On the determination of the å-K relationship for birefringent polymers

Abstract

Methods of utilizing dynamic photoelasticity with fracture-type specimens to simultaneously determine the stress-intensity factorK Iand the crack-tip velocity are reviewed. Problems associated with data analysis to obtainK Ifrom isochromatic-fringe loops are discussed. Errors resulting from the use of static near-field equations in the method of analysis are considered and a correction method is developed. Finally, the invariance ofK Im(the minimumK required to maintain a finite crack velocity) is noted and evidence is provided to indicate thatK Imcan be treated as a material propertly.