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Electrostatic (es) to solid mechanics (plain strain) domain coupling issue

Posted Sep 14, 2017, 4:05 p.m. EDT Electromagnetics, Structural & Acoustics, Interfacing Version 5.3 3 Replies

Abbin P Joy
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Hi,

I am trying to simulate a simple cantilever beam using electrostatics and solid mechanics coupled by moving mesh domain. The space charge densities are assigned to different domains within beam and electrostatic results are verified using theoretical calculations as well as other FEA tools. I am trying to calculate force generated by electrostatic domain and couple to solid mechanics by Maxwell's stress tensor in both X and Y direction using boundary load. The resultant output displacement is much smaller from theory and other FEA tools. Could you please help me to understand the mistake I am doing here? I have attached my simulation file here for reference.

Thanks in advance

3 Replies Last Post Sep 18, 2017, 12:37 p.m. EDT
Sergey Yankin COMSOL Employee

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Posted: 7 years ago Sep 15, 2017, 2:38 a.m. EDT

COMSOL has dedicated interface for such kind of problems - Electromechanics. Please check that model for example (especially equation for force calculation): https://www.comsol.com/model/pull-in-voltage-for-a-biased-resonator-2d-11751

-------------------
Sergey Yankin
www.linkedin.com/in/sergey-yankin/
COMSOL has dedicated interface for such kind of problems - Electromechanics. Please check that model for example (especially equation for force calculation): https://www.comsol.com/model/pull-in-voltage-for-a-biased-resonator-2d-11751
Abbin P Joy
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Posted: 7 years ago Sep 15, 2017, 3:12 a.m. EDT

Thanks Sergey for the response. I am using electrostatics (es) instead of electromechanics as it gives feature to enter space charge density for the junction domain. The electrostatic analysis solves for electric potential and electric field based on the biasing condition. The force generated by this field needs to be computed (Maxwells stress tensor) and coupled to solid mechanics for estimation of displacement. I am having trouble with this coupling part. Appreciate your feedback.

Regards Abbin

Thanks Sergey for the response. I am using electrostatics (es) instead of electromechanics as it gives feature to enter space charge density for the junction domain. The electrostatic analysis solves for electric potential and electric field based on the biasing condition. The force generated by this field needs to be computed (Maxwells stress tensor) and coupled to solid mechanics for estimation of displacement. I am having trouble with this coupling part. Appreciate your feedback. Regards Abbin
Abbin P Joy
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Posted: 7 years ago Sep 18, 2017, 12:37 p.m. EDT

Can anyone please help me?

Method of coupling: - Defined a boundary load (selected cantilever boundaries except fixed end) under solid mechanics - Maxwell's stress tensor for X and Y components are defined as follows: - Fx = es.nTx_Fes - Fy = es.nTy_Fes

The screenshot refering to boundary load is attached.

Thanks

Can anyone please help me? Method of coupling: - Defined a boundary load (selected cantilever boundaries except fixed end) under solid mechanics - Maxwell's stress tensor for X and Y components are defined as follows: - Fx = es.nTx_Fes - Fy = es.nTy_Fes The screenshot refering to boundary load is attached. Thanks

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