GM will make use of an aluminum frame which the company claims is 99 pounds lighter than its predecessor in the 2014 Chevrolet Corvette, says a company press release. The seventh-generation vehicle will be GM's first car to feature lightweight heat-activated shape memory alloy wire in place of a heavier motorised actuator to open and close the hatch vent that releases air from the trunk. With this, the trunk lid can be more easily closed compared with the previous models in which trapped air could make the lid harder to close. The wire actuator used on the new Corvette is 1.1 pounds (.5kg) lighter than a conventional motorised system, says GM.
A shape memory alloy wire is made of copper-aluminum-nickel or nickel-titanium and its shape and strength can be changed when activated by heat, stress, magnetic field or electrical voltage. The alloy returns to its normal shape when deactivated. “Smart materials like shape memory alloys offer new possibilities for many movable vehicle features. These new materials enable innovative designs and new and improved features at a lower cost than traditional motors and actuators”, said Jon Lauckner, Chief Technology Officer at GM. The use of shape memory alloys also eliminates unwanted mass, thereby leading to an improvement in performance and fuel economy of a vehicle. The alloy wire used in the new Corvette opens the hatch vent whenever the deck lid is opened, using heat from an electric current that works in a similar manner as the 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 electric current switches off, allowing the wire to cool and return to its normal shape, which closes the vent to maintain cabin temperature.
Significance: GM is looking to replace other components in its model vehicles with lightweight materials. With its shape memory alloy, the company has optimally found a way to achieve weight reduction in a car. “The shape memory alloy used on the new Corvette represents nearly five years of research and development work on smart materials for which GM has earned 247 patents… We have many more smart material applications in the pipeline that will bring even more improvements to our vehicles going forward”, said Paul Alexander, a smart materials and structures researcher at GM.
