# I. General Presentation

## A. Introduction

ATILA is a finite element code that has been specifically developed to aid in the design of sonar transducers, but can also be used for all types of transducers (industrial machining, cleaning,welding, nondestructive testing, acoustic imaging, actuators) or for passivestructures. Its working domain is one of small and linear strains. Itpermits the static, modal, harmonic and transient analysis of unloaded elastic,piezoelectric, or magnetostrictive structures, as well as the harmonic andtransient analysis of radiating elastic or piezoelectric structures (in any fluid,water or air, for example) and modal or harmonic analysis of periodicstructures with 1D, 2D or 3D periodicity. It is able to perform analyses ofaxisymmetrical, bi- or three-dimensional structures. Depending upon theproblem, it provides: the displacement field, the nodal plane positions, thestress field, near-field and far-field pressures, transmitting voltageresponse, directivity patterns, electrical impedance. Its ability to describethe behavior of different transducers (Tonpilz transducers, double head mass,axisymmetrical length expanders, free-flooded rings, flextensional transducers,bender-bars, cylindrical and trilaminar hydrophones) and the accuracy of theresults have been checked by modeling many different structures and comparingnumerical and experimental results. Most results have been described innumerous reports, papers and articles; some of them are listed in the bibliography in the next section.

ATILA is the result of many years of research done mainly by K. Anifrani, J. Assaad, R. Bossut, J.-L. Carton, J.-C. Debus, J.-N. Decarpigny, B. Dubus, R. Edde, A. Ghaddar, B.Hamonic, A.-C. Hladky-Hennion, P. Langlet, D. Morel and P. Tierce at I.S.E.N.,B. Tocquet, D. Boucher and F. Claeyssen at C.E.R.D.S.M. Development, R. LeLetty, N. Lhermet and F.-X. Zgainsky at Cedrat-Recherche, and testing is still being done at I.S.E.N.

ATILA is mainly written in standard FORTRAN 77, except for some system interfacings written in C. It totals more than 200,000 lines of code (including 4000 lines of C code). It has beencarefully designed to be easily portable on almost all platforms. Firstdeveloped on an IBM 370 series mainframe (VM/CMS), it is maintained at I.S.E.N.on IBM-PC compatible computers (32-bit applications under Windows 98, Windows NT,Windows2000, Windows XP and Linux). Other test platforms are: a HP715/75 (HP-UX9.03), two Sparc2 workstations (one with Solaris 2.3, one with SunOS 4.1.3), a DEC station 5000/125 (Ultrix RISC 4.2a), an IBM RS6000 workstation (AIX 3.2.5),and. Ports have been successfully tested on DEC Alpha workstations (OSF 1.2 and2.0), and on an SGI workstation (IRIX 4.0). Previous ports were done on DEC VAX stations and mainframes and on DEC Alpha stations with OPEN VMS, but these are no longer supported.

The ATILA code chairman is:

Dr. Pascal MOSBAH Tel:(+33) 320 30 40 50
Laboratoire d'Acoustique Fax:(+33) 320 30 40 51
Institut Supérieur d'Électronique du Nord
41. boulevard Vauban,
59046 LILLE CEDEX, FRANCE

A description of the different steps of an ATILA job and where to find them in the User's Manual follows the list of selected references. A detailed description of these steps appears in the following chapters.