Location independent CCL relations for standard fracture mechanics specimens

For the measurement of crack length during fatigue crack growth rate (FCGR) testing, the compliance technique is often used. Compliance crack length (CCL) relations that are available in the literature are specific to the location at which displacements are measured. In the present investigation, location independent CCL relations have been developed for the three-point bend, four-point bend and compact tension specimen geometries. The finite element method (FEM) has been used to simulate deformations in the specimens for obtaining compliance data. A forced-fitting methodology has been employed to obtain the location independent CCL relations using the data generated by FEM. The accuracies of the developed relations have been studied to ascertain their suitability for experimental use. For the specimen geometries considered, a number of location specific CCL relations with improved accuracies are also presented.