The Mechanical Damping subnode allows you to model mechanical losses in the
Piezoelectric Material and the
Magnetostrictive Material, either using loss factor material data for the stiffness, or in the form of Rayleigh proportional damping.
The Mechanical Damping subnode is only available with some COMSOL products (see
https://www.comsol.com/products/specifications/).
This choice is effective only in Eigenfrequency and Frequency Domain study. By default, the Loss factor for elasticity matrix cE ηcE uses values
From material. For
User defined enter other values or expressions in the matrix.
This choice is only available if the Constitutive relation in the parent node is
Strain-charge form, and it is effective only in Eigenfrequency and Frequency Domain study. By default, the
Loss factor for compliance matrix sE ηsE uses values
From material. For
User defined enter other values or expressions in the matrix.
This choice is effective only in Eigenfrequency and Frequency Domain study. By default, the Loss factor for elasticity matrix cH ηcE uses values
From material. For
User defined enter other values or expressions in the matrix.
This choice is effective only in Eigenfrequency and Frequency Domain study. By default, the Isotropic structural loss factor ηs uses values
From material. For
User defined enter another value or expression.
The damping parameter ξ is expressed in terms of the mass
m and the stiffness
k as
That is, Rayleigh damping is proportional to a linear combination of the stiffness and mass; there is no direct physical interpretation of the mass damping parameter αdM and the
stiffness damping parameter βdM. Note that the beta-damping is applied only to the mechanical part of the problem. To include the Rayleigh damping effect for the piezoelectric coupling terms, add a
Coupling Loss subnode
This choice can be used in Eigenfrequency, Frequency Domain, and Time Dependent study. Enter the Maximum loss factor ηmax together with the
Reference frequency fref , at which the maximum occurs.
Physics tab with Piezoelectric Material or
Magnetostrictive Material node selected in the model tree:
