Finite Element Analysis based Stress Intensity Factor Solutions for Surface Cracks

الملخص

The stress intensity concept is important in terms
of crack extension as critical values of the stress intensity
factors govern crack initiation. Therefore, the present work
determines stress intensity factors for semielliptical shallow
and deep surface cracks as a function of parametric angle,
crack depth, and aspect ratio for tension and bending loads.
The stress intensity factors are obtained from a threedimensional

finite-element analysis of semielliptical surface
cracks in finite plates subjected independently to tension
and bending loads under elastic conditions. The obtained
stress intensity factor is used to predict the crack growth
under linear elastic conditions. Results show that the stress
intensity factor varies along the crack front for shallow and
deep cracks. At the deepest point in bending and tension the
stress intensity factor increases as the ratio of the crack
depth to the crack length at surface decreases. However, at
the free surface the stress intensity factor becomes
maximum when the crack depth equals crack length. A
surface crack in tension loading is predicted to break the
wall thickness with a relatively small amount of crack
growth at surface. While in bending the crack breaks
through with large amount of crack growth in the width
direction.