Determining critical CTOA from energy-load curves with DWTT specimen

Running ductile fracture is one of the most catastrophic accidents of pipelines for natural gas transportation. Crack arrest toughness is important for preventing crack extension to a long distance along pipeline. Critical crack tip opening angle (CTOA(C)) is a promising parameter for characterizing crack arrest toughness. In this study, a new method is proposed to calculate the CTOA(C) from the energy-load curves in an instrumented drop weight tearing test (DWTT). Numerical analyses with the Gurson damage model have been conducted to verify the proposed method. It shows that results calculated from the energy-load curves are slightly lower than the results measured from specimen surface. Results calculated from the proposed method also agree well with experimental results reported in the literature. (C) 2017 Elsevier Ltd. All rights reserved.