A Combined Piezoelectric and Composite Actuator: a Novel Piezoelectric-composite-actuator and Its Application to Wing / Blade Tip

A novel composite-piezoelectric actuator configuration is proposed and analytically modeled in this book. The actuator is a low complexity, active compliant mechanism obtained by coupling a modified star cross sectional configuration composite beam with a helicoidal bimorph piezoelectric actuator coiled around it. The modified star beam is tailored and optimized to achieve increased torsional compliance and bending stiffness at constant axial stiffness. The coiled piezoelectric actuator is designed to directly generate finite rotation output without need for mechanisms to amplify the piezoelectric displacement output and/or to convert linear output to rotational output. The proposed cylindrical actuator configuration is compact and is a good candidate for use as a hinge tension-torsion bar actuator for a helicopter rotor blade flap or blade tip. For such cases the modified star composite beam also carries the centrifugal loads of the flap or blade tip, and those of the coiled actuator, thereby eliminating the need for a thrust bearing.