II. How To Use ATILA

6.2 Underwater Cymbal (2)
BOUNDARY CONDITIONS MESHING


PROBLEM - Cymbal 12 mm f x 2.4 mm t (Metal thickness 0.2 mm, PZT thickness 0.5 mm x two layer, Cavity hight 0.5 mm); 2D Axisymmetric with a full portion

  • New underwater transducer
  • Learn how to enhance the displacement/effective d coefficient
  • Learn the underwater sound propagation- Monopole & Dipole

BOUNDARY CONDITIONS
Polarization/Local Axes

High voltage should be applied on the center surface of the PZT two layers, and Ground on the metal side surface. Choose the polarization direction along the electric field direction.

Data -> Conditions -> Surfaces -> Geometry -> Polarization (Cartesian) -> Define Polarization (P1) (1,0) direction
Choose 3PointsXZ -> Center (0,0,0) -> Define X axis by putting (0,1,0) -> Then define Z axis by putting (1,0,0) -> Escape

Data -> Conditions -> Surfaces -> Geometry -> Polarization (Cartesian) -> Define Polarization (P2) (-1,0) direction
Choose 3PointsXZ -> Center (0,0,0) -> Define X axis by putting (0,1,0) -> Then define Z axis by putting (-1,0,0) -> Escape

Assign Polarization (Local-Axes P1 and P2) -> Choose the PZT surface -> Finish

Potential

Data -> Conditions -> Lines -> Potential 0.0 (or Ground in ATILA 5.2.4 or higher version) -> Assign the center line of the PZT -> Forced Potential 1.0 -> Assign the right- and left-side lines of the PZT

Surface Contraints

The bottom axisymmetric line of the whole system (including water) - Y component is clamped. The axisymmetric axis is taken along x axis (This is the rule in ATILA!).

Data -> Conditions -> Lines -> Line Constraints -> Y & Z components -> Clamped -> Assign the Axisymmetric X axis


Radiation Boundary

Data -> Conditions -> Lines -> Line Constraints -> X components -> Clamped -> Assign the left-side PZT and Water lines

Radiation boundary is applied not to reflect the water-propagating sound at this boundary (like an anechoic wall). In this sense, the radius of this water boundary is not essential.

To check the assignment -> Draw -> All conditions -> Include local axes

MESHING

Mapped Mesh

Meshing -> Structured -> Surfaces -> Select all Surfaces -> Then Cancel the further process
Meshing -> Structured -> Lines -> Enter number to divide line -> Choose "1, 2, 4" for the lines -> Generate