Multilayer piezoelectric ceramic actuators are increasingly being used for high-end applications that require high displacement accuracy and substantial force. For these applications, predicting the lifetime and reliability of piezoceramic actuators is of paramount importance. Therefore, TNO has developed an accelerated lifetime test for piezo actuators enabling us to predict piezo actuator lifetime and develop durable solutions.
The lifetime assessment system consists of a combination of lifetime experiments using an accelerated lifetime test, inspection of the actuator microstructure at different stages of the accelerated lifetime test and numerical simulation of the displacements and mechanical stresses that arise during actuator performance. The displacement and electrical properties measured during the lifetime test provide insight into the relationship between the microstructure and the mechanical stresses in the actuator and predict the piezo actuator lifetime, which helps develop durable solutions. A numerical model that has been developed simultaneously provides solutions for optimising the actuator design with respect to stress development and performance.
The complex problem of the lifetime assessment of multilayer actuators covers a multitude of disciplines. While numerical simulations provide relevant clues for optimal actuator design, these designs must be subjected to real tests to verify whether the design is in fact durable and reliable. TNO has designed and built an accelerated lifetime tester in order to verify rapidly and reliably that these designs show improved reliability and lifetime. This multidisciplinary approach and the design of dedicated test equipment has allowed us to offer our customers complete solutions in the form of verified device improvements.