Variable amplitude fatigue crack growth at monotonic large scale yielding experiments on stainless steel 316L

Fatigue crack growth in stainless steel 316L was investigated for two different variable amplitude block loads in the monotonic large scale yielding load range. The crack tip opening displacement, δ, was controlled in situ based on numerical computations on the coupling between the applied load, the crack length and δ. The average growth rates over the block sequences were determined from potential drop and visually measured crack lengths. The experimental growth rates were also predicted, based on small scale yielding fatigue crack growth data from closure free experiments, using a straight forward average procedure. The possibility to use small scale yielding material data was explained the by the large isotropic material hardening and closure free crack growth.