LASD Coatings Optimized for Damping of Aluminum Intensive Vehicle Bodies

Transcription

1 Global Automotive Lightweight Materials August 18-20, 2015 LASD Coatings Optimized for Damping of Aluminum Intensive Vehicle Bodies Ion Pelinescu, Ph.D. NVH-Acoustics Engineering Associate Coatings Innovation Center Allison Park, PA

2 Content LASD Acoustical Coatings Technology High Aluminum Body Content - Implications Aluminum vs. Steel Substrates Damping Coatings - NVH performance Designed for Aluminum Structures & Modal Densities NVH Noise & Damping Correlations Concluding Remarks

3 LASD Acoustical Coatings Technology Liquid Applied Sound Damper Vehicle sound package component Mitigates structure-borne NVH issues Fully automated application process Fully integrated with the paint shop cure processes

4 High Aluminum Vehicle Body Content - Implications Noise-vibration-harshness (NVH): Sources Paths Receivers Aluminum intensive vehicle bodies can be more than 3 db noisier than steel bodies, with the same sound package (e.g. SAE papers , ) Reduced weight leads to increased NVH issues at higher frequencies Preserved stiffness/strength at lower modulus leads to increased gage Sound package - mitigate NVH issues efficiently without adding weight

5 Aluminum vs. Steel - Substrates Center Point Modal Testing 1D beam (ISO 16940:2008) Symbol Units ST AL Modulus E GPa Thickness t mm Bending Stiffness E t 12 (1 θ ) N m Stiffness Mass FRF Plots Magnitude ST AL Stiffness Blank Beams k Frequency (Hz) k Stiffness of Aluminum & steel substrates are statically matched Coated Beams Aluminum emphasizes stiffness vs. mass dynamic participations

6 Aluminum vs. Steel - Stiffness (Res. frequencies ratio) 2 ~ (Stiffness Ratio) (f coated /f substrate ) 2 Center Point Modal Testing Results 1 st mode 2 nd mode 3 rd mode Frequency (Hz) (log scale) Stiffness ratios of AL & ST coated substrates are highly differentiated at frequencies > 300Hz Noise & vibration transmission through Aluminum structures expected to shift at higher frequencies

7 Damping Performance Designed for Aluminum Center Point Modal Testing 1D beams Damping Loss Coating A Coating B Temperature ( o C) Most damping treatments designed for steel do not perform at optimum level on Aluminum at similar weight/area Coating optimized for Aluminum - increased damping performance

8 Damping Performance Designed for Aluminum Center Point Modal Testing 1D beams Damping Loss Factor Coating C Coating D 1 st mode Hz 2 nd mode Hz 3 rd mode Hz Temperature ( o C) Most damping treatments designed for steel show lower damping performance at higher modal frequencies Coating optimized for Aluminum: increased damping above 300Hz

9 Complex Structures & Modal Densities FRF Plots Without damping coating Panel Beam With damping coating 1 khz band Panels exhibit higher modal densities vs. beams BIW is a complex multi-panels & multi-beams assembled structure, and. Resonance frequencies of Aluminum structures are shifted higher, while Coincidence frequencies for Aluminum panels < 8-9 khz

10 Damping Performance Modal Testing - 2D Panels (PPG SAE paper ) Damping Loss factor Frequency (Hz) Band Range Test samples: Size 0.8m X 0.8m Coated area: 0.6m X 0.6m LASD coated panels show high damping above 500Hz vs. CLD steel LASD performs optimally in higher modal densities structures (i.e. BIW) and at frequencies >500Hz

11 Damping & Noise - Correlations Panel APAMAT SPL (db) Panel Damping Loss Factor 500 (Hz) 1000 (Hz) 1/1 octave bands 2000 (Hz) A B C D E F A B C D E F Panel group Panels with higher damping consistently produce lower noise

12 Concluding Remarks Aluminum BIW changes NVH transmission path significantly Aluminum substrates shift structural resonances at higher frequencies vs. steel substrates at similar stiffness Damping treatment products designed for steel substrates do not perform optimally on Aluminum LASD optimized for Aluminum: Higher damping performance on Aluminum compared to steel Higher damping at higher frequencies (>300 Hz) Good damping performance in high modal densities structures (e.g. panels, BIW)

13 Author Contact Info Ion Pelinescu, Ph.D. NVH-Acoustics Engineering Associate PPG Industries, Inc. Coatings Innovation Center Allison Park, PA Phone: Q & A