Periodicities Changes of Nonlinear Oscillatory Behavior of a Fluttering Plate With Periodicity Ratio and Periodicity Change Rate

2013 ◽  
Author(s):  
Liming Dai ◽  
Lu Han
Keyword(s):  
High Velocity ◽  
Nonlinear Dynamic ◽  
Air Flow ◽  
Oscillatory Behavior ◽  
Dynamic Responses ◽  
Change Rate ◽  
System Parameters ◽  
Research Show

This study focuses on diagnosing the periodicity change of nonlinear dynamic responses of a fluttering plate excited by high-velocity air flow. The number and changing multiple-periodicities of the system with the implementation of Periodicity Ratio (PR) are investigated. The multiple-periodicity diagram is generated such that the periodicities and nonlinearity of the systems with respect to the system parameters can be graphically studied. The results of the research show that the number of period of periodicity of the systems increases when certain system parameters increase. Transitional characteristics of the systems are also investigated with Periodicity Change Rate as well.

scholarly journals Nonlinear Dynamic Analysis for Rectangular FGM Plates with Variable Thickness Subjected to Mechanical Load

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Khuc Van Phu ◽  
Le Xuan Doan ◽  
Nguyen Van Thanh
Keyword(s):  
Variable Thickness ◽  
Nonlinear Dynamic ◽  
Volume Fraction ◽  
Mechanical Load ◽  
Plate Theory ◽  
Geometrical Nonlinearity ◽  
Nonlinear Dynamic Analysis ◽  
Dynamic Responses ◽  
Rectangular Plates ◽  
Classical Plate Theory

 In this paper, the governing equations of rectangular plates with variable thickness subjected to mechanical load are established by using the classical plate theory, the geometrical nonlinearity in von Karman-Donnell sense. Solutions of the problem are derived according to Galerkin method. Nonlinear dynamic responses, critical dynamic loads are obtained by using Runge-Kutta method and the Budiansky–Roth criterion. Effect of volume-fraction index k and some geometric factors are considered and presented in numerical results.

scholarly journals Rattle dynamics of noncircular face gear under multifrequency parametric excitation

2021 ◽  
Vol 12 (1) ◽  
pp. 361-373
Author(s):  
Dawei Liu ◽  
Zhenzhen Lv ◽  
Guohao Zhao
Keyword(s):  
Dynamic Model ◽  
Parametric Excitation ◽  
Nonlinear Dynamic ◽  
Velocity Ratio ◽  
Harmonic Balance Method ◽  
Transmission Error ◽  
Dynamic Responses ◽  
Discrete Fourier Transformation ◽  
Nonlinear Dynamic Model ◽  
Face Gear

Abstract. A noncircular face gear (NFG) conjugated with a pinion is a new type of face gear which can transmit variable velocity ratio and in which two time-varying excitations exist, namely the meshing stiffness excitation and instantaneous center excitation. Considering the tooth backlash, static transmission error and multifrequency parametric excitation, a nonlinear dynamic model of the NFG pair is presented. Based on the harmonic balance method and discrete Fourier transformation, a semi-analytic approach for the nonlinear dynamic model is given to analyze the dynamic behaviors of the NFG. Results demonstrate that, with increase in the eccentric ratio, input velocity and error amplitude, the NFG will undergo a non-rattle, unilateral rattle and bilateral rattle state in succession, and a jump phenomenon will appear in the dynamic responses when the rattle state of the gears is transformed from unilateral rattle to bilateral rattle.

Blade Damage Forecast Research Based on Support Vector Machine

2012 ◽  
Vol 588-589 ◽  
pp. 278-282
Author(s):  
Zhi Wei Ma ◽  
Yu Xiu Xu ◽  
Shi Rong Xing
Keyword(s):  
Support Vector Machine ◽  
Strain Energy ◽  
Energy Change ◽  
Mode Shapes ◽  
Support Vector ◽  
Change Rate ◽  
Wind Turbine System ◽  
Mass Eccentricity ◽  
Damage States ◽  
Research Show

By doing modal analysis of the whole wind turbine system, we can get the first twenty orders natural frequencies and corresponding mode shapes, By analyzing the dynamic characteristics of the blade, the weakness points of blade were fund. Under rotor rotating excitation in the normal state, mass eccentricity states and stiffness damage states of blade, the strain energy change rates (SECR) of nacelle are obtained. While based on the SECR of nacelle, the methods of strain energy change rate and support vector machine are introduced to indentify locate the mass eccentricity and stiffness damages of blade. The research show that mass eccentricity and stiffness damages at different location and in different degree can be efficiency identified and forecasted by means of support vector machine classification method.

Nonlinear dynamic responses of a rigid rotor supported by active bump-type foil bearings

2020 ◽  
Vol 100 (3) ◽  
pp. 2241-2264
Author(s):  
Han-Qing Guan ◽  
Kai Feng ◽  
Ke Yu ◽  
Yuan-Long Cao ◽  
Yi-Hua Wu
Keyword(s):  
Nonlinear Dynamic ◽  
Dynamic Responses ◽  
Rigid Rotor ◽  
Foil Bearings

scholarly journals Influence of Piezoelectric Performance on Nonlinear Dynamic Characteristics of MFC Shells

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Xiangying Guo ◽  
Pan Jiang ◽  
Dongxing Cao
Keyword(s):  
Electric Field ◽  
Nonlinear Dynamic ◽  
Piezoelectric Properties ◽  
Great Influence ◽  
Dynamic Responses ◽  
Aerodynamic Forces ◽  
External Excitation ◽  
Structural Dynamic ◽  
Laminated Shells ◽  
Laminated Shell

Based on the structures of unmanned aerial vehicle (UAV) wings, nonlinear dynamic analysis of macrofiber composite (MFC) laminated shells is presented in this paper. The effects of piezoelectric properties and aerodynamic forces on the dynamic stability of the MFC laminated shell are studied. Firstly, under the flow condition of ideal incompressible fluid, the thin airfoil theory is employed to calculate the effects of the mean camber line to obtain the circulation distribution of the wings in subsonic air flow. The steady aerodynamic lift on UAV wings is derived by using the Kutta–Joukowski lift theory. Then, considering the geometric nonlinearity and piezoelectric properties of the MFC material, the nonlinear dynamic model of the MFC laminated shell is established with Hamilton’s principles and the Galerkin method. Next, the effects of electric field, external excitation force, and nonlinear parameters on the stability of the system are studied under 1 : 1 internal resonance and the effects of material parameters on the natural frequency of the structure are also analyzed. Furthermore, the influence of the aerodynamic forces and electric field on the nonlinear dynamic responses of MFC laminated shells is discussed by numerical simulation. The results indicate that the electric field and external excitation have great influence on the structural dynamic responses.

Investigation of nonlinear landing gear behavior and dynamic responses on high performance aircraft

2019 ◽  
Vol 233 (15) ◽  
pp. 5674-5688
Author(s):  
PS Suresh ◽  
Niranjan K Sura ◽  
K Shankar
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
Landing Gear ◽  
Flight Mechanics ◽  
Dynamic Responses ◽  
Nonlinear Stiffness ◽  
Response Model ◽  
Nonlinear Dynamic Response ◽  
Vertical Descent ◽  
Stiffness And Damping

The dynamic responses simulation of aircraft as rigid body considering heave, pitch, and roll motions, coupled onto a tricycle landing gear arrangement is presented. Equation of motion for each landing gear consists of un-sprung mass vertical and longitudinal motions considering strut nonlinear stiffness and damping combined with strut bending flexibility. Initially, the nonlinear dynamic response model is subjected to an input of riding over staggered bump and the responses are compared with linear landing gear model. It is observed that aircraft dynamics and important landing gear events such as vertical, spin-up and spring-back are truly represented with nonlinear stiffness and damping model considering strut bending flexibility. Later, landing response analysis is performed, with the input from nonlinear flight mechanics model for several vertical descent rate cases. The aircraft and landing gear dynamic responses such as displacement, velocity, acceleration, and reaction forces are obtained. The vertical and longitudinal drag forces from the nonlinear dynamic response model is compared with “Book-case method” outlined in landing gear design technical specifications. From the reaction force ratio calculation, it is shown that for lower vertical descent rate case the predicted loads are lesser using nonlinear dynamic response model. The same model for higher vertical descent rate cases predicts higher ratios on vertical reaction for main landing gear and longitudinal reaction for nose landing gear, respectively. The scope for increase in fatigue life for low vertical descent rate landing covering major design spectrum and the concern for static strength and structural integrity consideration for higher vertical descent rate cases are discussed in the context of event monitoring on aircraft in services.

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