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Static test for rubber model in LS DYNA  


sajjadganji
Posts: 3
(@sajjadganji)
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Joined: 2 years ago

Im a beginner in the implicit world and looking for any advise about the implicit setup.
I am trying to perform a static load analysis on a rubber part using the material model *MAT_HYPERELASTIC_RUBBER but I am running into failed to find equuilibrium error very often...
I am using Hex elements and have tried element formulations -1 and -2 as recommended by a source from Dynamore. (link - [url] https://www.dynamore.se/en/resources/webinars/tips-and-tricks/LS-DYNA_rubber_modelling.pdf[/url])

The loading rate is 10mm/min and the test is for 3 minutes. So Ive given DTMAX = 180 (seconds), DTMIN = 0.001 and DT0 = 0.1. But not getting the equilibrium. Is this the wrong way?

Further, I came across another source which says that the LS DYNA implicit functionality is not available for *MAT_077. Is this true? In that case, how do we perform the static case?
(Link - [url] https://www.dynasupport.com/howtos/implicit/elements-and-material-models-available-for-implicit[/url])

Thanks in advance.

Best Regards,
Heramb

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Jorgen
Posts: 3874
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(@jorgen)
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Joined: 11 months ago

If you are experiencing convergence problems then my first guess would be that your material model may have an inappropriate set of material parameters. I usually use the [URL= https://polymerfem.com/articles/material-model-calibration/25141-material-model-calibration-abaqus-ansys]MCalibration[/URL] software to calibrate those types of LS-DYNA material models. MCalibration make it easy to ensure that the material model is stable.

-Jorgen

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