Shape+Memory+Alloy

__ Introduction __
 * __ Shape memory Alloys __**

a shape-memory alloy: is an alloy that "remembers" its original, cold-forged shape: returning the pre-deformed shape by heating.

The three main types of shape-memory alloys are thecopper-zinc-aluminuim-nickel, copper-aluminium-nickel, and nickel-titanium alloys.

__ Material Characteristics __
 * Rememberit’s original shape(Regain it’s original shape when heated).
 * Changes it’s shape and mechanical properties in response to temperature.
 * Light weight,solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems.
 * Pseudo-elasticityduring the high-temperature (austenitic) phase.
 * The yield strength of shape-memory alloys is lower than that of conventional steel, but some compositions have a higher yield strength than plastic or aluminum.
 * High cost of the material.
 * high level of recoverable plastic strain that can be induced,The maximum recoverable strain these materials can hold without permanent damage is up to 8% for some alloys. This compares with a maximum strain 0.5% for conventional steels.

__ History __
 * The first reported steps towards the discovery of the shape-memory effect were taken in the 1930s. According to Otsuka and Wayman, A. Ölander discovered the pseudoelastic behavior of the Au-Cd alloy in 1932.
 * Greninger and Mooradian (1938) observed the formation and disappearance of a martensitic phase by decreasing and increasing the temperature of a Cu-Zn alloy.
 * The basic phenomenon of the memory effect governed by the thermoelastic behavior of the martensite phase was widely reported a decade later by Kurdjumov and Khandros (1949) and also by Chang and Read (1951).
 * The nickel-titanium alloys were first developed in 1962–1963 by the United States Naval Ordnance Laboratory and commercialized under the trade name Nitinol.
 * Metal alloys are not the only thermally-responsive materials; shape-memory polymers have also been developed, and became commercially available in the late 1990s.

__ Current industrial Applications __ Boeing, General Electric Aircraft Engines, Goodrich Corporation, NASA, and All Nippon Airways developed the Variable Geometry Chevron using shape-memory alloy that reduces aircraft's engine noise.
 * __ Aircraft __

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> e.g. oil line pipes for industrial applications, water pipes and similar types of piping for consumer/commercial applications. > the hobbyist robot Stiquito (and "Roboterfrau Lara"), as they make it possible to create very light robots.
 * __ Piping __
 * __ Automotive __
 * __ Telecommunication __
 * __ Robotics __

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> fixation devices for osteotomies in orthopaedic surgery, in dental braces to exert constant tooth-moving forces on the teeth.
 * __ Medicine __

__ Videos demostrating the functions of the materials __
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__ Pictures demostrating the operation and/or function of the material __



__ Links to external material __
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 * [|http://www.google.com.eg/webhp?rls=ig#hl=ar&rls=ig&site=webhp&q=shape+memory+alloys&> oq=Shape+me&aq=0&aqi=g3&aql=&gs> _sm=1&gs_upl=898l2189l0l3704l8l8l0l0l0l0l34l126l8l8l0&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=c221635092e02d33&biw=1366&bih=651]
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__ List of references __ > > Done by : Mohamed Sami >
 * Wikipedia. []
 * Wikispace
 * Youtube.com
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