Lead stress engineer, Mechanical Design and Development Department, British Aerospace PLC, Dynamics Group, Space and Communications Division, Stevenage,
Lecturer, Cambridge University Engineering Department, Cambridge,
Pages: 21 Published: Jan 1988
The Mode II crack flank displacement and crack growth responses of three precracked specimens made from structural steel were measured, using plastic replicas and a crack-tip compliance gage. Crack surface interaction was found to dominate behavior: at low stress intensity range (ΔKIInom = 9 MPa √m) the precracks did not suffer reversed slip to their tips and no crack growth occurred, while at high stress intensity range (ΔKIInom = 19 MPa √m) the effective stress intensity range was less than half that nominally applied. Three sources of crack flank frictional attenuation were identified: compressive residual stresses due to precracking, Mode I wedging over asperities, and gross plastic deformation of interlocking asperities. The measured unlocking response was modeled successfully by assuming that crack flank frictional stresses obeyed a constant interfacial shear stress friction law.
fatigue crack growth, Mode II, shear mode, steels, crack flank locking, crack flank slip, friction
Paper ID: STP23220S