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Prescribed stress on solid

Posted Mar 18, 2020, 11:42 a.m. EDT Structural & Acoustics Version 5.4 4 Replies

Andres SB
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Hello,

I would like to know if there's an option to apply prescribed stress or something alike instead of forces since I want to simulate deformations which are not caused by forces.

I know hygroscopic swelling exists but thats not what i want.

Thanks.

4 Replies Last Post Mar 19, 2020, 6:45 p.m. EDT
Jeff Hiller COMSOL Employee

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Posted: 4 years ago Mar 18, 2020, 2:38 p.m. EDT
Updated: 4 years ago Mar 18, 2020, 2:45 p.m. EDT

Physically you can only prescribe the components of the stress tensor acted on by the normal vector, i.e. forces. Or you can impose displacements. But not the full stress tensor - the problem would be overdetermined.

Let's take a step back. What is it you are trying to simulate? What are the governing partial differential equations and the boundary conditions?

Best,

Jeff

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Jeff Hiller
Physically you can only prescribe the components of the stress tensor acted on by the normal vector, i.e. forces. Or you can impose displacements. But not the full stress tensor - the problem would be overdetermined. Let's take a step back. What is it you are trying to simulate? What are the governing partial differential equations and the boundary conditions? Best, Jeff
Andres SB
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Posted: 4 years ago Mar 18, 2020, 3:51 p.m. EDT
Updated: 4 years ago Mar 22, 2020, 5:36 p.m. EDT

I'm trying to simulate a beam that deforms due to applied voltage.

I need to solve a second order differential equation (see picture) to obtain a expression of electric field (Ex) and then the electrostatic stress is proportional to the divengence of the electric displacement.

Boundary conditions: Top and bottom potential which are obtained from other physics. Thanks for replying.

I'm trying to simulate a beam that deforms due to applied voltage. I need to solve a second order differential equation (see picture) to obtain a expression of electric field (Ex) and then the electrostatic stress is proportional to the divengence of the electric displacement. Boundary conditions: Top and bottom potential which are obtained from other physics. Thanks for replying.
Henrik Sönnerlind COMSOL Employee

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Posted: 4 years ago Mar 19, 2020, 3:24 a.m. EDT

You can use features like External Stress, External Strain, or Initial Stress and Strain when you have this type of volumetric effect.

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Henrik Sönnerlind
COMSOL
You can use features like *External Stress*, *External Strain*, or *Initial Stress and Strain* when you have this type of volumetric effect.
Andres SB
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Posted: 4 years ago Mar 19, 2020, 6:45 p.m. EDT

Thank you! It helped me.

*For someone who is interested, you have to right click 'Linear Elastic Material' and place 'External Stress' or 'External Strain'.

Thank you! It helped me. *For someone who is interested, you have to right click 'Linear Elastic Material' and place 'External Stress' or 'External Strain'.

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