Paris law extensions for low (?K) and high (?K) regimes and applications in reliability-based engineering design against fatigue

摘要

Stochastic models have been used tocharacterize fatigue crack growth and fracture in structuralmetallic materials. The applicability of Paris law will bedemonstrated to cover the entire zones of low stress intensityfactor range (?K) and high intensity factor range (?K) instructural metallic materials, provided appropriatemodification are made to account for the "death rate" in theprobablistic or stochastic process model form thecharacterization of the low (?K) regime, and the "birth rate"in the stochastic process model for the characterization of thehigh (?K) regime. Stochastic process models whichincorporate the Paris law, including the essential effects ofmulti-parameter variables and their possible statisticalvariabilities, which can contribute to the effective driving forcewhich can cause fatigue crack growth and fracture, arepresented in this technical paper. Possible applications of theprinciples developed here, in the area of engineering design, inorder to minimize and control crack initiation, propagationand failure, in metallic materials and structures, will be discussed.