The essential assumption of Cauchy Stress

is the existence of the limit  (\Delta f)/ (\Delta A) as  \Delta A-->0. 

This means that a infinitesimal small area can only sustain infinitesimal

small surface force. Therefore in the framework of conventional continuum

mechanics, we can only talk about the "force density (stress)" at a point.

The expression int_A (f.n)dA has no physical meaning. Only int_A (stress.n)dA

can give the total force exerting on a closed surface A.

In the attached paper, we propose a procedure combining an XFEM/level-set technique and Gurtin-Murdoch surface elasticity to model nanostructures with arbitrary geometries. The effects of free surface which are dominant at small scales are easily captured in this framework.

Dear All,

 I was wondering whether anyone here knows any companies or institutions which can supply the complete Split Hopkinson Pressure Bars apparatus.

 Thanks for your input!

 Luming

Hi all

1. How to Compute the first three natural frequencies of vibration of cantilever beam?

2. How to Compute the first three natural frequencies of vibration of simple support beam?

3. What is Euler column formula?

http://arxiv.org/PS_cache/arxiv/pdf/0903/0903.5321v1.pdf



The above article is an April Fool's joke. It reminded me of the recent "discoveries" in the mechanics community regarding stress tensor.



Regards,

Arash

During Fatigue temperaure of materials increases due to plastic deformation.  I am trying to calcualte plastic dissipation in UMAT and use it as heat source in HETVAl to get temperature rise.  I do not know how to add plastic dissipation calculation in UMAt.  I am wondering if some body  give me an example which is done close to what I want to do.

Hi everyone,

Now I am trying to implement Ogden model in Comsol Multiphysics, but I had some problem.

Then I realized that in Comsol, it's possible to implement a nonlinear young's modulus.

But I am a little confused.

If you have a nonlinear Young's modulus, in the stress-strain curve, E is the tangent of this curve.

For hyperelastic material, let's say Ogden material. It's usually a nonlinear stress-strain curve as well.

I am trying to combine UMAT and UEL in my Abaqus calculation to simulate crack propagation by using a damage criterion. My UMAT calculates the damage variable in each time increment and whenever the damage variable violates the damage criterion in one or more elements, I should seperate the damaged element(s) via XFEM theory which can be implemented into a UEL code; therefore, I should use both UMAT and UEL in my calculation. Is there any way to combine these two codes together?