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Timoshenko Lectures

Listed in this post are the speeches given upon receiving the Timoshenko Medal.  Every November, at the Annual Applied Mechanics Dinner, the medalist of the year delivers a speech. Taken together, these speeches provide a long perspective of our field, as well as capsules of the lives of extraordinary individuals.

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Strain calculation in ABAQUS

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I have some troubles in calculating the strain in ABAQUS. I have the following Model with one element (see picture) and a linear elastic isotropic Material (Steel), which is sheared in the x-direction. The analytical result of the strain tensor gives me in xz-direction 0.25 (see picture). The result in ABAQUS is 0.5. I ran the same simulation in CalculiX CrunchiX and got the expected strain of 0.25 in the xz-direction

Can anyone tell me how ABAQUS calculates the strain for a linear static analysis? Why is the ABAQUS result exactly 50% higher?

SavanRGowda's picture

Abaqus DISP Subroutine

Hi everyone!! 

I am a student studying in Hamburg University of Technology. I am currently doing my thesis and want some help in finishing it. I am finding it a bit difficult to do subroutine in Fortran as I am new to it. I have tried learning from Abaqus Documentation but I didn't get answer to my needs. 

tigerofmahdi's picture


Hi Dears:

what is the solution when the jacobian in IGA Matlab code be zero??


Details about hydrogel mechanical test

Dear all,

I have some questions about hydrogel mechanical test. After curing, should i put samples in water (submerge in water) or not? I found there's big difference between same samples with different water content. Also, I can't get the tentile strength similar with literature with same materials. My tensile stress is more than 10 times smaller. I really don't know what did I miss.

I would greatly appreciate any help. Thank you!


tigerofmahdi's picture

Hi Dears

What is the difference between elastic wave and vibration?


Potential surface and yield surface


Would you please tell me the basic difference between potential plastic surface and yield surface with a physical meaning, if possible. I know that if both the surfaces match, then it is associated flow-rule, otherwise it is a non-associative flow rule.

I know that this is a very basic question, but I am facing difficulty in completely understanding it.


Thanks in advance.


tigerofmahdi's picture

Temperature dependent material

Hi Dears and of course metallurgist.

Who person can tell me the relation between the material properties such as Yang modulus, density, thermal coefficient etc. and temperature??

All of properties follow from one relation to temperature? For example if E(T)=Ea+100T then the density and another property have the same relation like P(T)=Pa+100T ??



tigerofmahdi's picture

Elastic wave propagation

Hi Dears:

Who works on Elastic wave propagation and its reflection? How I can fine the formolations of elastic wave after its reflection from arbitrary boundaries ?? Can you intruducing any refrences to me??

qieasa's picture

[Help] How to define a variation of volume during a phase change in Abaqus?

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Dear friends,

I am a beginner in using Abaqus. Now I am doing a project which calls for a simulation of the phase change probleme (two demensional Stephan problem).

I did a simple simulation with water, more prescisely a water slab of 10 C at the left I impose a temperature -10 C, so I got the results of the profils of temperature in every increment of time. 

Jianliang Xiao's picture

Professor John Rogers elected to NAS

Professor John Rogers, Swanlund Chair Professor of Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, was recently elected to the National Academy of Sciences. Congratulations to John!

Here is the link to the NAS press release:

Rui Huang's picture

Ken Liechti will receive the 2015 Adhesion Society Award for Excellence

Professor Kenneth M. Liechti of the University of Texas at Austin has been selected to recieve the 2015 Award for Excellence in the Adhesion Society. The Adhesion Society’s Award for Excellence, sponsored by 3M, is the Society’s premier award for outstanding achievements in scientific research relating to adhesion.

Rui Huang's picture

K. Ravi-Chandar will recieve the 2015 Drucker Medal

Professsor Krishnaswamy Ravi-Chandar of the University of Texas at Austin has been selected to receive the 2015 Daniel C. Drucker Medal, one of the ASME society awards for achievement.

Call for Gallagher Young Investigator Nominations

The US Association for Computational Mechanics (USACM) is calling for nominations for the Gallagher Young Investigator Medal.  The description from the USACM Awards page reads:

Weijie Liu's picture

How to understand the oscillating behaviour during calculating stress

Dear all,

Why we have an oscillating behaviour when calculating stress in FEM?

I saw the sentences in the paper:

'Another reason is that stresses are less accurately predicted than strains in FE simulations. Calculated stresses do also show a tendency for an oscillating behaviour, especially in dynamic explicit simulations.'

'stress is less accurate predicated than strain' is easier to understand, but I was wondering the existence of oscillating behaviour for calculating stress.


Any comments are welcome.

tigerofmahdi's picture

weighted residual

Hi dears:

why weighted residual is equal to zero ?? why integration of residual multiply by a weight function, over it's domain is equal to zero??

Anisotropic stiffness of isotropic material

Dear colleagues,


Consider a simple non-linear elastic material with stress given as

σ = D(εdev) εdev + B εiso

where εdev is the norm of εdev, D is a function of εdev and B is constant. The material is isotropic since the principal directions of  σ and ε will coincide.

If we differentiate σ wrt ε to obtain the material stiffness the form of the stiffness tensor will be

Professor Wei Lu Received the 2014 Gustus L. Larson Memorial Award

Professor Wei Lu received the 2014 Gustus L. Larson Memorial Award. This award was presented to Dr. Lu by the president of ASME, jointly with the president of Pi Tau Sigma, during the 2014 ASME International Mechanical Engineering Congress & Exposition. 

Pradeep Sharma's picture

Reminder (Deadline, Dec 5th): Call for Nominations for the Eshelby Mechanics Award for Young Faculty

It is my pleasure to solicit nominations for the "Eshelby Mechanics Award for Young Faculty". This award, launched in 2012, is given annually to rapidly emerging junior faculty who exemplify the creative use and development of mechanics. The intent of the award is to promote the field of mechanics, especially among young researchers. While interdisciplinary work that bridges mechanics with physics, chemistry, biology and other disciplines is encouraged, the ideal awardee will demonstrate clear inspiration from mechanics in his/her research.

Ted Belytschko passed away

It is with great sadness that we post this entry.  Ted Belytschko passed away early this morning, 15 September 2014.  


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