The investigation of $J_{IC}$ as well as J-Resistance curve of a commercial steel (SCM4) is carried out by single specimen unloading compliance method using compact tension and three point bending specimens.
Equation relating compliance with the amount of crack growth is modified here and the result is compared with experiment. It shows quite a good agreement with the experiment.
A new method of determining $J_{IC}$ from load-load line curve is proposed and the result is compared $J_{IC}$ obtained from other method.
