From its fiberglass body in
1953 to its aluminum chassis for 2014, Chevrolet Corvette has a six-decade
track record for introducing lightweight materials that improve vehicle
performance. With the 2014 Corvette’s aluminum frame weighing in 99 pounds lighter
than its predecessor, that trend continues.
In addition, the redesigned
seventh-generation sports car is the first vehicle to use a General
Motors’-developed lightweight shape memory alloy wire in place of a heavier
motorized actuator to open and close the hatch vent that releases air from the
trunk. This allows the trunk lid to close more easily than on the previous
models where trapped air could make the lid harder to close.
Considering there are about
200 motorized movable parts on the typical vehicle that could be replaced with
lightweight smart materials, GM is looking at significant mass reduction going
forward.
Shape memory alloys –
typically made of copper-aluminum-nickel or nickel-titanium – are smart
materials that can change their shape, strength, and/or stiffness when
activated by heat, stress, a magnetic field or electrical voltage. Shape memory
alloys “remember” their original shape and return to it when de-activated.
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 in a similar manner to 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 electrical current
switches off, 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 new and improved features at a lower cost than
traditional motors and actuators.”
Shape memory alloy also helps
remove unwanted mass, which can help improve vehicle performance and fuel
economy. The wire actuator used on the new Corvette is approximately 1.1 pound
(.5 kilogram) lighter than a conventional motorized system.
“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,” said Paul
Alexander, GM smart materials and structures researcher. “And it is just the
beginning. We have many more smart material applications in the pipeline that
will bring even more improvements to our vehicles going forward.”
-Courtesy of GM News
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