Actuation Requirements of a Warp-Induced Variable Twist Rotor Blade

Mistry, Mihir; Gandhi, Farhan; Nagelsmit, M.H.; Gürdal, Zafer

doi:10.1177/1045389x11404957

Cited by 18 publications

(17 citation statements)

References 8 publications

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“…Warp‐induced twist was also investigated for a helicopter blade concept by Mistry et al . In this parametric study, the influence of several parameters on the required actuation was assessed: blade span length, skin thickness, rib spacing and actuator nut spacing were considered. A finite element model, based on the built prototype shown in Figure , was developed and used in conjunction with an analytical model to predict the behaviour of the structure while varying the parameters.…”

Section: Review Of Aerodynamic Control Conceptsmentioning

confidence: 99%

Review of morphing concepts and materials for wind turbine blade applications

2012

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With increasing size of wind turbines, new approaches to load control are required to reduce the stresses in blades. Experimental and numerical studies in the fields of helicopter and wind turbine blade research have shown the potential of shape morphing in reducing blade loads. However, because of the large size of modern wind turbine blades, more similarities can be found with wing morphing research than with helicopter blades. Morphing technologies are currently receiving significant interest from the wind turbine community because of their potential high aerodynamic efficiency, simple construction and low weight. However, for actuator forces to be kept low, a compliant structure is needed. This is in apparent contradiction to the requirement for the blade to be load carrying and stiff. This highlights the key challenge for morphing structures in replacing the stiff and strong design of current blades with more compliant structures. Although not comprehensive, this review gives a concise list of the most relevant concepts for morphing structures and materials that achieve compliant shape adaptation for wind turbine blades.Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Review Of Aerodynamic Control Conceptsmentioning

confidence: 99%

Review of morphing concepts and materials for wind turbine blade applications

2012

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“…Figure 1b shows some representative examples, including a linear spring, a linear spring with a vertical offset, and a stiffening spring. Loads of this form would be expected for morphing aircraft concepts such as compliant leading or trailing edge camber changes, 20,21,22,23,24 elastic span extension, 25,26 warp induced variable twist, 27 and chord extension, 28 The impact of the mismatch in force profiles between actuator and load is a reduction in achievable deflection and a loss of efficiency, requiring more input energy and a larger, heavier actuator to perform a given task. Actuators convert energy input into force and displacement available.…”

Section: Actuator and Load Force Profilesmentioning

confidence: 99%

“…With θ min γ known for a given δ, the corresponding ∆L and l m can be found from Equations 17 and 25. As before, the PAM force, F P , at the current value of contraction is found from the PAM force model 39 and the resulting torque on the spiral pulley will be: (27) As in Equation 9, the torque on the FishBAC tendon spooling pulley, T F , will be modified by the gear ratio, GR: (28) And once again, the tendon spooling pulley rotation angle, δ F , is also modified; (29) Given the non-linearity of the governing equations and the larger number of design variables, a genetic algorithm was chosen to optimize the parameters of the spiral spooling pulley. The Genetic Algorithm function in the Matlab 2012b Global Optimization Toolbox was used.…”

Section: Spiral Spooling Pulley Analysismentioning

confidence: 99%

Advanced Kinematic Tailoring for Morphing Aircraft Actuation

Woods

Wereley

Friswell

2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Morphing aircraft concepts require powerful, compact and lightweight actuation technologies in order to realize the significant changes in shape and aerodynamic properties desired. One source of inefficiency and lost performance common to all types of actuators is the mismatch between the force available versus stroke profile of the actuator and that required by the load. This work investigates a novel spiral spooling pulley mechanism that allows for kinematic tailoring of the actuator load line to better match the load required. To show the impact of kinematic tailoring on actuator efficiency, a representative case study is made of a Pneumatic Artificial Muscle driven morphing camber airfoil employing the Fish Bone Active Camber concept. Pneumatic Artificial Muscles have a decreasing force available with displacement, which is the opposite behavior of the system being driven since the aerodynamic and structural loads on the active camber mechanism increase with deflection. This results in inefficient usage of the energy in the actuator, and reduced system performance. By using an advanced spiral pulley kinematic mechanism, the actuator force profile is successfully tailored to match that required, with an additional torque margin added to account for any unmodeled effects. Genetic algorithm optimization is used to select the geometric parameters of the spiral pulley that maximize energy efficiency of the actuator while ensuring it is able to produce the required torque levels. The performance of the optimized spiral pulley is compared to a baseline case employing an optimized circular pulley which does not alter the shape of the actuator force profile to show the performance improvement provided by the kinematic tailoring.

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“…Blade twist morphing is a concept which could modify the shape of the blade in flight to achieve the best performance in each flight condition. For helicopter rotors, the twist distribution that minimizes the power requirement is different in each flight condition [1]. Therefore, the predefined blade twist variation normally is chosen as a compromise between different flight conditions.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, the actuation behaviour was tuned by the heat treatment of SMAs. Mistry et al [1] developed a warp-induced twist variation concept for rotary-wing applications. In this method, the twist of the blade changes by rotation of a threaded rod.…”

Section: Introductionmentioning

confidence: 99%

The effect of a movable mass on the aeroelastic stability of composite hingeless rotor blades in hover

Amoozgar

Shaw

Zhang

et al. 2019

Journal of Fluids and Structures

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In this paper, the aeroelastic stability of a composite hingeless rotor blade with a chordwise movable mass is investigated. The point mass is located near the tip of the blade and its chordwise location is variable with respect to the elastic axis and can be moved during the flight. This movable mass is added to the blade to actuate the blade twist during flight. By actuating the mass in the chord direction of the blade during the flight, a bending moment which is the result of the centrifugal force of the mass and its offset is induced on the blade. This bending moment induces twist in the blade, due to bend-twist coupling in the composite lamination. The blade is modelled by using the geometrically exact fully intrinsic beam equations along with the variational asymptotic beam sectional analysis. The aerodynamic loads are simulated by using the two-dimensional strip theory combined with a uniform inflow. The nonlinear partial differential aeroelastic equations are discretized by a time-space scheme, and the converged results are compared with those reported in the literature and a very good match is observed. The results show that by positioning the mass near the tip of the blade, and also by using the ply angle of about 30 degree in this configuration, the highest possible twist change is achieved when the mass moves from the leading edge to the trailing edge of the blade. Moreover, the spanwise location of the mass slightly changes the stability boundaries, while the chordwise movement significantly affects the aeroelastic instability.

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Actuation Requirements of a Warp-Induced Variable Twist Rotor Blade

Cited by 18 publications

References 8 publications

Review of morphing concepts and materials for wind turbine blade applications

Review of morphing concepts and materials for wind turbine blade applications

Advanced Kinematic Tailoring for Morphing Aircraft Actuation

The effect of a movable mass on the aeroelastic stability of composite hingeless rotor blades in hover

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