• Shape Memory Alloy (SMA)    

A shape memory alloy is an alloy that "remembers" its shape, and can be returned to that shape after being deformed, by applying heat to the alloy.

In general, when elastic deformation is applied to metals by external forces, the metal can have the original form by eliminating the external forces. But, if the deformation exceeds the elastic area, plastic deformation is happened to the metals and then it can not be restored. Using the general plastic deformation, metal can be applied to the industries.  But, SMA can be returned to the shape after being plastic deformed, by applying heat to the alloy.

The first reported steps towards the discovery of the shape memory effect, which is from the AU-CCd alloy, were taken by L. C. Chang and T. A. Read. And the nickel-titanium alloys were first developed in 1962–1963 by the Naval Ordnance Laboratory and commercialized under the trade name Nitinol (an acronym for Nickel Titanium Naval Ordnance Laboratories). Their remarkable properties were discovered by accident. A sample that was bent out of shape many times was presented at a laboratory management meeting. One of the associate technical directors, Dr. David S. Muzzey, decided to see what would happen if the sample was subjected to heat and held his pipe lighter underneath it. To everyone's amazement the sample stretched back to its original shape.

The three main types of SMA are the copper-zinc-aluminum-nickel, copper-aluminum-nickel, and nickel-titanium (NiTi) alloys. Especially, Ti-Ni alloys are more efficient and stable than others. So, it can be applied to various fields of industries.

<Shape Memory Alloy>

• Research Fields

In this laboratory, various researches using piezoelectric material are in progress.

• Position tracking and vibration control of a smart structure using using shape memory alloy actuators
• Design of HDD Load/Unload suspension using shape memory alloy actuators
• Non-contact start stop motion control of HDD suspension using shape memory alloy actuators

• Applications

  (1) SMA HGA

<SMA HGA>