Design and performance of a linear piezoelectric wedgeworm actuator

A new concept in linear piezoelectric actuators is developed for applications in adaptive, conformable structures for flow control. Motivated by a desire for high actuation force (>1kN) and simplified drive signals, the design takes advantage of self-locking wedges to lock the clamping elements. The concept relies heavily on knowledge and manipulation of the friction coefficients between several surfaces, so the choice of coatings and lubricants are a major part of the investigation. Since the wedges are self-locking in one direction, the actuation force is limited only by the size of the piezoceramic and the strength of the actuator structure. The device contains a single piezoceramic stack (8x8x42 mm, PZT 5H), so the drive signals and amplifiers are drastically simplified from previous designs. A prototype of the concept is developed and experimentally tested. At a drive frequency of 200 Hz, the free velocity is 8 mm/s with a travel of 25 mm. An actuation force of 250 N is achieved with the prototype. The wedge concept also reduces the amount of precision necessary in machining and assembling the device.