Correlation and prediction of fatigue crack growth for different R-ratios using Kmax and ΔK+ parameters

This paper summarizes a study which has been conducted to examine the recently proposed fatigue crack driving force parameter, K∗=Kmaxα(ΔK+)(1−α), and its ability to predict the crack growth rate for different R-ratios. A validation of the effectiveness of the proposed K∗ parameter relative to the existing crack closure approach, ΔKeff, is analyzed and discussed. Experimental data for ten different types of materials taken from literature were used in the analyses. Presented results indicate that the K∗ parameter is equally effective or better than ΔKeff in correlating and predicting the R-ratio effects on crack growth rate.