Stability analysis and experimental verification for optimum notch configuration in chevron-notched round bar specimens

摘要

In some earlier communications [Ray and Poddar, FFEMS, 27 (2004), Sarkar and Ray, FFEMS, 31 (2008)], a methodology to estimate the minimum normalized stress intensity factor for chevron-notched round bar (CVNRB) specimens has been outlined. The primary aim of this report is to theoretically analyse stable crack propagation in CVNRB specimens in order to estimate conservative fracture toughness value associated with this specimen geometry. The theoretical analyses have been substantiated using fracture toughness tests on CVNRB specimens of steel having initial normalized notch lengths (α_0) between 0.2 and 0.5. The major inferences drawn from this investigation are: (1) the optimum notch geometry in CVNRB specimens corresponds to 0.2 < α_0 < 0.3 for the maximum stable crack extension, and (2) the estimated fracture toughness of the steel using CVNRB specimens indicates minimum K_(ICV) at α_0 = 0.29 in good agreement with the theoretical analyses.