An efficient methodology for the experimental characterization of mode II delamination growth under fatigue loading

Crack growth rate curves provide information about the delamination resistance of composite materials under cyclic loading. The existing methodologies for mode II fatigue testing using three-point bending end-notched flexure (3-ENF) under constant cyclic displacement conditions yield discontinuous delamination growth rate curves, therefore requiring a batch of several specimens to be tested under different severity conditions in order to fully characterize the crack growth. This work describes a variable cyclic displacement test procedure that, in combination with the real time monitoring of the specimen's compliance, allows the crack growth rate to be measured for the desired range of severities with a single specimen, thus avoiding any human intervention during the test.