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    BEHAVIOR DECISION-MAKING MODEL BASED ON BASAL GANGLIA MECHANISM
    Song Jian, Liu Shenquan, Zang Jie
    2020,18(6):1-31, DOI: 10.6052/1672-6553-2020-051
    [Abstract] (49) [HTML] (5) [PDF 5.65 M] (66)
    Abstract:
    Basal ganglia are a series of neurological nuclei in deep brain， which are mainly connected with the surrounding cerebral cortex， thalamus， cerebellum and brainstem. The main function of basal ganglia is to participate in motor regulation and random motion control， especially in decision-making and action selection of behavior. This paper mainly introduced the behavioral decision-making model based on the mechanism of basal ganglia， and focused on the progress of theoretical models of decision-making and action selection. Firstly， the anatomical structure of basal ganglia， composed of input nucleus， output nucleus， dopamine system and relay nucleus， were introduced， and then the functional connections of basal ganglia （direct pathway， indirect pathway and hyper-direct pathway） were described. Secondly， the theoretical progress of decision models in motion and action selection based on the interaction between multiple cortical-BG circuits in the basal ganglia was summarized， including Gurney’s select-control model， Humphries’ neuron population model， Frank’s cognitive decision model， Wang’s choice decision model and Rabinovich's phase space dynamics decision model. Finally， the relationship between these theoretical decision models and brain diseases （e.g. Parkinson's disease） was discussed.
    BIFURCATION OF A CLASS OF GEOMETRICALLY NONLINEAR DRY-FRICTION OSCILLATORS
    Zeng Chao, Xie Jianhua
    2020,18(6):32-37, DOI: 10.6052/1672-6553-2020-042
    [Abstract] (40) [HTML] (1) [PDF 900.48 K] (96)
    Abstract:
    The dynamic behaviors of a geometrically nonlinear oscillator with dry friction were studied by the event-driven method. Firstly， the geometrically nonlinear dry-friction oscillation system was modeled as a Filippov system. Then， the algorithm based on the event-driven method was introduced to solve the Filippov system with discrete vector field， which could accurately detect the entry and exit of the sliding motion area. Two different kinds of Poincare cross section were used to reveal the transformation process between different types of periodic motions with sliding process as parameters change. Finally， different types of sliding bifurcation and periodic doubling bifurcation were studied， and the existence of multiple sliding segments in the doubling process was found.
    STOCHASTIC STABILITY OF A TWO DEGREES-OF-FREEDOM SYSTEM UNDER COMBINED HARMONIC AND GAUSSIAN WHITE NOISE EXCITATION
    Hu Dongliang, Huang Yong
    2020,18(6):38-48, DOI: 10.6052/1672-6553-2020-040
    [Abstract] (25) [HTML] (1) [PDF 1.15 M] (64)
    Abstract:
    The stochastic stability of a two degrees-of-freedom system under combined harmonic and Gaussian white noise excitation were investigated. Firstly， the non-autonomous system was transformed into an autonomous system by increasing the dimension. Secondly， using both singular perturbation and double Fourier series， the approximate analytical solutions of the moment Lyapunov exponents and the largest Lyapunov exponents were obtained， which agree well with the results obtained by the Monte Carlo simulation. Finally， based on the moment Lyapunov exponents and the largest Lyapunov exponents， the effects of subharmonic resonance and combination additive resonance on the stochastic stability of the two degrees-of-freedom system were discussed.
    SINGLE DEGREE AND TWO DEGREES OF FREEDOM VORTEX-INDUCED VIBRATION OF CIRCULAR CYLINDER
    Cao Xing, Liu Yufei, Yu Heng, Kong Xiangxin, Li Qingling
    2020,18(6):49-56, DOI: 10.6052/1672-6555-2020-049
    [Abstract] (16) [HTML] (0) [PDF 2.01 M] (41)
    Abstract:
    A numerical investigation on vibration characteristics of flow around a circular cylinder was carried out. This study focused on mechanic properties， such as amplitude and spectrum， of vortex-induced vibration with both single degree of freedom （DOF） and two DOFs， and the applicable conditions of these two models were also discussed. Results indicate that for single DOF vortex-induced vibration， with the increment of reduced velocity， the time-average value of drag coefficient increases firstly and then decreases， whereas the amplitude of lift coefficient trends to increase at first， then decrease， and then increase again. Moreover， both of them fluctuate when they enter or leave the locking interval. For two DOFs vortex-induced vibration， the dimensionless amplitudes of both the cross-flow and in-line vibration firstly increase and then decrease with the increase of Reynolds number. The in-line vibration cannot be neglected for low mass ratio， whereas it can be neglected for high mass ratio.
    EXPERIMENTAL RESEARCH ON THE MODES OF DISC BRAKE SYSTEM
    Sui Xin, Ding Qian
    2020,18(6):57-66, DOI: 10.6052/1672-6555-2020-034
    [Abstract] (20) [HTML] (0) [PDF 2.63 M] (44)
    Abstract:
    Numerical simulation and experimental exploration to study the dynamic characteristics of the disc brake system， and the main content are shown in this paper. Partial results are verified by the experiment and finite element analysis. Disc’s modes with different pitch circles and pitch diameters are proposed. The orthogonal bending modes and torsional modes are proposed. Frequencies of the pad-on-disc coupled system are tested and responses are attained by dynamic experiments.
    DYNAMIC ANALYSIS AND CONTROL OF COMPOSITE PLATES IN SUPERSONIC AIRFLOW
    Zhou Kai, Ni Zhen, Huang Xiuchang, Hua Hongxing
    2020,18(6):67-76, DOI: 10.6052/1672-6553-2020-080
    [Abstract] (6) [HTML] (1) [PDF 5.02 M] (43)
    Abstract:
    The plate structures are the basic elements in the flight vehicle， and they are exposed in severe environment during the cruise with aerodynamic， thermal and mechanical loads acted on them. In this paper， the first order deformation plate theory and supersonic piston theory were employed to formulate the energy functionals of the composite plate in supersonic airflow. The governing equations of the system were obtained by using the Hamilton’s principle， and the dynamic responses of the plate were computed by adopting the Newmark method and Newton iteration method. The influence of key parameters on the dynamic behaviors of the composite plate was discussed. Finally， the vibration control of the plate was carried out by using the nonlinear energy sink， and the results showed that the dynamic responses can be suppressed by the nonlinear energy sink.
    A METHOD FOR IDENTIFYING NONLINEAR STIFFNESS OF HELICOPTER TAIL DRIVE SHAFT SYSTEM
    Zou Yachen, Wang ping, Ni De, Shan Weidong, Zang Chaoping, Zhang Genbei
    2020,18(6):77-83, DOI: 10.6052/1672-6555-2020-046
    [Abstract] (11) [HTML] (0) [PDF 1.41 M] (31)
    Abstract:
    A parameter identification method based on test data was proposed to evaluate the nonlinear stiffness of a tail drive shaft system. Firstly， modal testing on the tail drive shaft system under low-amplitude excitation was carried out， and a simplified dynamic model of the tail drive shaft system was established， which was verified by testing results. Then， the stepping sine sweep testing under different excitation levels was conducted， and the relationship between natural frequency and displacement amplitude was obtained based on the measured frequency response function. Moreover， the finite element iterative calculation of the simplified model was carried out to achieve the relationship between the natural frequency and the equivalent stiffness of the tail drive shaft system. Finally， the relationship between the equivalent stiffness and the displacement amplitude was established， and the nonlinear stiffness of the tail drive shaft system was identified.
    FINITE ELEMENT ANALYSIS AND EXPERIMENT ON VIBRATION OF Z-SHAPED MORPHING WING WITH VARIABLE SECTION
    Wang Songsong, Guo Xiangying, Wang Shuaibo
    2020,18(6):84-89, DOI: 10.6052/1672-6553-2020-047
    [Abstract] (10) [HTML] (2) [PDF 1.32 M] (37)
    Abstract:
    Z-shaped morphing wings with variable cross section is a kind of variant wing， and the folded angle has important influence on the dynamic stability of the wing. This paper studied the vibration characteristics of the Z-shaped morphing wing for different folded angles through both finite element analysis and experiment. Firstly， the experimental prototype of the Z-shaped folding wing was designed and fabricated. And then， a finite element model of the prototype was established， and simulations for different folding angles were conducted to obtain the first five natural frequencies and modes of the wing. Furthermore， frequency sweep tests on the prototype wing were carried out to obtain frequency responses under transverse excitations， and thus to reveal the first five natural frequencies and modes experimentally. Comparison between finite element simulations and experimental results showed good agreement， which verified the dynamic model of the Z-shaped morphing wing. This study would provide a reference for the design of morphing wing.
    OPTIMIZATION OF AERODYNAMIC NOISE FOR CLEANING SWEEPER’S DUST COLLECTOR
    Shan Baolai, Zhang Qichang, Zhang Pei, Liu Jun
    2020,18(6):90-100, DOI: 10.6052/1672-6553-2020-087
    [Abstract] (10) [HTML] (1) [PDF 1.41 M] (28)
    Abstract:
    Dust collector is the key component of the cleaning sweeper vehicle， so the product performance can be greatly improved by reducing the aerodynamic noise of the dust collector. Based on Fluent software and FW-H acoustic analogy model， the aerodynamic noise of dust collector was calculated. Firstly， a new kind of dust collector with shoulder structure and inclined wall was designed in this paper， and the comprehensive influence between shoulder angle and inclined angle of upper wall on the aerodynamic noise of the dust collector was mainly focused on. Based on MATLAB software， polynomial fitting was used to establish the function relations between dust collector’s total pressure and two parameters， and between total sound pressure level and two parameters， and then the objective functions were optimized by using multi-objective optimization genetic algorithm. The numerical results show that： the shoulder angle has a significant influence on aerodynamic noise， and between 0° and 20°， the noise can be reduced by 0.4dB for every one degree increase of the shoulder angle. Moreover， the aerodynamic noise of the dust collector can be reduced effectively by increasing the shoulder angle reasonably while reducing the energy loss of the dust collector， and the maximum reduction is 6.2dB.
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    Stochastic response surface based sensitivity analysis of uncertain parameters
    Fang Shengen, Zhang Qiuhu, Lin Youqin, Zhang Xiaohua
    2015,13(5):361-366, DOI: 10.6052/1672-6553-2014-064
    [Abstract] (485) [HTML] (0) [PDF 826.19 K] (3174)
    Abstract:
    Dynamic and control systems often contain uncertain parameters that may result in uncertain predictions. In the interest of quantifying the effects of parameter uncertainties on response variability, this paper develops a stochastic response surface based method for the sensitivity analysis of uncertain parameters. Stochastic response surfaces were firstly constructed to describe the explicit relationships between uncertain parameters and responses. Then partial derivations were performed on the mathematical expressions of stochastic response surfaces in order to obtain sensitivity indices that simultaneously embody the effects of parameter means and standard deviations. Lastly, the developed method has been verified against a numerical cantilever beam containing uncertain geometric and material parameters. The sensitivity analysis results were compared with those given by the analysis of variance method.
    Progress in spacecraft vibration testing control technology
    Ci Yongwei, Qiu Dalu, Fu Leping, Shao Xiaoping
    2014,12(3):193-200, DOI: 10.6052/1672-6553-2014-046
    [Abstract] (1903) [HTML] (0) [PDF 748.46 K] (3139)
    Abstract:
    The spacecraft's ability to adapt to the harsh dynamics environment is critical for the whole space mission. Vibration test control technology is the key part of the dynamic environment test. The current progress, fundamental principles and key techniques development level of the spacecraft and vibration control algorithms overseas were analyzed. The basic ideas, effective ways and suggestions were given to domestic following research.
    Nonlinear modeling and analysis of piezoelectic cantilever energy harvester
    Guo Kangkang, Cao Shuqian
    2014,12(1):18-23, DOI: 10.6052/1672-6553-2013-068
    [Abstract] (1936) [HTML] (0) [PDF 1.13 M] (3109)
    Abstract:
    The electromechanical coupling model of cantilevered piezoelectric harvester was developed by considering the nonlinearities of piezoelectric material, based on Hamilton theory, Rayleigh-Ritz method, Euler-Bernoulli beam theory and constant electrical field across the piezoelectric element. The response characteristics of the system were investigated numerically, and the influences of piezoelectric material nonlinear coefficient on the system response were analyzed. By exploring the nonlinear characteristics of the piezoelectric vibrator near the resonant frequency, the nature of the multi-solutions and jump phenomena in the resonance region was revealed. The results were verified experimentally. which provides a theoretical basis for the study of nonlinear mechanism of piezoelectric power generation system.
    Advances and challenges in dynamics of flexible multibody systems
    Tian Qiang, Liu Cheng, Li Pei, Hu Haiyan
    2017,15(5):385-405, DOI: 10.6052/1672-6553-2017-039
    [Abstract] (1004) [HTML] (0) [PDF 1.91 M] (2933)
    Abstract:
    In this review article, the growth and related academic communications in the dynamics of multibody systems are firstly surveyed. Then, the recent advances in the numerical algorithms for solving the dynamic equations of flexible multibody systems, the contact/impact dynamics of flexible multibody systems and the deployment of flexible space structures are systematically reviewed, together with several open problems of concern. Finally, some suggestions are made for the prospective researches on the dynamics of flexible multibody systems.
    Analysis in the windage of asd outside the frequency bandwidth in random vibration testing
    Qiu Dalu, Ci Yongwei, Shao Xiaoping, Fu Leping
    2014,12(3):243-247, DOI: 10.6052/1672-6553-2014-054
    [Abstract] (1665) [HTML] (0) [PDF 1.07 M] (2907)
    Abstract:
    Random vibration test is very important to the aerospace equipment. The windage of ASD outside the frequency bandwidth was analyzed. The reason, premonition, affection and effective way were given. And the commonly used random vibration test and vibration test metrology standard for the ASD outside the frequency bandwidth were analyzed.
    An automatic identification method for longitudinal modes of structural system of rocket
    Fang Bo, Tang Ye, Yang Feihu, Zhang Yewei, Zang Jian
    2014,12(3):269-273, DOI: 10.6052/1672-6553-2014-043
    [Abstract] (2293) [HTML] (0) [PDF 336.30 K] (2779)
    Abstract:
    Aiming at the problem that the longitudinal modes of structural system of rocket need to be identified from its integral modes in engineering, a method that automatically identifies the longitudinal modes of structural system of rocket was proposed according to the theory of modal effective mass. Taking the vibration characteristics of system with lumped mass as a computing example, applying the finite element software, the beam model of system with lumped mass was established, and the longitudinal modes of the system were automatically identified based on the method. Compared with the system modal information calculated by the method of modal analysis, this automatic identification method not only can accurately identify the longitudinal modes of vibrating system, but also has automatic and high efficiency identification feature. It provides a theoretical basis for the dynamic model of POGO vibrating system in liquid rockets and other model of engineering systems to be accurately and promptly established.
    Simulation of 'tail-slap' phenomenon of supercavitating projectiles with fluid/structure interaction
    He Qiankun, Wang Cong, Wei Yingjie
    2014,12(3):225-229, DOI: 10.6052/1672-6553-2014-051
    [Abstract] (1436) [HTML] (0) [PDF 1.38 M] (2679)
    Abstract:
    Based on the staggered solution procedure of ANSYS and CFX software, the fluid structure coupling response of projectile during tail slapping has been researched. Structural response was simulated by using FEM and flow field was simulated by using inhomogeneous model and SST turbulence model. Finally, the influences of fluid structure coupling effect have been analyzed and the change law of body stress has been given.
    Dynamics of tethered satellite system based on nonlinear unit model
    Liu Zhuangzhuang, BaoYin Hexi
    2012,10(1):21-26, DOI:
    [Abstract] (404) [HTML] (0) [PDF 567.09 K] (2619)
    Abstract:
    A discrete finite dimensional dynamical model was built to describe the space large overall motion of tethered satellite system with an infinite dimensional viscoelastic tether in a long time. The tethered satellite system is a complex nolinear dynamic system. Considering the tether’s viscoelasticity, distributed mass and space form, the established improved bead model can meticulously describe the tether’s vertical and horizontal vibration. According to tether’s characteristic of tensile and not compressive, the slack tether unit model was set up to accurately reflect real stress of tether. The determination of the number of degrees of freedom of the system was studied. Based on numerical integral calculation, the dynamic response was obtained via numerical simulation of the deployment, retrievement and retainment process of tethered satellite system in a long time. The result is convergent. The simulation proves the important role of the stable equilibrium position in the dynamics of tethered space system.
    Stable region of the feedback gainsin a controlled system with delayed feedback
    Wang Jingxiang, Wang Zaihua
    2008,6(4):301-306, DOI:
    [Abstract] (666) [HTML] (0) [PDF 0.00 Byte] (2554)
    Abstract:
    The problem of P and PI feedback control to a time delay system was investigated,with the emphasis on the determination of the feedback gains that ensured the asymptotical stability of the delayed system. By means of Lambert W function,the feedback gain of P control can be expressed explicitly,so that the optimal feedback gain can be easily obtained. For the system under a PI control,the stable region of the feedback gains was determined on the basis of stability switches and D subdivision,and the optimal feedback gains that enabled the system to admit maximal stable margin were figured out numerically by using Lambert W function. From the viewpoint of computation,the present method is much simpler than the available methods.
    An overview onmulti-agents cooperative control of unmanned ground system
    Wang Ronghao, Xing Jianchun, Wang Ping, Wang Chunming
    2016,14(2):97-108, DOI: 10.6052/1672-6553-2015-009
    [Abstract] (1204) [HTML] (0) [PDF 1.87 M] (2240)
    Abstract:
    Based on the current research status of multi agents system control theory and technology, the paper makes a detailed overview for unmanned ground systems. From two aspects of behaviour and task cooperative control for multi agents, the relevant theory and application problem is discussed. Moreover, some existed open problems are presented and a possible future development is proposed. For unmanned ground systems, cooperative control will be of great importance in promoting social and military benefits and maximizing the executive function of ground mission.
    Review and prospect on the research of aero-engine casing dynamics
    Wen Dengzhe, Chen Yushu
    2013,11(1):12-19, DOI: 10.6052/1672-6553-2013-003
    [Abstract] (1334) [HTML] (0) [PDF 530.95 K] (2187)
    Abstract:
    The dynamics of the whole aero-engine system has always been the important part that cannot be neglected in the research and design of the engine, as the framework of the engine, the vibration of the casing directly reflects the level of the whole aero engine vibration. In this paper, an analysis was made on the research of the problems and fault classification of aero-engine casing dynamics, and an overview was made on the research of present situation, development trend, problems and solutions of the domestic and foreign of casing dynamics, which expanded the present situation of the Inclusiveness problems of aero-engine casing dynamics. Finally, some proposals were put forward for the development of the casing dynamics suitable for our country aero-engine technology level.
    Study on deeoupled engine mounting system
    Li Zhiqiang, Chen Shuxun, Wei Qifeng
    2013,11(4):357-362, DOI: 10.6052/1672-6553-2013-041
    [Abstract] (521) [HTML] (0) [PDF 350.50 K] (2183)
    Abstract:
    At present, the main task of designing a mounting system of automotive engine powertrain is to select appropriate stiffness, position and angle of mounting components so that free-vibration modal frequency of the mounting system can avert from the exciting-force frequency at the idle speed of the engine and the natural frequency of vibration of the vehicle body and that the decoupling degree of each mode shape is increased as far as possible, so as to improve the vibration-isolation effect of the mounting system. The design of a mounting system based on strict decoupling at predetermined frequencies is to make the modal frequencies of the designed mounting system completely equal to the frequencies predetermined in accordance with the frequency planning of automotive design, and to enable strict decoupling of each mode shape of each mode, i.e., the decoupling degree of vibration energy in every direction equals to 1. Based on a free-vibration equation for a mounting system, this paper presents an equation system for designing a mounting system with strict decoupling at predetermined frequencies, provides a solving method for this equation system by using the theory of generalized inverse matrix or method of constructing function, so as to provide an optimal design method more efficient and simpler than the current modal optimization method of mounting system. Relevant example has validated the correctness of equations and solving method of the strict-decoupling design at predetermined frequencies.
    Reseach of the LuGre dynamic tire model based on ADAMS/MATLAB co-simulation
    Zheng Wengang, Lu Yongjie, Chen Enli, Li Shaohua
    2016,14(3):247-252, DOI: 10.6052/1672-6553-2015-052
    [Abstract] (1096) [HTML] (0) [PDF 2.18 M] (2129)
    Abstract:
    Tires are the only carrier of the contact between the vehicle and road surface. Their mechanical property is important for analysis and control on the vehicle dynamic response. At present, the tire simulation mostly focuses on the steady state model. But it can not describe the dynamic characteristic of the tire accurately. Therefore, it plays a significant role to add the dynamic tire model in the vehicle dynamics simulation. The tire friction model in the multi body dynamical software ADAMS is static, where the friction is regarded as a static value. However, in actual, the friction between the tire and road surface is dynamic, and it should be a dynamic function of the relative velocity and displacement. To this end, in this paper, the dynamic tire LuGre model using the Matlab/Simulink software is constructed. Through connecting the interface with Adams/Car, co simulation between the vehicle model and the simulink tire model is carried out in order to achieve the dynamic contact between tire and road and improve the accuracy of vehicle system analysis.
    Research on modeling and simulation of PMSM variable frequency speed regulating system
    Zhang Chen, Jin Tao
    2014,12(2):183-187, DOI: 10.6052/1672-6553-2014-025
    [Abstract] (856) [HTML] (0) [PDF 811.52 K] (2126)
    Abstract:
    PMSM due to little harmonic, high precision torque, commonly is used in the servo system and the high performance speed control system. In this paper,the physical model of PMSM is simplified and the mathematical model of the motor is established in order to facilitate research.Thispaper uses id=0 control manner which is the simplest manner is vector control methods,motor electromagnetic torque equation is established based on rotor field oriented vector control.The system model, speed and current control block are build and simulated with MATLAB/Simulink.Simulation results shows that the waveform is consistent with thoretical analysis,the model has fast response and small overshoot.The system runs stably with good dynamic and static characteristics. The simulation makes full use of modularization design. All the parameters and their influence on the system can be changed and observed.It also can easily validate the control strategies and select the most suitable one. So this kind of simulation is good for system design and adjusting and validating.
    Multi-objective topology optimization design method based on penalized density theory for aircraft lifting-surface
    Miao Xiaoting, Xu Quan, Liu Guang, Zhang Fenggang
    2014,12(3):253-258, DOI: 10.6052/1672-6553-2014-056
    [Abstract] (1383) [HTML] (0) [PDF 1.00 M] (2116)
    Abstract:
    Taking account of the structural stiffness and the low order vibration frequencies, two schemes of multi-objective topology optimization were proposed to obtain the best aircraft lifting-surface structural design. Based on penalized density theory, the scheme one (named as constrain method) is to convert the multi-objective optimization to single-objective optimization by considering the minimum structural mass as the objective with constraints of reference points displacements and the low order vibration frequencies. The scheme two (named as the combination of constrain method and criterion function method) settles the multi-objective optimization by defining combined compliance index (CCI) as the objective, with the constraints of volume fraction and the low order vibration frequencies. The CCI is the function of structural compliance and low order vibration frequencies. Numerical results demonstrate the proposed schemes not only realize reducing the structural mass but also raise the first and second order frequencies.
    Dynamic response calculation of a aero-engine's dual-rotor system
    Zhang Huan, Chen Yushu
    2014,12(1):36-43, DOI: 10.6052/1672-6553-2013-110
    [Abstract] (1128) [HTML] (0) [PDF 2.22 M] (2101)
    Abstract:
    The coupling nonlinear dynamic model of dual rotor system was established by using finite element method, and then the critical speed of revolution and mode shape were calculated by using the software MATLAB. In addition, the unbalance responses of dual rotor system were studied, and the vibration performances in different speeds of dual rotor casing systems were obtained. The research provides a theoretical basis for the design of the dual rotors system in engineering.
    A new method on flutter tailoring techniques of high-aspect-ratio wings
    Ren Zhiyi, Jin Haibo, Ding Yuliang
    2014,12(3):283-288, DOI: 10.6052/1672-6553-2014-061
    [Abstract] (1822) [HTML] (0) [PDF 479.50 K] (2037)
    Abstract:
    A method was presented to analyze the nonlinear flutter. Based on this method, the flutter characteristics of the high aspect wing were illustrated. The numerical results show that the flutter speed is decreased when the first horizontal bending mode involved. Secondly, this study discussed how the main direction of the composite influenced the character of the nonlinear vibration and flutter, and established the method of the flutter clipping to the high aspect wing. And the result shows that the stiffness of structure can be changed by changing the main direction of the composite. It mainly changes the horizontal bending mode, makes the main direction tend to the trailing edge, and then makes the section line move to the leading edge. Further analyzing the nonlinear flutter reveals that it is the changing of the horizontal bending mode that causes the flutter speed change obviously. And by the section line of this mode moves ahead, the flutter speed will become larger. In the study, two examples were illustrated to validate its truthiness.
    Space structure vibration control based on passive nonlinear energy sink
    Yang Kai, Zhang Yewei, Chen Liqun, Ding Hu, Zang Jian
    2014,12(3):205-209, DOI: 10.6052/1672-6553-2014-059
    [Abstract] (1497) [HTML] (0) [PDF 467.15 K] (2003)
    Abstract:
    This paper investigated the passive nonlinear vibration control method used for energy absorbing in structures of spacecrafts. The structure and the dynamic model of the nonlinear energy sink which could adapt to the space environment were proposed. As nonlinear spring could not be acquired easily in reality, we proposed a new design for the NES based on employing an asymmetric NES force which was generated by two pairs of aligned permanent magnets. Then, the dynamic model for a cantilever beam structure coupled with nonlinear energy sink had been built theoretically. In addition, the passive vibration suppression effect of the nonlinear energy sink on the cantilever beam structure under transient excitation had been analyzed through Galerkin method and numerical analysis method. The results showed that the NES acquired up to 92% dissipation of the system energy imposed by shock excitation, hence the NES could adapt to the space environment and improve the reliability of space system.
    Flutter analysis of 2-d aircraft wings in supersonic flow
    Ye xin, Chen Yushu
    2014,12(3):201-204, DOI: 10.6052/1672-6553-2014-048
    [Abstract] (1581) [HTML] (0) [PDF 296.79 K] (1973)
    Abstract:
    Non-linear factors cannot be avoided in the design of aircraft structures. In this paper, a two-degree-of-freedom airfoil and cubic stiffness nonlinearities in pitching degree-of-freedom operating in supersonic flight speed regimes has been analyzed. The averaging method and the theory of flutter were used to analyze the nonlinear dynamic system of the dualistic airfoil in the supersonic flow. Then the correctness of the theoretical calculation was verified by numerical calculation, and the analysis result was given.
    Spline finite point method for analyzing the effect of dead loads on natural frequencies of arch
    Kang Ting, Xu Jinyu, Bai Yingsheng, Sun Huixiang, Li Qing
    2014,12(1):62-66, DOI: 10.6052/1672-6553-2013-097
    [Abstract] (805) [HTML] (0) [PDF 832.87 K] (1972)
    Abstract:
    A spline finite point method was presented to study the natural frequency of arch. The displacement mode shape function of the arch free vibration was simulated with a linear combination of cubic B spline. The free vibration frequency equation of arch structures was derived according to Hamilton principle, in which the effect of the dead load was considered. Meanwhile, the effect of the dead load on the natural frequency of arch structures was analyzed. The results show that the natural frequency of arch is reduced. The effect of influence depends on the stiffness of the arch itself. When the arch stiffness is certain, the bigger the rise span ration and the radius to thickness ration, the higher the effect of the dead load on the natural frequency of arch structures.

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