R-CURVES OF ENERGY DISSIPATIVE MATERIALS .2. EXPERIMENTAL EVALUATION OF J-R CURVES

A hypothesis regarding the conversion of mechanical into thermal energ ies within the nonlocal damage region is formulated to model the fract ure behaviour of energy dissipative materials with rising crack resist ance characteristics. The material's capacity to develop nonlocal dama ge beyond blunting is assumed to decrease with the actual damage level . This decrease relates linearly with the remaining resources of the m aterial in dissipating energy. The hypothesis, wich proposes a square root function for theoretical J-R curves, is verified by the regressio n analysis of experimental data regarding a European round robin test of different steels.