Aeroelastic Tailoring of Helicopter Blades

2015 ◽  
Vol 10 (6) ◽  
Author(s):  
Donatien Cornette ◽  
Benjamin Kerdreux ◽  
Guilhem Michon ◽  
Yves Gourinat
Keyword(s):  
Dynamic Behavior ◽  
Center Of Gravity ◽  
Dynamic Loads ◽  
Modal Approach ◽  
Aeroelastic Tailoring ◽  
Helicopter Blades ◽  
Analytical Results ◽  
Aeroelastic Model ◽  
Elastic Couplings ◽  
Homogeneous Beam

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress on components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization uses couplings between the flapwise-bending motion and the torsion motion. The impacts of elastic couplings (composite anisotropy) and inertial couplings (center-of-gravity offset) on blade dynamic behavior and on dynamic loads are evaluated in this paper. First, analytical results, based on a purely linear modal approach, are given to understand the influence of these couplings on blade dynamic behavior. Then, a complete nonlinear aeroelastic model of the rotor, including elastic and inertial couplings, is derived. Finally, this last model is used to improve a simplified but representative blade (homogeneous beam with constant chord) and results are presented.

Aeroelastic Tailoring of Helicopter Blades

2013 ◽  
Author(s):  
Donatien Cornette ◽  
Benjamin Kerdreux ◽  
Yves Gourinat ◽  
Guilhem Michon
Keyword(s):  
Dynamic Behaviour ◽  
Vertical Shear ◽  
Dynamic Loads ◽  
Modal Approach ◽  
Aeroelastic Tailoring ◽  
Helicopter Blades ◽  
Shear Modification ◽  
Elastic Couplings ◽  
The Impact ◽  
Aerodynamic Lift

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization is done thanks to couplings between the flapwise-bending motion and the torsion motion. The impact of elastic couplings (composite anisotropy) on the blade dynamic behaviour and on dynamic loads are evaluated in this paper. Firstly, analytical results, based on a purely linear modal approach, are given to understand the influence of those couplings in terms of frequency placement, aerodynamic lift load and vertical shear modification. Then, those elastic couplings are introduced on a simplified but representative blade (homogeneous beam with constant chord) and results are presented.

scholarly journals Preliminary investigation of use of flexible folding wing tips for static and dynamic load alleviation

2016 ◽  
Vol 121 (1235) ◽  
pp. 73-94 ◽  
Author(s):  
A. Castrichini ◽  
V. Hodigere Siddaramaiah ◽  
D.E. Calderon ◽  
J.E. Cooper ◽  
T. Wilson ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Preliminary Investigation ◽  
Aircraft Design ◽  
Dynamic Loads ◽  
Induced Drag ◽  
Aeroelastic Model ◽  
Static And Dynamic Loads ◽  
Folding Wing ◽  
Wing Tips ◽  
Wing Tip

ABSTRACTA recent consideration in aircraft design is the use of folding wing-tips with the aim of enabling higher aspect ratio aircraft with less induced drag while also meeting airport gate limitations. This study investigates the effect of exploiting folding wing-tips in flight as a device to reduce both static and dynamic loads. A representative civil jet aircraft aeroelastic model was used to explore the effect of introducing a wing-tip device, connected to the wings with an elastic hinge, on the load behaviour. For the dynamic cases, vertical discrete gusts and continuous turbulence were considered. The effects of hinge orientation, stiffness, damping and wing-tip weight on the static and dynamic response were investigated. It was found that significant reductions in both the static and dynamic loads were possible. For the case considered, a 25% increase in span using folding wing-tips resulted in almost no increase in loads.

Dynamic Behavior of Aircraft Wings Modeled as Doubly-Tapered Composite Thin-Walled Beams

1999 ◽  
Author(s):  
Sungsoo Na ◽  
Liviu Librescu
Keyword(s):  
Composite Materials ◽  
Free Vibration ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Transverse Shear ◽  
Dynamical Behavior ◽  
Time Dependent ◽  
Aircraft Wings ◽  
Helicopter Blades ◽  
Thin Walled

Abstract A study of the dynamical behavior of aircraft wings modeled as doubly-tapered thin-walled beams, made from advanced anisotropic composite materials, and incorporating a number of non-classical effects such as transverse shear, and warping inhibition is presented. The supplied numerical results illustrate the effects played by the taper ratio, anisotropy of constituent materials, transverse shear flexibility, and warping inhibition on free vibration and dynamic response to time-dependent external excitations. Although considered for aircraft wings, this analysis and results can be also applied to a large number of structures such as helicopter blades, robotic manipulator arms, space booms, tall cantilever chimneys, etc.

scholarly journals Modeling of Gust Energy Extractions through Aeroelastic Tailoring

2021 ◽  
Author(s):  
Michael Melville
Keyword(s):  
Interaction Model ◽  
Computational Time ◽  
Energy Extraction ◽  
Flexible Wings ◽  
Aeroelastic Tailoring ◽  
Aeroelastic Model ◽  
Tightly Coupled ◽  
Explicit Finite Difference ◽  
Energy Gains ◽  
Explicit Finite Difference Method

A tightly coupled fluid-structure interaction model is presented for studying the performance of flexible wings that encounter atmospheric gusts. The aerodynamic module uses a higher-order potential flow method, that provides numerical robustness and efficiency. The structural dynamics is modelled through an explicit finite difference method of the time-depenedent Euler-Bernoulli equations. Coupled together, these approaches offer numerical accuracy at a fraction of the computational time than is required for higher fidelity approaches. Previous research has suggested energy gains are possible from atmospheric gusts through aeroelastic tailoring. Case studies were performed using the aeroelastic model to investigate the merit of using aeroelastic tailoring as a passive means for performance improvement. Design trends were established that highlight configurations that achieve the best energy extraction from a gust. Reductions in wing drag of between 6.9% and 10.5% were observed, while gains of 0.25% between different aeroelastic configurations were presented. The forward sweeping of the elastic axis was deemed to have the greatest effect on energy extraction capabilities.

Effects of Impact on the Behavior of a Flexible Multiple Disk Clutch and Brake

1987 ◽  
Vol 109 (4) ◽  
pp. 416-421 ◽  
Author(s):  
Kosuke Nagaya
Keyword(s):  
Dynamic Response ◽  
Laplace Transform ◽  
Dynamic Behavior ◽  
Circular Plate ◽  
Static Load ◽  
Equation Of Motion ◽  
Dynamic Loads ◽  
The Laplace Transform ◽  
The Impact

This paper discusses the dynamic behavior of a flexible multiple disk clutch subjected to dynamic loads. The expressions for obtaining the dynamic response and the transmission torque of the clutch have been derived from the equation of motion of a circular plate by applying the Laplace transform procedure. The results for the clutch subjected to a static load have also been obtained. The comparison between both static and dynamic results has been made to clarify the effect of the impact of the load on the behavior of the clutch.

scholarly journals Modeling of Gust Energy Extractions through Aeroelastic Tailoring

2021 ◽  
Author(s):  
Michael Melville
Keyword(s):  
Interaction Model ◽  
Computational Time ◽  
Energy Extraction ◽  
Flexible Wings ◽  
Aeroelastic Tailoring ◽  
Aeroelastic Model ◽  
Tightly Coupled ◽  
Explicit Finite Difference ◽  
Energy Gains ◽  
Explicit Finite Difference Method

A tightly coupled fluid-structure interaction model is presented for studying the performance of flexible wings that encounter atmospheric gusts. The aerodynamic module uses a higher-order potential flow method, that provides numerical robustness and efficiency. The structural dynamics is modelled through an explicit finite difference method of the time-depenedent Euler-Bernoulli equations. Coupled together, these approaches offer numerical accuracy at a fraction of the computational time than is required for higher fidelity approaches. Previous research has suggested energy gains are possible from atmospheric gusts through aeroelastic tailoring. Case studies were performed using the aeroelastic model to investigate the merit of using aeroelastic tailoring as a passive means for performance improvement. Design trends were established that highlight configurations that achieve the best energy extraction from a gust. Reductions in wing drag of between 6.9% and 10.5% were observed, while gains of 0.25% between different aeroelastic configurations were presented. The forward sweeping of the elastic axis was deemed to have the greatest effect on energy extraction capabilities.

scholarly journals Dynamic Behavior of a Railway Wheelset on a Roller Rig versus Tangent Track

2004 ◽  
Vol 11 (3-4) ◽  
pp. 467-492 ◽  
Author(s):  
N. Bosso ◽  
A. Gugliotta ◽  
A. Somà
Keyword(s):  
Numerical Simulation ◽  
Dynamic Behavior ◽  
Experimental Analysis ◽  
Test Bench ◽  
Contact Point ◽  
Full Scale ◽  
Analytical Results ◽  
Roller Rig

This paper addresses the comparison of dynamic behavior of a wheelset on roller and on rails. The development of equations of kinematics and motion allow to put in evidence the intrinsic differences between the dynamic behavior on rail and on roller. The stylized conical profile approximation of the wheel allows to focus the attention on the differences in creepages definition and in contact point shift due to the roller curvature. The treatise is addressed to a full scale roller and can be extended in the case of scaled roller rig to be applied in the case of the test bench developed for experimental analysis. In the present paper numerical simulation and examples are used to proof the analytical results.

Design of Fixed Offshore Platforms to Dynamic Ship Impact Loads

1992 ◽  
Vol 114 (3) ◽  
pp. 146-153 ◽  
Author(s):  
M. J. Sterndorff ◽  
J. Waegter ◽  
C. Eilersen
Keyword(s):  
Dynamic Behavior ◽  
Superposition Principle ◽  
Hydrodynamic Pressure ◽  
Dynamic Loads ◽  
Mode Shapes ◽  
Offshore Platforms ◽  
Detailed Calculation ◽  
Pull Out ◽  
Realistic Description ◽  
The Impact

A ship impact is a dynamic phenomenon and the dynamic global load effects can be significant, especially for small platforms where dynamic loads from the ship impact can be larger than the extreme environmental loads and the ship impact can govern the design of the platform. This paper describes a detailed procedure for dynamic analysis of fixed offshore platforms exposed to ship impacts. The procedure includes: • a consistent description of the motion of the vessel and dynamic interaction with the platform during the impact; • a realistic description of the global dynamic behavior of the platform during the impact; • detailed calculation of the transient hydrodynamic pressure forces acting on the vessel during the impact; and • a realistic description of the local deformation zone at the point of impact. The equations of motion for the vessel and the platform are solved simultaneously in the time domain, and the overall dynamic loads acting on the platform during the impact are determined by means of the modal superposition principle. The procedure has been applied for the design and subsequent risk analysis of three small tripod tower-type platforms to impacts from drifting supply vessels. The effect of the number of mode shapes used for representation of the dynamic behavior of the platforms, and the influence of the transient hydrodynamic pressure forces have been investigated. Critical velocity tables for different impact situations have been developed. For nearly all the situations investigated, the critical collapse criterion was overturning of the platform due to pull-out of piles in tension.

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