Probability of Helicopter Blade Flash Interception in Search Radar

The main goal of this study is the optimization of vibration reduction on helicopter blade by using macro fiber composite (MFC) actuator under pressure loading. Due to unsteady aerodynamic conditions, vibration occurs mainly on the rotor blade during forward flight and hover. High level of vibration effects fatigue life of components, flight envelope, pleasant for passengers and crew. In this study, the vibration reduction phenomenon on helicopter blade is investigated. 3D helicopter blade model is used to perform the aeroelastic behavior of a helicopter blade. Blade design is created by Spaceclaim and finite element analysis is conducted by ANSYS 19.0. Generated model are solved via Fluent by using two-way fluid-solid coupling analysis, then the analyzed results (all aerodynamic loads) are directly transferred to the structural model. Mechanical results (displacement etc.) are also handed over to the Fluent analysis by helping fluid-structure interaction interface. Modal and harmonic analysis are performed after FSI analysis. Shark 120 unmanned helicopter blade model is used with NACA 23012 airfoil. The baseline of the blade structure consists of D spar made of unidirectional Glass Fiber Reinforced Polymer +45°/−45° GFRP skin. MFC, which was developed by NASA’s Langley Research Center for the shaping of aerospace structures, is applied on both upper and lower surfaces of the blade to reduce the amplitude in the twist mode resonant frequency. D33 effect is important for elongation and to observe twist motion. To foresee the behavior of the MFC, thermo-elasticity analogy approach is applied to the model. Therefore, piezoelectric voltage actuation is applied as a temperature change on ANSYS. The thermal analogy is validated by using static behavior of cantilever beam with distributed induced strain actuators. Results for cantilever beam are compared to experimental results and ADINA code results existing in the literature. The effects of fiber orientation of MFC actuator and applied voltage on vibration reduction on helicopter blade are represented. The study shows that torsion mode determines the optimum placement of actuators. Fiber orientation of the MFC has few and limited influences on results. Additionally, the voltage applied on MFC has strong effects on the results and they must be selected according to applied model.

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Hybrid surrogate-model-based multi-fidelity efficient global optimization applied to helicopter blade design

Engineering Optimization ◽

10.1080/0305215x.2017.1367391 ◽

2017 ◽

Vol 50 (6) ◽

pp. 1016-1040 ◽

Cited By ~ 10

Author(s):

Atthaphon Ariyarit ◽

Masahiko Sugiura ◽

Yasutada Tanabe ◽

Masahiro Kanazaki

Keyword(s):

Global Optimization ◽

Surrogate Model ◽

Efficient Global Optimization ◽

Blade Design ◽

Helicopter Blade ◽

Model Based

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Modal Strain Energy Based Damage Detection Applied to a Full Scale Composite Helicopter Blade

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.569-570.457 ◽

2013 ◽

Vol 569-570 ◽

pp. 457-464 ◽

Cited By ~ 2

Author(s):

Fabio Luis Marques dos Santos ◽

Bart Peeters ◽

Herman van der Auweraer ◽

Luiz Carlos Sandoval Góes

Keyword(s):

Structural Health Monitoring ◽

Damage Detection ◽

Health Monitoring ◽

Rotor Blade ◽

Strain Energy ◽

Full Scale ◽

Experimental Results ◽

Main Rotor ◽

Helicopter Blade ◽

Main Rotor Blade

The use of composites in the aircraft industry has generated a great need for structural health monitoring and damage detection systems, to allow for safer use of complex materials. Such is the case with helicopter blades - these components nowadays are mostly composed of carbon fiber or glass fiber reinforced plastics laminates, epoxy and honeycomb filled core structures. The use of composite materials on the main rotor blade also allows for more complex and efficient shapes to be designed, but at the same time, their use requires an additional effort when it comes to structural monitoring, since damage can occur and go unnoticed. This work presents experimental results for structural health monitoring method based on strain energy. The test subject is a full-scale composite helicopter main rotor blade, which is a highly flexible, slender beam that can display unusual dynamic behavior with orthotropic behavior. This damage detection method is based on the modal strain properties, and a damage detection index is used to identify and quantify damage. A test setup was built to carry out an experimental modal analysis on the main rotor blade. For that purpose, a total of 55 uniaxial accelerometers were used on the helicopter blade to measure the displacement modes of the structure. To compute the strain modes from the displacement modes, central differences approximation is used. Damage is introduced on the blade by attaching a small mass to two different locations. Experimental results show the possibility of locating damage in this case.

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The Flutter of a Helicopter Rotor Blade in Forward Flight

Aeronautical Quarterly ◽

10.1017/s0001925900005217 ◽

1970 ◽

Vol 21 (1) ◽

pp. 18-48 ◽

Cited By ~ 7

Author(s):

C. W. Stammers

Keyword(s):

Equations Of Motion ◽

Approximate Solutions ◽

Speed Ratio ◽

Forward Speed ◽

Forward Flight ◽

Helicopter Blade ◽

Integer Multiple ◽

Tip Speed Ratio ◽

Half Integer ◽

Helicopter Rotor Blade

SummaryThe nature of flapping torsion flutter of a helicopter blade in forward flight is discussed. The essential complication in the analysis is the presence of periodic coefficients in the equations of motion; approximate solutions are obtained by use of a perturbation procedure. An unusual behaviour of the flutter equations which occurs when the fundamental frequency of flutter is a half-integer multiple of rotational speed is studied. Two different instability mechanisms can be distinguished and are related to the two energy sources in the system, namely the rotation of the rotor and the forward speed of the helicopter. It is found that forward flight can have a significant stabilising influence on flutter and that, as the tip speed ratio increases, flutter occurs predominantly at half-integer frequencies. The results are confirmed by the use of a numerical method.

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Effects of the actively morphing root chord and taper on helicopter energy

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-08-2019-0165 ◽

2019 ◽

Vol 92 (2) ◽

pp. 264-270

Author(s):

Firat Sal

Keyword(s):

Control System ◽

Energy Consumption ◽

Flight Control ◽

Design Methodology ◽

Chord Length ◽

Flight Control System ◽

Content Type ◽

Helicopter Blade ◽

Blade Root ◽

Practical Implications

Purpose The purpose of this paper presents the effects of actively morphing root chord and taper on the energy of the flight control system (i.e. FCS). Design/methodology/approach Via regarding previously mentioned purposes, sophisticated and realistic helicopter models are benefitted to examine the energy of the FCS. Findings Helicopters having actively morphing blade root chord length and blade taper consume less control energy than the ones having one of or any of passively morphing blade root chord length and blade taper. Practical implications Actively morphing blade root chord length and blade taper can be used for cheaper helicopter operations. Originality/value The main originality of this paper is applying active morphing strategy on helicopter blade root chord and blade taper. In this paper, it is also found that using active morphing strategy on helicopter blade root chord and blade taper reasons less energy consumption than using either passively morphing blade root chord length plus blade taper or not any. This causes also less fuel consumption and green environment.

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