Durability Characterization of Active Fiber Composite Actuators for Helicopter Rotor Blade Applications

Abstract

Theprimary objective of this work was to characterize the long-term durability performance of the Active Fiber Composite (AFC) actuator material system for the Boeing Active Material Rotor (AMR) blade application. The AFCs were a new structural actuator system consisting of piezoceramic fibers embedded in an epoxy matrix and sandwiched between interdigitated electrodes. These actuators were integrated directly into the blade spar as active plies within the composite structure to perform structural actuation for helicopter vibration control. Therefore, it was necessary to conduct extensive electromechanical material characterization to evaluate AFCs both as actuators and as structural components of the blade. The long-term durability characterization tests designed to extract important electromechanical properties were electrical fatigue tests and mechanical fatigue tests. This paper presents the test results as well as the comprehensive testing process developed to evaluate the relevant AFC durability properties. The durability tests conducted under simulated electromechanical loading conditions expected on AFCs during the blade operation provided an invaluable insight into the behavior of the AFCs under dynamic loading environment. The results from this comprehensive durability characterization of the AFC material system supported the design and operation of the Boeing AMR blade scheduled for wind tunnel tests.