A probabilistic approach to evaluate the reliability of piezoelectric micro-actuators

In this paper, a probabilistic design approach is presented to evaluate the reliability of piezoelectric micro actuators. Based on the relationship between the lifetime, and degradation mechanism of piezoelectric actuators, and the electric field strength, the concept of "electric strength" is proposed to indicate the electric field strength of the piezoelectric actuators at a specified lifetime. The lifetime (number of cycles to failure) of the piezoelectric actuator, electric strength, and electric load are considered as the random variables; and their probability distributions are discussed. The interference model of electric load, and electric strength is introduced to the reliability design of piezoelectric micro actuators. By this approach, the relationship between the reliability, and the lifetime of the piezoelectric actuator can be given. A case study of the disk drive head positioning system demonstrates the application of the approach.