Relation Between Power and Exponential Laws of Slow Crack Growth

The coefficients ₀, and N of the power law of slow crack growth, =₀ exp [–/(RT)](K/K_C)^N, are evaluated in terms of the fundamental parameters V₀. Q₀. and B of the exponential law, V=V₀ exp [(-Q₀+BK)/(RT)]. It is shown that N =θ(BK_C)/(RT),=₀−θBK_C, and ₀=V₀θ^−N, where θ is a dimensionless coefficient with a value ranging from 0.2858 to 1.0, depending on the ratio of stress intensity at the fatigue limit to the critical stress intensity factor.