Linear Elastic Dielectric
The Linear Elastic Dielectric node includes the equations of structural mechanics and electrostatics together with additional forces that originate from the electromechanical (or Maxwell) stress tensor. At the external interfaces of a Linear Elastic Dielectric the force contribution that results from the electromechanical (or Maxwell) stress tensor in the adjacent free space domains is added as a surface force through the Electromechanical Interface subnode. The combination of these surface forces and the additional domain level electromechanical forces results in the correct forces being applied both at the interface and within the solid.
The Thermal Expansion, Initial Stress and Strain, Damping, and Viscoelasticity subnodes are available from the context menu (right-click the parent node) or from the Physics toolbar, Attributes menu.
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Theory for the Electromechanics Interface
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Electromechanical Interface
For the Linear Elastic Material, Geometric Nonlinearity and Energy Dissipation sections, see Linear Elastic Material as described for the Solid Mechanics interface.
Electrostrictive Material Constants
Enter values for the Electrostrictive constant a1 and Electrostrictive constant a2 (SI units: F/m).
These material constants are frequently defined in the literature through a relation between the strain in the material and the electric polarization. To convert to the form used by COMSOL Multiphysics, which relates the polarization to the stress, the following values should be used for the coefficients:
where ε0 is the permittivity of free space, ν is the material’s Poisson’s ratio, EYM is its Young’s modulus and χ is its electric susceptibility. Q12 and Q11 are material properties defined in Ref. 3.