OS-E: 0310 Transfer Path Analysis

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

CQUAD4

CTRIA3

CBUSH

CBAR

RBE2

The linear material properties are:

MAT1

For Steel

For Glass

For Seats

MAT10

For Acoustic Cavity

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)

$$P_t={\Sigma }_{paths}\left[P_i\right]={\Sigma }_{paths}\left[{\left(\raisebox{1ex}{$P$}\!\left/ \!\raisebox{-1ex}{$F$}\right.\right)}_i\ast F_i\right]$$

Where,

$P$

Total pressure

${\left(\raisebox{1ex}{$P$}\!\left/ \!\raisebox{-1ex}{$F$}\right.\right)}_i$

Transfer function, pressure at driver ear for a unit load for path $i$

$F_i$

Attachment force for path $i$

Figure 3. Solver Response vs Calculated Response . (summation of all the paths)

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.

Figure 4. Top Contributors at a Particular Frequency in Bar Plot Format