smart+structures;material+that+can+actually+think+-by+Mahmoud+Essam+Barghout

=**Smart St****rutures**= Smart sturctures are structures that are capable of sensing and reacting to their environment in a predictable and desired manner, through the integration of various elements, such as sensors, actuators, power sources, signal processors, and communications network.

Optical-fiber sensor networks in smart structures.Smart structures are also used in many other applications,such as in aircrafts and aerospace applications. =**MagnetoRheological Fluid**= A **magnetorheological fluid** (MR fluid) is a type of [|smart fluid] in a carrier fluid, usually a type of oil. When subjected to a [|magnetic field], the fluid greatly increases its __ apparent viscosty __, to the point of becoming a viscoelastic solid(that is showing both viscosty and elasticity,ruled by certain conditions, namely the magnetic force ). Importantly, the yield stress of the fluid when in its active ("on") state can be controlled very accurately by varying the magnetic field intensity. The upshot of which is that the fluid's ability to transmit force can be controlled with an [|electromagnet], which gives rise to its many possible control-based applications. And thus the simple definition is that the **magnetorheological fluid** (MR fluid) is a liquid that changes to a near-solid when exposed to a magnetic force, then back to liquid once the magnetic force is removed. One of the important applications that are yet to be used in the future is using the MR fluid in buildings and bridges as it would help reduce damage taken from earthquakes.During an earthquake, MR fluid inside the dampers will change from solid to liquid and back as tre�­mors activate a magnetic force inside the damper. Using these dampers in buildings and on [|bridges] will create **smart structures** that automatically react to seismic activity. [] [] These videos show the unique properties that MR fluids have, clearly exibiting how MR fluids change from liquids to solids due to the effect of magnetism on them. This is used and could be used in many futuristic and advanced applications. =PiezoElectric﻿ Materials= Piezoelectric materials have the special property of producing an electrical voltage in response to an applied force. Usually crystals or ceramics, piezoelectric materials have a variety of uses including sonar, sound detection and high-voltage generation in addition to everyday uses, such as cigarette lighter ignition sources and barbecue-grill igniters.

[[image:thumbnail.aspxghiuurxt7u.jpg width="240" height="240"]]small microphone, made of piezoelectric materials
 Piezoelectricity is an electric charge that accumulates in certain materials such as crystals, ceramics and bone, when a stress or strain is applied to the material. Materials demonstrating the piezoelectric effect also show the opposite effect called converse piezoelectric effect. This means a piezoelectric material becomes deformed, as if undergoing stress, when being exposed to an electrical field. ====Put briefly, piezoelectric materials create electricity when stress is applied, and become stressed when electricity is applied.====

 The piezoelectric effect is found in a number of natural and man-made materials. Commonly used naturally-occurring crystals include quartz, topaz, tourmaline, Rochelle salts and cane sugar.

= Shape Memory Alloys = A **shape memory alloy** (**SMA**, **smart metal**, **memory metal**, **memory alloy**, **muscle wire**, **smart alloy**) is an [|alloy] that "remembers" its original, cold-forged [|shape]: returning the pre-deformed shape by heating. This material is a lightweight, solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems. Shape memory alloys have applications in industries including medical and aerospace. Shape memory alloys have many applications such as : Aircraft flap/slat adjusters,Cold start vehicle actuators, Electrical circuit breakers, Kettle switches, and Steam valves.



[] and this video is a simple demonstration of how shape memory alloys work. =Auxetic Materials= �While most materials get thinner when stretched and fatter when compressed, auxetic materials do just the opposite � they get fatter when stretched, and thinner when compressed�. This was the simplest and most direct definition of the unique traits seen in auxetic materials, as they tend 2 the defy the stereotypical behaviour exhibited by other materials.Unlike other materials,that when stretched get thinner than their normal relaxed state, auxetic materials tend 2 get fatter when stretched.This phenomenon attracted the practical interest of many materials scientists. This phenomenon is scientifically explained that, unlike other materials that have a positive Poisson ratio(which is the ratio of the contractile lateral strain to the tensile axial strain for a material stretched axially), auxetic materials tend 2 have a negative one. This is the main cause of the auxetics unusual behaviour.

Currently the uses for auxetics are limited, and in those applications they are probably not knowingly used for the auxetic effect itself. Examples include pyrolytic graphite for thermal protection in aerospace applications, large single crystals of Ni3Al in vanes for aircraft gas turbine engines, and an expanded form of PTFE used to make Goretex. However, the development of new auxetic materials and processing routes in recent years has been accompanied by a number of patent applications and publications from organisations including Toyota, Yamaha, Mitsubishi, AlliedSignal Inc, BNFL and the US Office of Naval Research, all relating to the emerging potential of these materials.

Refrences

 * Read more: [|http://www.answers.com/topic/smart-structures-engineering#ixzz1aV0vRgZ5].
 * Read more: [|What Are Piezoelectric Materials? | eHow.com] http://www.ehow.com/info_8251088_piezoelectric-materials.html#ixzz1aVHGQ0Yg.
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