The basic operation principle of elastic support/dry friction damper in rotor system was introduced and the unbalance response of the rotor with elastic support/dry friction damper was analyzed theoretically. Based on the previous structure using an electromagnet as actuator, an active elastic support/dry friction damper using piezoelectric ceramic actuator was designed and its effectiveness of reducing rotor vibration when rotor traverses its critical speed and blade-out event happened was experimentally verified. The experimental results show that the active elastic support/dry friction damper with piezoelectric ceramic actuator can significantly reduce vibration in rotor system; the vibration amplitude of the rotor in critical speed region decreased more than 2 times, and the active damper can protect the rotor when a blade-out event happened, so the rotor can traverse the critical speed and shut down smoothly. In addition, the structure is much simpler than the previous, the weight was reduced by half and the power consumption was only 5？W. 1. Introduction Rotors in aircraft engines mostly operate above the first critical speed, some even over second and third critical speeds. They must traverse their critical speeds frequently in the operation. When a blade-out event happens in an engine, it must be shut down immediately [1]. However in this case, the rotor will vibrate violently while traversing the critical speed region due to the excessive unbalance. This could cause further damage to the engine [1–3]. In Certification Specifications for Large Airplanes CS-25 [4], some clauses about aircraft engine rotor are as follows. “Design precautions must be taken to minimize the hazards to the airplane in the event of an engine rotor failure.” “There must be means for stopping the rotation of any engine individually in flight.” This is a crucial challenge to the design of aircraft engines. In order to deal with abovementioned problems, effective damping must be incorporated into rotor systems. It has been proven theoretically and experimentally that as a new rotor vibration damper, the elastic support/dry friction damper can significantly attenuate the vibration amplitude of rotor system in the critical speed region [5–7]; moreover, it is convenient to be controlled by adjusting control voltage [8–11]. However, due to its oversized electromagnetic actuator, the application of such a damper in aircraft engines will be restricted. In recent years, smart materials have received more and more attention in structure vibration control. It has brought some new
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