STRESS INTENSITY FACTOR CONSIDERING THE MATERIAL PLASTICITY LIMITED IN SCOPE

For the practical metallic material,preceding the fracture,there always exist thedomains of plasticity.For the plasticity limited in scope,the linear elastic mechanics is stillapplicable,but it is neccesary to correct the influence of the domain of plasticity.thetraditional method of correction(Irwin’s method)is to introduce the conception of theeffective fracture length,namely.owing to the existence of the domain of plasticity.thepractical length of the fracture increases.If we take the length of the fracture to be equal tothe effective fracture length 2(α+r).where 2a is the original length of the fracture and 2ris the added length.we may not regard the existence of the domain of plasticity and still usethe linear elastic fracture mechanics to deal with.In this paper.we regard that owing to the existence of the domain of plasticity,thepractical fracture length and the extrernal applied stress both increase,i.e.,the value of thetwo parameters a and σ(external applied stress)both change.In this