Control of friction forces with stationary wave piezoelectric actuator

"In the field of the research on piezoelectric motors, the control of friction forces by ultrasonic waves was studied mainly from an experimental point of view [1]. The principle of friction force reduction by imposed mechanical vibrations in unlubricated contacts was recently studied in order to reduce the friction losses in an internal combustion engine with Langevin type actuators [2]. This article deals with the advantages of flexural stationary wave piezoelectric actuators in the control of the friction forces thanks to their high pressures generated at high frequencies (>10 Khz). The use of specific contact geometry which is defined by the Hertz theory associated with partial slip contact conditions, allows optimizing the lubrication effect. In the case of piezoelectric torque limiter application, the design and the numerical simulation of dedicated piezoelectric actuator are compared. In agreement with the contact modeling, the characterization of the complete actuator on mechanical test bench validates the ""torque limiter"" function and the optimization of lubrication principle with dedicated contact geometry"