Systematic assessment and validation of compliance-based crack closure measurements in fatigue
Author
Xu, Y.
Gregson, P.J.
Sinclair, I.
Attention
2299/7482
Abstract
Different methods of closure measurement and issues related to the identification of closure points are examined. Based on compliance curves obtained from crack mouth clip gauges and near-tip strain gauges, a systematic assessment of closure measurements has been made by a variety of non-subjective methods. Closure results obtained from compliance curves are also compared with direct crack tip observations. For results obtained on a commercial Al alloy, AA2024-T351 plate, it is shown that curve fitting methods based on a combination of linear and quadratic functions provide particularly sensitive and consistent closure measurements. The potential separation of plane stress and plane strain closure effects that arise in real, three-dimensional specimens is demonstrated via a combination of global compliance measurements and the use of side-grooved specimens.