Published: Jan 1994
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Stable crack growth taken to large growths in the fully plastic state is characterized through the true energy dissipation rate, D, for real elastic-plastic (rep) material. The term is shown to be very closely related to the crack-opening angle (COA) model. A J-type R curve, Jdis, can be formed that degenerates exactly to G for linear-elastic fracture mechanics (LEFM). Unlike conventional J-based models for growth, it satisfies conservation of energy for the rep case and is not a function of crack growth rate in the rigid plastic limit. The dissipation rate, D, can be split into areal and volumetric components. These components, and also the COA, are geometry-dependent thereby offering an explanation for the size-dependent trends seen for R curves in the literature. The specific intensities of these rates of energy dissipation (SIRED) are also likely to be functions of constraint, but the known data are too sparse to allow a definite conclusion. Nevertheless, the use of areal and volumetric components of energy dissipation offers a new route for the conditional transference of estimates of R-curve data from one configuration to another.
R, curves, crack growth, elastic-plastic fracture, energy dissipation rate
Emeritus professor of materials in mechanical engineering, Imperial CollegeCity and Guilds College, London,