On matrix crack growth in quasi-isotropic laminates - I. Experimental investigation

Abstract

Matrix crack growth behaviour under quasi-static and mechanical fatigue loadings has been studied in quasi-isotropic (0/90/ - 45/ + 45)s GRP laminates. Detailed experimental observations were made on the initiation and growth of individual cracks in ± 45° and 90° plies. Degradation of elastic properties of the laminates due to matrix cracking was observed and recorded. The quasi-static results were compared with baseline data from a crossply (0/90)s laminate. Distinctly different crack growth behaviour was observed in quasi-isotropic laminates under quasi-static and fatigue loadings, suggesting a strong influence of load history. A higher density of ± 45° cracks and hence greater stiffness reduction appear to be the characteristics of fatigue damage in quasi-isotropic laminates, © 1997 Elsevier Science Limited.