Piezoelectric Driven Testing Facilities to Research the Very High Cycle Fatigue Regime

Cyclic low amplitude loading and a huge number of cycles characterizes the Very High Cycle Fatigue (VHCF) regime. The challenge in research of the Very High Cycle Fatigue regime is to apply this large number of cycles to fracture in an acceptable time frame. For this reason, it is essential to use a machine, which is able to operate at high frequencies of cycles. Two testing machine concepts with piezo actuators are presented in this study. In the first concept, a high performance piezo stack actuator is presented, in which the specimen and the load cell are mechanically assembled in series. This set-up applies forces up to 10 kN and testing frequencies up to 1000 Hz. The second testing facility is a hybrid testing system, which consists of an inertial mass actuator and a servo hydraulic actuator connected in parallel. Both systems are capable of testing normal specimen dimensions and provide the possibility to work with variable as well as constant amplitude loading.