Stress Triaxiality in ABAQUS

**Kumar Kurambakurash** · 2009-11-14, 07:27

Originally Posted by unsrohith

Hi Kumar,

I work with steel and mostly on isotropic materials (MISES). My codes are based on small deformation Hypo elasto plastic formulation. I won't use any large deformation terms like def grad, rotation tensors (R,V,U etc). But I am planing to implement them in future. I studied about anisotropic damage way back, but I am currently using isotropic damage because of its simplicity and easiness in implementation.

Can you tell something about your field..

regards,
Rohith

Hi Rohiht,

Thanx for the prompt response,

I have developed codes for damage coupled isotropic hyperelastic-plasticity with thermal effects also. I have seperately worked on anisotropic plasticity models (both 3D and plane stress) utilizing hypoelastic plasticity (co-rotational formulations) and written some subroutines which are now tested for industry.

Currently I am after developing anisotropic damage extensions.

I'd like to hear details on your damage anisotrpoy approach. Which references are you primarily following within this regard?

Best

Kumar

**unsrohith** · 2009-11-15, 13:52

Originally Posted by Kumar Kurambakurash

Hi Rohiht,

Thanx for the prompt response,

I have developed codes for damage coupled isotropic hyperelastic-plasticity with thermal effects also. I have seperately worked on anisotropic plasticity models (both 3D and plane stress) utilizing hypoelastic plasticity (co-rotational formulations) and written some subroutines which are now tested for industry.

Currently I am after developing anisotropic damage extensions.

I'd like to hear details on your damage anisotrpoy approach. Which references are you primarily following within this regard?

Best

Kumar

Hi Kumar,

Strictly speaking, I haven't learned plasticity particularly with names Hypo or Hyper etc. What my prof taught is classical plasticity from HILL with small deformation .I don't know much about hyper elastic based models. I think it involves the large deformation principles R, U and def gradiants Correct me if I am wrong.

The plasticity which I have learned and practicing currently is based on small deformations. And my damage code is coupled to this model.

I just need some references to understand "damage coupled isotropic hyperelastic-plasticity with thermal effects" ..Can you send me some references u have used to develop the code..

I worked on anisotropic damage formulation involving mixed hardening model 1 year back. I still have the formulation. But I haven't code it because of its involvement in more experimental data and complexity.
I followed Prof C. L Chow references a lot...
Still there are lot of unanswered questions in this area like
The condition for critical damage when you say damage is anisotropic etc I feel...
After that I haven't updated my knowledge in that area.

**Kumar Kurambakurash** · 2009-11-19, 12:58

On thermo-coupled damage framework there are not much indeed.

I will turn back to this subject in the morning and try to send you mention on some references when I go to the institute tomorrow morning.

**Kumar Kurambakurash** · 2009-11-19, 13:02

I'd like to see your derivations for the algorithmic portion regarding Chow's approach. I think that once one takes into account anisotropic damage, principal damage values should be utilized in comparison with the damage threshold.

Do you take anisotropic damage rate at the identical eigenvector space of stress rate or plastic strain rate?

**unsrohith** · 2009-11-20, 00:31

Originally Posted by Kumar Kurambakurash

I'd like to see your derivations for the algorithmic portion regarding Chow's approach. I think that once one takes into account anisotropic damage, principal damage values should be utilized in comparison with the damage threshold.

Do you take anisotropic damage rate at the identical eigenvector space of stress rate or plastic strain rate?

Hi Kumar,

Do you take anisotropic damage rate at the identical eigenvector space of stress rate or plastic strain rate..

I didn't get this exactly. I doubt whether I am answering your question..

My derivation is a collection from PROF CHOWS papers. I haven't added anything new in that but derived in a systematic fashion after going through around 10 of his papers..

Actually I have them in hard copy. Regarding critical damage Chow has assumed a Z function which intern will be a function of principles damage values, but this is his assumption But physically I feel there is no strong evidence for this. Infact i think that similar to equivalent plastic strain or stress one can think of a scalar quantity like equivalent damage (but how to calculate this???) would be a better option for comparison with critical damage_experimental.

Regarding your query, related to damage rate.. Damage growth law comes from the damage potential which is a function of damage strain energy release rate which intern is a function of stress tensor and intern the multiplier D-LAMBDA comes from plastic consistency and will involve equivalent plastic strain rate..

Regards,
Rohith