Transfer Path Analysis

Transfer Path Analysis (TPA) computes the distribution of vibro-acoustic responses from a source to a microphone or response node through both structural and acoustic pathways. You perform a TPA using SOL108 and SOL111. The software now computes the forces in connector elements modeled as CBUSH elements. The CBUSH forces are now considered when computing the TPA.

The TPA of input excitations and the vibro-acoustic responses is used to determine the most dominant vibro-acoustic pathway of a vehicle or industrial system. You can then change your vibro-acoustic model to determine the best alternative design to minimize vibration or noise at the receiver location.

Some uses are:

• Road/tire excitation to steering wheel vibration and noise at the operator's ear.

• Loudspeaker and cabinet vibro-acoustic responses.

• Machinery imbalance and noise.

Scenario Based Data-Visualization has been enhanced to support Transfer Path Analysis, Force Transmissibility, and Point Mobility using XY plotting, Bar Charts, and Vector Plots.

Transfer Path Analysis (TPA)

To compute the TPA of a vibro-acoustic structure there are several requirements:

• The FEM model can be based on an assembly FEM or a stand alone FEM.

• Component FEMs must represent an elastic structure coupled to an acoustic cavity. For example:Structural FEMs can represent an automotive body-in-white and other components, such as a sub-frame, or suspension. The acoustic FEM represents the acoustic cavity of the vehicle, such as the passenger cabin.If the acoustic mesh radiates into free air, you must use Automatically Matched Layers (AMLs) and microphone mesh to capture the external acoustic radiation.You can use alternate representations (Mode Sets or FRF Sets) for the component FEMs. In the case of large models this may provide a significant computation and resource savings.

• When you use connection elements to connect component FEMs, the connection elements must be elastic so that element forces can be computed. The connection elements are modeled as CBUSH elements. The software can output the element forces to an .op2 file.

• You must simulate rigid elements (RBE2s) using CBUSH elements. You can specify large stiffness to represent near-rigid behavior. If the CBUSH is very compliant and uniaxial, to reduce or eliminate unwanted motion, you can make the stiffness that is lateral to the line-of-action a large value.

TPA is a two-step process.

1. You use a SOL 108 Direct Frequency Response Functions or SOL 111 Modal Frequency Response Functions solution to compute the vibro-acoustic response from unit forces or unit enforced motions that are applied to the vibro-acoustic model at the connection elements. For example, excitations on a vehicle model can be applied to suspension components, engine mounts, or body-to-chassis attachments.Note: You must request force output at the connector elements (SORT2) and vibro-acoustic response at the microphone nodes.

2. You then use a SOL 108 Direct Frequency Response or SOL 111 Modal Frequency Response solution to compute the contribution at the microphone, or structural response node, from each connector element. You then use a post-processing scenario to determine the most, or least, dominant excitation contributor.

Transfer Path Analysis output

Learn more

Transfer Path Analysis (TPA) workflow

Transfer Path Analysis (TPA) scenario (Simcenter Nastran FEM acoustics)

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Command reference

Pre/Post video examples

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Transfer Path Analysis, Simcenter 3D 2021.1 Series

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