Mechanical Damping
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/).
Damping Settings
Select a Damping typeLoss factor for cE, Isotropic loss factor, Rayleigh damping, or Maximum Loss Factor.
Loss Factor for cE (Piezoelectric Material)
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.
Loss Factor for sE (Piezoelectric Material)
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.
Loss Factor for cH (Magnetostrictive Material)
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.
Isotropic Loss Factor
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.
Rayleigh Damping
This damping model can be used in Eigenfrequency, Frequency Domain, and Time Dependent study. Enter the Mass damping parameter αdM and the Stiffness damping parameter βdK.
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
Maximum Loss Factor
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.
Location in User Interface
Context Menus
Ribbon
Physics tab with Piezoelectric Material or Magnetostrictive Material node selected in the model tree: