MEMORY-METAL ACTUATORS FOR AUTOMOTIVE APPLICATIONS

Shape-memory alloys (SMAs) are a relatively recent addition to the range of materials that can be obtained by the automotive designer. Low-cost SMA springs are now available, which alter in length when their temperature is changed. SMA springs produce a larger force than bimetallic devices, and in addition the full length change occurs quite rapidly, as soon as the threshold temperature is reached, giving a useful 'bistable' effect. This technical note describes the application of SMA springs to the design of an actuator, intended for use as a radiator blind forming part of an automotive cooling system. The design process adopted is outlined, together with the subsequent testing of the prototype. It is shown that SMA devices can form the basis of a range of simple, flexible and reliable actuators.