Micro-macro relations for fatigue crack growth

摘要: Abstract A fatigue crack growth model for the threshold and power regimes is presented. The rate equation postulated by identifying driving force with difference between calculated strain intensity at tip an ideal material (HRR-type macro solution) actual yield strain. based on four micromechanic parameters: (i, ii) a characteristic slip distance (Neumann's type) it's statistical distribution coefficient, (iii) shape parameter, (iv) compliance, which represents materials response (crack growth) to above force. Since effective radius of curvature cannot be smaller than one distance, natural stress value exists, statistically distributed. direct connection found microscale coefficients characteristics curve: Paris law coefficients, near response. examined through comparisons experimental data three different metals. Good agreement experiments in both regimes, including scatter very low intensities.