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Drucker's stability check of MCalibration

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Joined: 3 years ago

Hello Jorgen,


I have a question regarding the stability check of hyperelastic model in MCalibration.


For example, I chose a neo-hooken material with C10=1 and D1=0.02. In the Drucker's stability check of MCalibration, it is shown that the material model with that particular parameters stable except for the simple shear deformation mode---which is unstable for strains larger than 5.85983e-07.

However, the MCalibration Drucker's stability check is inconsistent with two observations I found.

(1) I set a virtual experiments of simple shear in MCalibration. The stress-strain curve is quite normal which does not show negative stiffness, meaning the simple shear deformation mode is stable.

(2) I also defined the exact same neo-hooken material in ABAQUS and evaluated its stability. The results indicate that the material is stable for all deformation modes.


Do you have any comments? Thanks!




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Posts: 3998
Joined: 5 years ago

I tried the same test on my computer and it seems to work as expected.

What version of MCalibration are you using?

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Joined: 3 years ago

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Posts: 4

@jorgen Not sure if it's a bug in v6.3.1. But I upgraded to v6.5.14 and got the same result as you had. Thanks!