Journal ArticleDOI
A variational constitutive model for porous metal plasticity
TLDR
In this paper, a variational formulation of viscoplastic constitutive updates for porous elastoplastic materials is presented, which combines von Mises plasticity with volumetric plastic expansion as induced by the growth of voids and defects in metals.Abstract:
This paper presents a variational formulation of viscoplastic constitutive updates for porous elastoplastic materials. The material model combines von Mises plasticity with volumetric plastic expansion as induced, e.g., by the growth of voids and defects in metals. The finite deformation theory is based on the multiplicative decomposition of the deformation gradient and an internal variable formulation of continuum thermodynamics. By the use of logarithmic and exponential mappings the stress update algorithms are extended from small strains to finite deformations. Thus the time-discretized version of the porous-viscoplastic constitutive updates is described in a fully variational manner. The range of behavior predicted by the model and the performance of the variational update are demonstrated by its application to the forced expansion and fragmentation of U-6%Nb rings.read more
Citations
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Journal ArticleDOI
Fatigue behavior of porous biomaterials manufactured using selective laser melting.
S. Amin Yavari,Ruben Wauthle,J. van der Stok,A.C. Riemslag,M. Janssen,Michiel Mulier,Jean-Pierre Kruth,Jan Schrooten,Harrie Weinans,Harrie Weinans,Amir A. Zadpoor +10 more
TL;DR: The three-stage mechanism of fatigue failure of these porous structures is described and studied in detail, and it was found that the absolute S-N curves of these four porous structures are very different.
Journal ArticleDOI
Biomechanics of traumatic brain injury
TL;DR: A biomechanical model for traumatic brain injury and soft tissue damage is presented and future directions of this work, relating mechanical damage and physiological brain dysfunction, and application to relevant medical and engineering problems are discussed.
Journal ArticleDOI
Ultrasonic-assisted manufacturing processes: variational model and numerical simulations
Amir Siddiq,Tamer El Sayed +1 more
TL;DR: A fully variational porous plasticity model is modified to include ultrasonic softening effects and then utilized to account for instantaneous softening when ultrasonic energy is applied during deformation.
Journal ArticleDOI
Modelling of dynamic ductile fracture and application to the simulation of plate impact tests on tantalum
TL;DR: In this paper, a model of dynamic damage by void nucleation and growth is proposed for elastic-viscoplastic materials sustaining intense loading, which is dedicated to ductile materials for which fracture is caused by micro voiding.
Journal ArticleDOI
Homogenization of elasto-(visco) plastic composites based on an incremental variational principle
TL;DR: In this article, an incremental variational approach is proposed to compute the homogenized response of composite materials with elasto-visco plastic constituents. But the model is based on a single incremental potential constructed from a free energy and a dissipation function.
References
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Journal ArticleDOI
Continuum Theory of Ductile Rupture by Void Nucleation and Growth: Part I—Yield Criteria and Flow Rules for Porous Ductile Media
Journal ArticleDOI
Analysis of the cup-cone fracture in a round tensile bar
Viggo Tvergaard,Alan Needleman +1 more
TL;DR: In this article, a set of elastic-plastic constitutive relations that account for the nucleation and growth of micro-voids is used to model the failure of a round tensile test specimen.
Journal ArticleDOI
Elastic-Plastic Deformation at Finite Strains
TL;DR: In this paper, the authors generalize a previous theory to permit arbitrary deformation histories by considering two coupled thermodynamic systems: one comprising thermo- elasticity at finite strain and the other the irreversible process of dissipation and absorption of plastic work.
Book ChapterDOI
Material Failure by Void Growth to Coalescence
TL;DR: In this paper, a convected coordinate formulation of the field equations is used to describe the material failure by coalescence of microscopic voids, and a detailed micromechanical study of shear band bifurcation that accounts for the interaction between neighboring voids and the strongly nonhomogeneous stress distributions around each void has been carried out, and also elaborated in this chapter.
Journal ArticleDOI
Discontinuous Equilibrium Solutions and Cavitation in Nonlinear Elasticity
TL;DR: In this article, the existence of singular solutions to the nonlinear elastostatics problem with respect to radial motion has been studied for a class of strongly elliptic materials by means of the direct method of the calculus of variations, and it has been shown that the only radial equilibrium solutions without cavities are homogeneous.
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