DETERMINATION OF CRACK BRIDGING STRESSES FROM CRACK OPENING DISPLACEMENT PROFILES

This paper discusses the development of an optimization procedure to d educe the bridging stress from the crack opening displacements (COD) m easured during fatigue crack growth. Finite element analysis was condu cted using the center-cracked geometry To verify the optimization proc edure. The proposed procedure successfully predicted the bridging stre ss distributions with zero stresses at the crack tip and the bridging stress distributions with non-zero stresses at the crack tip. The resu lts also showed that COD measurements spaced at approximate to 0.8-1.0 mm are sufficient for reliable prediction of bridging stresses. Accur ate prediction of bridging stresses near the crack tip required COD da ta within approximate to 0.1 mm from the crack tip. The application of the proposed procedure to a metal matrix composite (SCS-6/TIMETAL(R)2 1S) is also discussed.