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How does one define Element based surface for a User defined Element?

Dear iMechanica community,

Hi! I am trying to verify Abaqus VUMAT with simple examples so I wrote a VUMAT for orthotropic material and compare the result with Abaqus built-in material model (Elastic -> Engineering constants). The material constants are given in 1.png and 2.png. All other settings from part to mesh is identical. The stress distribution of built-in material model is in 3.png and the stress distribution of VUMAT is in 4.png. The discrepancy is not ignorable. The VUMAT code is also attached as a .txt file.

I have differenet layups for cantilever beams. I run the static riks test from the eigen value in the first software ,giving values of initial arc increment of 0.005, mimumimum arc length increment as 1E-35 , maximum of 1000. The static riks gives good results for the notional loads for layup 30 -30 30 -30. However, keeping all other parameters same but for a different layup 30 -30 -30 30 ,the values from the staic riks are very very far from the experimental results.

Hi,

I am wondering if someone could suggest a good book for learning about creep deformation.

Thanks,

Gyan

Hi I tried to code a basic phase field model for fracture in octave.

It doesn't seem to converge to the correct load. It fails later.

Also mesh refinement did not improve the results.

The link to the GIT is here

https://github.com/dontcallmesuren/Phase-field-modelling.git

Any idea where I am wrong?

Ping me. Thanks in advance.

Hello every body,

I would like to use CDM (continuum damage mechanics) for modeling damage in my constitutive model and I need to incorporate a variable (or its effects) into my mechanical damage that doesn't evolve or change by time but changes by other factors (such as irradiation dose or etc..). Does anyone know of a paper which had been used the similar approach? I would really appreciate it if you can provide the link for me because I couldn't find any so far.

Regards,

Faezeh

Hello,

Does anyone know if Abaqus is able to calibrate/fit Johnson cook material parameters (A B n m & D1-D5) from uniaxial stress-strain curves at different strain rates.

I have these uniaxial stress-strain curves at different strain rates but i dont know how to generate the johnson cook parameters. Also i want to know how Johnson Cook is handeling different E-modules at different strain rates. I`m working with fiber reinforced thermoplastic which has different stiffness at different strain rate.

Appreciate you urgent help!

Best regards