Assistant professor, The University of British Columbia, Vancouver, B.C.,
Pages: 20 Published: Jan 1987
It is generally accepted that the onset and stable growth of edge delaminations under quasi-static loading can be characterized using the strain energy release rate G and delamination resistance curves (R curves). This study addresses the problem of edge delamination growth under fatigue loading. To characterize the fatigue growth successfully, it is shown that it is not sufficient to consider only the maximum energy (Gmax) released as the delamination grows. Instead, the energy released must be compared to the increasing resistance to further growth. This increasing resistance to delamination grwoth GR can be explained best in terms of the associated matrix cracking, which is observed under both static and fatigue loading. Using results from a [±30/±30/90/9¯0]s T300-5208 and a [45/0/−45/90]s XAS-914 graphite-epoxy laminate, separate power law correlations between the edge delamination fatigue growth rates and the term (Gmax/GR) are obtained. The measured exponents are in the range 4.1 to 6.
composite materials, graphite-epoxy, delamination, matrix cracking, stiffness loss, fracture mechanics, strain energy release rate, R, curve, fatigue, growth law
Paper ID: STP24380S