Learning Forum

[valerym.m5]

Dear colleagues,

 

I'm solving problems involving the deformation of parts made of hyperelastic materials with viscous properties.

 

I'm using TNV and Three-Networks models from the PolyUMod  library.

 

Has anyone used these models to simulate the failure of parts made of these materials?

 

Regards Valery

[Ram Gopisetti]

Hi, 

By default, all models from the PolyUMod Library, including TNM and TNV, do not provide failure modelling.

To enable failure capture, MAT_ADD_GISSMO or MAT_ADD_EROSION must be used in conjunction with these models.

Kind regards,
Ram

[valerym.m5]

 

 

Dear Ram,

haven’t used MAT_ADD_GISSMO or MAT_ADD_EROSION for TVM model before.

 

I would be very grateful if you could recommend blogs and/or videos on how to use MAT_ADD_GISSMO or MAT_ADD_EROSION specifically for TVM model.

 

I would be happy to confirm that the mentioned MAT_ADD_GISSMO or MAT_ADD_EROSION functions correctly when using the TNV model.

Please clarify:
Are "MAT_ADD_GISSMO or MAT_ADD_EROSIO" valid for hyperelastic materials with viscous properties?

 

Regards   Valery

 

 

[valerym.m5]

 

 

I seem to have solved a simple test problem—uniaxial tension of a flat specimen with failure—using the aforementioned method.

Quick Calibration of a PolyUMod Failure Model to Experimental Data
https://www.youtube.com/watch?v=Qd1Pvqh20vE                                                                                    

 

*** I’m using LS-Dyna and Polyumod 2022.

 

I’m seeing some issues:

 

1. When using the TNV model, LS-Dyna doesn’t record, or records incorrectly, deformations and displacements for the entire model.

That is, zero values ​​are returned if I try to plot graphs and then write the values ​​to a file.

 

2. Visualization issues:

 

- Visualization of the deformed model is possible before resolution, but if I try to display deformations or displacements for a single point, all values ​​will be zero.

 

- After failure begins, visualization of the ENTIRE model is impossible.

 

Despite the lack of deformation and displacement results in the database, the calculation itself—up until failure—results in a realistic model (like a full-scale experiment and the results of calculating and calibrating the constants).

 

*** I have some assumptions/hypotheses:

 

When solving problems, LS-Dyna incorrectly records the values ​​of some variables for this model in the database or records them in a way that the postprocessor “doesn’t see.”

 

The stress graphs constructed from LS-Dyna calculations are very similar to reality.

 

I solved the same model using an abacus without any problems —the calculation results are very similar.

 

 

 

 

 

[valerym.m5]

when the destruction of elements begins, the integration time step decreases by 15 orders of magnitude

 

[valerym.m5]

 

Dear Ram,

I would be very grateful if you could tell me:

How can I obtain the following information for models from the PolyMod library:

 

1. Viscous deformation

2. Absorbed energy due to viscous properties.

Regards   Valery

 

[valerym.m5]

I've run several test simulations using MAT_ADD_EROSION (the SIGP1 Maximum Principal Stress at Failure failure criterion).

The crack formation locations and shape are very similar to the results of the full-scale experiments.

However, the subsequent crack propagation and failure of the part are completely different from the full-scale experiment.

I would be grateful for your advice and comments.