Determination of stresses, strains, and crack characterizing parameters.

After a short introduction concerning the chain of simplifications necessary from physical reality to a numerical model, the evaluation crack tip loading parameters K sub 1, J, and CTOD by the finite element method is explained. Analytical and approximate solution techniques as well as handbooks are referenced. The virtual crack extension method for the evaluation of the J integral including correction integrals, e.g., for non-isothermal, dynamic, or non-proportional loads, is explained in some detail. The node shifting and releasing technique for two- and three-dimensional simulation of crack extension is presented. The methods presented are illustrated by a few applications within the context of reactor safety research. In particular, the role of the state of stress ahead of the crack front with respect to initiation toughness and slope of resistance curves is discussed.