APPLICATION OF ENERGY-DISSIPATION RATE ARGUMENTS TO STABLE CRACK-GROWTH

Energy dissipation rate, D, and crack tip opening angle (CTOA) have be en related for large amounts of ductile crack growth in a fully plasti c two-dimensional model of real elastic plastic material. Several J-ty pe rising R-curves have been constructed and related, some based on th e cumulative energy dissipated and some as a characterising term that relates closely to the far-field J contour value. These two meanings c o-exist but the relationship is geometry dependent. For deep notch ben d (DNB) cases the non-dimensional group L alpha/r (where L is normali sed load, alpha is CTOA and r defines the position of the instantaneo us centre of rotation) governs the value of dJ. Certain DNB cases wher e R-curves vary with size are resolved by this group rather than by CT OA itself whereas for centre-cracked tension there is a higher value o f CTOA than for DNB.