OS-E: 0310 Transfer Path Analysis

Demonstrate a Transfer Path Analysis (TPA) on a simplified vehicle model using OptiStruct. TPA is used to calculate and rank the noise or vibration contributions for a given Response Point, through the different structural transmission paths in a system.

Model Files

Refer to Access the Model Files to download the required model file(s).

The model file used in this example includes:

TPA.fem

Model Description

The model used is a simplified car model with an acoustic cavity. The model is already setup for a modal frequency response run. The response point is the node which approximates the location of the Driver Ear in the acoustic cavity. The source of excitation is a unit load in the Global Z direction at the Engine Block. The Engine Block is connected to the Body at 3 points using Engine Mounts modeled as RBE2+CBUSH. To setup TPA, use the PFPATH Bulk Data card and reference it using the PFPATH I/O Option card.
FE Model
Element Types
CHEXA
CPENTA
CTETRA
CTRIA3
CBUSH
CBAR
RBE2
The linear material properties are:
MAT1
For Steel
For Glass
For Seats
MAT10
For Acoustic Cavity

Results

The TPA utility in HyperView is used to post-process the results. Using the utility, the Calculated Response given by Equation 1 is plotted against the Solver Response for the Drive Ear Location. The Calculated Response should match up with Solver Response if all the paths have been considered and the co-ordinate system used for Attachment Forces output aligns with the co-ordinate system used for Transfer Function output.(1)
${P}_{t}={\Sigma }_{paths}\left[{P}_{i}\right]={\Sigma }_{paths}\left[{\left(P}{F}\right)}_{i}\ast {F}_{i}\right]$
Where,
$P$
Total pressure
${\left(P}{F}\right)}_{i}$
Transfer function, pressure at driver ear for a unit load for path $i$
${F}_{i}$
Attachment force for path $i$
Now select the problem frequency, i.e. peak in the response, which may be over the target level and find the top contributors to the response at that particular frequency.