PDF | On Dec 30, , Ghareeb N and others published Smart Materials and Structures: State of the Art and Applications. Smart structures or smart materials systems are those which incorporate actuators and sensors that highly integrate into the structures and have. Bookreviews Smart materials and structures page M.V. Gandhi In particular, there is no mention of the use of optical fibres in combination with.
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Smart materials can change their physical properties in response to a of smart materials and structures, together with its current status and. A smart structure is a system containing multifunctional parts that can perform sensing, control, and actuation; it is a primitive analogue of a biological body. An introduction to smart materials and structures. B S Thompson, M V Gandhi and S Kasiviswanathan*. Abstract - This paper presents an exposition on the.
This allowed them to go straight to build without materials with desirable performance and properties. In the need for costly intermediate-stage mock-up fabri- particular, new applications for shape memory materials, cation and assembly, with the accompanying tremendous electro- and magnetorheologic fluids, piezoelectrics, fer- cost savings on re-engineering of parts associated with roelectrics, magnetostrictives, and electroactive poly- unanticipated interference and the accompanying favor- mers are being realized.
One of the challenges is to able impact on rollout timeline. The opportunities for model short-term micro-scale material behavior through growth in the use of improved computation capabilities the meso-scale and macro-scale behavior into long-term for simulation and for real-time modeling and control in what is being recognized as information technology is just starting to be realized. E-mail address: aflatau nsf. Flatau, K. Scales in materials and structures, from Boresi and Chong .
A and structure as well as to interplay between compu- joint NSF—Sandia National Laboratory initiative on tations and data. For more information about the three model-based simulation and life-cycle engineering  foci and their particular emphases for FY , see the offers support to researchers who are developing new NSF Program Solicitation  and for abstracts of pro- computational tools in support of bridging these material jects supported through this initiative, search the internet and structural systems scales.
Additional NSF engineer- site: www. This is providing with both sensor and actuating elements to counter viol- unprecedented opportunities for providing rapid and ent vibrations; flying microelectromechanical systems efficient access to enormous amounts of knowledge, data MEMS with remote control for surveying and rescue including real-time data for smart structures and infor- missions; and stealth submarine vehicles with swimming mation; for studying vastly more complex systems than muscles made of special polymers.
Such multidisciplin- was hitherto possible; and for advancing in fundamental ary mechanical and civil infrastructure systems CIS ways our understanding of learning and intelligence in research , requiring participation of material scien- living and engineered systems.
Through these initiatives, the NSF new entity at the interface of these individual research aims to achieve the next generation of ability to generate, elements. Some of the structures it in new ways; to deepen our understanding of learning and materials currently being researched or that are in and intelligence in natural and artificial systems; and to use include smart materials with the properties described promote cross-disciplinary collaboration and sharing of below [8,9]: knowledge.
Current research activities aim at understanding, syn- Recent CIS activities call for efforts in: thesizing, and processing material systems which behave like biological systems. Among the topics requiring study are defense applications. For example, the need for the ability to predict safe in stress, temperature or acceleration. The National lifetimes with incomplete data is generic.
There is the associated problem of simply being able to detect predict when repair is needed and when it has been accomplished satisfactorily. The use of smart materials as sensors may make future improvements possible in this area. The concept of adaptive behavior has been an underlying theme of active control of structures that are subjected to earth- quake and other environmental type loads.
Through feedback control and using the measured structural response, the structure adapts its dynamic characteristics to meet the performance objectives at any instant. A futuristic smart bridge system . Other NSF-supported parameter choice in a few iterations. Although some researchers are studying shape memory alloys metal matrix composites have extensive research histor- University of Texas, Virginia Tech, and MIT ; surface ies and use in defense applications, their limitations are superelastic microalloying as sensors and microactuators still not understood from a total life-cycle cost point of Michigan State ; and magnetostrictive actuators Iowa view.
Pho- or the clean car must be as extensively developed as toelastic experiments at Virginia Tech demonstrated that these metal matrix composites in order to be able to pre- NiTiNOL shape memory alloy wires could be used to dict safe lifetimes, the whole enterprise may collapse, decrease the stress intensity factor by generating a com- hence the need for accurate lifetime simulation and pre- pressive force at a crack tip.
Other research needs include better Other examples are detailed below. University of Oklahoma onances and lead to undesirable system dynamic responses. With the need to be able to predict the impli- This is part of a 5-year NSF Structural Control Initiat- cations of the impacts through the course of normal ive.
The project was originally started by R. Sack and variability in lifetime performance of joints and fas- W.
A smart micro-controller coupled with teners, the dimensions of the problem become great. Figures 3a and b dissimilar materials, as important as that might be. Examples of smart structures and materials 3. Fiber-optic sensors in bridges, R. NSF grantees have been developing self- Fiber-optic cables are etched by laser with 5-mm-long healing concrete.
One idea is to place capsules or hollow internal gauges, spaced about 2 m apart. The sensors serve as a data col- Research Center, are looking into smart paints which lector as well as a wireless transmitter. Optical fibers which change in light trans- 3. Reliability and safety of structures using stability- mission due to stress are useful sensors. They can be based hybrid controls, Professor B. Spencer embedded in concrete or attached to existing structures.
University of Notre Dame NSF-supported researchers at Rutgers University studied optical fiber sensor systems for on-line and real-time MR fluid dampers are one of the most promising monitoring of critical components of structural systems smart damping intelligent isolation systems according to such as bridges for detection and warning of imminent Professor B.
Spencer, Jr, due to proven technology— structural systems failure. NSF grantees at Brown Uni- reliable and robust; low cost; insensitivity to tempera- versity and the University of Rhode Island investigated ture; low power; and scalable to full-scale civil engineer- the fundamentals and dynamics of embedded optical ing applications. Japanese researchers recently dampers in suppressing earthquake excitation in the lab- developed glass and carbon fiber reinforced concrete oratory.
Under NSF 3. Flexible wings for uninhabited air vehicles, P.
University of Florida researchers at the University of California—Berkeley recently completed a study of the application of ER Ifju and colleagues are conducting research on design fluids for the vibration control of structures.
Courtesy of the late W. Courtesy of B. Spencer, Notre Dame University. There is tional lifting body paradigm. The flexible wing design currently a trend toward thicker materials of the order consists of a carbon fiber skeleton and a latex rubber of hundreds of micrometers in MEMS because a larger skin with a thin under-cambered shape based on those aspect ratio is needed for a mechanical device to be able of biological counterparts.
The flight characteristics of to transmit usable forces and torques. The mechanical the flexible wings have many superior qualities, adapting testing techniques are being extended to MEMS. The air frame and wings of the aircraft are 3.
The function of the adsorbed water or other polar liquids is described to create water-bridge or mobile charge carriers on the surface of the particles due to its solvency to impurity ions.
The migration of these solved ions, as charge carriers, causes an interfacial polarization to induce ER effect under electric field. But, adsorbed water or other polar liquids greatly increases the current density of ER fluid and limits working temperature stability because of the diminution of adsorbed water or other polar liquids at high temperature.
These disadvantages result in unavailable in practical application. To overcome the shortcoming of extrinsic ER system, water-free ER fluid has been developed with anhydrous particles in oil since Aluminosilicate , carbonaceous , and semi-conducting polymers  are three famous ER material systems. These waterfree ER materials, whose ER effect is related to its natural structure, such as polar groups and intrinsic charge carriers, promote the improvement of ER effect and the understating about ER mechanisms.
In the past decade, many new ER materials with higher performance have been developed, which further promote the improvement of ER technology and the understating about ER mechanisms.
We present two important routes to design and preparation of ER materials including molecular and crystal structure design and meso-scale nanocomposite design.
In particular Filisko used anhydrous aluminosilicates as dispersed phase of ER fluids and found the strong ER effect in . This discovery, combined with semiconductiong polymer ER materials invented by Block et al , open era of anhydrous ER materials.
Figure 7 is the typical structure of type A zeolite. It is composed of tetrahedral AlO4 and SiO4 linked through oxygen atoms to form open frameworks. The negative charges that accompany each aluminum atom in the frameworkare balanced by the extra framework metal cations. The ER effect of these aluminosilicates systems is considered to be originated from the interfacial polarization induced by mobility of metal cations loosely bound in framework.
The ER activity can be changed with metal cations concentration and diameter, and thus we can easily obtain excepted physical and chemical properties for high ER performance by modification and design on the crystal structure, cation composition, etc. Furthermore, the surface area and pore size of the microporous molecular sieve materials is also important for ER activity due to the influence on carriers drift and aggregation.
Another shortcoming is large and irreversible particle sedimentation. Furthermore, aluminosilicate particles are hard, and abrasive to the ER device. This kind of fluid is claimed to show a strong ER effect, low electric power consumption, and excellent durability. Fullerene-type materials have also been found to show are markable ER effect. Fullerene-enriched soot and fullerene mixtures, particularly C60 mixed with C70 with a trace amount of C84 and C92, display ER behavior.
The ER properties of fullerene-type materials can be tailored by appropriate encapsulation of ions within the hollow sphere or by adsorption on the surface [10,32]. Metal Oxide Metal oxide has wide types and different electric properties and various types of metal oxides have been used in ER fluids, but no high-performance metal oxide based ER materials have been developed.
In particular, TiO2 is a very typical ER material that has attracted considerable attention as a potential candidate for high performance ER material due to its high dielectric constant . However, the very low yield stress of this ER fluid is in contrast with its distinct chain structure when in dry state.
This is amazing and cannot be understood by the conventional polarization mechanisms. It has been reported that the ER activity of TiO2 could be promoted by adsorption of moisture and this phenomenon had been explained by the increase of conductivity .
But the ER activity of pure crystalline TiO2 based ER system is still very weak after absorption of moisture even if its conductivity increases by several orders of magnitude. Moreover, the extrinsic effect of adsorbed water is not helpful to understand this particular ER material.
Therefore, TiO2 is a very good model material to understand ER mechanism of metal oxide and preparation of active metal oxide ER materials.
Smart materials alter their mechanical properties or provide some mechanical work in response to an external, e. A smart structure may incorporate smart material actuators or some other means of adapting to its surroundings.
An example of a smart structure is a morphing aircraft wing that adjusts its shape to adapt to varying flight conditions. The smart morphing wing may be fully active in that sensors, actuators, and a controller are integrated into the system to adjust the shape of the wing e.
Or the morphing wing may be passive where the structural properties of the wing are tailored such that the wing shape changes in response to aerodynamic surface pressure without the need for external sensors and actuators. Another example of a smart system is the use of shape memory alloys to automatically control air flow in building HVAC systems which do not need any power or wiring. In any case, there is a very wide variety of topics that encompass the research area of smart materials and structures; the papers in this special issue demonstrate this breadth.