Influence of Thickness on Three-Dimensional Elastic Properties of a Unidirectional Graphite/Epoxy Composite

The main objective of this study was to investigate the influence of laminate thickness on the three-dimensional elastic properties of a unidirectional graphite/epoxy composite cured in an autoclave. The in-plane mechanical properties were studied by means of tensile specimens while the out-of-plane properties were evaluated by a specially developed z-direction tensile test specimen. In order to determine the elastic modulus E ₃₃ , finite element stress analyses of the z-direction specimens were per formed. To characterize the degree of cure and the glass transition temperature of the resin in the laminates, Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were used.