Summary of Activities

Smart sensors are expected to be an important ingredient of third-generation structures. Candidate smart sensors for structural applications include optical fibre-based sensors, ferro-magnetic sensors, shape memory alloys and piezoelectric sensors. As sensor technologies advance, periodical evaluations of their performance should be conducted to identify the best-performing sensors available for the measurement of structural responses (e.g. displacement, velocity, acceleration, strain, and stress) and detecting structural damage (e.g. cracking, fatigue and corrosion). Such evaluations should consider their performance (e.g. reliability, sensitivity, integrity, and robustness) not only as stand-alone sensors but more importantly when externally attached to structural members as well as internally embedded in concrete and FRP materials.

The Centre research in this area covers:

• Active damage detection for composite material structures using embedded piezoelectric actuators and sensors
• Use of Optical Fibre Sensors for Civil Engineering Application
• Mechanical interaction issues in piezoelectric composite structures
• Robust damage detection of laminated plates using smart piezoelectric materials with wavelet analysis and strain modal technique
• Sensitivity analysis of sensor locations for vibration control and damage detection of thin-plate systems
• Optimal design of thickness and embedded depth of piezoelectric patch actuator embedded in piezolaminated structures
• Optimal design of number and locations of actuators in active vibration control of a space truss
• Crack detection of a honeycomb sandwich plate using wavelet analysis of vibration response acquired by bonded piezo-patches

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Representative Projects

• Automatic Damage Detection for In-service Laminated Composite Shells Partially Filled with Fluid (CERG project)
• Active Damage Detection for Composite material Structures Using Embedded Piezoelectric Actuators and Sensors (CERG project)
• Non-destructive Robust Damage Detection of Composite Plates Using Model-Based Neural Network (CERG project)
• Innovative Optical Fibre Sensors for Structural Health Monitoring of Tsing Ma Bridge
• Modal Strain Analysis and Dynamic Design for Vibrating Structure
• Research and Implementation of Operational Condition Monitoring and Fault Diagnosis System for Gear Boxes
• Vibration Analysis and Robust Active Control of Thin Plate System
• Structural Damage Detection and Characterization Based on Strain Mode Theory and Laser Speckle Pattern Interferometry
• Robust Damage Detection of Laminated Plates Using Smart Piezoelectric Materials with Nonlinear ARMAX and Wavelet Analysis
• Vibration and Acoustic Radiation of Planar Structures: Active Control and Damage Detection
• Damage Detection of Laminated Plates Using Strain Modal Technique
• Automatic Inspection and Location of Crack in In-service Laminated Composite Shells Partially Filled with Fluid
• Smart Vibration Isolation Technology for Automation and Precision Equipment (Funded by The Innovation and Technology Commission (ITC) - Innovation and Technology Fund-University-Industry Collaboration Program-Matching Grant for Joint Research (ITF-UICP-MGJR))
• Magnetoelectric Composites for Magnetic Field Sensor Applications (Funded by RGC)
• Consultancy on Piezoelectric Transducers and Vibration Control (Funded by ASM Assembly Automation Ltd.)
• Study of Magnetostrictive Composites for Transducer and Actuator Applications (Funded by PolyU)
• Dynamic Characterization of Terfenol-D Magnetostrictive Smart Composites (Funded by PolyU)
• A cost effective multi-point fibre grating sensor system for flow-induced structural vibration measurement (funded by RGC)
• Measurement of flow-induced vibrations on an array of cylinders in a cross flow using optical fibre Bragg grating sensors (funded by RGC)
• Fibre optic sensors for smart structures (funded by British Council)
• Networking of fiber optic strain sensors for large scale smart structures (funded by PolyU)
• Novel fibre Bragg grating devices for sensing and communications (funded by PolyU)
• Interfacial Behaviours of smart composites (funded by Heng Sheng Fund)
• Networking of fibre optic sensors (funded by PolyU)
• Multiplexing of fibre optic grating sensors (funded by PolyU)
• Quasi-distributed fibre optic strain/temperature sensors for smart structure applications (funded by PolyU)
  

Patents:

• S.W. Or, H. Zhu, Y.M. Wong and H. Ng, "Method of Bonding Wires", US Patent, Publication No. US 2002/0060239 A1 (2002); Taiwanese Patent, No. 521358 (2003).
• H.L.W. Chan, S.W. Or and C.L. Choy, "Ultrasonic Transducer", US Patent, No. US 6,286,747 B1 (2001); Chinese Patent, No. CN 1316310A (2001).
• L.W. Chan-Wong, S.S. Chiu, S.W. Or and Y.M. Cheung, "Piezoelectric Sensor for Measuring Bonding Parameters", US Patent, No. US 6,279,810 B1 (2001); Chinese Patent, No. CN 1310071A (2001); Japanese Patent, No. P,2001-242022,A (2001); Taiwanese Patent, No. 480199 (2002).
• H.L.W. Chan, S.W. Or, K.C. Cheng and C.L. Choy, "Ultrasonic Transducer", US Patent, No. US 6,190,497 B1 (2001); Chinese Patent, No. CN 1286147A (2001).

Dynamic Strain Measurment using FBG Sensors
	FBG sensors installed nearby an electrical strain gauge at rocker bearing of the Tsing Ma Bridge. Inset shows the FBG sensor inside a protective enclosure with its cover opened.
Principle of Fibre Bragg Grating (FBG) Sensors

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Major Facilities

• B&K 3557 Eight-channel Analyzer System including:
  
  • 2035 Signal Analyzer Unit
  • 3106 Generator & Sampling Module
  • 3023 Eight-channel Input Module
  • 3157 100KHz/Multichannel Zoom Processor
  • 7649 Basic Dual-channel Analysis Software
  • 7674 4/8 Channel Analysis Software
• B&K Portable Multi-analyzer System 3560C (15-channe Input, 2-channel Output)
• B&K 4397 Deltatron Accelerometers
• B&K 8202 Impact Hammer
• B&K 5961 Hand-held Excitation Hammer
• B&K 4809 Small Vibration Exciter
• B&K 2815 Power Supply Amplifier
• B&K 2525 Measuring Amplifier
• B&K 8200 Force Transducer
• B&K 2706 Power Amplifier
• B&K 2635 Charge Amplifiers
• DAQ Board (LAB-PCI-1200)
• 7750 C001 B&K STARMODAL Software for Modal Analysis
• Piezoelectric Smart Materials Manufacturing Facilities
• Magnetostrictive Smart Materials Manufacturing Facilities
• Disco DAD 341 Automatic Dicing Saw
• Buehler Isomet 4000 Linear Precision Saw
• Buehler Isomet 2000 Precision Saw
• Buehler Ecomet 3 Variable Speed Grinder-Polisher
• Philips X-Ray Diffractometer
• Scanning Electron Microscope
• Transmission Electron Microscope
• Horbia CAPA-700 Particle Size Distribution Analyzer
• Ferroelectric Hysteresis Measurement System
• Magnetostrictive Characterization Facility
• Magnetoelectric Characterization Facility
• Ono Sokki CF-5220 Multi-Purpose FFT Analyzer with a CF-0515 2-MHz Data Sampling Unit
• B & K 3550 Analysis System with a 2035 Signal Analyzer Unit, a 3106 Generator and Sampling Module, and two 3020 100-kHz Input Modules
• DSPT SigLab Dynamic Signal Analysis System with four 50-21 Modules
• LDS Shaking System with a V406 Shaker and a PA100E Power Amplifier
• AE Techron 7572 Power Supply Amplifier with Constant Voltage or Control Current Output
• NF Electronic Instruments 4025 High Speed Power Amplifier/Bipolar Power Supply
• Electromagnet with a DC Current Supply
• F.W. Bell 7030 Gauss/Tesla Meter with a PAA71-1908-05 High-Frequency Probe
• Walker LDJ MF-10D Microprocessor-Controlled Integrating Meter
• MTI-2000 FotonicTM Fiber-Optic Displacement Sensor
• Polytec Laser Doppler Vibrometer with an OFV-303 Single Point Laser Interferometer and an OFV-3001 Controller
• Polytec Laser In-Plane Vibrometer with an OFV-3300-2 Controller
• Agilent 4294A Precision Impedance Analyzer
• Pennebaker Model 8000 d33 Tester
• Agilent Infiniium 54810A Digitizing Oscilloscope
• Stanford Research Systems DS340 Signal Generator
• Stanford Research Systems SR560 Low-Noise Preamplifier
• Stanford Research Systems SR570 Low-Noise Current Pre-Amplifier
• HP3589A Spectrum/Network Analyzer
• Universal Tensile Testing Machine
• Pendulum Impact Tester
• Modal Analysis Software upgraded from 7750C to 7750D
• NASTRAN Software
• MATLAB® 6.5
• SIMULINK® 5.0.2
• dSPACE Control Kit

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Selected Publications

• Ling, H.Y., Lau, K.T., Cheng, L. Jin, W. Thomson, R.S. and Scott, Murray L Embedded FBG Sensor for Dynamic Strain Measurement for a Clamped-Clamped Composite Structure. Key Engineering Materials. 2003; Submitted.
• Lau, K.T. Fibre-optic Sensors and Smart Composites for Concrete Applications: A Review Article. Magazine of Concrete Research, 2003; 51(1): 19-34.
• Yuan, L.B., Zhou, L.M., JIN W and Lau, K.T., Effect of Thermally Induced Strain on Optical Fiber Sensor Embedded in Cement-based Composites. Optical Fiber Technology.2003; 9: 95-106.
• Yuan, L.B., Zhou, L.M., Lau, K.T., Jin, W. and Demokan MS Fiber Optic Extensometer for Concrete Deformation Measurements, Review of Scientific Instruments, 2002; 73: 2469-2474.
• Lau, K.T., Yuan, L.B. and Zhou, L.M. Applications of Composites, Optical Fibre Sensors and Smart Composites for Concrete Rehabilitation: An Overview. Appl. Comp. Mater., 2002; 9: 221-247.
• Lau, K.T. and Zhou, L.M. Investigation on Strengthening and Strain Sensing Techniques for Concrete Structures using FRP Composites and FBG Sensors. Mater. Struct., 2001; 34: 42-50.
• Lau, K.T., Zhou, L.M. and Ye, L. Rehabilitating and Real-time Strain Monitoring on Concrete Structures using Advanced Composites and Optical Fibre Sensor, Mag. Soc. Manu. Eng., 2001; CM01-02. Invited.
• Lau, K.T., Yuan, L.B. and Zhou, L.M. Thermal Effects on Embedded Grating Sensor for FRP Structure. Smart Mater. and Struct.,  2001; 10: 705-712.
• Yuan, L.B., Jin, W., Zhou, L.M. and Lau, K.T. The Temperature Characteristic of Fibre-optic Pre-embedded Concrete Bar Sensor. Sensors and Actuators A: Physical, 2001; 93: 206-213.
• CHAN KC, Jin, W., Lau, K.T. and Zhou, L.M. Multi-point Strain Measurement of Composite-bonded Concrete Materials with a FMCW Multiplexed FBG Sensor Array. Sensors and Actuators A: Physical, 2000; 87: 19-25.
• Lau, K.T., Zhou, L.M. and Ye, L. Investigation on Upgrading and Health Monitoring the Civil Concrete Structures using FRP and FBG Sensor. Adv. Comp. Letter., 1999; 8(6): 323-332.
• Chan, P.K.C., Lau, K.T., Jin, W. and Zhou, L.M. Utilisation of Fibre-optic Bragg Grating Sensors in Concrete Columns Confined with Glass-fibre-reinforced Plastic (GFRP) Laminate under Uni-axial Compression Test. Chapter, Edited by Marcus M. A. and Wang A., The International Society for Optical Engineering (SPIE) (ISBN 0-8194-2999-6), U.S.A. pp 64-72, 1999.
• Lau, K.T., Zhou, L.M. and Ye, L. Strain Evaluation on Strengthened Concrete Beam by using FBG Sensor. Non-destructive Characterisation of Materials, Chapter, Edited by R. E. Green, American Institute of Physics (AIP) (ISBN 1-5639-911-4), New York, pp 303-308, 1999.
• T. Li, S.W. Or and H.L.W. Chan, "Magnetoelectric Effect in a Parallel Sandwich of Magnetostrictive 1-3 Composite and Piezoelectric 2-2 Composite", Journal of Applied Physics (June 2004).
• N. Nersessian, S.W. Or and G.P. Carman, "Magnetoelectric Behavior of Terfenol-D Composite and Lead Zirconate Titanate Ceramic Laminates", IEEE Transactions on Magnetics (June 2004).
• J.G. Wan, S.W. Or, J.-M. Liu, H.L.W. Chan, C.L. Choy, G.H. Wang and C.W. Nan, "Magnetoelectric Properties of a Heterostructure of Magnetostrictive and Piezoelectric Composites", IEEE Transactions on Magnetics (June 2004).
• Y.X. Liu, J.-M. Liu, S.W. Or, J.G. Wan, H.L.W. Chan and CL Choy, "Numerical Modeling of Magnetoelectric Effect in a Bilayered Composite Structure", IEEE Transactions on Magnetics (June 2004).
• W.J. Ren, S.W. Or, C.L. Choy, X.G. Zhao, J.J. Liu and Z.D. Zhang, "Structural, Magnetic, and Magnetostrictive Properties of Tb1-xNdx(Fe0.9B0.1)2 Alloys", IEEE Transactions on Magnetics (June 2004).   
• W.J. Ren, S.W. Or, C.L. Choy, W.F. Li, X.G. Zhao and Z.D. Zhang, "Spin Orientation and Magnetostriction of Multi-Component TbxDy1-x-yPry(Fe0.9B0.1)1.93 Laves Phases", IEEE Transactions on Magnetics (June 2004).   
• P.W.P. Chu, S.W. Or, H.L.W. Chan and P.C.K. Liu, "Piezoelectric Ring Sensor for Ultrasonic Wire-Bonding Process Control", Ceramics International (in press).
• H.L.W. Chan, C.P. Chong, S.W. Or and P.C.K. Liu, "Study of 1-3 Composite Transducers for Ultrasonic Wirebonding Applications", Ceramics International (in press).
• D.G. Lee, S.W. Or and G.P. Carman, "Design of a Piezoelectric-Hydraulic Pump with Active Valves", Journal of Intelligent Material Systems and Structures (in press).
• S.W. Or, N. Nersessian and G.P. Carman, "Dynamic Magnetomechanical Behavior of Terfenol-D/Epoxy 1-3 Particulate Composites", IEEE Transactions on Magnetics (in press).
• N. Nersessian, S.W. Or and G.P. Carman, "Magneto-Thermo-Mechanical Characterization of [1-3] Type Polymer-Bonded Terfenol-D Composites", Journal of Magnetism and Magnetic Materials, Vol. 263, Issues 1-2, pp. 101-112 (2003).
• S.W. Or, N. Nersessian and G.P. Carman, "Effect of Combined Magnetic Bias and Drive Fields on Dynamic Magnetomechanical Properties of Terfenol-D/Epoxy 1-3 Composites", Journal of Magnetism and Magnetic Materials, Vol. 262, Issue 2, pp. L181-L185 (2003).
• S.S. Chiu, H.L.W. Chan, S.W. Or, Y.M. Cheung, and P.C.K. Liu, "Effect of Electrode Pattern on the Outputs of Piezosensors for Wire Bonding Process Control", Materials Science and Engineering B-Solid State Materials for Advanced Technology, Vol. 99, Issues 1-3, pp. 121-126 (2003).
• S.W. Or, N. Nersessian, G.P. McKnight, and G.P. Carman, "Dynamic Magnetomechanical Properties of [112]-Oriented Terfenol-D/Epoxy 1-3 Magnetostrictive Particulate Composites", Journal of Applied Physics, Vol. 93, No. 10, pp. 8510-8512 (2003).
• S.W. Or and H.L.W. Chan, "Resonance Characteristics of Lead Zirconate Titanate/Epoxy 1-3 Composite Rings", Ferroelectrics, Vol. 263, Issues 1-4, pp. 1517-1522 (2001).
• S.W. Or and H.L.W. Chan, "Mode Coupling in Lead Zirconate Titanate/Epoxy 1-3 Piezocomposite Rings", Journal of Applied Physics, Vol. 90, No. 8, pp. 4122-4129 (2001).
• S.W. Or, H.L.W. Chan and C.L. Choy, "P(VDF/TrFE) Copolymer Acoustic Emission Sensors", Sensors and Actuators A: Physical, Vol. 80, Issue 3, pp. 237-241 (2000).
• W.JIN, Y.B.LIAO, and Z.P. ZHANG, "Guided wave optical sensors", Science Press, Beijing, May 1998, 350 pages.
• L. YUAN, L. ZHOU AND  W. JIN, "Fibre optic differential interferometer," IEEE Transations on Instrumentation and  Measurement, Vol.49, No.4, 779-782, August, 2000. 
• C. C. CHAN, W. JIN and M. S. DEMOKAN, "Performance analysis of a time-division-multiplexed fibre Bragg grating sensor array by use of a tunable laser source," IEEE Journal of Selected Topics in Quantum Electronics, Vol.6, No.5, 741-749, Sep-Oct., 2000.
• C. C. CHAN, J.M. GONG, W. JIN, and M.S.DEMOKAN, "Minimisation of interferometric noise in a fibre Bragg grating sensor system using a tunable laser and a first derivative interrogation technique," Optical Communications, Vol.173, 203-210, 2000.
• W.JIN, Y.ZHOU, PETER K.C. CHAN and H.G.XU, "An optical fibre Bragg grating sensor for flow-induced structural vibration measurement,"  Sensors and Actuators A, Vol.79 (1), 36-45, 2000.
• P. K. C. CHAN, W. JIN and M. S. DEMOKAN, "FMCW multiplexing of fibre Bragg grating sensors," IEEE Journal of Selected Topics in Quantum Electronics Vol.6 No.5, 756-763, Sep.-Oct. 2000.
• P. K. C. CHAN, W. JIN, K.T. LAU, L.M.ZHOU, M. S. DEMOKAN, "Multi-point strain measurement of composite-bonded concrete materials with a RF-band FMCW multiplexed FBG sensor array," Sensors and Actuators A, Vol. 87, 2000, pp19-25.
• L. YUAN, L. ZHOU AND  W. JIN, "Quasi-distributed fibre optic strain sensor with white light interferometry: a novel approach," Optics Letters, Vol.25, No.15, August 2000, pp.1074-1076.
• L. YUAN, L. ZHOU,  W. JIN, and C. C. CHAN "Recent progress of white light interferometric fiber optic strain sensing techniques," Review of Scientific Instruments, Vol.71, No.12, December 2000, 4648-4654.
• K. T. Lau, C. C. Chan, L. M. Zhou and W. Jin, "Strain monitoring in composite-strengthened concrete structures using optical fibre sensors". Composites Part B-Engineering, 32(2001) pp.33-45.
• C. C. CHAN, W. JIN, H. L. HO, D.N. WANG AND Y. WANG, "Improvement of measurement accuracy of FBG sensor systems by use of gas absorption lines as multi-wavelength references," Electronics Letters, Vol.37, no.12, June 7 2001.
• Yuan LB, Jin W, Zhou LM, et al. The temperature characteristic of fiber-optic pre-embedded concrete bar sensor, SENSOR ACTUAT A-PHYS 93 (3): 206-213 OCT 15 2001.
• Yuan LB, Zhou LM, Lau KT, Jin W et al. Fiber optic extensometer for concrete deformation measurements,  REV SCI INSTRUM 73 (6): 2469-2474 JUN 2002 .

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Contact Information

Contact Person

Professor H.Y. Tam Department of Electrical Engineering The Hong Kong Polytechnic University Kowloon, Hong Kong Fax:     + 852 - 2330 1554 Phone:   + 852 - 2766 6175 E-mail:  eehytam@polyu.edu.hk

Professor C.S. Poon Department of Civil and Structural Engineering The Hong Kong Polytechnic University Kowloon, Hong Kong Fax:     + 852 - 2334 6389 Phone:   + 852 - 2766 6024 E-mail:  cecspoon@polyu.edu.hk

Other Investigators

Prof. Y.L. Xu (ceylxu@polyu.edu.hk)
Prof. H.L.W. Chan (apahlcha@polyu.edu.hk)
Prof. W. Jin (eewjin@polyu.edu.hk)
Dr T.H.T. Chan (cetommy@polyu.edu.hk)
Dr. K.W. Kwok (apkwkwok@polyu.edu.hk)
Dr. S.W. Or (apswor@polyu.edu.hk)
Dr. D.N. Wang (eednwang@polyu.edu.hk)
Dr L. Lam (cellam@polyu.edu.hk)
Dr. Y.Q. Ni (ceyqni@polyu.edu.hk)
Dr. K.T. Lau (mailto:mmktlau@polyu.edu.hk)
Dr. L.H. Yam (mmlhyam@polyu.edu.hk)