Fatigue crack closure of surface flaws loaded in pure bending

The objective of this paper is to report fatigue crack growth and closure behavior for surface flaws subjected to pure bending. An optical interference technique is employed with PMMA, a transparent polymer, to determine the three-dimensional crack-surface displacement field. The point-wise measure of crack closure along the crack front obtained from optical interference is compared with an average (bulk) crack-opening load determined via crack-mouth-displacement gage measurements. In addition, the effect of crack-closure loads on the subsequent growth of the surface flaw is examined. Dr. Ray is currently associated with The Boeing Company, Seattle, WA.