For piezoelectric materials, ensure that the polarization direction (defined by the element coordinate system) is correct. Regardless of the element axis (x, y or z) chosen as the polarization direction, all orthotropic material and piezoelectric constants must be defined accordingly.

For piezoelectric constants, the piezoelectric stress matrix ([e] form) or the piezoelectric strain matrix ([d] matrix) can be used. If using the piezoelectric strain matrix, however, the elastic properties must be input via the TB,ANEL command. Also, IEEE standards list the coefficients based on (x, y, z, yz, xz, xy) ordering, while Mechanical APDL input requires (x, y, z, xy, yz, xz) ordering. For more information, see Piezoelectric Matrix in the Coupled-Field Analysis Guide.

When calculating the electrical impedance, the current is calculated from the “reaction” charge, as indicated in Results from Prestressed Full Harmonic Response Analysis. Each node with voltage degrees of freedom constrained returns a portion of the “reaction” charge.  Instead of summing all “reaction” charges for the terminal nodes, however, if the voltage degrees of freedom are coupled, then the total “reaction” charge can be obtained at the master degree of freedom (MDOF). This method provides much simpler postprocessing, as results from only a single node (MDOF) need to be queried.

In a harmonic response analysis, all loads and boundary conditions are applied in sinusoidally. Consequently, if pretension elements (PRETS179) are present, constrain their adjustment to zero during the harmonic response portion of the analysis.

For linear perturbation analyses, use the RESCONTROL,LINEAR command in the base linear static analysis to generate the files needed for the multiframe restart (.Rnnn, .RDB, .ESAV). Linear perturbation analyses require use of multiframe restart files, but the restart files are not created for linear static analyses unless the RESCONTROL command is issued.