Universal Program for Computing Acoustic Waves

Basic features:

• Computation of planar acoustic surface waves in half spaces and layered systems. The layers can be arbitrary anisotropic materials in any orientation;
• computations of bulk and interface waves as well as in plates;
• computation of leaky waves and of waves in materials with complex material coefficients (i.e., with damping);
• solution of the inverse problem, i.e. the determination of one or more parameters (material constants, layer thickness, orientation etc.) from given phase velocities depending on other varying parameters;
• computation of derived quantities like power flow density and amplitudes over depth, slowness surfaces, temperature coefficients;
• powerful program control by a special script language with macros, input redirection, variable substitution, loops, step size control, extrapolation algorithms etc.;
• highly complex search strategies for finding leaky waves, computing branches of solutions in depence of varying parameters etc.

In interactive mode, the program is menu driven. Commands can be selected from the menu and be completed manually using a command line editor (including history function). The main menu looks like this (though with better graphic design):

+-------------------------------------------------------+
|   *** Acoustic surface wave computation ***           |
|        7.Dec 10:13 R.Wobst, IFW Dresden               |
+----------+----------+----------+----------+-----------+
|  data    |  h       |  light   |  state   |           |
|  start   |  v_iso   |  verbose |  type    |  pause    |
|  select  |  complex |  silent  |  print   |  help     |
|  metal   |  leaky   |  echo    |  result  |  EPS      |
|  turn    |  lambda  |  noecho  |  edit    |  compose  |
|  v=      |  frequ   |  tron    |  for     |  dselect  |
|  dv=     |  mode    |  troff   |  file    |  show_b3  |
|  search  |  change  |  iter    |  quit    |  sort_kb3 |
+----------+----------+----------+----------+-----------+
| Enter command: leaky                                  |
+-------------------------------------------------------+
+-------------------------------------------------------+
| syntax: leaky                                         |
| example: leaky {on|off|pos|neg|zero}                  |
+-------------------------------------------------------+

Explanation of some commands:

• data/compose/edit: select layered system / compose layered system from several materials / view and edit material constants; symmetry relations are automatically regarded
• mode: select wave mode: surface wave, plate mode, interface or bulk wave
• metal: metallization (electrical shortcircuit) of surfaces/interfaces
• turn: rotate a layer
• leaky: select "leakyness": real or complex solutions, positive or negative imaginary part etc.
• light: compute light waves or acoustic waves
• select/dselect: refined search method - looking for minima in certain matrix columns only instead of considering the minimum of all columns (cf. [1] - this is an essential help). "dselect" can be applied for leaky waves and fixes a set of partial waves which shall be contained in the solution.
• search: apply refined search strategies for finding solutions
• start: start of iteration (with a simple search strategy)

References:

[1] Wobst, R.: The Generalized Eigenvalue Problem and Acoustic Surface Waves Computations Computing 39(1987), pp.57-69

Contact:

Dr. Reinhard Wobst
IFW Dresden e.V.
'Magnetic and acoustic resonances' (Dept. 15)
Surface Dynamics Group
P.O.Box 270116
D-01171 Dresden, Germany
phone: ++49/351/4659 689
fax: ++49/351/4659 313
e-mail: r.wobst + @ifw-dresden.de (Sorry, but we try to prevent automatic SPAM)