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Journal Club for October 2017: Multiscale modeling and simulation of active matter

Tong Gao

Department of Mechanical Engineering and Department of Computational Mathematics, Science, and Engineering, Michigan State University

 

Introduction

Sundaraelangovan selvam's picture

In 1D wave propagation problem, how to find the curl of a given source function?

Choose a channel featured in the header of iMechanica: 

I am trying to solve 1-D wave equation by calculating potentials ϕ

Amit Acharya's picture

On Weingarten-Volterra defects

Amit Acharya

The kinematic theory of Weingarten-Volterra line defects is revisited, both at small and finite deformations. Existing results are clarified and corrected as needed, and new results are obtained. The primary focus is to understand the relationship between the disclination strength and Burgers vector of deformations containing a Weingarten-Volterra defect corresponding to different cut-surfaces.

Antonio Papangelo's picture

Discussion of “Measuring and Understanding Contact Area at the Nanoscale: A Review” by Tevis D. B. Jacobs and Ashlie Martini

M. Ciavarella(1) and A. Papangelo(2)

(1) Politecnico di BARI, Center of Excellence in Computational Mechanics, Deparment of Mechanics, Mathematics and Management. Viale Gentile 182. 70125 Bari (Italy)

(2) Hamburg University of Technology, Department of Mechanical Engineering, Am Schwarzenberg-Campus 1, 21073 Hamburg, Germany

michele.ciavarella@poliba.it, antonio.papangelo@poliba.it

Bin Liu's picture

How to Realize Volume Conservation During Finite Plastic Deformation

Volume conservation during plastic deformation is the most important feature and should be realized in elastoplastic theories. However, it is found in this paper that an elastoplastic theory is not volume conserved if it improperly sets an arbitrary plastic strain rate tensor to be deviatoric. We discuss how to rigorously realize volume conservation in finite strain regime, especially when the unloading stress free configuration is not adopted in the elastoplastic theories.

Amir Abdollahi's picture

Mechanical Reading of Ferroelectric Polarization

The mechanical properties of materials are insensitive to space inversion, even when they are crystallographically asymmetric. In practice, this means that turning a piezoelectric crystal upside down or switching the polarization of a ferroelectric should not change its mechanical response. Strain gradients, however, introduce an additional source of asymmetry that has mechanical consequences.

On the origins of the electro-mechanical response of dielectric elastomers

Recent theoretical works have shown that the electro-mechanical performance of dielectric elastomers can be enhanced through micro-structural design.

Shuze Zhu's picture

Metallic and highly conducting two-dimensional atomic arrays of sulfur enabled by molybdenum disulfide nanotemplate

https://www.nature.com/articles/s41524-017-0041-z

Element sulfur in nature is an insulating solid. While it has been tested that one-dimensional sulfur chain is metallic and conducting, the investigation on two-dimensional sulfur remains elusive. We report that molybdenum disulfide layers are able to serve as the nanotemplate to facilitate the formation of two-dimensional sulfur.

 

Time Integration scheme for non constant M, C and K matrices?

Can anyone suggest a time integration scheme for non constant mass (M), stiffness(K) and damping (C) matrices? I am trying to solve a dynamic system (Ma+Cv+Ku=R) where the matrices M,C and K are time dependent.

 

Any thoughts/ideas will be highly aprreciated. Thank you. 

Time integration scheme for XFEM? (dynamic crack propagation)

Hello everyone,

 

Can somebody suggest an implicit/explicit time integration scheme when the matrices involved(M,C,K) are time dependent? (They change at every time step because of the crack tip enrichment functions which are time dependent).

 

I used the implicit Newmark scheme (trapezoidal/constant average acceleartion method) but just discovered that all my matrices (M,C,K) are time dependent where the original scheme is probably for constant M,C and K matrices. I used the scheme as in reference [1]. 

 

keyhani's picture

A comprehensive investigation of natural convection inside a partially differentially heated cavity with a thin fin using two-set lattice Boltzmann distribution functions

Natural convection occurs in many engineering systems such as electronic cooling and solar collectors. Nusselt number (Nu) is one of the most important parameters in these systems that should be under control. This investigation is a comprehensive heat transfer analysis for partially differentially heated cavities with a small thin fin mounted on the hot wall of the cavity to increase or decrease the Nu. A Boussinesq approximation was utilized to model the buoyancy-driven flow.

mohsenzaeem's picture

Role of grain boundaries in determining strength and plastic deformation of yttria-stabilized tetragonal zirconia bicrystals

Mechanical properties of yttria-stabilized tetragonal zirconia (YSTZ) bicrystals under compressive loading are investigated by atomistic simulations. Previous studies on deformation of single-crystal YSTZ showed that some specific orientations promote dislocation emission, tetragonal to monoclinic phase transformation, or both. In this work, nanograins with different orientations are selectively combined to generate bicrystals with various grain boundaries (GBs).

Jingjie Yeo's picture

International Journal of Computational Materials Science and Engineering (IJCMSE)

As the Editorial Board member of IJCMSE, I enthusiastically welcome the high quality submissions from the community of iMechanica. The objective of the journal is the publication and wide electronic dissemination of innovative and consequential research in all aspects computational materials science and engineering, featuring the most advanced mathematical modeling and numerical methodology developments.

chenlei08's picture

Understanding cementite dissolution in pearlitic steels subjected to rolling-sliding contact loading: A combined experimental and theoretical study

Cementite dissolution behavior of pearlitic steels subjected to rolling-sliding contact deformation is comprehensively investigated by combining experimental characterization and phase-field modeling.

Fracture Mechanics Parameters Calculation

I'm working on Fracture Mechanics of Gravity dams using ANSYS Software.

Chiqun Zhang's picture

Finite element approximation of the fields of bulk and interfacial line defects

Chiqun Zhang            Amit Acharya            Saurabh Puri

A generalized disclination (g.disclination) theory [AF15] has been recently introduced that goes beyond treating standard translational and rotational Volterra defects in a continuously distributed defects approach; it is capable of treating the kinematics and dynamics of terminating lines of elastic strain and rotation discontinuities. In this work, a numerical method is developed to solve for the stress and distortion fields of g.disclination systems. Problems of small and finite deformation theory are considered. The fields of a single disclination, a single dislocation treated as a disclination dipole, a tilt grain boundary, a misfitting grain boundary with disconnections, a through twin boundary, a terminating twin boundary, a through grain boundary, a star disclination/penta-twin, a disclination loop (with twist and wedge segments), and a plate, a lenticular, and a needle inclusion are approximated. It is demonstrated that while the far-field topological identity of a dislocation of appropriate strength and a disclination-dipole plus a slip dislocation comprising a disconnection are the same, the latter microstructure is energetically favorable. This underscores the complementary importance of all of topology, geometry, and energetics in understanding defect mechanics. It is established that finite element approximations of fields of interfacial and bulk line defects can be achieved in a systematic and routine manner, thus contributing to the study of intricate defect microstructures in the scientific understanding and predictive design of materials. Our work also represents one systematic way of studying the interaction of (g.)disclinations and dislocations as topological defects, a subject of considerable subtlety and conceptual importance [Mer79, AMK17].

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