Advanced Finite Element Modeling of Rotor Blade Aeroelasticity

Straub, Friedrich K.; Sangha, K.; Panda, Brahmananda

doi:10.4050/jahs.39.56

Cited by 16 publications

(3 citation statements)

References 17 publications

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“…This methodology has been utilised to analyse the dynamics of the coupled blade and chord-wise absorber system and lag-wise loads control of variable speed rotors during resonance crossing (15,18) . The rotor model is based on a moderate-deflection elastic beam model with the assumptions of small strains and moderate rotations of beam cross-sections (20,21) . Usually, a blade is attached to hinges at its root; these may be flap hinges, lag hinges, feathering hinges, or some combination of these.…”

Section: Rotor Modelling With Flap-wise Absorbersmentioning

confidence: 99%

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Flap-wise loads reduction of rotor blades by embedded flap-wise absorbers

Han

2016

Aeronaut. j.

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Elastomeric and Fluidlastic®absorbers are proposed to be embedded in blade cavity to reduce troublesome second harmonic flap-wise blade loads of rigid rotors. A simple model of a blade with a flap-wise dynamic absorber is derived to investigate centrifugal force effects on the absorber's rotating frequency. The system's dynamic equations of motion indicate that centrifugal force has no effect on absorber's frequency under rotation. Aeroelastic simulation of the coupled rotor and absorber system based on an elastic beam model in generalised force formulation is used to explore load reduction extent and dynamic absorber behaviour. At a forward speed of 200 km/h, the elastomeric absorber reduces the second harmonic flap-wise root-bending moment by 88.8% for unacceptably large stroke; the Fluidlastic®absorber reduces the moment by 78.5% with a stroke 4.26% of blade chord length. Results indicate that placing an embedded Fluidlastic®absorber in the blade's flap-wise direction has potential for reducing load in different flight states with relatively small strokes. Increasing tuning port area ratio or Fluidlastic®absorber mass can distinctly decrease strokes without increasing loads. However, deviation from normal rotor speed significantly lowers Fluidlastic®absorber performance.

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Section: Rotor Modelling With Flap-wise Absorbersmentioning

confidence: 99%

“…The rotor model is based on a moderate-deflection elastic beam model with the assumptions of small strains and moderate rotations of beam cross-sections (20,21) . Usually, a blade is attached to hinges at its root; these may be flap hinges, lag hinges, feathering hinges, or some combination of these.…”

Section: Rotor Modelling With Flap-wise Absorbersmentioning

confidence: 99%

Flap-wise loads reduction of rotor blades by embedded flap-wise absorbers

Han

2016

Aeronaut. j.

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“…The moderate deflection beam model is employed to capture the coupled flap, lag, and torsion dynamics. 16 Figure 1. Configuration of the rotor system with a fluidlastic pitch link isolator.…”

Section: Elastic Blade Modelmentioning

confidence: 99%

Higher harmonic pitch link loads reduction using fluidlastic isolators

Han

Rahn

Smith

2013

Proceedings of the Institution of Mechanical Engineers, Part G:

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Fluidlastic isolators are proposed for higher harmonic pitch link loads reduction in helicopter rotors. An aeroelastic simulation of a soft in-plane rotor in high forward flight is conducted to investigate the dynamic characteristics of the coupled rotor and fluidlastic isolators. Using Hamilton's principle, the system equations of motion are derived based on the generalized force formulation. The results indicate that the application of the fluidlastic isolator can reduce the 4/rev pitch link load by 98.9% in high forward flight with small variations in the other harmonic loads. The isolator has significant influence on the higher harmonic torsional rotation of the blade tip. Increasing the tuning port area ratio can significantly reduce the tuning mass with little variation of the isolation ability. Within 5% variation of the normal rotor speed, the 4/rev isolator can reduce more than 80% of the 4/rev pitch link load. The effects of isolator's damping, forward speed, and thrust on the performance of the isolator are also studied. The ability to isolate other higher harmonic pitch link loads is also investigated.

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