## S. Harmonic Analysis of an Elastic or Piezoelectric or MagnetostrictiveStructure excited by an impinging wave (HAR6)

The pressure P and the flux rc2Y are split in two parts: the incidentpressure Pi and flux rc2Yi and the elastic scattered pressure Pes and flux rc2Yes. Since Pi is known, the corresponding terms can be moved to the right hand side of the set of equations. Also, Yi can be expressed in terms of thenodal values of the pressure normal derivative:

where [D] is a matrix already provided by the dampingelements (see HAR3). Using the operator [G] describedin HAR3, the system of equations is written, insymmetric form:

It is possible to apply simultaneously several prescribedexcitations (electrical potentials, displacements, pressures, currents in themagnetic sources) and/or loads (force, electrical charge). The user mustprovide the excitation frequency and define the prescribed excitations and/orloads (see Section III.D, EXCITATIONS and LOADS entries) andthe incident pressure field via a FORTRAN function INCPRE (see Section III.D, PRESSURE command). The code computes the real and imaginaryparts of the entire pressure and displacement fields, the electrical potential,the reduced magnetic potential, the excitation currents, and the electricimpedances. The information given in HAR3 on dampingelements, conditions of near field and far field on the boundary surface isstill valid.