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SMART MATERIALS AND STRUCTURES Lecture at Swiss Federal Institute of Technology Ză urich (ETH) Ză urich, 14 Sept.,2015 Bohua Sun Member of Academy of Science of South Africa(ASSAf) Professor in Engineering Cape Peninsula University of Technology Cape Town South Africa sunb@cput.ac.za CAPE PENINSULA UNIVERSITY OF TECHNOLOGY (2015) c Copyright ⃝2015 by Bohua Sun All rights reserved Published by Cape Peninsula Univerisity of Technology Cape Town, South Afica No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose No warranty may be created or extended by sales representatives or written sales materials The advice and strategies contained herin may not be suitable for your situation You should consult with a professional where appropriate Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages Smart Materials and Structures / Bohua Sun [et al.] Printed in South Africa To My Dear Father, Mother and Family [I hope that I may succeed in deserving and obtaining your confidence But in the first place, I can ask nothing of you but to bring with you, above all, a trust in science and a trust in yourselves The love of truth, faith in the power of mind, is the first condition in Philosophy Man, because he is Mind, should and must deem himself worthy of the highest; he cannot think too highly of the greatness and the power of his mind, and, with this belief, nothing will be so difficult and hard that it will not reveal itself to him ] —Georg Wilhelm Friedrich Hegel, Oct 28, 1816 at Heidelberg University PREFACE Smart structures or smart materials systems are those which incorporate actuators and sensors that highly integrate into the structures and have structural functionality, as well as highly integrated control logic, signal conditioning, and signal power amplification electronics Such actuating, sensing and controlling are incorporated into a structure for the purpose of influencing its states or characteristics, be they mechanical, thermal, optical, chemical, electrical, or magnetic For example, a mechanically smart structure is capable of altering both its mechanical states (its position or velocity) or its mechanical characteristics (its stiffness or damping) Optically smart structures could, for example, change color to match its background In the following decades, it is expected that there will be widespread application of the technology under development, in its current and evolutionary forms The breath of application of this technology is expected not only towards high-tech but also towards civilian fields This lecture notes is specially prepared for the Seminar at Institute of Structural Engineering at ETH I would like to take this opportunity to address important issues of smart materials and structures and to introduce some work from my research group I would like to express my deep gratitude to Prof Dr Eleni Chatzi1 for his warm hospitality and to the South African National Research Foundation for financial support B OHUA S UN Cape Town, South Africa and Zu ărich, Switzerland Prof Dr Eleni Chatzi is the Chair of Structural Mechanics at ETH v CONTENTS Preface v List of Figures xi List of Tables xv INTRODUCTION 1.1 1.2 1.3 1.4 1.5 1.6 1.7 The Needs Smart Material Age Smart Structures and Development Background Smart Materials Smart Structures Critical Component Technologies of Smart Structures Smart Materials and MEMS SMART MATERIALS AND STRUCTURES 2.1 2.2 Piezoelectric Materials 2.1.1 General Concepts 2.1.2 Piezo Transducers 2.1.3 PZT Application Shape Memory Materials 2.2.1 General Concepts 2.2.2 Ferromagnetic Shape Memory Alloys 9 12 12 16 16 18 vii viii CONTENTS 2.3 2.4 2.5 2.6 2.2.3 SMA Application Magnetostrictive Materials 2.3.1 General Concepts 2.3.2 Basics of Magnetostriction 2.3.3 MS Applications Electrorheological Fluids 2.4.1 General Concepts 2.4.2 EF Applications Magnetorheological fluids 2.5.1 Introduction to MR Fluids 2.5.2 MR Actuators 2.5.3 Design of MR Systems Fibre Optic Sensors 2.6.1 The Structure of Optical Fibres 2.6.2 Characteristics, Advantages and Capabilities of Fibre Optic Sensors 2.6.3 Capabilities and Significance 2.6.4 Intensiometric Fibre Optic Sensors 2.6.5 Interferometric fibre optic sensors 2.6.6 Bragg (Grating) Fibre Optic Sensor 2.6.7 Polarimetric Fibre Optic Sensors 2.6.8 Modalmetric Fibre Optic Sensors 19 20 20 22 23 24 24 25 25 25 27 29 30 30 31 31 32 33 33 34 34 DISTRIBUTED PIEZOELECTRIC ACTUATING SMART STRUCTURES 35 SOME GENERAL ASPECTS OF PIEZOELECTRIC SENSOR MECHANICS 41 4.1 4.2 4.3 4.4 4.5 Introduction Smart structure and active control Sensory Elements Working Principle of Piezoelectric Smart Structures Sensor Analysis 4.5.1 Piezo Composite Beam 4.5.2 Modal sensor 41 41 42 43 44 45 46 SMART PIEZO COMPOSITE MINDLIN BEAMS 47 5.1 5.2 5.3 47 48 51 Introduction Formulations Numerical Example RECTANGULAR AND CIRCULAR SHAPE DISTRIBUTED PIEZOELECTRIC ACTUATOR 55 6.1 Introduction 55 CONTENTS 6.2 6.3 56 56 57 57 58 58 ELECTRO-MECHANICAL PERFORMANCE OF C-SHAPE PIEZOELECTRIC ACTUATOR 61 7.1 7.2 7.3 7.4 7.5 Rectangular DPA element 6.2.1 Polarization of Rectangular DPA Element 6.2.2 Distributed Charge Density Analysis 6.2.3 Capacitance Analysis of the DPA Element 6.2.4 The Mechanical Performance Analysis of the Rectangular DPA Element The Electrical Field Distribution in the Part-circular Shape DPA ix Introduction Displacement and Force Equations Displacement Analysis and Discussion Force Analysis and Discussion Conclusions and Recommendations 61 63 64 64 66 MONITORING STRUCTURAL INTEGRITY USING FIBRE OPTIC SENSORS 67 8.1 8.2 References Formulations Conclusions 67 69 71 60 RECTANGULAR AND CIRCULAR SHAPE DISTRIBUTED PIEZOELECTRIC ACTUATOR Figure 6.4 The strain result comparison between the analytical model and the FEM Figure 6.5 The DPA element with part-circular shape CHAPTER ELECTRO-MECHANICAL PERFORMANCE OF C-SHAPE PIEZOELECTRIC ACTUATOR 7.1 Introduction Widespread application of curved shape piezoelectric actuators in certain smart structures and devices demand a comprehensive study on this particular shape Active controls of satellite dishes or mirrors are examples of applications of curved piezoelectric actuators smart flap drive for individual blade control [3], circular multilayered diaphragm-type actuators for MEMS, micropumps and acoustic devices, Deshpande and Saggere Performance characteristics of a piezoelectric device are determined by material, geometry and electromechanical coupling properties Woo et al , from their investigation, they reported that dome height and stored elastic energy induced by thermal deformation during curing have influence on the flexural displacement and load capability of a platetype piezocomposite actuator In order to obtain a wide motion range and ultra-precision D.S Stampleman, A.H von Flotow, Microgravity isolation mounts based on piezoelectric films in active and vibration control, ASMEWAM (1990) 57–67 G.W Bahaman, V.H Schmidt, R.J Conant, Piezoelectric Polymer Actuators in a vibration isolation application, Proc SPIE 3987 (2000) 331–342 M Deshpande, L Saggere, An analytical model and working equations for static deflections of a circular multilayered diaphragm-type piezoelectric actuator, Sens Actuators A: Phys 136 (2) (2007) 673–689 S.-C Woo, K.H Park, N.S Goo, Influences of dome height and stored elastic energy on the actuating performance of a plate-type piezoelectric composite actuator, Sens Actuators A: Phys 137 (1) (2007) 110–119 Smart Materials and Structures c 2015 Bohua Sun By Bohua Sun Copyright ⃝ 61 62 ELECTRO-MECHANICAL PERFORMANCE OF C-SHAPE PIEZOELECTRIC ACTUATOR simultaneously, Dong et al.5 , developed a macro/micro dual compliant parallel positioner system in which piezoelectric motors and piezoelectric ceramics are integrated together in one system The influence of substrate/PZT thickness ratio on the optimum performance of the Cshape actuator is the main focus of this work The C-shape piezoelectric actuator, which is a semicircular shell, is an invention of Moskalik and Brei in 19966 When individual C-shape actuators are combined in series and/or parallel it is possible to generate displacement and force larger than a comparable straight bender The force produced by an array of C-shape actuators is proportional to the number of individual C-shape actuators in a parallel arrangement, while the resulting displacement equals the sum of displacements of individual actuators in a series arrangement7 Aunimorph individual C-shape piezoelectric actuator (Figure 7.1) consists of three layers laminated together to form a semicircular shell i.e one active layer (piezoceramic) and passive layers (bonding and substrate) The piezoceramic (PZT) layer is preplated with electrode layers on its inner and outer surfaces The piezoceramic layer together with its electrode is bonded on the outer surface of the substrate Epoxy is used as the bonding material and a strong bond is created between the piezolayer and the substrate This ensures that all loads applied by the active layer are transmitted fully to the passive layer With the unimorph actuator, when the piezoelectric layer expands/contracts in the radial direction the strain in the plane normal to the poling direction (i.e in the circumferential direction) undergoes a contraction/expansion The “perfect bond”between the piezoceramic layer and the substrate leads to a concentrated couple or moment M pe at the edges of the piezoelectric actuator layer once a voltage is applied8 The concentrated moment will eventually cause the whole structure to flex The assumption of a “perfect bond”also implies continuity of displacement/strain between the interfaces of the laminate For the PZT material, the unimorph configuration is preferred particularly when the actuating device is to be subjected to both tensile and compressive loads PZT materials are weak in tension; therefore for an actuator to perform well and in safety it is important that when determining the stacking sequence of the layers in the laminate, the piezoceramic layer must be positioned on one side of the neutral axis This will ensure that the PZT layer experiences only compressive stresses during its operation In addition, by locating the active layer as far as possible from the neutral axis a larger moment arm will be obtained and hence larger bending moment The location of the neutral axis is normally achieved by the introduction of passive layers (i.e substrate) of appropriate geometry (thickness) and elastic modulus W Dong, L.N Sun, Z.J Du, Design of a precision compliant parallel positioner driven by dual piezoelectric actuators, Sens Actuators A: Phys 135 (1) (2007) 250–256 A.J Moskalik, Diann Brei, Quasi-static behavior of individual C-block piezoelectric actuator, J Intell Mater Syst Struct (1997) 577–587 A.J Moskalik, Diann Brei, Force-displacement behavior of piezoelectric C-block actuator arrays, Smart Struct Mater (1999) 531–543 E.F Crawley, J de Luis, Use of piezoelectric actuators as elements of intelligent structures, AIAA J 25 (10) (1987) 1373–1385 DISPLACEMENT AND FORCE EQUATIONS 63 C-shape piezoceramic actuator Figure 7.1 Figure 7.2 Unimorph C-shape actuator 7.2 Displacement and Force Equations Since the C-shape actuator is considered to have a thin cross section, it is reasonable to consider a unidirectional state of loading The radial displacement and force at the tip of the free end can be defined by the force-displacement equation obtained using the Castigliano Method for thin piezoelectric curved beams The internal moment ‘M’at any angular position Figure 7.2 is the sum of moment due to externally applied force and the piezoelectric moment, M = −Px Rna sin θ + M pe (7.1) where Px is the available force at the free end tip, M pe is the piezoelectric moment, Rna is the radius from the origin of the semi-circle to the neutral axis ∂M = −Rna sin θ ∂Px From Figure 7.2, the complementary energy is obtained by the equation: ∫ π M Rna dθ Uc = 2QIz (7.2) (7.3) where Q is the Young’s modulus of elasticity of the material and Iz is the moment of inertia of the cross-section of an actuator about the neutral axis The displacement of the free end can be obtained using complementary energy as follows: ∂Uc 2M pe Rna πPx Rna δx = = − , (7.4) ∂Px C 2C 64 ELECTRO-MECHANICAL PERFORMANCE OF C-SHAPE PIEZOELECTRIC ACTUATOR where δx is the radial displacement at the free end, C = QIz is the composite bending stiffness Expressing the available force in terms of the piezoelectric moment and radial displacement we obtain net force at the tip of the free end, Px = 4M pe 2Cδx − πRna πRna (7.5) The blocking force (i.e the force obtained when the displacement of the tip of the free end is equal to zero in the equation 7.4) is given by Pblock = 4M pe πRna (7.6) The free-displacement at the free end (i.e when the piezoelectric forcing term is not resisted exremally in any way) becomes δf ree = 2M pe Rna C (7.7) The piezoelectric moment M pe , the radiu of neutral axis Rna and the bending composite stiffness C can be obtained by Mpe = n ∑ j=1 bj Qj (h2j − h2j−1 )(d31 E3 )j , Rna = C= n ∑ j=1 ∑n 2 j=1 0.5Qj bj (rj −rj−1 ∑ , n j=1 Qj bj (rj −rj−1 ) bj Qj (h3j − h3j−1 ), (7.8) where bj is the width of the jth layer, hj is the coordinate of the outer surface of the jth layer, hj−1 is the coordinate of the inner surface of the jth layer, hj = rj − Rna , and d31 is the piezoelectric strain constant For a thin piezoelectric actuator it is sufficient to assume that an electric field is equal to the change of voltage between the electrodes V divided by the thickness t of the piezoceramic layer concerned, i.e t = hj − hj−1 ; hence E3 = V hj − jj−1 (7.9) 7.3 Displacement Analysis and Discussion From the results obtained it was observed that actuators with smaller substrate/PZT thickness ratio give larger displacement than the ones with greater ratios The experimental results agree with the theoretical as well as with those from FEM analysis that is, increased displacement when the substrate/PZT is increased and subsequently decreases when the ratio of approximately 0.28 is reached Figure 7.3 shows typical experimental, theoretical and the finite element analysis results for displacement of the free end tip of the C-shape actuator 7.4 Force Analysis and Discussion Larger force is obtained from an actuator with larger substrate/PZT thickness ratios (stiffness dependence) It is observed that the actuator output force is increased when the FORCE ANALYSIS AND DISCUSSION 65 Figure 7.3 at 50 V) Results for Displacement for substrate/PZT thickness ratios (for 1mm PZT thickness, Figure 7.4 V) Results for the force for substrate/PZT thickness ratios (for 1mm PZT thickness, at 50 substrate/PZT thickness ratio is increased, at least up to a ratio of 1:1 after which a decrease is also noted This is obviously due to the fact that the actuator becomes too thick to be deformed by the generated piezoelectric actuator force Experimental, theoretical finite element analyses results for the actuator are as shown in Figure 7.4 66 7.5 ELECTRO-MECHANICAL PERFORMANCE OF C-SHAPE PIEZOELECTRIC ACTUATOR Conclusions and Recommendations Figure 7.5 Numerical simulations of deflection and forces Numerical simulations have been animated in Figure 7.5, which can be concluded that, for a given PZT actuator material and applied voltage, free displacement and blocked force are influenced by the actuator stiffness which is partly contributed by the substrate material’s elastic properties and the geometry (in this case, the thickness) The thickness of the substrate material, apart from altering the actuator stiffness, also has the role of determining the location of the neutral axis (N.A.), and thus the moment arm which is defined as the distance between the midline of the PZT layer (i.e where the piezoelectric force is assumed to act) to the neutral axis On the other hand, the thickness ratio also determines the portion/part of the cross-section of the PZT layer which will be subjected to compression/tension load during the forward and backward strokes of the device, especially when subjected to alternating voltage For a unimorph actuator, where a PZT layer is on top i.e outside of the substrate layer, at lower thickness ratios, a bigger portion will suffer tensile load during the inward stroke and compressive load during the outward stroke At higher ratios, the situation will be the other way round The farther the neutral axis goes away from the midline of the structure, the larger the moment arm and hence the larger the piezoelectric moment At the ratio of 1:1, the whole PZT layer will either be fully loaded by a tensile load or a compressive load during the inward stroke and vice versa In general, the location of the neutral axis will alter the distribution of stress along the thickness and thus the amount of displacement and force Piezoceramic materials are reported weak in tension therefore the location of the neutral axis of the composite is important with regard to its operating life expectancy For the thickness ratio which gives the peak displacement, low voltages can be used to produce the same amount of displacement which would have demanded higher voltages if a much thicker actuator was used From the study, it was found that thickness ratios between 0.25 and 0.30 produce maximum displacement and relatively smaller force For ratios beyond this range, the displacement decreases while the force increases From this study, it was concluded that total actuator thickness alone could not be used to determine the actuator performance The results should be of interest to designers wishing to establish how much force will be sacrificed by choosing to have a certain amount of displacement and vice versa The results also help to determine the appropriate geometry (i.e thickness ratio) if one aims for large displacement and/or large force CHAPTER MONITORING STRUCTURAL INTEGRITY USING FIBRE OPTIC SENSORS 8.1 Formulations In the past few decades, we have been witnessing drastic changes in materials technology Latest developments such as the use of materials with embedded devices have changed the way of thinking in modern design and manufacturing Figure 8.1 Embedded optical fibres into the test piece Smart Materials and Structures c 2015 Bohua Sun By Bohua Sun Copyright ⃝ 67 68 MONITORING STRUCTURAL INTEGRITY USING FIBRE OPTIC SENSORS Crack propagation in materials is considered a mechanical fault that needs attention because it may develop as a result of mechanical deformation In aerospace, aviation, construction, mining and many other industries there are certain structures where, due to dynamic and/or static loading in specific points, mechanical deformation may lead to crack initiation, propagation and subsequent catastrophic failure Mechanical deformation from fatigue loading has been taken as a major influencing factor in crack creation and propagation On the other hand, some researchers consider a crack to serve a positive role as a stress relief mechanism (residual stress) Due to the fact that cracks sometimes develop from the inner side (core) of the material, it is difficult to detect or visualize their occurrence, and in most cases to locate their propagation path Several existing non-destructive testing (NDT) techniques such as magnetic particles detection, acoustic emission, ultrasonic, electronic speckle pattern interferometry (ESPI), shearography, as well as physical visualization, are employed in order to detect crack occurrence and propagation6 Recently researchers have been attempting to detect crack orientation using strain as measured with optical fibres7,8, The optical fibre has been proven to have reasonably high enough elastic yield when subjected to a tensile force Optical fibres are also considered to have the mechanical properties, which permit them to withstand deformation under a reasonable extension and as such, when experiencing geometrical changes, it will change the optical radiation characteristics of the light that they may be transmitting through them Since light is characterized by amplitude (intensity), phase, frequency and polarization, any one of these parameters may be singled out to be monitored as it might undergo changes The paper reports on the research which aimed to develop a system that could detect and give warning of a crack initiating and propagating within a critical component When the optical fibre that is transmitting a light beam is stretched, the light beam encounters the necked section of the fiber, whereby an analogous effect of a reduced aperture occurs Utou1 has shown that, the input - output optical power transmission ratio with respect to the change in optical fiber diameter can be predicted by P0 △d α =1−( ) , (8.1) Pr d where Pr and P0 are the optical power through the fiber before and after deformation respectively, △d and d are the reduced and original diameters of the optical fiber and a is the attenuation coefficient per unit length of the optical fibre material Recalling that the elongation of the optical fibre equals the crack opening of the host specimen (expressed in terms of elastic and plastic behaviour of the host material), at the position where the fibre is fixed, one can obtain a relationship of the optical fibre diameter to the applied load, fibre properties (subscripted with f) and physical parameters of the host material10 as follows: √ K2 0.4(W − a)vp df = [ I + ] (8.2) πFf lf Ef 2σE 0.4W + 0.6a The change in optical fiber diameter is obtained by differentiating the above equation with respect to the applied force with all other quantities forming a constant C √ C 3/2 , △df = − C 1/2 Ff (8.3) df = Ff F Utou, Fibre sensors ensuring structural integrity, Doctorate Thesis, Cape P Uni of Tech, Cape Town, South Africa, 2005 CONCLUSIONS 69 √ KI2 0.4(W −a)Vp where C = πlf Ef [ 2σE + 0.4W +0.6a , KI is fist fracture mode intensity factor, Vp is plastic components of measured displacement, Ff is axial applied force on fibre Combining above equations we obtain an expression which characterizes the optical power output through the fibre that has deformed as a result of the host specimen experiencing a propagating crack √ ]α [ △Ff C P0 = 1− , (8.4) Pr 2d Ff Figure 8.2 Comparison of experimental and theoretical prediction for optical power through a fibre subjected to elongation due to an axial force Figure 8.2 below depicts the predicted and experimental values of the optical power ratio through the optical fibre, as it elongates by being fixed across the path of a crack that is propagating and widening in the host specimen 8.2 Conclusions The sensor, based on the principles of fiber optics may be embedded in a critical section of a component monitoring structural health In particular the sensor by being capable of detecting unwanted excessive distortion, displacement, the initiation and propagation of a crack, presents us with a promising method in warning of impeding catastrophic events The research on the subject accomplished the development of a complete system including the sensor, the light emitting and detecting modules While there is a fair degree of confidence in the experimental work that was performed, the theoretical analysis aimed at predicting the optical output power through the optical fibre that has been subjected to dimensional changes, requires further attention toward increasing the accuracy of predicted results Further work is also envisaged in the process of not only detecting and monitoring crack propagation with optical fibres but also the incorporation of shape memory alloy wires embedded (as part of the host material) to form a smart structure that heals or retards the crack mechanism REFERENCES Crawley E F and Anderson E H, Detailed models of piezoelectric actuation of beams, J Intell Mater Syst Struct., 4-25, 1990 Wada B K, Fanson J L, and E F Crawley, Adqptive Structures, Journal of Intelligent Material Systems and Structures,Vol No.2 pp 157-174, 1990 Gandhi, M.V and Thompson, B S., Smart Materials and Structures, Chapman and Hall, 1992 Crawley E F, Intelligent Structures for Aerospace: A Technology Overview and Assessment, AIAA Journal, Vol.32 No.8, pp1689-1699, August, 1994 Vijay K Varadan, et al, Smart Material Systems and MEMS, John Wiley and Sons Ltd, 2006 Mel Schwartz, The Encyclopedia of Smart Materials, John Wiley and Sons Ltd, 2002 Udd E, Fiber Optic Smart Structure, John Wiley and Sons Ltd, 1995 http://www.piezo.com/，http://www.mide.com/ Marino Kekana and Bohua Sun, Smart materials and structures, The South African Mechanical Engineer, Vol 48, 13-17, July 1998 10 Bohua Sun, Some problems of piezoelectric sensor mechanics, Journal of Wave-Material Interaction, Vol.14, No.1-2, January/April 1999 11 B Sun and D Huang, On the feedback control gain of smart composite beams based on MindlinReissner lamination theory, R and D Journal, 16(2), 41-45, 2000 12 Bohua Sun and D Huang, Analytical vibration suppression analysis of composite beams with piezoelectric laminae, Smart Materials and Structures, 9, 751-760, 2000 13 D Huang and B Sun, Approximate Analytical Solutions of Smart Composite Mindlin Beams, Journal of Sounds and Vibration, 244(3), 379-394, 2001 Smart Materials and Structures c 2015 Bohua Sun By Bohua Sun Copyright ⃝ 71 72 REFERENCES 14 Bohua Sun and Yan Qiu, Analysis of circular shape distributed piezoelectric actuators, Composite Structures, 62,177-191, 2003 15 Bohua Sun and Yan Qiu, Rectangular shape distributed piezoelectric actuator: analytical analysis, Smart Mater Struct, 13, 337-349, 2004 16 Bohua Sun, Overview of smart materials and structures, World Engineers Convention 2004, Shanghai, China, November 2-6, 2004 17 A.N Mtawa, Bohua Sun and J Gryzagoridis, An investigation of the influence of substrate geometry and material properties on the performance of the C-shape piezoelectric actuator, Smart Mater Struct., 16, 1036–1042, 2007 18 A.N Mtawa, Bohua Sun and J Gryzagoridis., Effect of substrate to piezoceramic layer thickness ratio on the performance of a C-shape piezoelectric actuator, Sensors and Actuators: A Physical, Vol 141/1, 173-181, 2007 19 F E Utou, J Gryzagoridis and B Sun Parameters affecting the performance of fiber optic displacement sensors，Smart Mater Struct, 15, S154-S157, 2006 20 J Gryzagoridis, F Utou and Bohua Sun, Monitoring structural integrity using fibre optic sensors, Insight, The British Institute of Non-Destructive Testing, Vol49, No5, 264-266, May 2007 21 F.E Utou, J.Gryzagoridis and B.Sun, Detection of Crack Travel and Opening of a Standard Notched Specimen Mode I Using Embedded FOS Device, Applied Mechanics and Materials, Vol 442, pp 360-366, 2007 22 Bohua Sun, Smart Materials and Smart Systems, Inaugural Professorial Lecture, Cape Peninsula University of Technology, August 31, 2001 23 Da Huang, Approximate analytical solution for vibration control of smart composite beams, Master Thesis, Cape Peninsula University of Technology, 1999 24 Yan Qiu, Distributed piezoelectric actuator with complex shape, Master Thesis, Cape Peninsula University of Technology, 2002 25 O Philander, The development of a computational design tool for use in the design of SMA actuator systems, Doctorate Thesis, Cape Peninsula University of Technology, 2004 26 F E Utou, Fiber optical sensors ensuring structural integrity, Doctorate Thesis, Cape Peninsula University of Technology, 2005 27 A N Mtawa, Influence of geometry and material properties on the optimum performance of the C-shape piezo-composite actuator, Doctorate Thesis, Cape Peninsula University of Technology, 2007 28 Fei Guo, Micromachined capacitive accelerometer with crab-shape, Master Thesis, Cape Peninsula University of Technology, 2005 29 Rui Zhang, mechanics of micromachined bridge-type accelerometer, Master Thesis, Cape Peninsula University of Technology, 2005 30 in Wang, Mechanics of micro capacitive accelerometer with U-shape cantilever beam, Master Thesis, Cape Peninsula University of Technology, 2005 31 Jose Olivera, Deformation and damage analysis of composite beams equipped with polyvinylidene fluoride film sensors, Master Thesis, Cape Peninsula University of Technology, 2008 32 Lifeng Han, The Mechanical Analysis of Micromachined Accelerometer with Piezoelectric Thin Films Read-out, Master Thesis, Jinan University, 2006 33 Yuyang Jiang, Mechanics analysis of capacitive gyro with electrostatic actuation, Master Thesis, Jinan University, 2008 34 Fangyin Diao, Mechanics analysis of gyroscopic decelerator, Master Thesis, Jinan University, 2009 REFERENCES 73 35 Fei Chen, Mechanics analysis of uncooled nonlocal infrared sensor, Master Thesis, Jinan University, 2010 36 Zhaojun Qin, Studies based on one-plane system of electro-wetting on dielectric (EWOD), Master Thesis, Jinan University, 2011 37 Ding Wang, Interaction of protein-protein interaction of Hemagglutinin(HA) and Neuraminidase(NA) on surface of influenza a virus, Master Thesis, Jinan University, 2010 74 REFERENCES ETH Ză urich (Swiss Federal Institute of Technology in Ză urich) is an engineering, science, technology, mathematics and management university in the city of Zăurich, Switzerland Like its sister institution EPFL, it is an integral part of the Swiss Federal Institutes of Technology Domain (ETH Domain) that is directly subordinate to Switzerland’s Federal Department of Economic Affairs, Education and Research ETH Zăurich is consistently ranked among the top universities in the world It is currently ranked as 3rd best university in the world in engineering, science and technology, just behind the Massachusetts Institute of Technology and Stanford University in the QS World University Rankings Twenty-one Nobel Prizes have been awarded to students or professors of the Institute in the past, the most famous of whom is Albert Einstein in 1921, and the most recent is Richard F Heck in 2010 It is a founding member of the IDEA League and the International Alliance of Research Universities (IARU) and a member of the CESAER network The school was founded by the Swiss Federal Government in 1854 with the stated mission to educate engineers and scientists, serve as a national center of excellence in science and technology and provide a hub for interaction between the scientific community and industry Cape Peninsula University of Technology, a university in Cape Town, South Africa, is the only university of Technology in the Western Cape province with over 32,000 students It was formed in January 2005 from the merger of the Cape Technikon and Peninsula Technikon, following years of change in the higher education landscape of South Africa In 1993, the Technikons Act was promulgated, which allowed Technikons to offer Bachelor’s degrees (B.Tech), Master’s and Doctoral degrees in Technology In March 2001, Kader Asmal (then Minister of Education) announced the National Plan on Higher Education, and in May 2002 he announced the possible merger of the two institutions, with the national working committee also recommending the University of the Western Cape to be included in the merger Towards the end of 2002, the final merger was announced, and in October 2003 the new name was approved View publication stats