Modeling of Ductile Damage and Fracture Behavior Based on Different Micromechanisms

2010 ◽  
Vol 20 (4) ◽  
pp. 558-577 ◽  
Author(s):  
Michael Brünig ◽  
Daniel Albrecht ◽  
Steffen Gerke
Keyword(s):  
Continuum Model ◽  
Failure Modes ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Yield Condition ◽  
Lode Parameter ◽  
Material Parameters ◽  
Damage And Failure ◽  
Damage And Fracture ◽  
The Continuum

The article deals with the effect of stress triaxiality on the inelastic deformation behavior of aluminum alloys. The proposed continuum model takes into account stress triaxiality dependence of the yield condition as well as of the damage criterion and the fracture condition with different branches corresponding to various damage and failure modes depending on the stress triaxiality and the Lode parameter. Results of numerical cell simulations on the microscale are presented and corresponding identification of micromechanically motivated material parameters is discussed. Furthermore, numerical results of three-dimensional macromechanical finite element analyses are compared with experimental data obtained from smooth and pre-notched tension specimens. The analyses allow verification of the continuum model and identification of further material parameters.

A Continuum Damage and Failure Model Based on Stress-State-Dependent Criteria

2012 ◽  
Author(s):  
Michael Brünig ◽  
Steffen Gerke ◽  
Vanessa Hagenbrock
Keyword(s):  
Stress State ◽  
Continuum Model ◽  
Stress Triaxiality ◽  
Failure Criteria ◽  
Basic Material ◽  
Failure Behavior ◽  
Deformation And Failure ◽  
Damage And Failure ◽  
Wide Range ◽  
The Continuum

The paper deals with the effect of stress state on inelastic deformation and failure behavior of ductile solids. The continuum model takes into account stress-state-dependence of the damage and failure criteria with different branches corresponding to different micro-mechanical mechanisms depending on the stress triaxiality and the Lode parameter. Basic material parameters are identified using various tests with smooth and differently notched tension and shear specimens. To get more insight in the complex damage and failure mechanisms on the micro-scale additional series of three-dimensional micro-mechanical numerical analyses of void-containing unit cells have been performed. These calculations cover a wide range of stress triaxialities and Lode parameters in tension, shear and compression domains. The numerical results are used to discuss general trends, to develop equations for the damage and failure criteria, and to identify corresponding parameters of the continuum model.

On the Motion of Granular Materials Due to Shear

2000 ◽  
Author(s):  
Mehrdad Massoudi ◽  
Tran X. Phuoc
Keyword(s):  
Finite Difference ◽  
Granular Materials ◽  
Continuum Model ◽  
Theory Model ◽  
Governing Equations ◽  
Flat Plates ◽  
Material Parameters ◽  
Finite Difference Technique ◽  
Linear Differential ◽  
The Continuum

Abstract In this paper we study the flow of granular materials between two horisontal flat plates where the top plate is moving with a constant speed. The constitutive relation used for the stress is based on the continuum model proposed by Rajagopal and Massoudi (1990), where the material parameters are derived using the kinetic theory model proposed by Boyle and Massoudi (1990). The governing equations are non-dimensionalized and the resulting system of non-linear differential equations is solved numerically using finite difference technique.

scholarly journals Discrete-to-continuum modelling of weakly interacting incommensurate two-dimensional lattices

2018 ◽  
Vol 474 (2209) ◽  
pp. 20170612 ◽  
Author(s):  
Malena I. Español ◽  
Dmitry Golovaty ◽  
J. Patrick Wilber
Keyword(s):  
Continuum Model ◽  
Domain Walls ◽  
Three Dimensional ◽  
Variational Model ◽  
Dimensional System ◽  
Two Dimensional ◽  
Starting Point ◽  
Continuum Modelling ◽  
Three Dimensional System ◽  
The Continuum

In this paper, we derive a continuum variational model for a two-dimensional deformable lattice of atoms interacting with a two-dimensional rigid lattice. The starting point is a discrete atomistic model for the two lattices which are assumed to have slightly different lattice parameters and, possibly, a small relative rotation. This is a prototypical example of a three-dimensional system consisting of a graphene sheet suspended over a substrate. We use a discrete-to-continuum procedure to obtain the continuum model which recovers both qualitatively and quantitatively the behaviour observed in the corresponding discrete model. The continuum model predicts that the deformable lattice develops a network of domain walls characterized by large shearing, stretching and bending deformation that accommodates the misalignment and/or mismatch between the deformable and rigid lattices. Two integer-valued parameters, which can be identified with the components of a Burgers vector, describe the mismatch between the lattices and determine the geometry and the details of the deformation associated with the domain walls.

Micro-mechanical analyses of the effect of stress triaxiality and the Lode parameter on ductile damage and failure

PAMM ◽  
2014 ◽  
Vol 14 (1) ◽  
pp. 163-164
Author(s):  
Vanessa Hagenbrock ◽  
Steffen Gerke ◽  
Michael Brünig
Keyword(s):  
Stress Triaxiality ◽  
Ductile Damage ◽  
Lode Parameter ◽  
Damage And Failure

Analysis of Oxygen Exchange Between Arterioles and Surrounding Capillary-Perfused Tissue

1992 ◽  
Vol 114 (2) ◽  
pp. 227-231 ◽  
Author(s):  
R. Hsu ◽  
T. W. Secomb
Keyword(s):  
Theoretical Model ◽  
Flow Rate ◽  
Oxygen Transport ◽  
Continuum Model ◽  
Capillary Flow ◽  
Three Dimensional ◽  
Continuum Approach ◽  
Oxygen Loss ◽  
Tissue Region ◽  
The Continuum

A theoretical model is used to analyze oxygen transport in a three-dimensional tissue region containing an arteriole surrounded by an array of capillaries in planes perpendicular to the arteriole. Convective removal of oxygen from the vicinity of the arteriole by nearby capillaries is shown to increase diffusive oxygen loss from the arteriole. This effect depends on the locations of the capillaries, particularly those nearest to the arteriole. The arteriolar oxygen efflux is comparable to that predicted by a previous model which used a continuum approach, but the efflux does not increase with increasing perfusion as rapidly as predicted by the continuum model. Even a small capillary flow rate strongly influences the oxygen field surrounding the arteriole.

scholarly journals High-fidelity continuum modeling predicts avian voiced sound production

2020 ◽  
Vol 117 (9) ◽  
pp. 4718-4723
Author(s):  
Weili Jiang ◽  
Jeppe H. Rasmussen ◽  
Qian Xue ◽  
Ming Ding ◽  
Xudong Zheng ◽  
...  
Keyword(s):  
Continuum Model ◽  
Sound Production ◽  
Three Dimensional ◽  
High Fidelity ◽  
Terrestrial Vertebrates ◽  
Acoustic Performance ◽  
Tissue Material ◽  
Primary Form ◽  
The Continuum ◽  
Model Approach

Voiced sound production is the primary form of acoustic communication in terrestrial vertebrates, particularly birds and mammals, including humans. Developing a causal physics-based model that ultimately links descending vocal motor control to tissue vibration and sound requires embodied approaches that include realistic representations of voice physiology. Here, we first implement and then experimentally test a high-fidelity three-dimensional (3D) continuum model for voiced sound production in birds. Driven by individual-based physiologically quantifiable inputs, combined with noninvasive inverse methods for tissue material parameterization, our model accurately predicts observed key vibratory and acoustic performance traits. These results demonstrate that realistic models lead to accurate predictions and support the continuum model approach as a critical tool toward a causal model of voiced sound production.

scholarly journals The response of precast concrete segmental columns subjected to near base impact

2019 ◽  
Vol 10 (2) ◽  
pp. 229-250 ◽  
Author(s):  
Xihong Zhang ◽  
Hong Hao
Keyword(s):  
Failure Modes ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Three Dimensional ◽  
Impact Testing ◽  
Lateral Impact ◽  
Damage And Failure ◽  
Segmental Column ◽  
Response Modes ◽  
Different Response

Precast concrete segmental column has attracted many attentions for the past decades due to its unique features especially in improving the construction quality and efficiency. However, the performance of precast segmental column under lateral impact loading has been less studied. Our previous studies performed laboratory pendulum impact tests on scaled segmental columns to investigate their behaviours when impacted at mid-span of the column. This article studies the response of segmental column when impacted near the column base, which generates different response modes and failure mechanisms compared to the columns subjected to the mid-span impact. Lateral impacts are applied either to segmental joint between the two bottom segments or directly onto the centre of the base concrete segment. A detailed three-dimensional numerical model is created and validated with laboratory impact testing results on scaled segmental columns. A full-scale 3-m tall segmental column is then numerically built to study the behaviour under near base impact. The column damage and failure modes are analysed. The influences of prestress level in the post-tensioning tendon and concrete strength on the performance of segmental column subjected to near base impacts are investigated through numerical simulations.

scholarly journals On localization and void coalescence as a precursor to ductile fracture

2015 ◽  
Vol 373 (2038) ◽  
pp. 20140121 ◽  
Author(s):  
C. Tekoğlu ◽  
J. W. Hutchinson ◽  
T. Pardoen
Keyword(s):  
Ductile Fracture ◽  
Void Nucleation ◽  
High Stress ◽  
Three Dimensional ◽  
Stress Triaxiality ◽  
Normal Band ◽  
Void Coalescence ◽  
Softening Effect ◽  
Damage And Failure ◽  
Doubly Periodic Array

Two modes of plastic flow localization commonly occur in the ductile fracture of structural metals undergoing damage and failure by the mechanism involving void nucleation, growth and coalescence. The first mode consists of a macroscopic localization, usually linked to the softening effect of void nucleation and growth, in either a normal band or a shear band where the thickness of the band is comparable to void spacing. The second mode is coalescence with plastic strain localizing to the ligaments between voids by an internal necking process. The ductility of a material is tied to the strain at macroscopic localization, as this marks the limit of uniform straining at the macroscopic scale. The question addressed is whether macroscopic localization occurs prior to void coalescence or whether the two occur simultaneously. The relation between these two modes of localization is studied quantitatively in this paper using a three-dimensional elastic–plastic computational model representing a doubly periodic array of voids within a band confined between two semi-infinite outer blocks of the same material but without voids. At sufficiently high stress triaxiality, a clear separation exists between the two modes of localization. At lower stress triaxialities, the model predicts that the onset of macroscopic localization and coalescence occur simultaneously.

FORMATION AND STABILITY OF A STRONG-COUPLING LARGE BIPOLARON IN THE LIGHTLY DOPED CUPRATES

2005 ◽  
Vol 19 (06) ◽  
pp. 1061-1064
Author(s):  
E. DUSHANOV ◽  
S. DZHUMANOV
Keyword(s):  
Ground State ◽  
Stability Region ◽  
Continuum Model ◽  
Adiabatic Approximation ◽  
Three Dimensional ◽  
Dielectric Constants ◽  
Coulomb Correlation ◽  
Ground State Energies ◽  
Broad Region ◽  
The Continuum

The ground-state energies of large polaron Ep and bipolaron EB in three-dimensional lightly doped cuprates are calculated variationally taking into account the short- and long-range electron-phonon interactions and Coulomb correlation in the continuum model and adiabatic approximation. The binding energy of a large bipolaron and its stability region are determined as a function of the ratio of dielectric constants η = ε∞/ε0. It is found that the large bipolaron is stable in a broad region of η.

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