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viscoelastic material

Posted Jan 8, 2024, 3:28 a.m. EST LiveLink for MATLAB, Structural Mechanics, Material Models Version 6.0 2 Replies

Hamza Haddad
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Hello,

I want to model the viscoelastic behavior of a material using the solid mechanics module and the Maxwell model. Up to this point, it's easy to set up. However, I want to define a viscosity for the model that depends on the shear rate.

I have a second question. Why is the fractional Maxwell model not considered in the case of a time study? Is there an alternative?

Thank you !

2 Replies Last Post Jan 11, 2024, 6:44 a.m. EST
Henrik Sönnerlind COMSOL Employee

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Posted: 10 months ago Jan 9, 2024, 9:10 a.m. EST

The viscosity in the viscoelastic Maxwell material is isotropic. A dependency on the shear rate tensor could, in general, cause an anisotropic viscosity tensor. But even if you would just use some kind of scalar norm of the shear rate, the implementation of the viscoelastic material is not suited for a non-constant viscosity.

As for the fractional viscoelastic models, the problem with fractional derivatives in time domain is that they mathematically correspond to a convolution integral over the whole local history. This is not easily implemented. We will however investigate approximate methods, so it may become possible to remove this limitation in future releases.

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Henrik Sönnerlind
COMSOL
The viscosity in the viscoelastic Maxwell material is isotropic. A dependency on the shear rate tensor could, in general, cause an anisotropic viscosity tensor. But even if you would just use some kind of scalar norm of the shear rate, the implementation of the viscoelastic material is not suited for a non-constant viscosity. As for the fractional viscoelastic models, the problem with fractional derivatives in time domain is that they mathematically correspond to a convolution integral over the whole local history. This is not easily implemented. We will however investigate approximate methods, so it may become possible to remove this limitation in future releases.
Hamza Haddad
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Posted: 10 months ago Jan 11, 2024, 6:44 a.m. EST

Thank you for your response. I would like to explain my issue. I wanted to model the viscoelastic behavior of a ceramic paste.

The targeted application is in the video below (08:03 mins).

Link: https://www.comsol.com/video/modeling-non-newtonian-fluids-with-the-polymer-flow-module.

Do you think it is possible to do this on COMSOL? If so, which modules should us buy? We have only access to the Solid Mechanics and Heat Transfer modules.

thank you !

Thank you for your response. I would like to explain my issue. I wanted to model the viscoelastic behavior of a ceramic paste. The targeted application is in the video below (08:03 mins). Link: https://www.comsol.com/video/modeling-non-newtonian-fluids-with-the-polymer-flow-module. Do you think it is possible to do this on COMSOL? If so, which modules should us buy? We have only access to the Solid Mechanics and Heat Transfer modules. thank you !

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