Plug repairs of marine glass fiber / vinyl ester laminates subjected to in-plane shear stress or in-plane bending moment

Abstract

Glass fiber / vinyl ester composite laminates represent an important class of modem fiber composites being proposed or used in state-of-the-art shipbuilding. This thesis examined the effectiveness of chopped strand mat (CSM) plug repairs of glass fiber / vinyl ester woven roving laminates subjected to in-plane shear and bending. An advantage of this type of repair scheme is its simplicity when compared to more traditional schemes such as scarf or step repairs. The stress concentrations around circular holes in glass fiber / vinyl ester woven roving laminates subjected to in-plane shear and bending were calculated before and after repairs using CSM plugs, also of glass fiber / vinyl ester, having varying fiber volume fractions. The laminates were orthotropic and ranged from balanced to unidirectional woven roving, and the CSM plug fiber volume fractions ranged from 0 to 0.40. For in-plane shear stress, as the plug fiber volume fraction increased from 0 to 0.40, the maximum stress concentration along the circular holes in the laminate was reduced from about 25% to 61%. For in-plane bending, as the plug fiber volume fraction increased from 0 to 0.40, the maximum stress concentration in the laminate was reduced from about 25% to 45%.