APPLICATION OF A NORMALIZATION METHOD FOR DETERMINING J-R CURVES IN GLASSY POLYMER PVC AT DIFFERENT CROSSHEAD SPEEDS

A new single-specimen testing method, the normalization method with th e so-called LMN calibration function, based on the load separation pri nciple and function calibrations from an individual test record, was u sed to construct J-R curves directly from load versus load-line displa cement records without any additional on-line crack-length monitoring equipment. The research was done on CT-specimens of a glassy polymer P VC at different crosshead speeds ranging from 0.01 to 50 mm/min. The J -R curves evaluated from the normalization method are in good agreemen t with those from the conventional multiple-specimen testing method in the whole range of the tested crosshead speeds. The results demonstra ted the applicability of the normalization method for developing J-R c urves at different crosshead speeds in PVC. The crack initiation J-int egral values, J(0.2), showed a two-regime dependence on the crosshead speeds in the tested crosshead speed range.