Analysis of Plasticity-Induced Crack Closure by the Extended Body Force Method : (Comparison of Various Analytical Results Based on Dugdale Hypothesis)

抄録

Using the extended body force method, crack closure analyses based on the Dugdale hypothesis were carried out. Based on the calculated results, the connection among the several models of plasticity-induced crack closures was clarified. From the present simulation analysis of crack growth, when ΔK is constant the stretched material remaining at the upper and lower crack surfaces becomes constant, and when Δσ^∞ is constant it becomes proportional to the length of the crack. This means that the closure behaviors of the former can be represented by the constant residual stretch model in which the thickness of the residual stretched material is assumed to be constant along the crack surfaces, and that the closure behaviors of the latter can be represented by the proportional residual stretch model in which the thickness of the residual stretched material is assumed to be proportional to the crack length. When the load is small, both the result from the constant stretch model and the proportional stretch model are close to the results obtained by Budiansky-Hutchinson analysis. Especially, if the stress ratio R≤0 and σ^∞_<max>/σ_s tends to zero, all results are close to the results of Budiansky-Hutchinson analysis for the case of R=0.