Improved crack growth corrections for J–R-curve testing

The ASTM J–R-curve testing standard contains an incremental crack growth correction to J, whereas the ESIS P2 test procedure contains a correction for the total crack growth. The ASTM expression is only applicable to single specimen J–R-curve testing in contrast to the ESIS expression which is also applicable for multi-specimen tests. The ASTM expression is, however, considered to be more accurate than the ESIS expression. It is of interest to unify the test procedures so that irrespective of standard, the same result would be obtained. Having this goal in mind, the different crack growth corrections have been examined and compared both with each other as well as with other analytical and numerical estimates, applicable both in incremental as well as integral form. As a result a new correction is proposed, which is capable of unifying the different testing standards.