CHAPTER 2
COMPUTATION OF STRESS INTENSITY FACTORS
FOR
SINGLE CRYSTAL : LITERATURE REVIEW
Stress intensity factor (SIF) about a crack tip p.1i' a significant role in the
propagation of the crack. The SIF is a measure of intensity near the crack tip
under linear elastic conditions. The knowledge of SIF is necessary to predict the
growth of a fatigue crack or to determine the residual strength of a cracked struc-
ture. This factor characterizes the intensity of the stress field in the neighborhood
of the crack tip and depends substantially on specimen geometry, material proper-
ties, external loads and crack size. In cases with idealized geometry and loads the
SIF can be found in handbooks for isotropic elastic materials. In the case of more
complex structures the SIF has to be computed by numerical methods.
Isotropic materials have uniform material properties in all directions, whereas
anisotropic materials are directional in nature (i.e., they have different material
properties in different directions). Because of this property SIF is direction
invariant for isotropic materials while SIF varies in anisotropic materials due to
change in material coordinate system, while keeping all the other parameters same.
A study of the effect of anisotropy and inhomogeneity on the SIF using the
FEA was done by K rn-,v- and Kitamura [10]. It was found that in a pcli, i--I 1
specimen, the SIF is influenced by the