The Piezoelectric Material node defines the piezoelectric material properties either in stress-charge form using the elasticity matrix and the coupling matrix, or in strain-charge form using the compliance matrix and the coupling matrix. It is normally used together with a Layered Piezoelectric Effect multiphysics coupling node and a corresponding Piezoelectric Layer node in the Electric Currents in Layered Shells interface. This node is added by default to the Layered Shell interface when adding a Piezoelectricity, Layered Shell multiphysics interface.

When working with layered shells, you almost invariably take the material data from what has been defined using Layered Material Link, Layered Material Stack, or Single Layer Material nodes. It is however possible to override some data from a Piezoelectric Material node too.

In order to have a correct model, all layers must have been assigned material data for all boundaries selected in the settings for the interface. The override rules for the material models in the Layered Shell interface cannot enforce this, in the same way as for other physics interfaces. You can have several Piezoelectric Material nodes with the same (or partially overlapping) geometrical selections, but with different layer selections.

By adding the following subnodes to the Piezoelectric Material node you can incorporate many other effects:

Data given in the other sections of this node applies to all layers. Thus, if you enter material data explicitly, rather relying on the default From material option, you will override that material property for all selected layers.

Select a Constitutive relation — Stress-charge form or Strain-charge form. For each of the following, the default uses values From material. For User defined enter other values in the matrix or field as needed.

If any material in the model has a temperature dependent mass density, and From material is selected, the Volume reference temperature list will appear in the Model Input section. As a default, the value of Tref is obtained from a Common model input. You can also select User defined to enter a value or expression for the reference temperature locally.

If a study step is geometrically nonlinear, the default behavior is to use a large strain formulation in all domains. There are, however, some cases when the use of a small strain formulation for a certain domain is needed. In those cases, select the Geometrically linear formulation check box. When selected, a small strain formulation is always used, independently of the setting in the study step. The check box is not selected by default to conserve the properties of the model.

When a geometrically nonlinear formulation is used, the elastic deformations used for computing the stresses can be obtained in two different ways if inelastic deformations are present: additive decomposition and multiplicative decomposition. The default is to use multiplicative decomposition. Select Additive strain decomposition to change to an assumption of additivity.

Select the Calculate dissipated energy check box as needed to compute the energy dissipated by Mechanical damping.

Select the Reduced integration check box to reduce the integration points for the weak contribution of the feature. Select a method for Hourglass stabilization — Automatic, Manual, or None to use in combination with the reduced integration scheme. The default Automatic stabilization technique is based on the shape function and shape order of the displacement field.

Control the hourglass stabilization scheme by using the Manual option. Select Shear stabilization (default) or Volumetric stabilization.

When Shear stabilization is selected, enter a stabilization shear modulus, Gstb, and the shear correction factor kstb. The value for Gstb should be in the order of magnitude of the equivalent shear modulus.

When Volumetric stabilization is selected, enter a stabilization bulk modulus, Kstb. The value should be in the order of magnitude of the equivalent bulk modulus.

Physics tab with Layered Shell selected: