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.



Figure 1. Simplified Vehicle Model


Figure 2. Connections from Engine Block to Body Representing the Structural Transmission Paths

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
CQUAD4
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 = Σ p a t h s [ P i ] = Σ p a t h s [ ( P F ) i F i ] MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuamaaBa aaleaacaWG0baabeaakiabg2da9iabfo6atnaaBaaaleaacaWGWbGa amyyaiaadshacaWGObGaam4CaaqabaGcdaWadaqaaiaadcfadaWgaa WcbaGaamyAaaqabaaakiaawUfacaGLDbaacqGH9aqpcqqHJoWudaWg aaWcbaGaamiCaiaadggacaWG0bGaamiAaiaadohaaeqaaOWaamWaae aadaqadaqaamaaliaabaGaamiuaaqaaiaadAeaaaaacaGLOaGaayzk aaWaaSbaaSqaaiaadMgaaeqaaOGaey4fIOIaamOramaaBaaaleaaca WGPbaabeaaaOGaay5waiaaw2faaaaa@5406@
Where,
P MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaaaa@36CB@
Total pressure
( P F ) i MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaaeWaaeaada WccaqaaiaadcfaaeaacaWGgbaaaaGaayjkaiaawMcaamaaBaaaleaa caWGPbaabeaaaaa@3A4B@
Transfer function, pressure at driver ear for a unit load for path i MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyAaaaa@36E4@
F i MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOramaaBa aaleaacaWGPbaabeaaaaa@37DB@
Attachment force for path i MathType@MTEF@5@5@+= feaagKart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq=Jc9 vqaqpepm0xbba9pwe9Q8fs0=yqaqpepae9pg0FirpepeKkFr0xfr=x fr=xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyAaaaa@36E4@


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

Model Files

The model files used in this example include:

<install_directory>/demos/hwsolvers/optistruct/examples/TPA.fem