Influence of Specimen Size on J-, Jm- and δ5-R-Curves for Side-Grooved Compact-Tension Specimens

Abstract
The influence of specimen size and geometry on R-curves has been studied for a pressure vessel steel and an aluminum alloy using side-grooved compact-tension specimens. The specimen thickness reduction (necking) was used to quantify changes of constraint in laboratory specimens. The results show that the crack tip opening displacement, δ5, and the modified J-integral Jm, can correlate significantly more stable crack growth than the conventional J-integral.