Automated Analysis of Crack Growth Rate for Obtaining da/dN versus Delta K Relation

摘要

A computer program, called GROWFIT, which uses linear and nonlinear regression analyses with the crack closure concept to fit a stepwise linear relation (in a log-log scale) to experimental data on the crack growth rate versus stress intensity range was written. The program can take into account experimental data for several different stress ratios in a single run. A minimum of data have to be supplied by the user in addition to the experimental data sets (delta K, da/dN). The advantage of the program compared to normal procedures is that different users can obtain the same results based on the same experimental data. The disadvantage is that experimental data for different stress ratios may not be equally well fitted, since the stress ratio dependence is governed by the assumed crack closure formula.