Facade study

In this phase of material integration, the Nitinol-based panel is applied to a generic facade in order to experiment with scale, orientation, and general placement.  The facade operates in an "on - off" manner, applying or removing electricity from the Nitinol wire which actuates movement across the facade.  During the off phase, the panels appear flat and unprovoked.  When electricity is applied in the on phase, the wire returns to a preconfigured form and causes the panel to fold and encroach on its center.  This movement manipulates the facade in all dimensions, bringing 3D qualities to the surfaces.

The initial concept was to apply the system to lightweight aluminum sheets to emphasize deformation of metals.  However, it may be more economical and visually lighter to form the panels using tensile structures such as fabrics.  The panels are suspended in front of the facade like a screen and balanced by a counterweight to promote two-dimensional translation.

Modular surface actuated by Nitinol wires

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Nitinol Typology

The term Nitinol does not have one specific type of material attached to it.  It refers to materials that contain nickel and titanium which have certain response characteristics. These different materials are super-elastic Nitinol, SMA Nitinol, and Flexinol.  Each material has specific abilities, and each material has overlapping abilities.  Each look exactly the same as the other, but the difference in type is dictated by the processes they undergo at production.

Super-elastic Nitinol


SE Nitinol is a type of Nitinol that is used for super-elastic applications such as in the medical field.  Characteristics are:

• A super-elastic ability that deforms the crystalline structure rather than kink like other metals.
• A low transition temperature, usually below room temperature in order to stay in the austenite phase at room temperature.
• The ability to change to the softer martensite phase when strain is applied, and change back to the stiffer austenite phase when the strain is released.
• Typically "as-drawn."  A rougher surface treatment, unless being used as a medical device.
• High electrical resistance

SMA Nitinol

SM Nitinol is not the most common form of Nitinol, but it is the type that is typically referenced when mentioned.  The characteristics of Nitinol are:

• A mixture of titanium and nickel
• The ability to be flexed and strained below the transition temperature, and returned to a "memorized" shape when heated above its transition temperature.
• The ability to be given many surface treatments by machining, etching, polishing, sandblasting, coating, or plating.
• Bio-compatibility when given an oxide and electro-polished surface treatment.
• A certain amount of super-elasticity.
• Infinite shelf life under normal conditions (below 200C).
• High electrical resistance

Flexinol

Flexinol was developed by Dynalloy Corporation to produce a type of Nitinol that is specifically engineered for actuation applications. Characteristics of Flexinol include those of SMA Nitinol, plus:

• Super processed and controlled to produce much smaller diameter wires (50um, 100um, 150um, 250um, and 370um).
• Designed to contract from 2%-5% of their length when actuated.