IMPROVED CRACK GROWTH CORRECTION FOR RESISTANCE CURVE DETERMINATION

摘要

Resistance curves (J-integral vs. crack growth) are commonly generated by measuring load, deformation (crack-mouth opening displacement or load-line displacement), and crack length (by unloading compliance or some other technique) during testing of a pre-cracked specimen. The J-integral calculated from the work done must then be corrected for crack growth. A method has been described in the literature, and incorporated into test standards, to do this using deformation plasticity theory. However, the commonly-used equations include an approximation that is valid for small increments of crack growth, introducing an uncertainty that increases with the increment size. In the present work, a much better approximation is described that essentially removes the sensitivity to increment size, and applied to results of single-edge tension SE(T) fracture toughness tests.