THE GROWTH OF CORNER CRACKS BY FATIGUE

Room temperature fatigue crack growth rates in Ti-6Al-4V and Ti-5331S have been determined using corner notched test pieces consisting of te nsile loaded bars containing a single small quarter-circular crack. Th e loadings employed involve both major and minor stress cycles which w ere applied separately or in combination. The measured crack growth ra tes have been compared with those generated using compact tension test pieces. The expectation that the fatigue crack growth rates in corner notched specimens would be less than those in compact tension specime ns was realised in the single case of Ti-6Al-4V subjected to a major c ycle only loading. There was no significant difference in the growth r ates in compact tension or corner notched test pieces for tests involv ing either Ti-5331S or combinations of major and minor stress cycles. These results may be rationalised in terms of the crack closure behavi our associated with the different combinations of specimen, material a nd loadings under investigation. (C) 1997 Elsevier Science Limited.