Comparison of finite element results and experimental measurements of CTODdelta(5) in CT specimens

Elastic-plastic finite element modeling of the CTOD delta(5) measuring proc edure is performed for CT specimens made from 22NiMoCr37 containing fatigue precracks with curved crack fronts. It is shown that a discrete model with curved crack front and actual position of the clip gage provides reasonabl e accuracy of results. An approximate model with straight crack front of av erage crack depth and actual location of the clip gage can also be used. It is proposed to adjust experimental delta(5) values for the deviation of ac tual crack front curvature alpha from a specific value. The use of the adju stment procedure decreases the scatter of experimental values of CTOD delta (5) considerably.