Learning Forum

[lantonini]

Hello!

I am trying to perform a simulation where a metal blade (rigid body) penetrates a hyperelastic tissue (Ogden model). To represent the damage of the tissue while preserving the initial mass, I modeled the part that comes into contact with the blade using the SPG section (KERNEL = 1; ITB = 3; ISC = 1). I have tried to include material failure both through the SPG section using the IDAM variable, and through the *MAT_ADD_EROSION keyword.

However, the simulation results do not seem sensitive to the values I input for material failure: the blade penetrates deforming and cutting the SPG part even when I disable material failure.

What could be the explanation for this behavior?

Thank you very much in advance.

[Ram Gopisetti]

Hi Lantonini, 

Let's first check the material model, I am assuming MAT_077_O here, if yes we do support this material model but it's not fully validated with FEA. So expect some differences in behavior and results. 

It is recommended to use *MAT_ADD_DAMAGE_GISSMO rather than *MAT_ADD_EROSION as SPG only supports *MAT_ADD_DAMAGE_GISSMO with R15. However, MAT_ADD_EROSION can turn on GISSMOfrom R14.1 but after R15 it has to be correctly defined to be MAT_ADD_GISSMO 

It is also recommended to use dtye.ne.0, GISSMO damage model to work. The failure process is not controlled by SPG. The failure phenomena in SPG part is the result of particle deformation. Additionally, you need to set IDAM =0 and set FS to a large value along with MAT_ADD_GISSMO to drive failure based on the failure card or switch off this card and only set FS and Stretch values 

So, please check by either disability one option and post the results here to know what's happening and please use R15 and up for consistency.

Cheers, Ram 

 

 

 

[lantonini]

Hi Ram, 

Thank you very much for your response.

I am using MAT_077_O, but I am considering simplifying the model by adopting an elasto-plastic material.

Currently, I am running the simulations with R14. How can I upgrade to R15 to run the tests you suggest?

Cheers