Actran Analysis Submission

Flexible Body

A flexible body within the Adams model must be chosen; the vibrational results of this flexible body from an Adams simulation will be used as the basis for the acoustics analysis.

Output File Prefix

Specifies the name of the files written to disk by the acoustics analysis

Actran Analysis

Specifies the name of the acoustics analysis job

MDF File Name

Specifies the name of the modal deformation file containing the participation factors

Analysis

Select the Adams analysis whose results for the selected flexible body should be the basis of the acoustics simulation

Output Time Start/End

Defines the start of the time range from the Adams analysis for which the acoustics analysis should be run

Skip

Adams time steps can be skipped to reduce the computational time of the acoustics analysis.

Advanced Setup

Opens the advanced setup tabs, available tabs are Mesh, Results Content, DFT, Environment, Far Field, and Analysis Setup.

Export FE Data

selecting this directs Adams to copy the following files in the analysis directory:

OK

Starts the acoustic simulation and closes the dialog

Apply

Starts the acoustic simulation and keeps the dialog open

Cancel

Closes the dialog

Mesh Type

Select the mesh type dependent on your needs.

Mesh File

Browse for and specify the mesh file if either "Mesh already provided" or "Shrinkwrap provided" are chosen for Mesh Type.

Maximum Frequency

Defines the maximal frequency that should be supported by the acoustic mesh. The higher the frequency, the finer the acoustic mesh will become because the acoustic wavelength will be used for the mesh criteria.

Elements per Wavelength

Distance from Structure

Defines the distance of the shrinkwrap to the structure.

0.0 to 1 cm are good choices depending on the size and complexity of the structure. Default value is 0.0

Fill hole size (% of structure size)

Defines which holes will be filled by the automatic mesh generation algorithm. Please note that if all holes are not filled, the shrinkwrap might enter inside the structure. This should be absolutely avoided. See Edit button for checking the shrinkwrap.

Acoustic Volume Scaling

A factor '?' used to define the limit of the computational domain around the structure. The limit is a sphere whose diameter 'D' is the following:

D = * (maximum dimension of the structure)

Use Hexa mesh

Activates the usage of hexahedral elements in the volume mesh. If the volume mesh generation fails, try de-activating this option. Default: activated.

Select

This button opens an additional dialog box (see below) to select acoustic mesh files individually.

Dialog to select the acoustic mesh files individually. for:

Create

This button will create the acoustic mesh if the "Automatic mesh" or "Shrinkwrap provided" options are chosen for Mesh Type.

Show

This button displays the acoustic mesh in Adams View.

Edit

This Button opens the shrinkwrap mesh in Actran VI. Please note that for mesh modifications, an Actran VI license is necessary, the "Actran Entry for Adams" license is not sufficient for this option.

Status

Output Format

Defines the output format of the results. Images, ascii-format and both can be chosen.

Overall Acoustic Pressure (3D Plots)

Plots the time dependent results of each microphone in a waterfall diagram.

Acoustic Pressure at microphone(s)

Creates the acoustic pressure results for each microphone defined in Microphone for Post on the Far Field tab.

Audio File

Creates a wave-file for each microphone defined in Microphone for Post on the Far Field tab.

SPL over time at microphone(s)

Creates the Sound Pressure Level (SPL) per time period in a time dependent plot.

Refreshing Rate

The time period (in seconds) over which the Sound Pressure Level SPL is integrated.

SPL output in dBA

Applies the A weighting function to acoustic results expressed in dB.

Discrete Fourier Transform Output

Activates the transformation of time results in frequency domain.

Time Windowing

Defines the form of the window. While Rectangular windows will apply a constant factor of 1 (thus no window) to the sampled time signal, other window types will apply factors from [0,1] to the sampled time signal. Options are Triangular, Hamming, Hanning, Blackman and Blackman Harris. For example, the Hanning windowing is defined by the formula with n the number or the

sample points, M the quantity of sample points in the window and w the window function

Time Interval

Defines the length of each time interval where the DFT is applied

Overlap of Time Interval

Defines the percentage of the overlap of the subsequent time interval.

Start Frequency

Defines the first computed frequency in the DFT. Default value is defined by the period of the time interval

End Frequency

Defines the last frequency to be computed during the DFT. Note that the time step length influences the maximal frequency that can be computed, through the Nyquist criterion.

Acoustic Environment

Allows to automatically define the properties of the Air at a given temperature. Following properties are influenced by the temperature defined.

Speed of Sound

The speed of sound is the distance travelled per unit of time by a sound wave propagating through an elastic medium (m/sec)

Fluid Density

The mass of the fluid per unit volume (kg/m*3)

Order of Infinite Elements

Defines the number of interpolation points for each infinite element, which is used to model nonreflecting boundary conditions and the acoustic radiation outside of the finite element mesh. Default value is 10.

Microphone Table File

Defines the position of the microphones; the default position is based on the ISO3744 and can be found in the installation folder "<top_dir>\acoustics\examples\ISO3744_meter.mic"

Radius of Infinite Elements

Defines the coordinate system of the infinite elements.

Center of Infinite Elements

Defines the location of the center of the infinite elements.

Scale Factor Microphones

Scales the coordinates of the microphone positions.

Show Microphones

This button is enabled after the acoustic mesh is generated and displays all the microphones available as yellow or red spheres (the red ones indicate microphones selected for extra post-processing results).

Microphone for post

Select the microphones used for additional post-processing output; the button "All" will select all microphones.

Overwrite defaultss

Radius of Infinite Elements, Center of Infinite Elements and Scale Factor for Microphones all have automatic defaults. This "Overwrite defaults" button allows users to change those inputs. For instance the, user can change the distance of the microphones from structure by modifying the scaling factor for microphones.

Gap Tolerance

Defines the tolerance parameter to couple the shrinkwrap with the structural acoustic surfaces. Default value is twice the distance specified in Mesh tab, which can be used in other cases as well. If distance is 0.0, Gap Tolerance is set to 0.01 m.

Output Map

Allows the user to create an acoustic 3D map in time domain. Please note that to open the map in Actran VI the license for Actran VI is needed, the "Actran Entry for Adams" license is not sufficient. Note that asking for maps may increase computational time significantly. Default value is 'No'.

Output Map Steps

Specifies the time steps of the output map. Please note that an output map can demand a lot of hard drive space thus removing steps from the output could be important. Maps are output at each time step for value=1, every two steps for value=2 and so on.

Memory

Memory dedicated to the calculation. Quantity depends on the size of the acoustic mesh. Unit is MB.