Three-Dimensional Finite and Boundary Element Calibration of the Short-Rod Specimen

Abstract

The results of numerical calibration of a proposed standard short-rod specimen are reported. Three-dimensional finite and boundary element approaches were used to compute compliance and average stress-intensity factor as a function of crack length. Local variation of stress intensity along the crack front was computed for nine crack lengths. Calibration constants for fracture toughness evaluation were found to be: ¯Ymin = 28.3 and Amin = 23.4. A convergence study indicated that these values are lower bounds accurate to within 1%. Stress intensity was found to be minimum at the specimen centerline and maximum at the chevron edge for each crack length analyzed. At the critical crack length, the edge value was about 20% higher than the centerline value for an assumed straight crack front. Comparison of the boundary and finite element approaches indicated that, for the same stress intensity factor accuracy, the boundary element solution time was about 15% less than that of the finite element method.