Acoustic Signature for Seat Rattle
-
Upload
khai-win-er -
Category
Documents
-
view
343 -
download
2
Transcript of Acoustic Signature for Seat Rattle
Acoustic Signature for Automotive Seat Rattle
Tuan Quach, Joseph Hasna,
Khai Win Er, Wenhao Li
School of Aerospace, Mechanical and Manufacturing Engineering
Supervisors: Dr. M. Fard (RMIT) Tony Baxter (FUTURIS)
Introduction
05/01/2023 Acoustic Signature for Automotive Seat Rattle 2
Why is it important to investigate NVH?
• Characteristics of noise and vibration are important factors in terms of design quality and build for mechanical systems.
• Vital to a vehicle’s success that noise and vibration be reduced as much as possible.
• Automotive seat rattle is particularly important as there is direct interaction between passenger and the seat.
• In order to mitigate noise and vibration, the sources must be identified.
Project Objective
05/01/2023 Acoustic Signature for Automotive Seat Rattle 3
Main Objectives• Analyse seat structural behaviour and sound characteristics.
• Characterise rattle behaviour to locate noise sources.
• Provide recommendations to diagnose rattle prior to design phase.
RESEARCH EXPERIMENT VALIDATE RECOMMENDATIONS
Characterising rattle
Experimental Process
Correlate & Validate Managing rattle
NVH – Seat Rattle Optimization of experiment
Rattle Noise Database
Importance of Research
05/01/2023 Acoustic Signature for Automotive Seat Rattle 4
Why focus on Seat Rattle noises?• Seat serves as a final link for vibrational sources.
• Overall vehicle satisfaction directly correlates to interior quietness
Rat
ing
of O
vera
ll Ve
hicl
e Q
ualit
y
Rating of Overall Interior Quietness
Overall vehicle satisfaction
Importance of Research
05/01/2023 Acoustic Signature for Automotive Seat Rattle 5
Why focus on Seat Rattle noises?• Resonance can lead to violent vibration
• Constant resonant noises can be hazardous to concentration
Methodology
05/01/2023 Acoustic Signature for Automotive Seat Rattle 6
Modal Analysis TestingTo determine the resonance frequencies of the seat along with its respective mode shapes.
Acoustic Camera Testing Recommendation
Results
05/01/2023 Acoustic Signature for Automotive Seat Rattle 7
g.N
Am
plitu
de250e-3
Lateral Mode 8.65 Hz
Twisting Mode 237.16 Hz
Twisting Mode 122.88 Hz
Bounce Mode16.97 Hz
Methodology
05/01/2023 Acoustic Signature for Automotive Seat Rattle 8
Acoustic Camera TestingTo pin-point the source of the rattle noise at its respective resonance frequencies.
Modal AnalysisTesting
Recommendation
Results
05/01/2023 Acoustic Signature for Automotive Seat Rattle 9
Lateral Mode- 8.65 Hz
Twisting Mode 2- 37.16 HzTwisting Mode 1- 22.88 Hz
Bounce Mode- 16.97 Hz
Results Refinement
05/01/2023 Acoustic Signature for Automotive Seat Rattle 10
• Some spectrogram shows unclear results due to noise from the overall seat. • Refinement of the excitation range would pin-point the main source of noise (rattle).
Conclusion
05/01/2023 Acoustic Signature for Automotive Seat Rattle 11
• Controlling of rattle in early design phase is challenging and industry is still
using find & fix for rattle.
• Strong correlation has been found between seat structure dynamics and
rattle noise (structural vibration modes).
• Management of the three main seat vibration modes in early design phase
can significantly reduce time and cost.
• Experiments revealed resonant frequencies at 8.65Hz, 16.97Hz, 22.88Hz
and 37.16Hz.
Recommendation
05/01/2023 Acoustic Signature for Automotive Seat Rattle 12
Altering the natural frequency of the seat• Resonance occurs when the input frequency is the same as the natural
frequency of the seat.
• Vibration sources such as engine’s combustion usually vibrate below 30Hz.
• By shifting the natural frequency to a higher frequency, resonance could possibly be avoided.
• This could be done by changing the material properties of the seat (stiffness and mass).
Natural Frequency
Recommendation
05/01/2023 Acoustic Signature for Automotive Seat Rattle 13
Minimize the impacting surface area• From the results, it was found that most of the noises come from
connection points.• By minimizing the impacting surface area, it could restrict the movement at
the connection points, therefore further reduce the sound emitted.
• This could be by changing the direction of the pin at the point of interest.
Mode Recommendation
Lateral Mode 8.65 HzRestriction in the
horizontal directionRestriction in the vertical
directionBounce Mode 16.97 Hz