## Doctoral Dissertations

Spring 1997

Dissertation

Engineering

#### Degree Name

Doctor of Philosophy

The resistance Mode II stress intensity factor was found to exhibit a yield strength dependence while an inverse elastic modulus effect was observed. The magnitude of the K$\sb{\rm llres}$ was found to have a direct dependence on the applied mode mixity. The lock up mode of interaction behavior implied by the measured crack face displacements and the estimated SIF was yield strength and elastic modulus dependent with lock up observed prior to sliding or smearing where normalized yield strength, ${{\sp{\sigma}\rm ys}\over{E}} > 0.006$ and not observed where ${{\sp\sigma{\rm ys}}\over{E}} < 0.002.$ It was proposed that the distinctly different behaviors observed in identical specimens were due in part to differences in the state of contact between opposing fracture surfaces.