<title>Evaluation of new actuators in a buffet loads environment</title>

Abstract

Ongoing research in buffet loads alleviation has provided an application for recently developed piezoelectric actuators capable of higher force output than previously existing actuators could provide and that can be embedded within the vehicle's structure. These new actuators, having interdigitated electrodes, promise increased performance over previous piezoelectric actuators that were tested on the fin of an F/A-18 aircraft. Two new actuators being considered by the United States Air Force to reduce buffet loads on high performance aircraft were embedded into the fins of an F/A-18 wind-tunnel model and tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center. The purpose of this test program, called ENABLE (Evaluation of New Actuators in a Buffet Loads Environment), was to examine the performance of the new actuators in alleviating fin buffeting, leading to a systems -level study of a fin buffet loads alleviation system architecture being considered by the USAF, Boeing, and NASA for implementation on high performance aircraft. During this windtunnel test, the two actuators performed superbly in alleviating fin buffeting. Peak values of the power spectral density functions for tip acceleration were reduced by as much as 85%. RMS values of tip acceleration were reduced by as much as 40% while using less than 50% of the actuators' capacity. Details of the wind-tunnel model and results of the wind-tunnel test are provided herein.

F-16 Ventral Fin Buffet Alleviation Using Piezoelectric Actuators

“…Both Moses [35,43] and a team from the National Research Council of Canada [9], in developing controllers for the F/A-18 vertical tail, evaluated two different types of feedback sensors in several control systems, some using accelerometers mounted at the tips of the tails, which provided feedback for the first torsion mode, and others using strain gauges mounted at the root, which provided feedback for the first bending mode.…”

“…Hanagud's approach simplified the design in that damping was the only design variable necessary to define the controller.Buffet alleviation efforts on F/A-18 vertical tails saw many different control approaches. Moses[35,43] employed frequency domain compensation techniques in SISO control designs that used feedback from either accelerometers or strain gauges.The resulting control algorithms resembled low pass or band pass filters with peaks near the targeted natural frequency in order to concentrate control energy at those frequencies. In an additional effort on the F/A-18 buffet problem, Pototozky[38] and a team from the National Research Council of Canada[9] used the LQG optimal control method, which is a special formulation of the H 2 technique, to design acceleration feedback controllers.…”

A comparison of packaged piezoactuators for industrial applications

“…Industrial and commercial applications such as these have driven the need for higher performance, lower cost, and increased flexibility in the packaged strain actuator (see, e.g., Ref. 15). Some newer versions of the packaged strain actuator have been developed in response to these needs.…”

Lightweight High Voltage Electronic Circuits for Piezoelectric Composite Actuators

“…Piezoceramics remain the most widely used 'smart' or active material because they offer high actuation authority and sensing over a wide range of frequencies. Moses et al (2001) used both Active Fiber Composite (AFC, a precursor of MFC) and MFC to actively reduce vibration levels in the tail fins of a wind-tunnel model of a fighter jet subjected to buffet loads. The model was tested at a Mach number of 0.105 and a 25 angle of attack.…”