## H. Exploration

Together with the results file, a graphic display of thedistorted structure (Draw the mesh), the voltageresponse (Transmitting Voltage), the sensitivity (Sensitivity), the directivity patterns (Directivities),or the parallel resistance and capacitance plot (Rp/Cp)can easily be obtained using the ATILA explorationsupervisor. Animated views of the vibrating structure (Animate)are also available.

The user can also use ISOVAL to plot contours of constant value (iso-displacements, iso-potentials, iso-pressures,iso-stresses, etc.) on the modeled structure. ISOVAL can be used only if the generation of the PST file wasrequested in the job’s data file (see chapter ‎III and paragraph ‎5 of this section). Each of these commands is described below.

Note that the AtiCurve and PostAti buttons are enabled when the Preflu2D/3Dand Preati modules are installed.

### 1. Rp/Cp

When dealing with underwater piezoelectric transducers, thedesigner needs to know the electrical impedance, generally given as anequivalent parallel circuit composed of a resistance and a capacitance. The Rp/Cp button provides plots of the values of these twocomponents against the frequency. Using the Copy command, the data can be copied to an Excel file.

The frequencies provided in the data file are plotted byfitting a spline curve to the input data. The values of the parallel resistanceand of the parallel capacitance as a function of the frequency are in the .rpcp file. Similarly, the .rjx file contains the real part and the imaginary part of impedance for each inputfrequency.

Using the Draw parameter button, onecan choose a linear scale or a logarithmic scale for the frequency axis. Moreover, the frequency can be normalized(Reference frequency).

Note: If the symmetries detected by the solver areincorrect, the user has to correct the values of Rp/Cp as well as the values ofRjX.

### 2. TransmittingVoltage and Sensitivity

When dealing with underwater piezoelectric transducers, thedesigner needs to know the far field pressure in the fluid medium and itsspatial distribution. He might also need to find out its sensitivity, which canbe calculated from the transmitting voltage response and the electricalimpedance via the reciprocity equation. The directivity index may also bevaluable information. These parameters are available using the Transmitting Voltage button and the Sensitivity button.

The transmitting voltage response is the magnitude of thefar field pressure, expressed in dB, ref. 1 mPa/Voltat 1m.

The sensitivity (voltage magnitude measured on thetransducer for an incoming plane wave) is expressed in dB ref. 1 Volt/mPa:

These plots are made for different directions, as a functionof the frequency. The Copy command enables you to storethe values in an Excel file.

Using the radio buttons appearing in the Draw parameters dialog, the directivity index (for atwo-dimensional structure) can be plotted. It describes the increase of sourcelevel compared to the omni-directional case. The user can also change the direction in which Sensitivity, Transmitting Voltage and Directivity index are calculated. Moreover, it is possible to introducethe Cable capacitance that can affect the transducerimpedance, to choose a linear or logarithmic scale, and to normalize the frequency (Reference frequency).

Inthe .ATI data file, the user must ensure that theexcitation voltage magnitude is 1 Volt (which is the reference level). Thefrequencies provided in the data file are plotted by fitting a spline curve tothe input data.

### 3. Directivities

When dealing with underwater piezoelectric transducers, thedesigner needs to know the far field pressure in the fluid medium and itsspatial distribution. The aim of the Directivities button is to provide plots of the far field directivity patterns for severalfrequencies.

In the .ati data file, the user mustensure that the excitation voltage magnitude is 1 Volt (which is the referencelevel). Patterns are plotted by fitting a spline curve to the computed data.

The Directivities command uses a .pat file containing information about the far field pressurethat the ATILA solver creates. This file can berecreated from the .sy4 file (which is also created duringthe computation).

Initially, a quarter of the directivity pattern is drawn forthe first six frequencies. Using the Draw parameters dialog, it is possible to plot 1, 2 or 4 quadrants. Using the Copy command, the diagrams can be inserted into any text file.

### 4. Draw the mesh

Initially, a Simple mesh is displayed. Draw parameters modifies the display. Thebuttons are similar to those from pre-processing, except that Draw parameters reads a .sy4 file created aftersolving the problem with ATILA, instead of the datafile. It also has buttons for dynamic views that are described below.

· Displaced structure: full lines, rest structure: dashed lines.This option is used to plot the deformed shape of a structure. The solidelements of the structure at rest are shown with a dashed line, while those ofthe deformed shape are shown with a full line. Fluid elements and nodes do notappear.

The user can modify the selected frequency (harmonic or modal analysis) or selected time (transient analysis), and the displacement scale. No frequency value is requested for astatic analysis or when solving was performed for one frequency or time only.When a complex solver has been used, two graphics are provided. Thesecorrespond to the real and imaginary parts of the displacement (remember thatthe real displacement is the real part of the product of the complexdisplacement and the time dependency, which is ejwt in ATILA).

· Displaced structure: full lines, no rest structure. This optionis identical to the previous one, except that the mesh at rest is not shown.

· Electrical iso-potential lines in 2D elements. This option isused to plot iso-values of the electric potential magnitude in piezoelectricdomains of a two-dimensional mesh. The solid elements of the structure areshown with a full line. Iso-values of the electric potential magnitude areshown with a full line, except the null iso-value, which is shown with a dashedline. Fluid elements and nodes do not appear.

The user can modify the selected frequency (harmonic ormodal analysis) or selected time (transient analysis). No frequency value isrequested for a static analysis or when solving was performed for one frequencyor time only.

· Isobaric lines in 2D fluid (magnitude). This option is used toplot iso-values of the pressure magnitude in fluid domains of a two-dimensionalmesh. The fluid elements of the structure are shown with a full line. Iso-valuesof the pressure magnitude are shown with a full line, except the null pressureiso-value, which is shown with a dashed line. Solid elements and nodes do notappear.

The user can modify the selected frequency (harmonic or modal analysis) or selected time (transient analysis). Nofrequency value is requested for a static analysis or when solving wasperformed for one frequency or time only.

For magnetic and magnetostrictive domains, the followingoptions are available.

· Magnetic B field in 2D elements (magnitude). This option is usedto display vectors of the magnetic field B in magnetic or magnetostrictivedomains of a two-dimensional mesh. The magnetic field includes the rotationalpart coming from the magnetic sources and the irrotational part deduced fromthe magnetic potential. The magnetic and magnetostrictive elements of thestructure are shown with a full line. Magnetic field vectors are shown with afull line, starting from Gauss integration points, and of length proportionalto the magnitude. Fluid elements and nodes do not appear.

The user can modify the selected frequency (harmonic ormodal analysis) or selected time (transient analysis). No value is requestedfor a static analysis or when solving was performed for one frequency or timeonly. When a complex solver has been used, two graphics are provided. Thesecorrespond to the real and imaginary parts of the magnetic excitation field(remember that the real value is the real part of the product of the complexvalue and the time dependency, which is ejwt in ATILA).

- Magnetic H field in 2D elements (magnitude). This option is identical to the Magnetic B field in 2D elements (magnitude) option, exceptthat the magnetic field H is shown instead of the magnetic induction B.
- Demagnetizing field only. This option is identical to the Magnetic B field in 2D elements (magnitude) option, except that the rotationalpart of the magnetic field, coming from the magnetic sources, is not included. The irrotational part deduced from the magnetic potential is sometimes calledthe "demagnetizing field".
- Magnetic iso-potential lines (magnitude). This option is used to display iso-values of the reduced magnetic potential magnitude in magnetic or magnetostrictive domains of a two-dimensional mesh. The magnetic and magnetostrictive elements of the structure are shown with a full line. Iso-valuesof the reduced magnetic potential magnitude are shown with a full line, exceptthe null iso-value, which is shown with a dashed line. Fluid elements and nodesdo not appear.
- The user can modify the selected frequency (harmonic ormodal analysis) or selected time (transient analysis). No value is requestedfor a static analysis or when solving was performed for one frequency or timeonly.

### 5. WISOVAL

WISOVAL is an interactivepost-processing graphical program for the creation and display of a shading orcontour plot of results of an ATILA run (a shading plotis the default). WISOVAL displays in different colorsthe variation of a scalar value throughout the domain under study (iso-valuesof the displacement field components, of the stress field, iso-potentials, iso-pressure,etc.). Iso-values are always represented in a plane. These can be plotted onthe outer surface of a structure or in a cross-section.

WISOVAL requires the data stored inthe post-processing file .pst. This file is generatedby ATILA if a GENERATION PST entry has been provided in the .ati data file beforeusing the solver (see Chapter ‎III). If this command does not appear in the .ati file, it is possible to rebuild the .pst file using the program sy4topst in Expert (see section ‎I.I.2).

Initially, the X-displacement is displayed for the first frequency input in the .ati file.

Edit and Option commandsmay be used.

In the Edit menu, Axes (see section I.F) and Draw parameters are available. The plot type may be selected: Displacement in the x direction (Ux),in the y direction (Uy), in the z direction (Uz) and the amplitude, iso-values ofthe Pressure field and the iso-values of the Electric potential. The user can also modify the selectedfrequency. For a three-dimensional structure, cuts along planes are available.

In the Option menu, the mainavailable commands are: Legend, to show or hide thelegend on the right, Mesh, to show or to hide the fulllines of the mesh, Node numbering, to show the nodesnumbers and Element numbering, to show the elementsnumbers. Using Color scale, one shaded color can beselected, and Composite combines different options.

### 6. Animate

Animate performs animations. Infact, it can animate the displacement Snapshots that are equally spaced in onecycle of the harmonic response and are created from the .sy4 file that the solver creates.

By moving the arrow on the screen, the view angle ischanged.

The main available options are: Select frequency, Animation, Pause. With Animation properties, Frequency and magnitude may be changed. Wire mode displays the structure in wire frame view. Colors and materials may be selectedand changed using the Select material button.

The color white is assigned to any new material created. Tomodify this color, click on Material, then on Add the material.