3.23. Transfer Admittance Matrix

This acoustic model enables you to specify a transfer admittance matrix to trim structures such as a complex perforated structure, a square grid structure, or a hexagonal grid structure. The connection at the interface between the two entities is between two acoustic regions or a structural and uncoupled acoustic region. The transfer admittance matrix can be specified using two Ports and if one interface is an FSI interface, then Port 1 is assigned to that interface. For additional information, see the Trim Element with Transfer Admittance Matrix topic in the Mechanical APDL Acoustic Analysis Guide.

Analysis Types

Transfer Admittance Matrix is an Acoustics Model that is available for the following analysis types.

Common Characteristics

This section describes the characteristics of the boundary condition, including the application requirements, support limitations, and loading definitions and values.

Note:  Only Transparent Ports on Exterior Face are allowed in Transfer Admittance Matrix.

Dimensional Types

  • 3D Simulation: Supported.

  • 2D Simulation: Not Supported.

Scoping: The Transfer Admittance Matrix is scoped using Port objects.

Loading Data Definition: Enter loading data using one of the following options.

  • Constant

  • Tabular (Frequency Varying): Supported for Harmonic Acoustics only.

Boundary Condition Application

To apply a Transfer Admittance Matrix:

  1. On the Environment Context tab: select Acoustic Models > Transfer Admittance Matrix. Or, right-click the Environment tree object or click in the Geometry window and select Insert > Acoustics > Transfer Admittance Matrix.

  2. Define the Port1 and Port2 properties.

Details View Properties

The selections available in the Details view are described below.

CategoryFields/Options/Description
Definition

Type: Read-only field that describes the object - Transfer Admittance Matrix.

Model Type: This property specifies the type of structure to be trimmed. It provides a drop-down with the options: Perforated Plate (default), Square Grid Structure, and Hexagonal Grid Structure.

Based on the entry of the Model Type property, the following properties are available.

Perforated PlateSquare Grid Structure or Hexagonal Grid Structure

Port1

Y11 [Real]
Y11 [Imag]
Y12 [Real]
Y12 [Imag]
Alpha1 [Real]
Alpha1 [Imag]

Port2

Y21 [Real]
Y21 [Imag]
Y22 [Real]
Y22 [Imag]
Alpha2 [Real]
Alpha2 [Imag]

Port1

Port2

Hole Radius

Grid Period

Structure Thickness

Mass Density of the Fluid

Dynamic Viscosity of the Fluid

Ratio of Inner and Outer Radius

Suppressed: Include (No - default) or exclude (Yes) the boundary condition.

Mechanical APDL References and Notes

Transfer Admittance Matrix Models of Perforated Structures is applied using the command:

TB,PERF,,,,TBOPT

Where:

  • TBOPT = YMAT for Model Type = Perforated Plate. This corresponds to the case of General transfer admittance matrix.

  • TBOPT = SGYM for Model Type = Square Grid Structure.

  • TBOPT = HGYM for Model Type = Hexagonal Grid Structure.

API Reference

See the Transfer Admittance Matrix section of the ACT API Reference Guide for specific scripting information.