A Numerical Study of Crack Tip Parameters in Creeping Solids

There is a clear need for reliable procedures capable of assessing the integrity of structural components which operate in the creep regime. However, due largely to a lack of understanding of the parameters which control crack growth during creep, present procedures often require that a component be retired from service while a significant portion of its life may still remain. The crack tip parameters commonly used when attempting to correlate crack growth rate are the stress intensity factor K [1], the net section stress [2], the crack tip opening displacement rate [3,4] and C* [5,6], the rate dependent J-integral. Experimental studies [1–7] have shown that while crack growth rates obtained from a single geometry may correlate well with some of these parameters, correlation for a range of geometries is generally poor (although C* does appear to show some promise in this regard).