Compressive Failure Behaviour of Unid ir ectional and Woven Kevlar/Epoxy Composite Laminates under Various Angles of Fiber Orientation

Abstract

Studies have shown that the angle of fiber orientation significantly affects the mechanical properties of a composite laminate. Due to this, accurate prediction of the laminate response because of the loading effect is crucial. Many investigations on the properties of composite materials have been conducted. However, there is still the lack of study related to Kevlar/Epoxy laminate. Therefore, this study aims to investigate the effect of the angle of fiber orientation to woven and unidirectional (UD) Kevlar/Epoxy laminates under compression state. The study was conducted in two stages comprising of numerical validation and failure analysis. For the failure analysis, a flat plate and flat plate with circular hole under compression were modelled using ANSYS. Two of the most common failure models, Maximum Stress Theory and Tsai-Wu Failure criteria were selected for the failure prediction. The laminates were made of 24 layers woven Kevlar/Epoxy and the stacking sequence was (θ4/04/-θ4)s. The angle of fiber orientations, θ, have been varied from 0° to 90° and failure loads for both flat plate and flat plate with circular hole were determined. The trend of displacement and failure behaviour for both types of plate were compared. The results show that the angle of fiber orientation affects significantly the trend of the displacement and failure curves of UD and woven Kevlar/Epoxy. The curves for UD and woven; flat plate and flat plate with circular hole are different and unique in nature; and thus should be treated individually. These analysis and findings are important in aiding the engineers at designing a stronger woven Kevlar/Epoxy composite laminate. Therefore, it can be concluded that the current study has contributed towards enhancing knowledge about the compressive failure behaviour of unidirectional and woven Kevlar/Epoxy composite laminates.