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Adaptive Blade Twist - calculations and experimental results

Büter, A. and Breitbach, E. (2000) Adaptive Blade Twist - calculations and experimental results. Aerospace Science and Technology, 4 (5), pp. 309-319.

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Abstract

Applying adaptronics to helicopters has a high potential to significantly suppress noise, reduce vibration, and increase the overall aerodynamic efficiency. This paper present investigations on a very promising specific concept described as Adaptive Blade Twist (ABT). This concept allows us to directly control the twist of the helicopter blades by smart adaptive elements. This influences positively the main rotor area which is the primary source for helicopter noise and vibration. Since the interaction of non-stationary helicopter aerodynamics and elastomechanical structural characteristics of the helicopter blades causes flight envelope limitations, vibration and noise, a good comprehension of the aerodynamics is essential for the development of structural solutions to effectively influence the local airflow conditions and finally develop the structural concept. With respect to these considerations, the ABT concept will be presented. This concept is based on the actively controlled tension-torsion-coupling of the structure. For this, an actuator is integrated within a helicopter blade that is made of an anisotropic material based on fiber composites. Driving the actuator results in a local twist of the blade tip in such a way that the blade can be considered as a torsional actuator. Influencing the blade twist distribution finally results in a higher aerodynamic efficiency. The paper starts at giving a review on conventional concepts and potential adaptive solutions for shape control. After, some calculations of the adaptive twist control concept are presented. These are based on a representative model which the active part of the rotor blade is simplified with a thin-walled rectangular beam, that is structurally equivalent to a model rotor blade of the Bo105 with a scaling factor 2,54. The calculations are performed using an expanded Wlassow theory. The results are valid for static and dynamic conditions. For the dynamic condition excessive deformations near the blade resonance frequency shall be utilised. Therefore, the actuated blade section has to be properly designed for this precondition. This has been demonstrated and verified in experiments, which will not be discussed in this paper.

Document Type:Article
Additional Information: LIDO-Berichtsjahr=2000,
Title:Adaptive Blade Twist - calculations and experimental results
Authors:
AuthorsInstitution or Email of Authors
Büter, A.UNSPECIFIED
Breitbach, E.UNSPECIFIED
Date:2000
Journal or Publication Title:Aerospace Science and Technology
Refereed publication:Yes
In ISI Web of Science:Yes
Volume:4
Page Range:pp. 309-319
Status:Published
Keywords:adaptive rotor systems, adaptive rotor control, adaptive materials and structures
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:other
DLR - Research area:Aeronautics
DLR - Program:L DT - Drehflüglertechnologien
DLR - Research theme (Project):UNSPECIFIED
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Institut für Strukturmechanik
Deposited By: Sibylle Wolff
Deposited On:16 Sep 2005
Last Modified:14 Jan 2010 15:57

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