Engineers have to address numerous challenges before smart materials go mainstream. For example, the use of shape-memory alloys is different than traditional actuation technologies used in mechanisms, due to their unique characteristics and behavior.
Shape-memory alloys and polymers are referred to as “smart materials.” They change their shape, strength or stiffness when heat, stress, a magnetic field or electrical voltage is introduced.
Smart materials “remember” their original shape and can return to it, opening new possibilities for many movable features, such as replacing the electric motors traditionally used to activate car seats, windows and locks. There are numerous applications for the technology in the automotive, aerospace, appliance, medical and electronics industries.
However, engineers have to address numerous challenges before smart materials go mainstream. For example, the use of shape-memory alloys (SMAs) is different than traditional actuation technologies used in mechanisms, due to their unique characteristics and behavior.
“Shape-memory alloys appear simple on the surface, but they require more expertise and understanding than most engineers think,” warns Jeff Brown, program manager at Dynalloy Inc., a leading supplier of shape-memory alloys that are used by a wide variety of manufacturers. “The technology can be very complex to use. The most successful products have been designed around SMA technology from the ground up vs. an existing product that has been engineered for decades around existing technologies.”
“Shape-memory alloys must be incorporated very early in the design process to eliminate issues resulting from drop-in of SMAs into traditional designs,” adds Geoff McKnight, manager of the active materials and adaptive structures technologies department at HRL Laboratories LLC, an R&D facility that’s owned by Boeing and General Motors. “In addition, since there are no in-depth design tools for SMAs, it is critical to include at least one team member who has experience working with SMAs.”
Because SMAs are thermally controlled materials, McKnight says component and system design should be engineered carefully to permit operation over wide ranges of usage conditions and environments. “The lifetime of the SMA element is a strong function of the particular work cycle of the component, which requires the component to be designed carefully to achieve the greatest lifetime duration,” he points out.