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R.Mehrabi's picture

A thermodynamically-consistent microplane model for shape memory alloys

In this paper, a macroscopic model in a thermodynamically-consistent framework for shape memory alloys is proposed.

Baohong Chen's picture

Stretchable and Transparent Hydrogels as Soft Conductors for Dielectric Elastomer Actuators

       A soft ionic conductor can serve as an artificial nerve in an artificial muscle. A polyacrylamide hydrogel is synthesized containing a hygroscopic salt, lithium chloride. Two layers of the hydrogel are used as ionic conductors to sandwich a dielectric elastomer and fabricate a highly stretchable and transparent actuator. When the two layers of the hydrogels are subject to a voltage, the actuator reduces its thickness and expands. An areal strain of 134% is demonstrated.

linear hyperelastic material model??

The St. Venant-Kirchhof, Neo-Hookean are nonlinear for finite deformation (finite strain).

The St. Venant-Kirchoff is only linear in Lagrangian frame, as the 2.PK S stress is "linear" w.r.t. Green-Lagrange strain G. But the relationship of true stress and true strain (Cauchy stress and Almansi strain) is highly nonlinear in the Eulerian frame. 

Question 1:

Why do we always say that the material is linear? Is there any material model linear? What is about Biot stress or Biot strain energy?

Question 2:

Chris Yakacki's picture

Journal Club: Overcoming Challenges in Mechanically Actuating Liquid-Crystalline Elastomers

Smart materials are designed to have a controlled response to external stimuli. Shape-memory polymers (SMPs) are one of the most well known classes of mechanically active smart materials and have experienced an incredible amount of research attention over the last decade. They are able to recover programmed deformations when heated above a thermal transition; however, are generally considered a one-time event. Liquid-crystalline elastomers (LCEs) are another class of actively moving polymers; however, these materials can demonstrate reversible and repeatable shape memory without the need for “re-programming” after each actuation cycle.

shear correction factor in laminated composite plates

Dear friends

Hello

How can I calculate shear correction factor in laminated composite plates?

 

Best regards.

Xiujun Fang's picture

Job position at GEM in Princeton, NJ

Global Engineering and Materials, Inc. (GEM) is looking for candidates to fill a position of Research Engineer. Please refer to the attached file for detailed information. Thanks!

post-doctoral position in the following areas: blood compatibility and design/development of blood contacting medical devices - University of Maryland

The Artificial Organs Laboratory at the Department of Surgery of the University of Maryland seeks highly motivated individuals for a post-doctoral research associate position in the following areas: blood compatibility and design/development of blood contacting medical devices. The lab is conducting applied cardiovascular research, engaged in research and development of blood-contacting artificial organs and biologic responses to these devices.

Need help in orthogonal machining

Hello All,

I am Ganesh, trying to simulate 2D othogonal machining. But in simulation, the chip is not seperating from the rake face of the tool. 

can any body tell me how to resolve this problem.

 

Thank you in advance.

 

Polyurethane material model

I need help for material data for modeling Polyurethane material used in finite element ABAQUS software package.

 

 

 

Professor of Mechanics

The Department of Mechanical and Process Engineering (www.mavt.ethz.ch) at the ETH Zurich invites applications for a full professorship in Mechanics.

Isotropic Hardening VUMAT Problem

Hi All,

      I have a problem of an Expression of the VUMAT for Isotropic hardening code. part of the code is as follows.

subroutine vumat(

c Read only -

     1  nblock, ndir, nshr, nstatev, nfieldv, nprops, lanneal,

     2  stepTime, totalTime, dt, cmname, coordMp, charLength,

     3  props, density, strainInc, relSpinInc,

     4  tempOld, stretchOld, defgradOld, fieldOld,

     5  stressOld, stateOld, enerInternOld, enerInelasOld,

     6  tempNew, stretchNew, defgradNew, fieldNew,

WaiChing Sun's picture

Symposium on Geomaterials: Poromechanics and Failure at EMI International Conference, Hong Kong January 7-9,2015

Dear Colleagues, 

We are currently organizing a Symposium on Geomaterials: Poromechanics and Failure, for the upcoming EMI International Conference  "Mechanics for Civil Engineers Against Natural Hazards" in Hong Kong Polytechnic University, Hong Kong, from January 7th to 9th, 2015. 

We would like to invite submission for abstracts on modeling, characterization, and experimental studies on geomaterials for disaster prevention (landslides, earthquake) and for problems related to new energy applications (e.g. fracking, induced seismic events). 

jenda_z's picture

Modeling of Localized Inelastic Deformation 2014

Dear colleagues,

I would like to bring to your attention the advanced course on Modeling of localized inelastic deformation that will be taught by Milan Jirasek in Prague, Czech Republic on 15-19 September 2014. More detailed information on the course is posted at http://mech.fsv.cvut.cz/~milan/course2014.html. We are looking forward to seeing you in Prague!

How to put concrete in a brb(Buckling restrained brace) in Abaqus?

hi every body
I model a brb(Buckling restrained brace) in Abaqus but my question is How to put concrete in a brb or How do I define the concrete inside the brb that work together?
thanks

Charles Augarde's picture

Postdoc position in computational geomechanics at Durham University

We have EPSRC funding for a 39 month project modelling seabed ploughing (for cable and pipeline installation) starting in October 2014. We are recruiting two postdocs one in computational geomechanics (based at Durham, details here, closing August 4th) and another in experimental geomechanics (based at Dundee, details here).

coriolis load in linear perturbation analysis with Abaqus

Hi!

I am trying to perform a linear perturbation analysis with Abaqus, on a mechanism which is affected by the coriolis force.

brifely describing, I have a Mass which is vibrating (at its natural frequency), let's say along x direction on a plane, and the plane and mass together are rotating along y direction. so due to the coriolis effect the mass should have a vibration along the z idrection out of the plane .

Pradeep Sharma's picture

Society of Engineering Science Call for Award Nominations

 

The Society of Engineering Science (SES) oversees several awards and honors to members and eminent scholars of the field. A total of five medals are offered on an annual basis as well as election to Fellow grade of the Society. The awards are: A.C. Eringen Medal, Engineering Science Medal, William Prager Medal, G.I. Taylor Medal and the SES Young Investigator Medal.

jiangyuli's picture

Ferroelectric Switching of Elastin

Please see our recent paper in PNAS if you are interested.

doi:10.1073/pnas.1402909111

http://www.pnas.org/content/early/2014/06/18/1402909111.abstract

One time calculation in UEL

Dear All,

I'm a new UEL user. In my UEL I have a big Matrix which eigenvalues and eigenvectors of these matric is needed. the matrix is not changing during the time and it has constant elements. As you may know, calculating eigenvalues and eigenvectors is a time consuming procedure. In every time incerement, ABAQUS calculating eigenvalues and eigenvectors with bunch of other things in UEL.

Assistant / Associate Professor in Mechanical Engineering, Heriot-Watt University, Edinburgh, UK

The School of Engineering and Physical Sciences seeks to make two or more academic appointments to extend and enhance one or more of the core research elements in the Institute of Mechanical, Process and Energy Engineering (IMPEE).

Bo Li's picture

Electromechanical deformation of dielectric elastomer in two types of pre-stretch

A pre-stretched dielectric elastomer is capable of large deformation, when subject to voltage. This paper investigates the effect of two types of pre-stretch: by strain and by stress. The difference is compared and discussed using thermodynamics models. The significance of the pre-stretch in actuation is explained by examining the true stress in actuation. Under both pre-stretch strategies, during the actuation, the dielectric elastomer exhibits hysteresis loops due to snap-through but differs in shape and physical quantity.

Computational Methods in Engineering: A Variety of Primal & Mixed Methods, with Global & Local Interpolations, for Well-Posed or Ill-Posed BCs

Computational Methods in Engineering: A Variety of Primal & Mixed Methods, with Global & Local Interpolations, for Well-Posed or Ill-Posed BCs

by L. Dong, A. Alotaibi, S.A. Mohiuddine, S. N. Atluri

This paper can be freely downloaded at: http://care.eng.uci.edu/pdf/Dong2014a.pdf

And all the MATLAB codes for various computational methods are available at: http://care.eng.uci.edu/pubs.htm

Arash_Yavari's picture

Three interesting, recent books

Dear friends:

I’d like to bring to your attention three recently published books that I have read. The following are a few words about each book in the order that I read them.

1) “Vito Volterra” by A. Guerraggio and G. Paoloni
http://www.amazon.com/Vito-Volterra-Angelo-Guerraggio/dp/3642272622/ref=...

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