A demonstration of passive blade twist control using extension-twistcoupling

Lake, Renee C.; Nixon, Mark W.; Wilbur, Matthew L.; Singleton, Jeffrey D.; Mirick, Paul H.

doi:10.2514/6.1992-2468

Cited by 17 publications

(8 citation statements)

References 3 publications

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“…Reference [44] The work of Ref. [47] was further expanded in [40,39] which included an experimental study leading to a "proof-of-concept" for extension-twist coupled rotor blades.…”

Section: Chapter 2 a Survey Of Passive Blade Twist Control Applicationsmentioning

confidence: 99%

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Extension-Twist Coupling Optimization in Composite Rotor Blades

Ozbay

2005

46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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This work could not have been completed without the help of many people to whom I would like to give my thanks. I would like to express my deepest gratitude to Dr. Erian Armanios for his patient guidance throughout my life at Georgia Tech. This work would have never been possible without his immeasurable professional and emotional support, encouragement and above all his trust. I am also grateful to Dr. D. Stefan Dancila for his support in this work. His valuable critiques and guidance helped me improve my work. I also would like to acknowledge Dr. Olivier A. Bauchau. I am thankful to him for providing the DYMORE and VABS programs. I would like to thank Dr. Dewey H. Hodges and Dr. Abdul-Hamid Zureick for their willingness to serve on my thesis committee. This work has been completed under a grant from the National Rotorcraft Technology Center. I am sincerely thankful for their support. Additionally I would like to thank my officemates, true friends, Samer Tawfik, Xinyuan Tan and Dr. Roxana Vasilescu for their technical and emotional support. I sincerely thank my parents Nedime and Engin Ozbay. Without their love, support and sacrifices, I would not be who I am now. Thank you for your belief in what I could achieve eventually. Finally I would like to express my great gratitude to my lovely wife Tuba, for her unconditional love, support and confidence. It is a huge understatement to say that I could achieve this without her. I love her. The rest of my days are special because of her. v TABLE OF CONTENTS

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“…Reference [44] The work of Ref. [47] was further expanded in [40,39] which included an experimental study leading to a "proof-of-concept" for extension-twist coupled rotor blades.…”

Section: Chapter 2 a Survey Of Passive Blade Twist Control Applicationsmentioning

confidence: 99%

“…2-1. Rotor Blade Cross-Section[39] A geometrically nonlinear finite element analysis based on MSC/NASTRAN was also conducted to validate the tests. The results of the hover tests and finite element analysis…”

mentioning

confidence: 99%

Extension-Twist Coupling Optimization in Composite Rotor Blades

Ozbay

2005

46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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“…In contrast, another approach to aircraft morphing has been to exploit changes in operating state to realize structural shape change, without any dedicated actuation energy input. In rotary-wing aircraft, in particular, changes in rotor RPM, and the resultant changes in centrifugal forces acting on the blade, have been used in several studies to realize rotor span extension morphing (Misiorowski et al, 2015; Prabhakar et al, 2007), chord extension morphing (Moser et al, 2014), and rotor blade twist change (DiPalma et al, 2018; Lake et al, 1992; Nampy and Smith, 2006; Ward et al, 2017a, 2017b). Such an approach, where reconfiguration is achieved without the use of dedicated actuation energy input, can be referred to as autonomous morphing.…”

Section: Introductionmentioning

confidence: 99%

Autonomous camber morphing of a helicopter rotor blade with temperature change using integrated shape memory alloys

DiPalma

Gandhi

2020

Journal of Intelligent Material Systems and Structures

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The present study proposes and explores a new autonomous morphing concept, where a 12–13° increase in camber is realized over a spanwise section of a helicopter rotor blade with increase in ambient temperature. The camber change is achieved through integration of Shape Memory Alloys (SMAs) on the lower surface of the blade, aft of the leading-edge spar. For a reference rotor of a utility-class helicopter generating 21,000 lbs thrust, a loss in lift of 2590 lb was observed due to operation in hot conditions. With the SMA camber morphing section extending from the blade root to 25%, 50%, and 75% span, the rotor recovered up to 11%, 43%, and 82% of the lift loss at high temperature (compared to a no-SMA blade). If the morphing section instead spans the outboard 25% of the blade (from 75% span to the blade tip), up to a 66% lift recovery is achieved due to the higher dynamic pressures over this region. While these results are achieved with existing SMA properties, idealized target values are also presented. For the SMA considered in the study, while a 40–115°F temperature change was required to achieve the full 12–13° design camber change, partial camber is achieved over a smaller temperature range. The paper identifies desired SMA properties that would produce a 12–13° camber change over an 80–100°F temperature change.

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“…A distinct advantage of composites over other materials is the tailorability for specific applications and is one of its greatest attractions. The tailorability of composites for the application of prop rotors of tiltrotor aircraft is discussed in literature [1,2], based on the extensional-twist coupling exhibited by the laminates of antisymmetric lay-up of off axis plies. The tiltrotor aircraft operate as helicopter during lift off and as airplane during flight.…”

Section: Introductionmentioning

confidence: 99%

Macro-fiber composite (MFC) as a delamination sensor in antisymmetric laminates

Krishna

Harursampath

2006

SPIE Proceedings

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The change in extension-twist coupling due to delamination in antisymmetric laminates is experimentally measured. Experimental results are compared with the results from analytical expression existing in literature and finite element analysis. The application of the Macro-Fiber Composite (MFC) developed at the NASA Langley Research Center for sensing the delamination in the laminates is investigated. While many applications have been reported in the literature using the MFC as an actuator, here its use as a twist sensor has been studied. The real-life application envisaged is structural health monitoring of laminated composite flexbeams taking advantage of the symmetry in the structure. Apart from the defect detection under symmetric conditions, other methods of health monitoring for the same structure are reported for further validation. Results show that MFC works well as a sensor.

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A demonstration of passive blade twist control using extension-twistcoupling

Cited by 17 publications

References 3 publications

Extension-Twist Coupling Optimization in Composite Rotor Blades

Extension-Twist Coupling Optimization in Composite Rotor Blades

Autonomous camber morphing of a helicopter rotor blade with temperature change using integrated shape memory alloys

Macro-fiber composite (MFC) as a delamination sensor in antisymmetric laminates

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