminate with multiple holes lined up along the loading direction results in reduction of stress. It is also found that laminate with circular patch on both sides of the parent laminate exhibits lower stress. It can be concluded that this paper would serve as a good design guide for composite patch repair.