An extended model for void growth and coalescence

TL;DR: In this article, the authors present an analysis of void growth and coalescence in isotropic, elastoplastic materials exhibiting sigmoidal hardening using unit cell calculations and micromechanics-based damage modeling.

TL;DR: Shinohara et al. as mentioned in this paper investigated the fracture properties of a mother plate for API grade X100 line pipe after pre-straining up to 6% using tensile notched bars and CT pre-cracked specimens.

TL;DR: In this paper, the effect of the strain rate on the ductile fracture of DP980 12t steel sheet has been investigated with three different shapes of specimens: the diagonally notched specimen for the in-plane shear test, the dog bone specimen for uniaxial tension test, and the plane strain tension test.

TL;DR: In this paper, an approach to ductile failure modeling derived based on continuum thermodynamics and damage is presented, where a continuum damage enhanced formulation of the effective material is used to describe the degradation of the response.

Abstract: Widely used constitutive laws for engineering materials assume plastic incompressibility, and no effect on yield of the hydrostatic component of stress. However, void nucleation and growth (and thus bulk dilatancy) are commonly observed in some processes which are characterized by large local plastic flow, such as ductile fracture. The purpose of this work is to develop approximate yield criteria and flow rules for porous (dilatant) ductile materials, showing the role of hydrostatic stress in plastic yield and void growth. Other elements of a constitutive theory for porous ductile materials, such as void nucleation, plastic flow and hardening behavior, and a criterion for ductile fracture will be discussed in Part II of this series. The yield criteria are approximated through an upper bound approach. Simplified physical models for ductile porous materials 6ggregates of voids and ductile matrix) are employed, with the matrix material idealized as rigid-perfectly plastic and obeying the von Mises yield criterion. Velocity fields are developed for the matrix which conform to the macroscopic flow behavior of the bulk 4 DISTRIBUTION 0£ :LHIS DOCUMENT IS UNUrv#TE n material. Using a distribution of macroscopic flow fields and working through a dissipation integral, upper bounds to the macroscdpic stress fields required for yield are calculated. Their locus in stress space forms the yield locus. It is shown that normality holds for this yield locus, so a flow rule results. Approximate functional forms for the yield loci are developed.

TL;DR: In this paper, the effect of microscopic voids on the failure mechanism of a ductile material is investigated by considering an elastic-plastic medium containing a boubly periodic array of circular cylindrical voids.