Discussion Forum

Hello Yalcin,
In a nutshell, we wanted to implement many additional nonlinear material laws but also realized that many users of the Structural Mechanics Module and MEMS Module did not need nonlinear material laws and did not want to pay for that development effort. Offering a separate module for Nonlinear Structural Materials gives our customers the choice whether or not to provide us the resources to pursue our development efforts in that area. This also gives us a chance to implement many exciting news features into the Structural Mechanics Module and the MEMS Module (See www.comsol.com/products/4.3/#structuralmechanics and www.comsol.com/products/4.3/#mems for details on these new capabilities) without raising these products' prices.
Best regards,
JF

Hello Jean,

thank you for the reply. I understand that. But at least the standard structural mechanics module should continue to support the existing nonlinear models. Otherwise, it make nonsense to bring restrictions to given rights in previous versions! As it is not something new, why should I then pay for development!

Regards
Yalcin

Hi again,

- If your license of either the Structural Mechanics Module or the MEMS Module was on subscription at the time of the release of version 4.3, you automatically received the Nonlinear Structural Materials Module with version 4.3, free of charge.

- If you were satisfied with those nonlinear material laws implemented in either the Structural Mechanics Module or the MEMS Module at version 4.2a, you can continue using that version. It is absolutely possible to have both version 4.2a and 4.3 installed on the same machine at the same time.

JF

You are right! I take back my complain. I hope in the future Nonlinear Material Model will be much more sophisticated for advances uses :)

We'd love to hear what specific material laws you would like to see added to the Nonlinear Structural Materials Module.
JF

How can I implement the plasticity in comsol (without Nonlinear Structural Materials Module)?
Are there any example models?
How can I define my gauss-point state variables (scuh as plastic strains) and how can I integrate these state variable?

Specifically I would like to implement a special plasticity (which is called as phase transformation induced plasticit or TRIP). This is very similar to classical plasticity, ie the plastic strain rate is proportional to stress-deviator except that in TRIP, the phase transformation rate is also a multiplier without yield creiteria.

Phase transformation rates are computed seperately in other physics.

I am looking for an example model where the plasticity in manually implemented.

regards
Yalcin Kaymak

I found current Nonlinear Structural Materials Module not so useful in two aspects:

+ It does not allow us to obtain material paramters, i.e. fit a material model to specific test data.
+ It has only simple material models which are not so useful for industrial calculations. I have recently used Three Network Model (by Bergstrom at Veryst Eng.) for polymers and I had to implement this model in COMSOL on my own.

Chien

Hi Chien,

Good to hear that you implemented Bergstrom’s Three Network Model in COMSOL!

I just want to let you know that we are working on making our material calibration software MCalibration work with COMSOL. That way you can use it to calibrate/fit any of the material models in the Nonlinear Structural Module to your specific test data. You should also be able to use it to calibrate any material models that you implement directly using COMSOL’s powerful PDE/ODE capabilities.

Nagi Elabbasi
Veryst Engineering

Yalcin, I realize your question is several months old, but there is a very good example on how to implement specialty plasticity models in COMSOL. It’s Model ID 4488 from the COMSOL model gallery titled “Viscoplastic Creep in Solder Joints”. Make sure you download that example for the 4.2 version or earlier because back then that material model was not available internally to COMSOL and had to be defined as a PDE.

Nagi Elabbasi
Veryst Engineering

Hi Nagi,

It's good to hear that MCalibration will work with COMSOL. Can't wait to see that.

Chien