ABSTRACT

The EnJ method. The EnJ method allows use of (a), (b) and (c) above by simply updating crack length and equating J to JR instead of J Ie when evaluating eqn. (5.24) with er/ey as the unknown, which must then be interpreted as u/uy and hence load. Use of the cbse term to convert er/ey to u/uy will of course introduce approximations into the estimate of load comparable to the degree of conservatism intended when using cbse to estimate J. The writer is hinting at a subjective feeling that an estimate of maximum load should be to closer limits than the estimate of toughness whereas one simply reflects the other. The maximum value found, if any, is for the global stress u. The 'local' term, here cbse, increases whilst u/uy increases and mayor may not still increase thereafter. Once initiation has occurred there is no further guard against 'local snap through after some tearing' unless some relevant local term is monitored. Such a term might be net section stress, ub/W, which is governed by the balance between the increase of u/uy and the decrease of b/W as tearing occurs. For combined bending and tension the 'net section stress' would be a term such as ud/w where d/w is defined by Fig. 5.6 from R-6 or from some similar analysis of the fully plastic behaviour under combined loads. A factor such as in Table 5.1 would also be relevant for three-dimensional problems and an allowance for hardening, whereby the net section stress continues to increase as the hardening increases the maximum load the ligament can carry, perhaps by un/uy .