Effect of load duration on the fatigue behaviour of graphite/epoxy laminates containing delaminations

At high sustained loads it is known that creep-rupture can occur in short periods of time or contribute damage to carbon fibre composite components. This paper investigates the effect of load holds on the fatigue performance of impact damaged carbon fibre composite coupons by using two modified versions of a loading spectrum, static failure tests and application of sustained static loading, and examines damage growth together with coupon stiffness during fatigue testing. Stiffness degradation, shown to be associated with delamination growth, could be used to predict coupon failure.