The method of normalization has been used to develop J-R curves for metallic materials based only on analysis of load and displacement pairs in a ductile fracture test record. This method eliminates the need for crack length monitoring equipment. It not only provides a method for more easily conducting and evaluating J-R curve tests; but it could be useful for tests conducted under special conditions such as under dynamic loading, in restructive facilities such as a hot cell, or even in a facility with limited instrumentation.

The method uses a normalized deformation curve which has a functional relationship resembling a power law in the beginning and a straight line later. A functional form is proposed to fit this material deformation pattern. This form was used along with the load versus displacement records to evaluate J-R curves for many materials. The results showed that the new method was a more accurate and versatile one for the assessment of the J-R curve. Compared with previous application of this method, the accuracy is remarkably improved in the beginning stages of the J-R curve where a J_Ic point is determined. The J_Ic point was analyzed on more than 60 specimens and found to be consistent with methods used in the ASTM test standards.