Helicopter flap/lag energy exchange study

Abstract

This is the accepted version of the paper.This version of the publication may differ from the final published version. Abstract This paper presents a study on the energy exchange taking place on articulated helicopter main rotor blades. The blades are hinged and the flap/lag modes are highly coupled. These dynamical couplings existing between the two degrees of freedom are clearly identifiable as the nonlinear terms that appear in the equations of motion, are key to understand the energy exchange process. The work here conducted is carried out using VehicleSim, a multibody software specialized in modelling mechanical systems composed by rigid bodies. A spring pendulum system is also studied in order to examine its nonlinear behaviour, and to establish existing analogies with the rotor blade nonlinear dynamics. The nonlinear couplings of both systems are compared to each other, and commensurability condition is analysed by means of Short Time Fourier Transform (STFT) methods as well as the flap and lag amplitudes spectrum. Simulations are carried out and the obtained results show clear analogies in the energy exchange process taking place in both systems. The stability of these modes is also studied using Poincare' map method. Permanent repository link

Development of a method for computer simulation of a swinging spring load movement path

“…Study of features of the swinging spring oscillations is of interest for practical applications. For example, study of atmospheric balance of the planet is carried out with the help of a swinging spring model in [4], carbon dioxide molecule oscillation is studied in [5], oscillation of high-voltage wires is considered in [6] and helicopter vibration is modeled in [7]. Description of spring oscillation is similar to equations from "predator-prey" problems [8].…”

“…To set up a system of differential Lagrange equations of the second kind, use relation (7). As a result, the system of Lagrange equations of the second kind is obtained in this form: Solve the system of equations (8) with initial conditions u(0)=0; du(0)=1; v(0)=2; dv(0)=0 using numerical Runge-Kutta method.…”

Resonant Passive Energy Balancing of Morphing Helicopter Blades with Bend-Twist Coupling

“…Inducing control on flexible aerostructures helps to optimize the aerodynamic loads and reduce the energy consumption in different flight conditions [2,3]. In addition, energy exchange between different motions of rotor aerostructures such as flapping, lagging, and pitching is a property that have received attention for controlling such structures ([4]- [6]). The shape-adapting capability of morphing aircraft gives the ability of controlling the performance of aerostructures.…”

Geometric Modeling of the Trajectory Cargo Swinging Spring With Movable Suspension

“…Наприклад, з використанням моделі хитної пружини досліджується атмосферний баланс планети, коливання молекули вуглекислого газу, коливання високовольтних проводів, моделюються вібрації гелікоптера. Список можна продовжувати [3][4][5][6][7]. У цих, на перший погляд, розрізнених впровадженнях є спільна особливість -можливість їх дослідження на основі моделі хитної пружини.…”

“…Аналіз останніх досліджень. В роботах [1][2][3][4][5][6][7] наведено переважно теоретичні результати. Для інженерної практики необхідні способи побудови реальних нехаотичних періодичних траєкторій вантажів хитних пружин.…”