DEVELOPMENT AND HOVER TESTING OF A SMART TRAILING EDGE FLAP WITH A PIEZO-INDUCED BENDING-TORSION COUPLED ACTUATOR

This paper presents a new actuation mechanism for a smart rotor with an active trailing edge flap, using a piezo activated composite bending-torsion coupled beam as actuator. A novel spanwise variation in the beam layup and piezoceramic element phasing is used to maximize the twist response, while minimizing the bending response. The surface bonded piezoceramic elements are excited to induce spanwise and chordwise bending of the beam. This results in an induced twist via the structural coupling. The composite beam with an outboard integral flap is located parallel to the length of the blade. The flap deflection corresponds to the tip twist of the beam. A proof-of-concept actuator beam was developed and tested. Tip twist with essentially zero tip bending deformation was demonstrated. Two operational 1/8th scale model rotor blades were manufactured for hover testing. Hover testing of the blades was conducted at various rotor speeds and collective settings to evaluate performance of the flap drive system. The actuator beam was also excited at various frequencies and RMS voltages. The flap deflection was measured in order to evaluate flap performance. In hover tests, 4/rev peak to peak flap deflections of 3-4 degrees were achieved at an operating speed of 900 rpm.