Rapid crack propagation - The failure mode that never was?

The international standardisation of tests for rapid crack propagation (RCP ) is approaching completion and requirements for product and systems standa rds are well established. Yet some basic issues about RCP remain contentiou s. In contrast to slow crack growth, there is a near absence of service fai lure data and in this void extreme views have been expressed. At one end of the spectrum, it has been denied that RCP is a threat worth designing agai nst. At the other, the extensive RCP test programme that underpinned this e xcellent record has been turned round to imply that the material most widel y used is inherently at risk! Avoiding details of analysis or of data, the present paper aims at a rational assessment of the status of RCP - a 'failu re mode' which must never be allowed to cause failure - and to review the c urrent state of knowledge about it. PRCPA/1530 (C) 1998 The Institute of Ma terials.