PLASTIC-ETA AND GAMMA-FACTORS FOR COMPACT TENSION SPECIMEN IN J-INTEGRAL ESTIMATION

The empirical expressions for the plastic eta and gamma factors adopted by ASTM in the standard test methods for J(Ic) and J-R curve testing (E 813 and E 1152) were determined from the results of experimental work. This note proposes instead expressions of eta-p and gamma-p that are derived from a limit load solution. The results show that over the range of crack lengths recommended for testing in the ASTM standard test methods, a/W = 0.5 to 0.75, the proposed eta-p value is 5.11 to 1.42% greater than the ASTM value, and the proposed gamma-p value is 12.93 to 5.82% greater.