Design issues of a high-stroke, on-blade piezostack actuator for a helicopter rotor with trailing-edge flaps

A compact actuator to oscillate blade trailing-edge flap on a full-scale he licopter has been investigated for vibration suppression. The actuator cons ists of piezoelectric stacks and a dual-stage mechanical stroke amplifier. It is recommended that commercially available piezostack be used for timely manufacturing and maintenance rather than a custom-designed piezostack. An analytical approach to estimate the maximum actuator force requirement for the rotor in hover condition is discussed first. A piezostack down-selecti on through the experimental evaluation is presented, which is to select a p iezostack with high stiffness as well as good strain/block force output amo ng twelve commercial piezostacks. The design requirements of on-blade piezo electric actuator are discussed, and one-dimensional stiffness modeling and finite element beam modeling are presented to evaluate the analytical/nume rical actuator performance. The prototype actuator with a double-lever stro ke amplifier was fabricated and tested on bench-top as well as in vacuum ch amber. An amplification factor of 19.4 and the consistent actuator output u p to 600 g of centrifugal loading were obtained. An improved actuator has b een designed with a design refinement to reduce structural losses.