bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Material Evaluation of Shape Memory Composites
Authors: Furuya Yasubumi 
Published: August 2009

Shape memory alloy (SMA) is regarded as one promising intelligent material element natively with thermo-sensor, shape memory actuator functions. A fundamental design concept for intelligent materials using SMAS is firstly proposed. Two types of composites which show some intelligent functional properties relating to the shape memory phase transformation were fabricated. One is the shape memory TiNi fiber/Al matrix plate. Another is the plaster matrix composite as a model of building material which contains both shape memory TiNi fibers and high damping TiNi particles having different phase transformation temperatures with each other. The former (TiNi)f/Al composite showed unique properties such as self-strengthening by the compressive stresses in Al matrix due to shape memory shrinkages of the embedded TiNi fibers. The increases of tensile property (yield stress) as well as fatigue resistance (crack growth retardation) at higher temperature were experimentally confirmed. The latter (TiNi),f/plaster showed the increases of resistance to fracture as well as vibration damping.
Multi-Freedom Tube Type Manipulator with SMA Plate
Authors: Kaneko Shinji , Aramaki Shinji , Arai Kazuhiko , Takahashi Yuichiro , Adachi Hideyuki , Yanagisawa Kazuhisa 
Published: August 2009

The tube type multiple link micromanipulator using SMA (Shape Memory Alloy) has been conducted. The conceptual model of this manipulator has five linked pipes with 1 mm in diameter. On each link, a temperature/strain sensor and a control IC chip are equipped for position and/or force feedback control. We have successfully fabricated a prototype. This tube type manipulator, which is 2 mm in diameter, has two links. This prototype manipulator has two flexible SMA plate links which are given all direction shape memory effect over 60 degrees in vending angle. These links mutually bend at a right-angle. These SMA plates are fixed SUS pipes through which a silicon rubber tube is arranged. By using the technology of semiconductor manufacturing, the MIF (Multifunction Integrated Film) has been developed for integration of electrical elements for the manipulator. The MIF has several functions; strain sensor, temperature sensor, heater, and wires to interconnect links. In this manipulator, the MIF with 7 itm in thickness is attached to each SMA plate. As a flip-flop circuit chip is mounted on each MIF in a state of bare chip, many heaters and sensors are controlled serially by shift-resisters. Therefore, this manipulator is controlled by eleven common wires even if the number of links increases. The heater is constructed with Ti film. The sensors are constructed with Ti film and Pt film. As these two materials have different gage factors and temperature coefficients, the value of temperature and strain can be calculated from the change of the resistivity. By PID feedback control with strain and temperature, the positioning error at the end of the link is less than 0.2 mm.
A Consistent Theory of Thin Piezoelectric Plates
Authors: Bisegna Paolo , Maceri Franco 
Published: August 2009

In this paper a theory of thin piezoelectric plates is obtained throigh a rational derivation from the three-dimensional linear theory of piezoelectricity. The coupling between the ekictric and mechanical fields is taken into account, leading to a consistent definition of the bending and stretching stiffnesses. In particular, it is shown that a piezoelectric plate has a different stretching stiffness when it is used as an actuator or as a sensor. The procedure used to derive the field equations governing the piezoelectric plate problem is based on the initial functions method, in conjunction with a rescaling of the applied loads. The field equations are then rewritten in a variational form, according to a generalized statement of the virtual work principle, in order to deduce the compatible boundary conditions. The theory established here is used to find closed-form expressions of the solutions of some technical problems, involving piezoelectric plates used as sensors or actuators.
Composite Structure Analysis of a Hollow Cantilever Beam Filled with Electro-Rheological Fluid
Authors: Berg C. D. , Evans L. F. , Kermode P. R. 
Published: August 2009

Unwanted vibrations within structures can become an ever increasing problem as structural components are made lighter with the use of advanced materials and tighter design tolerances. Increased operating bandwidth further compounds the problem resulting in the build up of unwanted vibrations within optimally designed structures. The alteration of the spectral signature of a structural component will enable the aforementioned design criteria to be satisfied. The use of a hollow structural component filled with Electro-Rheological fluid will enable the spectral signature of the component to be altered electrically. Experimental data obtained for a hollow cantilever beam filled with Electro-Rheological fluid is presented in this paper. Analysis of the data is carried out to determine heuristic values for the beams effective stiffness and damping coefficient. The effects of applying an electric field to the ER fluid are outlined from the results obtained. Comparison of the results is then made with those predicted by a model of an oscillating composite structure cantilever beam. Differences between the predicted and the heuristic data is then examined with regard to a hypothesis based on the behaviour of the induced ER fluid's microscopic structure.
One-Dimensional Thermomechanical Constitutive Relations for Shape Memory Materials
Authors: Liang C. , Rogers C. A. 
Published: August 2009

The use of the thermoelastic martensitic transformation and its reverse transformation has recently been proposed and demonstrated for several active control applications. However. the present constitutive models have lacked several important fundamental concepts that are essential for many of the proposed intelligent material system applications such as shape memory hybrid composites. A complete, unified, one-dimensional constitutive model of shape memory materials is developed and presented in this paper. The thermomechanical model formulation herein will investigate important material characteristics involved with the internal phase transformation of shape memory alloys. These characteristics include energy dissipation in the material that governs the damping behavior, stress-strain-temperature relations for pseudoelasticity, and the shape memory effect. Some numerical examples using the model are also presented.
Design of Shape Memory Alloy Springs with Applications in Vibration Control
Authors: Liang C. , Rogers C. A. 
Published: August 2009

Shape memory alloys (SMAs) have several unique characteristics, including their Young's modulus-temperature relations, shape memory effects, and damping characteristics. The Young's modulus of the high-temperature austenite of SMAs is about three to four times as large as that of low-temperature martensite. Therefore, a spring made of shape memory alloy can change its spring constant by a factor of three to four. Since a shape memory alloy spring can vary its spring constant, provide recovery stress (shape memory effect), or be designed with a high damping capacity, it may be useful in adaptive vibration control. Some vibration control concepts utilizing the unique characteristics of SMAs will be presented in this paper. Shape memory alloy springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some design approaches based upon linear theory have been proposed for shape memory alloy springs. A more accurate design method for SMA springs based on a new nonlinear thermomechanical constitutive relation of SMA is also presented in this paper.
A Review on the Modelling of Piezoelectric Sensors and Actuators Incorporated in Intelligent Structures
Authors: Chee Clinton Y. K. , Tong Liyong , Steven Grant P. 
Published: August 2009

The main objective of this article is to present an overview of the modelling that has been proposed by various workers in the field of smart or intelligent structures. Before the main discussion on the various models, some background information will be presented in relation to intelligent structures and the types of adaptive materials that are available. Although there are several categories of materials that can be implemented in intelligent structures, this article will focus on models that use piezoelectric materials as sensors and/or actuators (S/A). The modelling of the intelligent structures can be categorised in terms of the structural configuration (e.g., rod composites, fibre composites, monolithic structures, etc.) and also according to the type of modelling whether by finite element modelling or by analytical exact solutions. Models in this field of work had incorporated concepts from different background including three-dimensional linear elastic theory and dielectric theory to give rise to the linear piezoelectric model. Rules of Mixture and methods for calculating effective properties of fibre composites were extended to include piezoelectric fibre composite models. Classical Laminated Plate Theory was also adopted in laminated composite models where some laminae were piezoelectric materials. Exact solutions were applied to simple models and illustrated the potential of using piezoelectrics. Finite element techniques were used for more complicated problems that included complex geometries, nonlinear behaviour and dynamic control of the structure. The difference between induced strain and actuation strain is usually not addressed when using FE techniques, instead the piezoelectric strain can be regarded as an equivalent external force/moment or incorporated into the strain energy. In regard to control algorithms, the most common form applied by investigators in this field seems to be the negative velocity feedback control with single input and single output and some included linear quadratic control. More advanced control algorithms such as using multiple input and multiple output or even neural networks are less established.
Piezoelectric Coefficients of Thin Polymer Films Measured by Interferometry
Authors: Zheng Zhenji , Guya Ian L. , Tansley Trevor L. 
Published: August 2009

The effective d33 of sub-micron piezoelectric polymer films, deposited on glass substrates, has been measured using an optical interferometer. The polymers used were polyvinylidene fluoride (PVDF) and copolymers of PVDF with trifluoroethylene (TrFE). The interferometer measures movement of the polymer surface in response to an applied electric field, and is easily able to detect motion of a picometre. In this situation, the rigid glass substrate effectively clamps the soft polymer film in the lateral direction. Nevertheless, effective d33 values approaching 10 pm Vhave been observed. One advantage of such thin films, is the ability to pole them with quite low voltages. For example, a 100 nm film can be poled by 10 volts. The low voltage required to achieve poling in such thin films means that the poling voltage can be left permanently connected, thus maintaining the piezoelectric activity. By adding a periodic bias voltage to the driving signal, it is possible to observe hysteresis in the piezoelectric coefficient corresponding to the polarization hysteresis loop. The piezoelectric coefficient shows an abrupt change in sign at the coercive field. corresponding to the reversal of the net polarization.
The Application of a Smart Landing Gear Oleo Incorporating Electrorheological Fluid
Authors: Berg C. D. , Wellstead P. E. 
Published: August 2009

The objectives of this paper are to outline the use of Electrorheological (ER) fluid within an aerospace system. The advantages of ER fluid-based systems are given followed by design considerations which include those related to the non-linear behaviour of an ER fluid subjected to oscillatory shear. A control strategy is outlined for the use of a smart landing gear (LG) oleo incorporating ER fluid. The paper also considers the issues associated with airworthiness requirements and ER fluid devices. For airworthiness approval a smart oleo based LG system must primarily be shown to be safe and as such has to be fault tolerant. A major failure for this application would be if the control strategy failed and the oleo damping coefficient was consistently too low; a backup system is therefore incorporated into the design and other potential modes of failure considered. A semi-active control strategy applied to a variable damping coefficient LG oleo has specific requirements, partly due to the fact that for the take-off and landing phases of flight they are different. A semi-active control strategy is outlined based on the requirements for the alteration of damping coefficient according to the phase of an aircraft's flight. The strategy is the focus of current work to estimate the effectiveness of semi-active vibration control as applied to an undercarriage.
Damage Detection in Structures Using Precursor Transformation Method
Authors: Mehrabi Armin B. , Tabatabai Habib , Lotfi Hamid R. 
Published: August 2009

In this paper, a new concept for damage detection and long-term health monitoring of structures is presented. The Precursor Transformation Method (PTM) is based on determining the causes (precursors) of change in the measured state of the structure under non-variable loading conditions (e.g., dead loads in bridges). The PTM concept addresses the inability of the current structural monitoring methods to discriminate, in structural behavior terms, the meaning of voluminous measured sensor data on a timely and cost effective basis. This method offers advantages in sensitivity and cost efficiency when compared to conventional vibration-based or parameter estimation methods. PTM was developed as part of a research project sponsored by the Federal Highway Administration on bridge stay cable condition assessment. Measured changes in the state of a structure (displacements, strains, internal forces) can be related to precursors through a transformation matrix. This matrix is formed by determining the patterns of change in the state of structure associated with externally imposed strains (temperatures) or displacements representing possible damage scenarios. A finite element model of the undamaged structure is used to calculate these patterns. The use of an undamaged model of the structure in determining damage patterns simplifies the calculation process significantly, while introducing some approximation in results. Theoretical derivations and special case studies indicate that these approximations are limited to second order effects, and in many cases well within measurement and calculation accuracies. Examples using simulated damages on two truss structures and a cable-stayed bridge are also presented.
Flexural Piezoelectric Transducers with Frequency Agility Obtained via Membrane Loads
Authors: Htbert Chad A. , Lesieutre George A. 
Published: August 2009

Broadband transducers find uses in many applications. One approach to increasing the bandwidth of a flexural transducer is to add damping to the device, usually decreasing its sensitivity in the process. An alternative approach, useful in some applications, involves active tuning of the natural frequency of a high-sensitivity narrowband device. In this research, membrane loads were used to alter the natural frequencies and electromechanical coupling coefficients of three-layer (trilaminar) piezoelectric ceramic transducers. A coupling coefficient is a measure of the effectiveness with which a piezoelectric material or device converts electrical energy to mechanical energy or vice versa. Applying in-plane loads increased the effectiveness of the transducers by increasing their operating frequency range, while maintaining high coupling coefficients. Two types of trilaminar flexural piezoceramic transducers were studied: beams and disks. The measured electrical impedance of individual devices was used to determine shortand open-circuit natural frequencies, and then coupling coefficients. In addition, finite element models were developed and used to predict the same quantities. Rotational springs were used in these models to account for non-ideal experimental boundary conditions, while reduction of the piezoelectric material coupling accounted for loss of performance due to stress depoling and aging. Good agreement between experimental data and theory was obtained. Significant changes in natural frequencies, as well as increases in coupling coefficients were obtained for both beam and disk transducers. Experiments with the trilaminar piezoceramic beams yielded a 36% change in frequency, with an accompanying 38% increase in coupling coefficient. Experiments with the disks yielded a change in frequency of 13%, and an increase in coupling coefficient of 15%. These results demonstrated the feasibility of using membrane loads to improve the frequency-agility of flexural piezoceramic transducers. Candidate applications include acoustic transducers and pneumatic valves.
Multi-Objective Optimization of an Adaptive Composite Beam Using the Physical Programming Approach
Authors: Suleman A. , Gonicalves M. A. 
Published: August 2009

The objective of this paper is to present the optimization of an adaptive composite structure using the physical programming approach. To this end, a multi-objective optimization problem of an adaptive composite beam with piezoelectric actuators bonded to its surface is performed. The goal is to optimize the size and placement of the actuator pairs, in order to maximize the performance of their actuation power, to minimize the mass of the piezoelectric material and to maintain the required actuation voltages below maximum operating values. A generalized tri-dimensional version of the Heaviside function has been used to represent the distribution of the piezoelectric actuators. A closed form solution for the equations of equilibrium is presented. Physical programming presents the following advantages over the more conventional optimization methodologies: reduced computational effort and time, elimination of both iterative selection of weights and prioritization of objective functions.
Intelligent Sensing for Innovative Bridges
Authors: Shehata Emile , Rizkalla Sami 
Published: August 2009

This paper discusses two types of fiber optic sensors used for monitoring highway bridges in Manitoba, Canada. The first, the Taylor Bridge, is the longest smart bridge built in North America and was completed in 1997. Four girders, large portions of the deck slab and the barrier wall are reinforced with carbon and glass fiber reinforced polymer (FRP) materials. The bridge is remotely monitored using fiber optic sensors embedded in the girders, the deck slab and the barrier wall to provide continuous information on the health and structural performance of the bridge. Signals obtained from the optical sensors are transmitted through a telephone line, thereby allowing an office-based engineer to monitor the stresses and strains via a computer anywhere in the world. The paper discusses the expert system program used to reduce the data collected from the bridge into engineering information which can be used to assess the performance of the FRP material and the behavior of the bridge. The second, the Norwood Bridge, is another innovative bridge also built in Winnipeg, Manitoba. The bridge is a complex precast reinforced concrete structure including an innovative mechanical connection at the supports to provide continuity. Monitoring of the bridge was requested by the owner, the City of Winnipeg, to verify structural behavior during different stages of construction and operation. A different type of fiber optic system was used in this bridge. Both the Taylor and the Norwood Bridge projects were undertaken by the Network of Centres of Excellence on Intelligent Sensing for Innovative Structures (ISIS Canada) which was able to provide the valuable link between the emerging new technology in structural remote monitoring and the construction industry.
Political cultures compared
Authors: Meer Nasar , Mouritsen Per 
Published: August 2009

One outcome of the Muhammad cartoons controversy has been an opportunity for comparative critical examination of public discourse on conceptions of citizenship and belonging vis-à-vis Muslim minorities in different national contexts. In this article, we focus upon the press reaction in two north-western European countries that on first appearance offer radically different cases. While Britain is a formerly imperial power where ‘legitimate’ public articulations of the collective ‘we’ must take stock of the sensibilities in this diverse inheritance, Denmark’s emergence as a modern constitutional state is premised on a cultural, linguistic and ethnic homogeneity. It would only be fair to anticipate, therefore, that any comparison of press discourse on matters of religious minority toleration and respect for difference would herald very different outcomes to these traditions. Yet this article shows that, on closer inspection, Jyllands-Posten’s more ‘radical’ approach marked a departure from other Danish newspapers in a manner that left it relatively isolated, and that the self-restraint shown by the British press in not reprinting the cartoons was far from universally supported, and subject to significant internal criticism. Indeed, the press discourse in both countries cast the reaction to the cartoons controversy by Muslims themselves as a sign of failed integration, and each moreover stressed a need for civility and respect — even where there was disagreement over the kinds of ‘dialogue’ that should take place. Nevertheless, significant divergences and cleavages remained, and the explanation for these differences rests not only on Britain’s more ‘multicultural’ traditions, but also the experiences of the Rushdie affair and the subsequent debate that had already taken place in Britain. What is striking is the ways in which the Danish discourse appears to be plotting a course that is not that radically different from one taken in the British case, specifically the extent to which a recognition of religious minority sensibilities needs to be offset with a civic incorporation that is cast in interdependent terms in a way that is inclusive of — and not alienating to — Muslims.