Hygro-Mechanical Behaviour of Fibre Matrix Laminates for Different Fibre Orientations

Abstract

Composite materials have the versatility in their properties which enables them to be applied in large number of fields. Fibre reinforced polymer (FRPs) mainly have large advantages over conventional metals. FRPs are found to be sensitive to the hot and humid environments. Under theses environmental conditions, moisture absorption in FRPs causes deterioration and can limit their lives considerably during in-service applications. In this study, the moisture diffusion kinetics inside the fibre reinforced polymer matrix composites with angle and cross ply orientations are investigated. In particular, the effects of different fibre orientations have been investigated on both moisture diffusion and moisture diffusion induced stresses. Different analytical as well as experimental work is carried out for the investigation. A micromechanical model of three-dimensional fibre polymer matrix composites is modelled using FEA (Abaqus) and bond graph elements (Symbols Shakti). Fick’s law based moisture diffusion analysis is conducted to analyze the effect of fibre orientation on the moisture diffusion process. It is also observed that moisture diffusion in FRPs leads to development of stresses. The stresses are developed in composites due to moisture absorption with displacement boundary conditions. Therefore, different displacement boundary conditions according to concentric cylinder assemblage and plane strain boundary conditions are applied to study the effect of moisture absorption and different displacement boundary conditions on the stresses induced. It is seen that cross ply orientations have better moisture barrier properties and stress behaviour as compared to the other orientations with similar fibre volume fraction. All the results are validated using some widely used theories of composite micromechanics.