In this paper, the effect of loading mode, and the resulting crack tip constraint, on the crack tip opening angle (CTOA) was investigated. This was achieved through a comparative analysis of a standard drop weight tear test (DWTT) specimen, and a variation whereby it is placed in a tensile loading mode. The tensile loading mode is similar to that of a clamped single edge notch tensile (SENT) specimen. Both models are examined under a quasi-static loading rate. In all analyses the same materials were used, namely, API standard X70 and X100 pipeline steels. A cohesive zone model (CZM) was used to simulate ductile fracture, and it was assumed that the cohesive parameters were constant for both loading modes. The results show that there is a weak dependence of the CTOA on the loading mode. Moreover, this work reinforces the notion of the transferability of the CTOA from the DWTT (bending) to a more representative loading mode for pipeline applications (tensile).

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Conference 14th International Conference on Fracture, ICF 2017
Citation
Bassindale, C. (C.), Wang, X, Tyson, W.R. (W. R.), & Xu, S. (S.). (2017). Numerical simulation of ductile fracture in pipeline steels under bending and tensile loading conditions. In ICF 2017 - 14th International Conference on Fracture (pp. 466–467).