On a fatigue crack-front marking technique for polymers

Abstract

A fatigue crack-front marking technique using small tensile overloads is described. In this technique, two small overloads are chosen to produce distinct striation spacings which can be used to encode a binary marker on the fatigue fracture surface. Post-mortem detection of these binary coded markers then enables a direct correlation with the load history. This technique is particularly useful for the study of early crack development or crack initiation in smooth bar samples. Periodic insertion of binary coded markers during the entire testing period could allow a precise determination of the crack initiation time. The study of fatigue fracture mode transitions is also facilitated with this crack-front marking technique.