Improved Helicopter Aeromechanical Stability Analysis Using Segmented Constrained Layer Damping and Hybrid Optimization

Abstract

Aeromechanical stability plays a critical role in helicopter design and lead-lag damping is crucial to this design. In this paper, the use of segmented constrained damping layer (SCL) treatment and composite tailoring is investigated for improved rotor aeromechanical stability using formal optimization technique. The principal load-carrying member in the rotor blade is represented by a composite box beam, of arbitrary thickness, with surface bonded SCLs. A comprehensive theory is used to model the smart box beam. A ground resonance analysis model and an air resonance analysis model are implemented in the rotor blade built around the composite box beam with SCLs. The Pitt-Peters dynamic inflow model is used in air resonance analysis under hover condition. A hybrid optimization technique is used to investigate the optimum design of the composite box beam with surface bonded SCLs for improved damping characteristics. Parameters such as stacking sequence of the composite laminates and placement of SCLs are used as design variables. Detailed numerical studies are presented. It is shown that optimum blade design yields significant increase in rotor lead-lag regressive modal damping compared to the initial system.

Get full access to this article

View all access options for this article.

References

Badre-Alam, A. , Wang, K.W. and Gandhi, F. 1999. “Optimization of Enhanced Active Constrained Layer (EACL) Treatment on Helicopter Flexbeam for Aeromechanical Stability Augmentation,” Journal Smart Materials and Structures, Vol. 8, pp. 182-196.

Baz, A. and Ro, J. 1993 “Partial Treatment of Flexible Beams with Active Constrained Damping,” Proc., Conference of the Society of Engineering Science (ASME-AMD), Charlottesville, VA, Vol. 167, pp. 61-68.

Baz, A. and Ro, J. 1994. “Finite Element Modeling and Performance of Active Constrained Layer Damping,” Proc., 9th VPI&SU Conf. Dynamics and Control of Large Structures, Blacksburg, VA, pp. 345-358.

Beri, R. , Chattopadhyay, A. and Nam, C. 2000. “Integrated Structures/Control Optimization of a Smart Composite Plate with Segmented Active Constrained Layer Damping,” Paper No. SPIE 3985-80, Proc., SPIE’s 7th International Symposium on Smart Structures and Materials, Newport Beach, CA, March 2000.

Chattopadhyay, A. , Seeley, C.E. and Jha, R. 1999. “Aeroelastic Tailoring Using Piezoelectric Actuation and Hybrid Optimization,” Smart Materials & Structures, Vol. 8, pp. 83-91.

Gu, H. , Chattopadhyay, A. and Nam, C. 1999. “Modeling Segmented Active Constrained Layer Damping Using Hybrid Displacement Field,” Proc., 1999 AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, St. Louis, MO., 12-15 April, pp. 2703-2711.

Kamath, G.M. and Wereley, N.M. 1995. “Development of ER-Fluid Based Actuators for Rotorcraft Flexbeam Applications,” Proc., SPIE’s 2nd International Symposium on Smart Structures and Materials, CA, February, Vol. 2443, pp. 120-133.

Liu, Q. , Chattopadhyay, A. , Gu, H. and Zhou, X. 1999. “Effect of Active Constrained Damping Treatment on Helicopter Aeromechanical Stability Analysis” Proc., 55th American Helicopter Society Annual Forum, Montreal, Canada, May 25-27, pp. 2228-2239.

McGuire, D.P. , 1994. “Fluidlastic® Dampers and Isolators for Vibration Control in Helicopters,” Proc., 50th American Helicopter Society Annual Forum, Washington, D.C., pp. 295-303.

10.

Pitt, D.M. and Peters, D.A. 1981. “ Theoretical Predictions of Dynamic In-flow Derivatives,” Vertica, Vol. 5, No.1, March 1981, pp. 21-34.

11.

Ro, J. and Baz, A. 1996. “Optimum Design and Control of Active Constrained Layer Damping,” Journal of Mechanical Design and Journal of Vibration and Acoustics (special combined edition), vol. 117, pp. 135-144.