# mechanician

## Professor Thomas JR Hughes Elected to the Grade of Distinguished Member of ASCE- USA.‏

Professor Thomas JR Hughes Elected to the Grade of Distinguished Member of ASCE- USA.

## Strain calculation in ABAQUS

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Hello,

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?

## 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.

## Isogeometric

Hi Dears:

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

thanks

## 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!

## Potential surface and yield surface

Hello,

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.

-Shivani

## 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 ??

## 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??

## [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.

## 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.

## 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

## Non Linear Analysis Ansys

When Working on Ansys Non Linear Static Structural Analysis, I couldn't comprehen while defining and assigning material properties to corrosponding bodies.

When I give different random values for density in Engineering Data and runing the jobs parallely the results look SIMILAR for all the independent values, I couldn't fish out on what basis do the software is giving out results.