Smart materials are materials that have properties that react to changes in their environment.This means that one of their properties can be changed by an external condition, such as temperature, light, pressure or electricity. This change is reversible and can be repeated many times.There are a number of types of smart material, some of which are already common. For example, shape-memory alloys and shape-memory polymers are materials in which large deformation can be induced and recovered through temperature changes or stress changes. The shape memory effect results due to respectively martensitic phase change and induced elasticity at higher temperatures.
Developing alloys that will remember their original form distortion
In order to explain how smart materials work, I decide to use a device called Air Flow(er) as an example. The Air Flow(er) is an energy independent thermally active ventilation device which behaves like a flower, whose “petals” open wide when exposed to warmer temperatures.
As can be seen in the picture, the four leaf prototype could be used as the operable blind or shade on either the exterior or interior face of a naturally ventilated double-skin facade system. The main advantage of a double-skin façade is the greater control they provide over the thermal/fluid exchange between the perimeter zone and the outside environment. In the summer, the cavity between the inner and outer skin could be vented out of the building through the Air Flow-er’s automatic response to rising temperatures – mitigating solar gain and decreasing the cooling load on the building’s mechanical equipment. In the winter, a double-skin facade can act as a passive solar heater by using the Air Flow-er to seal the cavity and using the absorbed radiation to minimize the façade heat loss.
The active component in the Air Flow(er) device is a custom manufactured Shape Memory Alloy (SMA) wire, which is commonly regarded as a smart material because of its unique response to changes in temperature. When an SMA is in its lower temperature form, it can be easily deformed into a new shape.
The first reported steps towards the discovery of the shape-memory effect were taken in the 1930s. 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).
A girl in front of a wall which is created by Air Flowers
Owners and developers of new and existing buildings can use the Air Flow(er) to lower their energy expenses through passive ventilation, even under the most demanding of situations.As a device which is not a energy consumption, the benefit to socity of this device is not doubt.Because the panels open and close according to the material characteristics of the SMA wire, there are no complicated sensors, circuits, or processing devices required to operate the system. It will largely decrease maintenance and operating costs,which can bring a lot of benefits to society.
Thus,there is no doubt that smart materials can be used as a energy saving product, which can help to save money and resources. It can take so many benefits to society and human's future and make our planet longer and better.
Jaronie Mohd Jani, Martin Leary, Aleksandar Subic, Mark A. Gibson, A review of shape memory alloy research, applications and opportunities, Materials & Design (1980-2015), Volume 56, April 2014, Pages 1078-1113, ISSN 0261-3069
Sun, L.; Huang, W. M. (2010). "Nature of the multistage transformation in shape memory alloys upon heating". Metal Science and Heat Treatment. 51 (11–12): 573. doi:10.1007/s11041-010-9213-x.
Wilkes, K. E.; Liaw, P. K.; Wilkes, K. E. (2000). "The fatigue behavior of shape-memory alloys". JOM. 52 (10): 45. doi:10.1007/s11837-000-0083-3.
Jump up Mihalcz I. (2001). "Fundamental characteristics and design method for nickel-titanium shape memory alloy". Periodica Polytechnica Ser Mech Eng. 45: 75–86.
Air Flower http://www.liftarchitects.com/air-flower/