Acoustics Operators

The acoustics operators are designed to maximize flexibility and are designed to work together, and can accommodate both vector and scalar participation input.

The NVH library contains the following Acoustics operators:

Calculates the resultant response by summing nodal acoustic grid participations.

Inputs

raw_participation: scalar or vector value table.

response_id: the ID of the node where the sum will be output.

summation_mode: RSS or complex value sum (default).

summation_set: a file name specifying the nodes to sum (optional).

Outputs

answer: a nodal scalar value table.

Notes

•

summation_mode is optional and will default to component mode of not specified, in which case the complex value summation method be used to calculate the sum of nodal participation values. If the mode is set to “RSS”, the root-sum-squared method will be used to calculate the sum of each nodal participation value.

•

summation_set is optional and will compute the sum of participation from all nodes that have a value. If a summation set file is given, only those values will be processed. This file must be a text file with a single line containing a node ID. This support was added because entity set support did not exist when this operator was created, and it is necessary for acoustic participation analysis. No pool support exists, and this support will be replaced with a set in a future version.

Expression Builder

SumParticipation(raw_participation,response_id)

XML Example

<call name="SumParticipation"

raw_participation="rawpart_tab" response_id="resp_id"

answer="ans_tab" />

Extracts the specified participation component.

Inputs

normalized_participation: scalar or vector value table.

total_response: the ID of the node where the total response will be used for projection.

direction_component: directional component of the participation value to be extracted (default = “XYZ”).

complex_component: complex component of the participation value to be extracted (default=”Proj”).

Outputs

answer: a scalar value table.

Notes

•	normalized_participation is computed by dividing the elemental participation by shell area, from which the specified participation component is to be extracted.

•	direction_component can be any directional component (“x”, “y”, or “z”), or the entire vector (“xyz”). “xyz” is the default.

•	complex_component controls how scalars are extracted from complex participation values. Valid options are “proj”, “mag”, “phase”, “real”, and “imag”. The default is “proj”.

Expression Builder

ExtractParticipation(normalized_participation,total_response, direction_component,complex_component)

XML Example

<call name="ExtractParticipation"
total_response="total_resp_tab"

normalized_participation="area_norm_tab"

direction_component="x" complex_component="mag"

answer="ans_tab" />

Scales participation values to ensure contour patterns stand out.

Inputs

projected_participation: scalar or vector table to be scaled.

logrefval: log scaling reference value (1.0, .1, .01, .001, or .0001).

Outputs

answer: a scalar value table.

Notes

•	projected_participation is the participation component to be scaled for contour.

•	logrefval defaults to 1.0, meaning no log scaling, only scaling by the max value.

Expression Builder

ScaleParticipation(projected_participation,logrefval)

XML Example

<call name="ScaleParticipation"

projected_participation="projpart_tab" logrefval="1.0"

answer="@usgp_ret" />

Calculates the RMS value of the absolute value of complex vector components per part.

Inputs

src: complex nodal vector.

elems: element entity table.

Outputs

answer: a part-bound scalar value table.

Notes

•	nodes without values do not contribute to the average.

•	rms value is computed as follows (per part):

sqrt( sum(ss_nv) / num_nv)

where:

sum(ss_nv) = sum of squared components of src.

num_nv = number of values in each part.

Expression Builder

ScaleParticipation(projected_participation,logrefval)

XML Example