Shape Memory alloys

Shape Memory Alloys (SMAs) are a unique class of metal alloys that can recover apparent permanent strains when they are heated above a certain temperature. The SMAs have two stable phases - the high-temperature phase, called austenite and the low-temperature phase, called martensite. In addition, the martensite can be in one of two forms: twinned and detwinned, as shown in Figure 1. A phase transformation which occurs between these two phases upon heating/cooling is the basis for the unique properties of the SMAs. The key effects of SMAs associated with the phase transformation are pseudoelasticity and shape memory effect.

2 States

   Austenite

   -High temperature phase

   -Cubic crystal structure  

   Martensite

   -Low temperature phase

   -Monoclinic crystal structure

When the material cools it goes into its Martensite(twinned)form.  When heated it returns back to it's austenite form.

When a load is applied at low temperatures to the twinned form the material becomes detwinned.  When heat is applied to the detwinned form it will revert back to the austenite form.

Shape Memory Alloy engine

Shape Memory Alloys

Smart Wall


I am researching sustainability in the studio that I am taking and have been looking at sustainability techniques that are both passive and active.  And to integrate an SMA could bring a new level of sustainability to it.

 

One thing that Sustainability is concerned with(LEED) is light and heat and the ability of the sun to provide both of those. If I could Make a wall that would react to where the sun is or how the sun is acting and have it power itself I could have the building be involved with its own sustainability.


Passive Solar Design

A passive solar Design tries to keep the comfort level of the building by taking into account the angle of the sun and the relative climate outside and keeping that in the green without having to use an active system.


Wall


because the Nitnol requires heat in order for it to work and no heat that it could get from the sun itself or at least during the winter it doesn't get warm enough to power itself it will need some kind of external power source in order for it to work. If I were to integrate some sort of photovoltaic into it so that will be able to generate a small amount of electricity in order for it to power itself.

The nitnol would use this power to move a series of vertical louvers on the building which will give the building a dynamic envelope. This dynamic envelope will be active during the day and stay closed during the night. This will give the system an added benefit of privacy during the night.  The louvers will be active in the day and react to the sun.




Structure

I have chosen to use a structural system by Novum that uses a series of cables to hold up a glazing system. If I can retrofit this system to the building the wall system will become very light and allow for a different level of movement.

                                   


 

Reef

Reef is a responsive, kinetic installation by Rob Ley and Joshua Stein Which investigates the role emerging material technology can play in the sensitive reprogramming of an architectural space.  Operated by Shape memory alloys (SMAs) it changes shape according the temperature and offers movement without the use of mechanized components.  Based on organic reaction like a sunflowers fallowing the sun or a sea anemones on a reef this system has the characteristics of life without consciousness.

 

 

Muscle wire (Nitinol) was developed in the 50's and 60's but practical applications have only started in the last 20 yrs. Through the simple application of a small electric current Nitinol is able to contract up to 5% of its overall length meaning that a 100mm wire will contract to 95mm.  This allows for fluid motion to be achived without the use of mechanized actuators.