CSVR in Hong Kong PolyU

Transcription

1 CSVR in Hong Kong PolyU Li Cheng ( Chair Professor and Head Director, Consortium for Sound and Vibration Research (CSVR) The Hong Kong Polytechnic University Department of Mechanical Engineering

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3 The Hong Kong Polytechnic University Established in 1937 Largest tertiary institution in HK (32,427 students) 310,000 alumni 232 taught programmes 26 Departments/schools in 8 large faculties

4 Research Foci in ME Combustion and Pollution Control Aeronautical Engineering Integrated Product Development Fluid- Structure Interaction Sound and Vibration Department of Mechanical Engineering

5 Growing need for the society Environmental noise pollution worldwide Competitiveness of the products Enabling Technology

6 History Research Centre for Noise abatement and Control in 2001 Consortium for Sound and Vibration Research (University Niche Area) in 2007 Academic Strength L. Cheng (ME), Structural acoustics, SHM, Flow-induced vibration and noise SK Tang (BSE), Building acoustics, aeroacoustics Randolph CK Leung (ME), Aeroacoustics Tracy YS Choy (ME), Noise control, duct and fan noise ZQ Su (ME), Structural health monitoring, acousto-elastic wave. XJ Jing (ME), nonlinear system dynamics, vibration and control WO Wong (ME), Vibration control J Yuan (ME), Active noise and vibration control, Algorithms CF Ng (CEE), Building and construction noise and vibration CM Mak (BSE), Building and construction noise and vibration Productivity 50 journal publications/year Visibility 8 th ICSV, 14 th APVC, Symposia, Seminars JASA, SHM Assoc. Editors

7 Research Themes Aero-acoustics and structural acoustics Building and environmental noise Computational methods Dynamics, vibration and control Embedded Structural Health Monitoring Fluid-structure-sound interaction General acoustics

8 Research Facilities Anechoic Chamber Holography system Laser vibrometer Reverberant Chamber Acoustic windtunnel SysNoise

9 Decentralized Sensing Unit Doppler Laser Vibrometer Anechoic chamber Traffic noise measurement Aircraft noise abatement High-performance signal processing SHM System

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11 Fan Noise Research and Innovation Mechanisms understood Tone noise 12dB Wide potential applications, but commercialization requires product where fan noise is very crucial

12 Active Suppression of vortex, vibration and noise Sensor Laser Vibrometer FBG Sensor PVDF Hot-wire Controller Control off Structure Pressure Sensor Actuator Plastic plate Control on Z. B. Lu, D. Halim and L. Cheng, J. Acoust. Soc. Am., 133(3), , 2013.

13 Guided Wave-based Structural Health Monitoring Fundamental study of elastic waves guided Nonlinearities of elastic waves 1.0 Normalised Magnitude 0.5 second harmonic third harmonic Frequency [MHz] Signal feature extraction and data fusion Probability-based damage diagnostic imaging Zhou, C., Su, Z and Cheng, L. Mechanical Systems and Signal Processing. 25, , 2011.

14 Vibration-based Damage Characterization & Wavelet-based Multi-scale Damage Modelling Vibration-based Damage Characterization wxy (, ) wxy (, ) wxy (, ) DI = D + + h w x y x x y y c 2 (, ) ρc cω Wavelet-based Multi-scale Damage Modelling 4 4 d W( x) 2 d W( x) 2 EI A0 W( x) rei r 4 2 0A0 W( ) ( x ) d x ρ ω = d x ρ ω ξ δ ξ x= ξ H. Xu, L. Cheng, ZQ Su and JL Guyader, Journal of Sound and Vibration, 332, , 2013.

15 SHM System Development Centralized sensor network SHM software Decentralized sensing unit Online SHM system with application

16 System (Hardware) High-frequency arbitrary wave generator High sampling rate data acquisition board Generation Signal preamplifier Acquisition Power amplifier Central control unit

17 Interior Noise Modelling and Control Modeling of the interior problems Fully-coupled vibroacoustic model Interior noise control Avoid the use of microphones Double-walled isolation PZT Joint PVDF Outer vibrating structure THUNDER actuators Mech. Excitation Acoust. Excitation Inner wall Smart sensors & actuators Internal noise filed

18 Interior Noise Modelling and Control Interior noise; bulkhead fixation of Regional Jet (Canadair, Canada) Modal efficiency (d B ) Classification of sound radiating modes Frequency (Hz)

19 Active control of floor panels and isolation of Dash-8 (Supported by De Havilland Bombardier, Canada) Modeling /Analyses Sensor /Actuator Electronics Controller Tests

20 Virtual Sensors for Active Control in Vibroacoustic Application Aim: Development of robust virtual sensors for vibro-acoustic sensing and active control applications using structural sensors, without the use of acoustic sensors. Significance: Virtual sensors can be made to be robust against potential dynamic changes that may occur in practical applications. The use of multiple potentially-bulky acoustic sensors for sensing and active control purposes can be avoided. Structural sensors are used instead. Standard control systems can be integrated with the virtual sensors to regulate structural vibration for minimizing the noise inside a cavity. Primary disturbance Panel Virtual Sensor Estimate acoustic noise Structural sensor Control input Cavity Controller K F Structural sensing Virtual acoustic sensing Halim, D, Cheng, L. and Su, Z. J. Acoust. Soc. Am. 129(4), , 2011.

21 Compact Plate Silencer Passive control of duct noise without causing pressure drop in case of flow. A silencer composed of light panels to reflect low frequency noise is developed. This silencer provides a total noninvasiveness for the flow conduit, almost eliminates the undesirable pressure loss and occupies a minimal space outside the main flow conduit. Application Six-plate silencer Exhaust muffler in automobile Ventilation and air conditioning system Carbon fiber attached on the panel XN. Wang, YS Choy and L. Cheng, J. Acoust. Soc. Am. 132(6), , 2012

22 Light plate Compact plate silencer 2 4 η η m + B + ( Δp + I) = t x I = R + T + Damping Non-uniform plate m=2.4; B=0.18 (8.24Pam 4 ) E=0.24GPa (6mm thickness) m = m * * ( ρ h 0 * ) Uniform plate B = B * * ( ρ c 0 * 2 0 h * 3 ) m=3.17, B=0.1357, L=5 m=3.18, B=0.1813, L=5 m=3.4, B=0.2247, L=5 TL(dB) PMI 6mm 5CF m=3.18; B= β Frequency (Hz) Frequency (Hz)

23 LONG T-SHAPED ACOUSTIC RESONATORS FOR NOISE CONTROL IN SMALL ENCLOSURES Broadband control with multiple acoustic resonators Modeling of the T-shaped acoustic resonators Fully coupled vibroacoustic model Control mechanism Vs bandwidth Controllability Optimal placement Branch 1 60 Branch 2 Branch 3 (A) Long T-shaped acoustic resonator (B) Zoom view of a wall Integrated long T-shaped acoustic resonator L p (db) A Acoustic resonator orifice A (C) A-A section view of a wall (D) Steel rectangular box integrated with long T-shaped acoustic resonators Frequency (Hz) G. H. Yu and L. Cheng, Journal of Sound and Vibration, 328, 42-56, 2009

24 Application to Window design A) Double-partition window Glass panel Branch 2 Air cavity Elastomer with damping Spacer Branch 3 Mass v Orifice of Branch 1 Spacer integrated with TAR Glass sheets B) Incorporated tuned vibration absorbers Sash C) Structurally integrated long T-shaped acoustic resonator One resonators Four resonators D. Y. Li, XH Zhang, L. Cheng and GH Yu, Journal of Sound and Vibration, 329, , 2010.

25 SOUND ABSORPTION OF MICRO-PERFORATION IN COMPLEX ENVIRONMENT Micro-perforated panels Applications Modeling h * Pi * Pr * z * Pt * x * hc * 0 Flow-duct silencers L * Signal Cabel MPP Resonator Holder air flow F Microphone Cabin noise Wave Trapping Barrier L. Maxit, C. Yang, L. Cheng and JL Guyader, J. Acoust. Soc. Am. 131(3), , 2012.

26 MPP SOUND ABSORBERS WITH IRREGULAR- SHAPED CAVITY Improved absorption efficiency due to multi-modal acoustic resonances; Practical need for a more efficient noise barrier (the wave trapping barrier). incident wave MPP baffle control nodes fixed nodes 3D Configuration Acoustic Loadings Sound Absorption Coefficient Sound Absorption Vs Incident Angle C. Yang, L. Cheng and J. Pan, J. Acoust. Soc. Am. 133(1), , 2013.

27 Modeling and Optimization of Cascade Vibroacoustic Structure with aperture Concept of equivalent combined panel element Efficient modeling of cascade structures with air opening Ventilation Noise Reduction Window Ventilation Noise Reduction Window Transimission Loss Double Panel Double Panel + Internal Panel Double Panel + Internal MPP 40 Transmission Loss (db) Frequency (Hz)

28 A Wavelet-Galerkin Framework for Inner Acoustic Problems - Shape optimization of polygonal cavities Boundary treatment The cavity boundary is treated as a whole without the need of discretization. Accurate representation of the sound pressure at a relatively long interval. Ideal for shape optimization problem. Γ 2 S O Γ 1 Z Reduction of 16 db in Sound pressure within rectangular area.

29 Department of Mechanical Engineering Aeolian tone at M = 0.2 Sound wave Cavity noise at M = 0.6 Vorticity field Vorticity field Sound wave Impinging Jet at M = 1.2 Sound wave Shock wave

30 Department of Mechanical Engineering Acoustic generation efficiency scaling Vorticity field

31 Resolved panel vibration modes ( o theory; x simulation ) Department of Mechanical Engineering Transmission loss ( Line theory; symbol simulation )

32 Nonlinear Analysis and Design in the Frequency Domain U(jω) Linear systems Y(jω) U(jω) Nonlinear systems Y(jω) System output: h y ( t) = ( τ ) u( t τ ) dτ Transfer function h H ( jω) = ( τ )exp( j( ωτ)) dτ Output spectrum Y(jω)=H(jω)U(jω) Xiao, Jing, Cheng 2013a,b Jing et al 2006, 2012, 2013 System output: y( t) = H n ( jω,, jω ) h ( τ ) u( t τ ) dτ + n 1 n 1 1 h ( τ,, τ ) u( t τ ) dτ + n= 1 i= 1 n 1 1 u( t τ ) dτ = hn ( τ1,, τ n )exp( j( ω1τ ωnτ n )) dτ1dτ n n h ( τ, τ ) 2 1 i 2 2 Generalized frequency response functions Nonlinear output spectrum Y( jω) = N 1 i= 1 H n ( jω j n 1 1,, ωn ) n(2π ) n = 1 ω + + ω = ω i= 1 1 n i n i U( jω ) d i i σ ω

33 Isolation system allowing adjustable stiffness and damping with MR fluid and Pneumatic chamber 20 CAD prototype Magnitude of transmissibility function x / x b (db) ξ=0.05,φ DVMR =0 ξ=0.368,φ DVMR =0 ξ=0.686,φ DVMR =0 ξ=1.323,φ DVMR =0 ξ=0.05,φ DVMR =5 ξ=0.05,φ DVMR =10 ξ=0.05,φ DVMR = Angular frequency Ω Independent adjustable stiffness and damping Large manoeuvrable ranges Competitive performance over a broad frequency band X. C. Zhou, X. J. Jing and L. Cheng, Smart Materials and Structures, 20, (18pp), 2011.

34 Building and Environmental Acoustics Noise barrier Façade noise screening device Ventilation Window Beam-forming technique for source localization and property recovery

35 The Hong Kong Polytechnic University Department of Mechanical Engineering