Ductile fracture analysis in a steel plate by cohesive zone modeling

Seif, Tayyebe (2014) Ductile fracture analysis in a steel plate by cohesive zone modeling. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (7MB)

Abstract

There are several theories used to describe fracture process including Linear Elastic Fracture Mechanics (LEFM), Elastic-Plastic Fracture Mechanics (EPFM), and Cohesive Zone Models (CZM), which allow for development of predictive capabilities. The main disadvantage of LEFM and EPFM techniques is that only structures with an initial crack can be modeled. Other drawbacks of these techniques are geometry dependence and validity limits. In contrast, CZM can simulate fracture in any structures, with or without a crack. CZM is not confined to a class of materials, but it can be used for arbitrary materials. In this research, the CZM was used to numerically simulate crack initiation and growth in steel plates. Within the CZM, material separation (i.e. damage of the structure) is described by interface elements, which open irreversibly and lose their stiffness at failure, causing the continuum elements to be disconnected. Numerical simulation of tensile tests was conducted to determine and validate the cohesive parameters and then these parameters were used for modeling mode I fracture in steel plates. It was shown that the cohesive model is capable of simulating ductile fracture in cases where the crack path is not known in advance and the crack can evolve anywhere in the specimen.

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