Improving Fatigue Crack Growth Testing By Using Prior Data: An Experimental and Analytical Study

Fatigue crack growth (FCG) tests in Pure Shear specimens were conducted under constant loading conditions (ISO 27727) and under conditions where the peak loading was varied. An approach is presented to vary the peak loading using an expected powerlaw FCG slope and a test design that ensures crack length change at each energy release rate is nearly constant. This approach is then generalized allowing the simultaneous constraints on estimated crack length change, test length, initial, andfinal energy release rates. Experiments on two materials were conducted with this generalized approach and the methodology was shown to successfully provide an estimate of threshold crack growth and energy release rates, transition energy release rate, and powerlaw slope.