STRESS-CONCENTRATION DUE TO A HEMISPHERICAL SURFACE INCLUSION

Fatigue cracks often initiate at surface inclusions, and sometimes app ear at inclusions within the bulk. To clarify the relative efficiency of these crack sources, an approximate solution for the elastic stress of a hemispherical surface inclusion is provided and compared with th e existing result of a spherical interior inclusion. The approximate s olution is obtained from the Eshelby solution for the elastic field of an ellipsoid inclusion by introducing the Green's function of an elas tic half-space. The numerical calculated results indicate that the str ess concentration of a surface inclusion is higher when the inclusion is harder than the matrix, while that of an embedded inclusion is high er when the inclusion is softer than the matrix.