No abstract

To study the influence of the stress intensity factor and the R‐ratio on the fatigue crack growth rate different kind of crack propagation experiment have been carried out on the steels X5CrNi18‐10 and C45E. The experiments show that both parameters the maximum stress intensity Kmax and the R‐ratio affect the crack growth rate. Consequently, the authors developed a 3D‐model, which describes the dependence of da/dN on Kmax and the R‐ratio. Discussing the experiments, special attention has been paid to the threshold behavior of the investigated materials. Finally, a new model to describe the influence of the R‐ratio on the threshold Kmax,th for R‐ratios from −∞ to 1 is presented.

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