In the new Corvette, a shape memory alloy wire opens the hatch vent whenever the deck lid is opened, using heat from an electrical current.
While much of the news about weight savings on the revised 2014 Corvette concentrates on the aluminum chassis that saves 99 pounds compared to its steel predecessor, GM is also using a heat-activated shape memory alloy that replaces a heavier motorized part. An electric wire will be used in place of a heavier motorized actuator to open the hatch vent that releases air from the trunk to allow for easier closing. After the hatch closes, the vent closes.
Shape memory alloys are a class of materials change their shape, strength, and/or stiffness when activated by heat, stress, a magnetic field or in the Corvette’s case, electrical voltage. They are typically made of copper-aluminum-nickel or nickel-titanium and are sometimes referred to as smart materials. They can be used to replace electric motors or actuators, which can total a hundred or more on new vehicles, an expensive, weight adding design challenge.
There’s more than one way to save weight with new alloys.
In the new Corvette, a shape memory wire opens the hatch vent whenever the deck lid is opened, using heat from an electrical current applied in a similar manner to conventional trunk lights. When activated, the wire contracts and moves a lever arm to open the vent, allowing the trunk lid to close. Once the trunk lid is closed, the electrical current switches off, just like a trunk light, allowing the wire to cool and return to its normal shape, which closes the vent to maintain cabin temperature.
“Smart materials like shape memory alloys offer new possibilities for many movable vehicle features,” said Jon Lauckner, GM’s chief technology officer. “These new materials enable innovative designs and improved features at a lower cost than traditional motors and actuators.”
The wire actuator used on the new Corvette is 1.1 pounds lighter than motorized system it replaces. GM says that nearly five years of research and development work on smart materials has resulted in 247 patents. GM also says it has many more smart material applications coming.
