FINITE-ELEMENT ANALYSIS OF STABLE CRACK-GROWTH IN 3 SIZES OF COMPACT SPECIMENS OF A508-STEEL

Plane strain, elastic-plastic finite element analyses have been undertaken to simulate stable crack growth in an A508 forging steel for three different sizes of compact tension specimen and for small scale yielding by enforcing the same experimentally-measured deformation theory J resistance curve. The results show that path-dependence of the numerically calculated J-integral occurs from the very beginning of crack growth, and the degree of path-dependence is not strongly related to the amount of crack growth expressed as a proportion of the uncracked ligament. Crack tip stresses and strains are only mildly sensitive to changes in specimen size for the range of crack extension investigated. Small specimens appear to produce more intense deformation than small scale yielding and therefore cause more damage. For a tough steel such as A508 the parameter bsigma(f)/J(d) appears to be the most important in limiting the validity of J-characterized fields of deformation ahead of the growing crack.