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Development of a Micromechanics Based Cohesive Zone Model and Application for Ductile Fracture

In this paper, derivation and implementation of a micromechanically motivated traction separation law for cohesive zone modeling of ductile fracture is discussed. The formulation of the framework is based on the growth of pores in an array of representative volume elements where pores are idealized as cylinders. Two relations are derived under normal and shear loading for mode-I and mixed-mode respectively, based on the upper bound for a perfectly plastic material (Yalcinkaya and Cocks (2015), Yalcinkaya and Cocks (2016)). The obtained traction-separation laws are used as the constitutive model for cohesive elements. Numerical simulations are conducted for a compact tension specimen to illustrate the performance of the model under mode-I loading where the effect of the size and the shape of the pores are illustrated explicitly. It was observed that increasing initial pore fraction or decreasing initial pore height has a detrimental effect on the material, which decreases the strength and the toughness as expected. (C) 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review line: Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers.