Dp. Boothman et al., THE SENSITIVITY OF J-INTEGRALS TO MATERIAL LAW VARIATIONS FOR SEMIELLIPTIC SURFACE CRACKS, International journal of fracture, 80(4), 1996, pp. 365-375
In finite element analysis of cracked bodies, it is quite common to re
present the material law (stress-strain curve) in a simplified form e.
g. bilinear approximation. Many steels, however, have a more complex m
aterial law, which includes a perfectly plastic region before work har
dening. Two dimensional finite element analyses have shown that fractu
re parameters, such as the J-integral, are very sensitive to variation
in material law for shallow cracks, and the writers have now commence
d three dimensional analyses for surface semi-elliptical cracks in pla
tes. Some computations have been made for specimens tested experimenta
lly by Dodds and Read [1], and the results show that what appears to b
e a reasonable approximation of the material law is inadequate in mode
lling the deformation behaviour, and that more accurate modelling of t
he material law, especially the plastic part immediately after yield,
which may include perfectly plastic behaviour, is required for reliabl
e results.