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Triple Composite Gradient Representation and Stability Analysis of Non Autonomous Generalized Birkhoff Systems
Chen Kemu, Xie Yu
2026,24(1):1-11, DOI: 10.6052/1672-6553-2025-067
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Abstract:
This paper proposes a novel stability criterion for non autonomous generalized Birkhoff systems based on triple combined gradient system framework. Firstly, the differential equations and fundamental properties of four distinct gradient systems and their corresponding triple combined gradient systems are systematically discussed. Secondly, for the governing differential equations of non autonomous generalized Birkhoff systems, a representation method based on matrix combinations is proposed, establishing four different forms of triple combined gradient representations. On this basis, the Lyapunov function can be directly derived from the corresponding triple combined gradient representation equations via given matrix combinations, thereby simplifying the stability determination process. Compared with existing methods, the proposed approach significantly reduces the difficulty associated with constructing Lyapunov functions, providing an effective tool for studying the stability of non autonomous generalized Birkhoff systems. Finally, the validity and accuracy of the proposed method are verified through stability analysis and numerical simulations of representative examples.
Improved Definite Integral Method for Directly Calculating Modal Frequencies of Multiple Time Delayed Systems
Sun Gaoyuan, Xu Qi, Li Yinghui
2026,24(1):12-19, DOI: 10.6052/1672-6553-2025-065
[Abstract] (0) [HTML] (0) [PDF 680.01 K] (0)
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The eigenvalues of a time delay system are infinite, and exhibit complex distributions. The classical definite integral method is an effective approach for analyzing the stability of multi time delay systems. However, it cannot directly solve the modal frequencies, i.e., the imaginary parts of the eigenvalues of the system, and instead requires first determining the real parts and then applying additional techniques, such as two dimensional Newton iteration to solve the modal frequencies. For most stable systems, modal frequency is often of greater concern, and indirect determination introduces unnecessary steps and increases computational complexity. Therefore, this article extends the definite integral method by using a new integration path and a new characteristic root translation direction, which can directly solve the modal frequency of time delay systems, while retaining the advantages of the classical definite integral method, such as being suitable for multi time delay systems, simple programming, and high efficiency. The paper verifies the wide applicability and the effectiveness of the proposed method for calculating the modal frequencies of time delay systems through two engineering examples.
Dynamic Analysis of the Error Model for Gyro Accelerometers under Base Angular Motion Conditions
Jin Yanfei, Shi Chongji, Jing Zheng, Cheng Xiuyan, Meng Jingwei
2026,24(1):20-31, DOI: 10.6052/1672-6553-2025-077
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Abstract:
Inertial navigation systems often operate in complex mechanical environments. Under conditions of high speed motion or severe vibration, the output of accelerometers can be affected by the base angular velocity, leading to measurement errors. Therefore, this paper investigates the formation mechanism and dynamic characteristics of the output error of the Pendulous Integrating Gyroscopic Accelerometer (PIGA) under base angular motion. First, starting from the dynamic modeling of the PIGA, a comprehensive error model incorporating the combined effects of linear acceleration, angular velocity, and angular acceleration is established. Then, based on the simultaneous consideration of three axis angular velocity and angular acceleration inputs, the error expression of the PIGA is derived. The generation mechanism, magnitude, and coupling relationship with system parameters of error terms related to angular motion are analyzed, revealing the key error components that significantly impact output accuracy and require compensation. Finally, based on the dynamic simulation model, the influence of base angular motion inputs on the dynamic response of the PIGA output is studied. The results show that under different combinations of angular velocity and angular acceleration inputs, the error characteristics of the PIGA output exhibit significant differences. Therefore, the effect of dynamic base angular velocity on the PIGA output is substantial and should be addressed and compensated for in practical engineering applications.
Stability and Hopf Bifurcation Analysis of the Disc Brake System
Wang Guoyu, Zhang Wen, Wu Xin, Su Han, Yue Yuan
2026,24(1):32-40, DOI: 10.6052/1672-6553-2025-075
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Abstract:
Based on the smoothed Stribeck friction model, a nonlinear dynamic model of a two degree of freedom disc braking system was established. The stability of the equilibrium points was analyzed using the Routh Hurwitz criterion, and the influence of different parameters on the stability of the braking system was discussed. The Hopf bifurcation point was obtained using the Hurwitz criterion, and the first Lyapunov coefficient at the bifurcation point was calculated by introducing the projection method to determine the type of Hopf bifurcation. The theoretical analysis results were verified through numerical simulations. The study shows that when the angular velocity of the brake disc is low, the system remains stable; whereas when the angular velocity is high, increasing the attenuation factor or reducing the dynamic friction coefficient can significantly improve the stability. As the braking force increases and the angular velocity decreases, the unstable region of the system also expands; moreover a reasonable design of the stiffness ratio between the brake disc and the brake pad can optimize the stability of the system. In addition, the system undergoes subcritical Hopf bifurcation under critical parameters, whereby the stability of the equilibrium point changes, an unstable limit cycle is generated, and self excited vibration is triggered.
Dynamic Research on an Integrated Vibration Suppression and Energy Harvesting Device for Galloping Systems with Piezoelectric Absorbers
Yue Haoyang, Lu Yuxi, Li Haitao, Wei Zhouchao, Song Ni
2026,24(1):41-54, DOI: 10.6052/1672-6553-2025-079
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This study investigates a galloping system integrated with a series of piezoelectric dynamic vibration absorbers (PDVAs), achieving the dual functions of vibration suppression and energy harvesting. The incremental harmonic balance method (IHBM) is employed to derive the periodic solutions of the galloping suppression system equipped with different vibration absorbers, and the results are validated through numerical simulations. Comparative analyses of wind speed displacement curves, wind speed voltage characteristics, phase portraits, and time history responses demonstrate excellent agreement between the IHBM and numerical solutions. Notably, under identical computational conditions, the IHBM exhibits significantly higher computational efficiency than numerical methods, providing a more efficient analytical approach for the analysis of galloping systems. Furthermore, parametric studies are conducted to evaluate the influence of PDVA parameters including mass, stiffness,and damping on both the primary system’s vibration suppression performance and the output voltage. The comparative assessment elucidates the effects of these parameters on vibration mitigation, thereby guiding the optimal design of absorbers through appropriate parameter selection.
Reconstruction Method of Solar Wing Displacement Field under Rigid Flexible Coupled Response
Hu Benang, Lai Wangjie, Huang Changyang, Lin Chenghui, Zhang Shunqi
2026,24(1):55-63, DOI: 10.6052/1672-6553-2025-073
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Abstract:
With the wide application of large flexible solar wings in new generation spacecraft, the demand for real time monitoring of the displacement field induced by rigid flexible coupling dynamics is becoming increasingly prominent. Aiming at the limitation that the existing displacement field reconstruction studies are mostly based on the static working conditions and are difficult to adapt to the complex dynamic excitation of the spacecraft, this paper proposes a dynamic displacement field reconstruction method based on the hybrid coordinate method and the assumed modal method. By analyzing the rigid flexible coupled spacecraft dynamics model, a high precision reconstruction algorithm for the global displacement field of the solar wing is constructed by combining the modal analysis techniques. The method can realize real time reconstruction of the dynamic displacement field under the coupling conditions of attitude maneuver and flexible vibration with only a small amount of sensing data. The results show that the proposed method can realize high precision reconstruction of the global displacement field of the solar wing under dynamic excitation.
Research on Passive Control of Fluid Conveying Pipe under Elastic Boundary
Luo Longhui, Ye Siqin, Yin Lairong
2026,24(1):64-74, DOI: 10.6052/1672-6553-2025-068
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Abstract:
As a critical fluid conveying component in mechanical structures, the stability and safety of fluid conveying pipes during operation are of particular importance. Taking a fluid conveying pipe as an example, this paper investigates the passive boundary control of the pipe by coupling an Inertial nonlinear energy sink at its elastic boundary. Firstly, the nonlinear control equations of a fluid conveying pipe with elastic supports coupled with an inertial-based nonlinear energy sink are derived using the generalized Hamilton’s principle. Subsequently, the natural frequencies and mode shapes of the fluid conveying pipe are obtained. Then, the control equations are discretized using the Galerkin truncation method, and the steady state response of the coupled system is solved through numerical simulation based on the Runge Kutta method. Finally, the influence of key parameters of the vibration absorber on the vibration reduction effect of the structure is discussed. The results indicate that the coupled inertial nonlinear energy sink exhibits effective vibration control for the fluid conveying pipe without altering its inherent dynamic characteristics. The parameters of the inertial based nonlinear energy sink have different effects on the vibration suppression performance: there exists an optimal damping coefficient, while increasing the inertance and the cubic nonlinearity enhances the vibration mitigation.
An Equivalent Mechanical Model for Aircraft Fuel Sloshing Based on Finite Element Mesh
Li Bin, Miao Nan, Yan Jiajun, Du Yahang, Wang Sen
2026,24(1):75-83, DOI: 10.6052/1672-6553-2025-070
[Abstract] (0) [HTML] (0) [PDF 1.65 M] (0)
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Fuel sloshing within aircraft fuel tanks can generate significant forces and moments on the tank walls, thereby affecting the aircraft’s dynamic characteristics. To enable accurate and efficient prediction of sloshing induced forces and moments, this study develops an equivalent pendulum mechanical model based on the finite element method. The study focuses on fuel within auxiliary and wing tanks at a 50% fill ratio. Using this model, the sloshing forces, moments, and the motion of the fuel’s center of mass are predicted under three typical flight conditions: pitch, roll, and yaw. The predicted results are further compared with those from computational fluid dynamics simulations, demonstrating the accuracy of the proposed model in capturing the dynamic response of fuel sloshing.
Research on the Modulating Effect of a Bistable Component on the Non reciprocity of Energy Transfer
Ding Tian, Chen Jian’en, Kong Na, Sun Min
2026,24(1):84-92, DOI: 10.6052/1672-6553-2025-064
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The non reciprocity of energy transfer, particularly strong non reciprocity, achieved within a wider range of excitation parameters, can enhance the performance of non reciprocal devices. The influences of bistable elements on the energy transfer mode and the modulation of non reciprocity are investigated. Initially, the dynamic equation for a system incorporating linear stiffness, cubic stiffness, and bistable components is derived. The semi analytical solutions for this system are obtained using the complexification averaging and least square methods. The numerical solutions are obtained via the Runge Kutta method. Then, the accuracy of the analysis procedure is confirmed through a comparison of semi analytical and numerical solutions. Building on this, the non reciprocal characteristics of the system under harmonic excitation and the effects of excitation amplitude are analyzed. The results show that regardless of the presence of the bistable component, the nonlinear system undergoes a transition from the reciprocal to a non reciprocal state and then back to the reciprocal state. However, the bistable component significantly alters the non reciprocal characteristics. Furthermore, it is found that an appropriate negative stiffness in the bistable system can effectively decrease the excitation amplitude threshold for activating the non reciprocal state.

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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] (3800) [HTML] (0) [PDF 336.30 K] (22025)
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.
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] (3594) [HTML] (0) [PDF 748.46 K] (19530)
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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.
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] (2343) [HTML] (0) [PDF 1.91 M] (19362)
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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.
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] (3411) [HTML] (0) [PDF 1.13 M] (18980)
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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.
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] (2837) [HTML] (0) [PDF 1.07 M] (18570)
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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 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] (2849) [HTML] (0) [PDF 1.87 M] (18408)
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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.
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] (1548) [HTML] (0) [PDF 826.19 K] (18234)
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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.
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] (2785) [HTML] (0) [PDF 1.38 M] (18155)
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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.
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] (2804) [HTML] (0) [PDF 530.95 K] (18029)
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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.
Stable region of the feedback gainsin a controlled system with delayed feedback
Wang Jingxiang, Wang Zaihua
2008,6(4):301-306, DOI:
[Abstract] (1553) [HTML] (0) [PDF 0.00 Byte] (17701)
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.
Dynamics of tethered satellite system based on nonlinear unit model
Liu Zhuangzhuang, BaoYin Hexi
2012,10(1):21-26, DOI:
[Abstract] (1112) [HTML] (0) [PDF 567.09 K] (17670)
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.
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] (1634) [HTML] (0) [PDF 811.52 K] (17397)
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.
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] (2400) [HTML] (0) [PDF 467.15 K] (14902)
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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.
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] (3469) [HTML] (0) [PDF 479.50 K] (14234)
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.
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] (1710) [HTML] (0) [PDF 350.50 K] (12277)
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] (2188) [HTML] (0) [PDF 2.18 M] (9523)
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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.
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] (2506) [HTML] (0) [PDF 2.22 M] (7969)
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.
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] (2379) [HTML] (0) [PDF 1.00 M] (6373)
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.
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] (2479) [HTML] (0) [PDF 296.79 K] (6073)
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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] (1935) [HTML] (0) [PDF 832.87 K] (5507)
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.