Patent ID: 7889840

Claim:
A method for component damage prediction in real world service environments comprising: determining ΔK appl and K max,appl of the component from service life load data, said service life having varying maximum loads and environmental conditions; experimentally determining K int and ΔK int of the component by measuring crack tip displacements as a function of distance from crack tip; determining ΔK total as a sum of the ΔK appl and the ΔK int of the component; and predicting crack growth rate da/dN according to ⅆ a ⅆ N = C ⁢ { Δ ⁢ ⁢ K total 1 - p ⁢ K max , total P } γ , wherein p is a driving force constant, γ a fatigue growth equation exponent, and p and γ are empirically determined from fitting a Coffin-Manson curve to strain-controlled fatigue test data of the component, C is a fatigue crack growth constant computed from the Coffin-Manson curve and the strain-controlled fatigue test data, ΔK appl is applied stress intensity range, K max,appl is a maximum applied stress intensity factor, K int and ΔK int are internal stress intensity factors due to internal stresses, and K max,total is a total maximum stress intensity factor calculated as a sum of K int and K max, appl .