PARTIAL CLOSURE AND FRICTIONAL SLIP OF 3-D CRACKS

The effects of partial closure and frictional slip of three-dimensiona l cracks on the stress intensity factors are studied using the eigenst rain method. The formulation, based on the correct modelling of the bo undary conditions on the crack faces, is presented separately for part ial closure and frictional slip, and applied to two simpler cases: par tial closure of a surface-breaking crack normal to the free surface an d under a residual stress field; and frictional slip of a completely c losed crack under normal and shear tractions. The evolution of crack c losure with the increase of crack depth and its influence on the stres s intensity factor are examined and compared with a simple model for t he first problem. The effect of coefficient of friction between crack faces on the stress intensity factors is investigated for the second p roblem.