Analysis and Testing of a Froude Scaled Helicopter Rotor with Piezoelectric Bender Actuated Trailing Edge Flaps

Abstract

This paper presents an analytical model and validation tests of a Froude scaled rotor featuring piezoelectric bender (bimorph) actuated trailing-edge flaps for active vibration suppression. The analytical model for the coupled bimorph actuator trailing-edge flap dynamic response in the rotating environment takes into account the aerodynamic, centrifugal, inertial and frictional loads acting on the actuator-flap system. The linkage arm length associated with the mechanical amplification mechanism is selected to maximize flap performance in the rotating environment. The bimorph clamping is improved to prevent actuator slippage under high centrifugal loads. The analytical model is validated by carrying out a series of bench tests, vacuum chamber tests and hover tests. In hover, flap deflections of ±6 degrees at 4/rev flap excitation are achieved at 900 RPM, thus demonstrating the potential of the piezoceramic bender as a lightweight and compact actuation system for individual blade control purposes. This paper also includes a feasibility study for piezo-bimorph actuation of a trailing-edge flap for a Mach scaled rotor model.

Get full access to this article

View all access options for this article.

References

1. Nguyen, K. and I. Chopra . 1990. "Application of Higher Harmonic Control to Rotors Operating at High Speed and Thrust", Journal of the American Helicopter Society, 35(3):78-79.

2. Ham, N. D. 1987. "Helicopter-Individual Blade Control Research at MIT 1977-1985", Vertica, 11(1/2):109-122.

3. Straub, F. K. 1995. "A Feasibility Study of Using Smart Materials for Rotor Control", Journal of Smart Materials and Structures, 5(1): 68-75.

4. Chen, P. C. and I. Chopra . 1997. "Development of a Smart Rotor Blade with Induced Strain Actuation of Blade Twist", AIAA Journal, 35(1): 6-16.

5. Samak, D. K. and I. Chopra . 1993. "A Feasibility Study to Build a Smart Rotor: Trailing Edge Flap Actuation", Proc. SPIE North American on Smart Structures and Materials, Albuquerque, NM, February.

6. Walz, C. and I. Chopra . 1994. "Design and Testing of a Helicopter Rotor Model with Smart Trailing Edge Flaps", Proceedings of the 35th AIAA Structures, Structural Dynamics and Materials Conference, Adaptive Structures Forum, Hilton Head, SC, April.

7. Ben-Zeev, O. and I. Chopra . 1996. "Development of an Improved Helicopter Rotor Model with Smart Trailing Edge Flaps for Vibration Suppression", Journal of Smart Materials and Structures, 5(1):11-25.

8. Spangler, R. L. and S. R. Hall . 1990. "Piezoelectric Actuators for Helicopter Rotor Control", Proceedings of the 31st AIAA/ASME/ASCE/ AHS Structures, Structural Dynamics and Materials Conference, Long Beach, CA, April.

9. Prechtl, E. F. and S. R. Hall . 1996. "Development of a Piezoelectric Servoflap for Helicopter Rotor Control", Journal of Smart Materials and Structures, 5(1):26-34.

10.

10. Bothwell, M. C. , R. Chandra and I. Chopra . 1994. "Torsional Actuation with Extension-Torsion Composite Coupling and Magnetostrictive Actuator", AIAA Journal, 33(4):723-729.

11.

11. Spencer, B. T. and I. Chopra . 1996. "Advances in the Development of an Intelligent Helicopter Rotor Employing Smart Trailing-Edge Flaps", presented at the SPIE Conference on Smart Structures and Integrated Systems, San Diego, CA, February.

12.

12. Chandra, R. and I. Chopra . 1997. "Actuation of Trailing-Edge Flap in a Wing Model Using a Piezostack Device", Proc. of the 38th Structures, Structural Dynamics and Materials Conference, Adaptive Structures Forum, Kissimmee, FL, April.

13.

13. Bernhard, A. and I. Chopra . 1996. "Development and Hover Testing of a Smart Flap with a Piezo-Induced Bending-Torsion Coupled Actuator", Proc. of the 52nd Annual Forum of the American Helicopter Soci- ety, Washington, DC, June.

14.

14. Bernhard, A. and I. Chopra . 1996. Development of a Smart Moving Blade Tip Activated by a Piezo Induced Bending-Torsion Coupled Beam", presented at the SPIE Conference on Smart Structures and Integrated Systems, San Diego, CA, February.

15.

15. National Instruments. "Lab VIEW for Macintosh Data Acquisition Reference Manual", August 1993 Edition.

16.

16. Theodorsen, T. 1935. "General Theory of Aerodynamic Instability and the Mechanism of Flutter", NACA report 496.

17.

17. Hariharan, N. and J. G. Leishman . 1996. "Unsteady Aerodynamics of a Flapped Airfoil in Subsonic Flow by Indicial Concepts", Journal of Aircraft, 33(5):855-868.

18.

18. "University of Maryland Advanced Rotorcraft Code (UMARC)", theory manual, Alfred Gessow Rotorcraft Center, University of Maryland, College Park, MD, July, 1996.