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Exploiting the properties of piezoelectric materials to minimize vibration in rotor-blade actuators, this book demonstrates the potential of smart helicopter rotors to achieve the smoothness of ride associated with jet-engined, fixed-wing aircraft. Vibration control is effected using the concepts of trailing-edge flaps and active-twist. The authors´ optimization-based approach shows the advantage of multiple trailing-edge flaps and algorithms for full-authority control of dual trailing-edge-flap actuators are presented. Hysteresis nonlinearity in piezoelectric stack actuators is highlighted and compensated by use of another algorithm. The idea of response surfaces provides for optimal placement of trailing-edge flaps.

The concept of active twist involves the employment of piezoelectrically induced shear actuation in rotating beams. Shear is then demonstrated for a thin-walled aerofoil-section rotor blade under feedback-control vibration minimization. Active twist is shown to be significant in reducing vibration caused by dynamic stall. The exposition of ideas, materials and algorithms in this monograph is supported by extensive reporting of results from numerical simulations of smart helicopter rotors.

This monograph will be a valuable source of reference for researchers and engineers with backgrounds in aerospace, mechanical and electrical engineering interested in smart materials and vibration control.

Advances in Industrial C ontrol aims to report and encourage the transfer of technology in control engineering. The rapid development of control technology has an impact on all areas of the control discipline. The series offers an opportunity for researchers to present an extended exposition of new work in all aspects of industrial control.

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Introduction.- Mathematical Modeling.- Preliminary Studies with Active Flaps.- Flap Configuration and Control Law.- Active Flap Controller Evaluation.- Trailing-edge Flap Placement.- Piezoceramic Actuator Hysteresis.- Active Rotating Beams.- Box-beam Active Rotor Blade.- Airfoil-section Rotor Blade.- Dynamic Stall Alleviation Using Active Twist.- Appendices: Kinetic- and Strain-Energy Terms; Section Properties; Shape Functions for Space; Shape Functions for Time.

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Professor Ranjan Ganguli has been working in the area of rotorcraft for the past 25 years. He has published over 150 journal papers and is an expert in helicopter dynamics. Doctor. Sathyamangalam Ramanarayanan Viswamurthy and Professor Dipali Thakkar are former PhD students of Professor Ganguli who are working in the National Aerospace Laboratory, Bangalore and SVIT, Vadodara, respectively. Together, they have published over a dozen journal papers in the area of the smart helicopter rotor. Some of their ideas have been taken up for practical implementation by industry. In this book, they have put together their work on smart helicopter rotors for the benefit of researchers and engineers working in this area.

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