Plastic Rotation Factors of Three-Point Bend and Compact Tension Specimens

Plastic rotation factors (r_p) for three-point bend and compact tension specimens were obtained for a range of normalized crack depths (a/W) from 0.25 to 0.88 and power law hardening materials. The theoretical slip-line field solutions were used for non-strain hardening materials (i.e., n = ∞) and the Kumar-German-Shih finite element plastic displacement solutions for strain hardening materials (i.e., n < ∞) in these r_p calculations. For crack depth a/W = 0.50, the factors r_p are approximately independent of strain hardening if n > 5 and are in reasonable agreement with those values recommended by ASTM Subcommittee E24.08 for calculation of crack tip opening displacements in these two types of specimens. For n ≤ 5 the error in r_p becomes appreciably large.