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- Crises in Chaotic Pendulum with Fuzzy Uncertainty
pp.215–221 | DOI: 10.5890/JAND.2015.09.001
Ling Hong, Jun Jiang, Jian-Qiao Sun
Abstract |
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Abstract
Crises in chaotic pendulum in the presence of fuzzy uncertainty are
observed by means of the fuzzy generalized cell mapping method.
A fuzzy chaotic attractor is characterized by its topology and membership
distribution function. A fuzzy crisis implies a simultaneous
sudden change both in the topology of a fuzzy chaotic attractor and
in its membership distribution. It happens when a fuzzy chaotic attractor
collides with a regular or a chaotic saddle. Two types of fuzzy
crises are specified, namely, boundary and interior crises. In the case
of a fuzzy boundary crisis, a fuzzy chaotic attractor disappears after
a collision with a regular saddle on the basin boundary. In the case
of a fuzzy interior crisis, a fuzzy chaotic attractor suddenly changes
in its size after a collision with a chaotic saddle in the basin interior.
- On a Class of Generalized Hydrodynamic Type Systems of Equations
pp. 223–228 | DOI: 10.5890/JAND.2015.09.002
V.E. Fedorov, P.N. Davydov
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Abstract
By means of the degenerate semigroups theory methods the local existence
of a unique solution is proved for initial-boundary value problems
to a class of partial differential equations systems of generalized
hydrodynamics type. General results are illustrated by examples of
a system with the nonlinear viscosity and a weighted system.
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- Influence of Systematic Coupling Stiffness Parameter on Coupling Duffing
System Lag Self-synchronization Characteristic
pp. 229–237 | DOI: 10.5890/JAND.2015.09.003
Zhao-Hui Ren1, Yu-Hang Xu1, Yan-Long Han2, Nan Zhang1, Bang-Chun Wen1
Abstract |
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Abstract
Self-synchronization, compound synchronization and intelligent control
synchronization widely exist in the mechanical system engineering,
while lag self-synchronization movement is a special form
of cooperation movement. Based on coupling Duffing system, this
paper studies lag self-synchronization problem, analyses general
change law of the system co-rotating synchronization frequency, antisynchronization
frequency and lag phase angle by analytic analysis
and numerical quantitative analysis, studies coupling parameter influences
on systematic lag self-synchronization, and analyses the cause
of lag self-synchronization. The results show that the root cause of lag
self-synchronization is systematic stiffness namely systematic natural
characteristic; that co-rotating synchronization vibration frequency
and phase difference depend on coupling stiffness parameter; and
that frequency and phase difference of anti-synchronization vibration
are independent of coupling stiffness parameter; and when coupling
stiffness parameter is larger, phase difference of two oscillators in the
two kinds of synchronization is nonzero constant value.
- Tribo-dynamics Analysis of Satellite-bone Multi-axis Linkage System
pp. 239–250 | DOI: 10.5890/JAND.2015.09.004
Jimin Xu1, Honglun Hong1, Xiaoyang Yuan1, Zhiming Zhao2
Abstract |
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Abstract
Friction torque is the most important factor that influences stability
and precision of multi-axis linkage system during low-speed running.
It is primarily related to shafting structure, external load, motion
state and other factors, and presents highly nonlinear characteristics.
In this paper, satellite-bone multi-axis linkage system in microgravity
environment is taken as the research object to focus on the coupling
tribo-dynamics issues of influencing system’s precision. The shafting
structural features of two degrees of freedom (2-DOF) vertical-axis
turntable, source of friction torque and coating antifriction technology
are studied. The corresponding tribo-dynamics model is established.
The model shows motion process of multi-axis linkage system is a
coupling process of tribology and dynamics. In order to eliminate
the effect of friction torque fluctuations, friction compensation based
on LuGre friction model is introduced. Then tracking precision of the
visual axis is about 40 (large movement range). For the imperfect
situations with friction compensation, local actuator is introduced
to combine with wide-range basic multi-axis system to realize the
accurate movement within small range. Then the tracking precision
of visual axis is expected to reach about 2 to 4 (small movement
rang).
- Stability and Bifurcation of a Nonlinear Aero-thermo-elastic Panel in Supersonic
Flow
pp. 251–257 | DOI: 10.5890/JAND.2015.09.005
Wei Kang1, Yang Tang1, Min Xu1, Jia-Zhong Zhang2
Abstract |
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Abstract
Stability and bifurcation of a nonlinear supersonic panel under
aerothermal loads are analyzed numerically in the present study. In
the structural model, von Karman’s large deformation theory is taken
into account for the geometric nonlinearity of the panel. In light
of Hamilton’s principle, the governing equation of motion of a twodimensional
aero-thermo-elastic panel is established. Coupling with
the panel vibration, aerodynamic pressure is evaluated by first order
supersonic piston theory and aerothermal load is approximated by
quasi-steady theory of thermal stress. By transforming the partial
differential equation to a series of ordinary differential equations via
Galerkin method, fixed points and their stabilities of the system are
studied using nonlinear dynamic theory. The complex dynamic responses
regions are discussed with temperature loads as a bifurcation
parameter. The results show that the thermal stress has a significant
influence in the stability of the panel. The panel system undergoes
Hopf bifurcation, period doubling, quasi-period and chaos with the
increase of the temperature.
- Nonlinear Effects of Dusty Plasmas using Homogenous Nonequilibrium Molecular
Dynamics Simulations
pp. 259–265 | DOI: 10.5890/JAND.2015.09.006
Aamir Shahzad1,2, Mao-Gang He1
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Abstract
Three-dimensional strongly coupled complex (dusty) plasma (SCCDP)
is modeled using homogenous nonequilibrium molecular dynamics
(HNEMD) simulations. The thermal conductivity (&lambda 0) and
the effects of external force field (F.) strength on the &lambda 0 of SCCDP are
calculated at higher screening strengths (&kappa ) from generalized Evan’s
algorithm. It has been shown that the presented investigations exhibit
a non-Newtonian effect that the &lambda 0(&Gamma) increases with increasing
force field strength that represents interaction contributions in
Yukawa conductivity. It is also verified that the results obtained with
different external force filed strengths are in satisfactory agreement
with earlier numerical results and with reference set of data showed
deviations within less than ± 10% for most of the present data point.
Our very recently computed thermal conductivity at lower &kappa is validated
by comparing the results of &lambda 0(&Gamma) at higher &kappa that also extended
the range of force field strength (0.001 &le F. &le 0.1) which explains the
nature of nonlinearity of SCCDP.
- The Adaptive Synchronization of the Stochastic Fractional-order Complex Lorenz
System
pp. 267–279 | DOI: 10.5890/JAND.2015.09.007
Xiaojun Liu, Ling Hong?
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Abstract
In this paper, the adaptive synchronization of a stochastic fractionalorder
complex Lorenz system is analyzed. Firstly, the Laguerre polynomial
approximation method is applied to investigate the fractionalorder
system with a random parameter which obeys an exponential
distribution. Based on this method, the stochastic system is reduced
into the equivalent deterministic one. Besides, based on the stability
theory of fractional-order systems, the adaptive synchronization for
the deterministic system with unknown parameters is realized by designing
appropriate synchronization controllers and estimation laws
for uncertain parameters. Numerical simulations are used to demonstrate
the effectiveness and feasibility of the proposed scheme.
- Nonlinear Dynamic Characteristic Analysis of Planetary Gear Transmission
System for the Wind Turbine
pp. 281–294 | DOI: 10.5890/JAND.20156.09.008
Zhao-Hui Ren1, Liang Fu1, Ying-Juan Liu2, Shi-Hua Zhou1, Bang-Chun Wen1
Abstract |
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Abstract
Foreign Object Debris (FOD) is debris or article alien, which may
A compared with the translational-torsional dynamic model of planetary
gear transmission system (PGTS) used in wind turbine is established
in order to analyze the dynamic characteristics of the PGTS
more accurately. The influences of the meshing stiffness, input and
output torques, meshing error, nonlinear characteristics of the support
bearing and gravity are considered in the model. Based on previous
model, the vibration differential equations of the drive-train
are obtained through the Lagrange’s equation. The dynamic response
characteristics are investigated using the Runge–Kutta numerical
method, and the factors of the above proposed excitation
are analyzed. The results show clearly that the vibration responses
have different characteristics due to the different speeds of each component
in the PGTS. The nonlinear behaviour of support bearing
causes the dynamic response more complicated In addition, under the
internal and external excitations, more frequency multiplication and
frequency combination components appear. The vibration frequency
components of the system are mainly concentrated in the frequency
range below 200Hz. The results of the study in this paper can provide
necessary theoretical basis for natural characteristics study, dynamic
response and optimization design method of the MW wind turbine
PGTS.
- Real-time 2D Concentration Measurement of CH4 in Oscillating Flames Using
CT Tunable Diode Laser Absorption Spectroscopy
pp. 295–303 | DOI: 10.5890/JAND.20156.09.009
Takahiro Kamimoto1, Yoshihiro Deguchi1, Ning Zhang1,2, Ryosuke Nakao1, Taku Takagi1,
Jia-Zhong Zhang2
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Abstract
Foreign Object Debris (FOD) is debris or article alien, which may
One of the major problems of gas turbine combustors is the combustion
oscillation. The combustion oscillation of gas turbines has many
complex causes such as pressure fluctuations, combustion instabilities,
and mechanical designs of the combustion chamber. Although
the significant research efforts have been dedicated to this topic, the
combustion oscillation problems have not yet been solved because
of its complexity and nonlinearity. In this study, the theoretical
and experimental research has been conducted in order to develop
the noncontact and fast response 2D CH4 distribution measurement
method to elucidate nonlinear combustion oscillation problems. The
method is based on a computed tomography (CT) method using tunable
diode laser absorption spectroscopy (TDLAS). The CT-TDLAS
method was applied to oscillating flames and the time resolved 2D
CH4 concentration distributions were successfully measured using 16
path CT-TDLAS measurement cell. CT-TDLAS has the kHz response
time and the method enables the real-time 2D species concentration
measurement to be applicable to the nonlinear phenomena of
combustion oscillation problems in gas turbines.
- Fluid-Structure Coupling Effects on the Aerodynamic Performance of Airfoil
with a Local Flexible Structure at Low Reynolds Number
pp. 305–312 | DOI: 10.5890/JAND.20156.09.010
Wei Kang1, Min Xu1, Jia-Zhong Zhang2
Abstract |
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Abstract
Foreign Object Debris (FOD) is debris or article alien, which may
A fluid structure interaction method for an airfoil with a local flexible
structure is presented for flow control of Micro Air Vehicles. An
improved ALE-CBS scheme is developed for unsteady viscous flow
coupling in combination with the theory of shallow arch with large
deformation. After the verification of the presented algorithm, the
method is used to study the interaction between flow and airfoil with
a local flexible structure with different elastic stiffness. The momentum
and energy exchange are investigated to reveal the unsteady coupling
effects on aerodynamic performance. The results show that the
coupling between fluid and structure enhances the momentum and
energy exchange from main flow into the boundary layer. It induces
the separation bubble moving downstream, and decreases the negative
pressure in the separation zone on the upper surface, which leads
to lift enhancement. The utilization of local flexible structure can be
considered as an effective flow control technique for enhancement of
the aerodynamic performance of Micro Air Vehicles.
- Modal Analyses of a Thin Shell with Constrained Layer Damping (CLD) Based
on Rayleigh-Ritz Method
pp. 313–327 | DOI: 10.5890/JAND.20156.09.011
Xu-Yuan Song, Hong-Jun Ren, Jing-Yu Zhai, Qing-Kai Han
Abstract |
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Abstract
Foreign Object Debris (FOD) is debris or article alien, which may
This paper presents analytical results of natural frequencies and
loss factors of node-diameter and node-circumferential modes of a
thin shell treated with constrained layer damping (CLD) based on
Rayleigh-Ritz method. General differential equations of motion of the
thin CLD shell are derived firstly by following the Donnell-Mushtari
shell theory. By taking the beam characteristic functions as the admissible
functions, the Rayleigh-Ritz method is employed to deduce
the higher degree equations of natural frequencies of the thin CLD
shell under different boundary conditions. It is confirmed that the
present method is accurate and convenient so that it is applicable to
the thin CLD shell compared with classic analytic method or transfer
matrix method. Several examples are achieved and compared to
illustrate the effects of the viscoelastic material (VEM) and constrain
layer’s thickness ratios on the natural frequencies and modal loss factors,
besides the effect of boundary conditions. The results show that
the thickness ratio of VEM affects sensitively the modal frequencies
and the total damping capacity of the thin CLD shell.
- The Method of High Order Fatigue Test of Thin Plate Composite Structure
With Hard Coating
pp. 329–337 | DOI: 10.5890/JAND.20156.09.012
Hui Li†, Wei Sun, Zhong Luo, Bengchun Wen
Abstract |
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Abstract
Foreign Object Debris (FOD) is debris or article alien, which may
In order to solve the high order fatigue test problem of thin plate
composite structure with hard coating, a new test method and its
technological process is proposed based on the summarizing the experience
of massive experiments. Besides, by considering technical
difficulties of the high order fatigue test of the hard coating composite
structure, several key techniques are described in details, such as
how to measure dynamic strain without damaging the hard coating,
how to predict excitation amplitude required by the high order fatigue
test, and how to avoid the interference resulted from the strain
softening of hard coating and to measure high order nature frequencies
accurately. Finally, an experimental test is done to verify the
practicability and reliability of this method.
