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Multiple scattering theory for polycrystalline materials

This work is a natural extension of the author’s previous work: “Multiple scattering theory for heterogeneous elastic continua with strong property fluctuation: theoretical fundamentals and applications” (arXiv:1706.09137 [physics.geo-ph]), which established the foundation for developing multiple scattering model for heterogeneous elastic continua with either weak or strong fluctuations in mass density and elastic stiffness. Polycrystalline material is another type of heterogeneous materials that widely exists in nature and extensively used in industry.

Multiple scattering theory for heterogeneous elastic continua with strong property fluctuation: theoretical fundamentals and applications

Scattering of elastic waves in heterogeneous media has become one of the most important problems in the field of wave propagation due to its broad applications in seismology, natural resource exploration, ultrasonic nondestructive evaluation and biomedical ultrasound. Nevertheless, it is one of the most challenging problems because of the complicated medium inhomogeneity and the complexity of the elastodynamic equations.

Ph.D. Student Positions in Computational Materials Science and Mechanics

Several Ph.D. student positions are available in Professor El-Azab’s group with the School of Materials Engineering, Purdue University. The group performs advanced theoretical and computational research in the areas of mesoscale plasticity and dislocation dynamics, radiation effects in materials, microstructure evolution, phase field method development, and computational methods for materials science and mechanics. Applicants with MS in mechanical, aerospace, or materials engineering, with background in microstructure science, continuum mechanics and elasticity, numerical methods or computational techniques such as finite element method are highly preferred. Knowledge of at least one advanced programming language such as Fortran or C++ is required. Exceptional applicants with BS degree will also be considered. The openings are for spring 2018, summer 2018 and fall 2018. Applicants must meet Purdue University and School of Materials Engineering admission criteria. For inquiry please send email to Professor El-Azab (aelazab@purdue.edu).

Piezoelectric Stack Modelling in ABAQUS

How does one model a piezoelectric stack Actuator in ABAQUS?

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

(in Journal of Elasticity)

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.

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

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.

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