Accounting for residual stress in fatigue crack growth rate tests: Validation of residual stress intensity factor measurements

Fatigue crack growth rate (FCGR) test data are a key to ensuring structural safety by design and inspection, but residual stress in test specimens can lead to significant (and unknown) bias in FCGR data. In turn, biased FCGR data confound estimates of structural capability for fielded systems. The presentation describes an experimental method for measuring the residual stress intensity factor as a function of crack size, K_res(a), during FCGR tests and provides data for validation. Further test data show that simultaneous measurements of FCGR and K_res(a) enable residual stress bias to be removed from FCGR test data.