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    2021,19(3):1-4, DOI: 10.6052/1672-6553-2021-042
    Abstract:
    The state of art of vehicle dynamics and control is surveyed in this special issue, being focused on longitudinal, lateral, and vertical dynamics, with recent hot topics like electric vehicles and intelligent network being also included. Vehicle longitudinal dynamics is devoted to vehicle transmission system shift control, brake system design & control, and vehicle state parameter estimation. Vehicle lateral dynamics focuses on vehicle steering system design and lateral stability control. Vehicle vertical dynamics deals with optimal design and semi-active/active control of suspension systems. The present special issue encompasses various different topics in vehicle dynamics and control, providing meaningful references for related future research.
    2021,19(3):5-14, DOI: 10.6052/1672-6553-2021-015
    Abstract:
    In order to improve handling stability of an in-wheel-drive electric vehicle, influences of the vehicle yaw rate and the sideslip angle on the vehicle stability are analyzed theoretically. A double-layer controller based on sliding mode control theory and direct yaw moment control is designed. A four-wheel-driven vehicle simulation experiment platform built in Carsim and Carsim / Simulink co-simulation is carried out. In standard lane-change condition, the improved effects of sliding mode control strategy based on sideslip angle and the control strategy based on yaw rate are verified and the effectiveness, confirming robustness of the two-layered stability control strategy proposed.
    2021,19(3):15-21, DOI: 10.6052/1672-6553-2021-004
    Abstract:
    For the active safety performance of heavy-duty vehicles, the dynamic performance of the hydraulic brake-by-wire for heavy-duty vehicle braking process is studied. The principle and working mode of the hydraulic brake-by-wire are analyzed and the key hydraulic components of the system are mathematically modeled. The hydraulic model of the hydraulic brake-by-wire system is established in the AMESim. The accumulator pressure maintaining control strategy and the wheel cylinder pressure following control strategy based on PID algorithm are designed. The control strategy is embedded in the electronic control unit and the HBW test bench is developed. Under typical braking conditions, the dynamic characteristics simulation and test verification of wheel cylinder pressure are carried out. The results show that the established hydraulic model is accurate, and the hydraulic brake-by-wire system is effective with quick dynamic response and high precision.
    2021,19(3):22-30, DOI: 10.6052/1672-6553-2021-005
    Abstract:
    In view of the power limitation and low speed output instability of BLDCM in EHPS system for medium and heavy vehicles, permanent magnet synchronous motor(PMSM) is used as the power motor of the system in this paper. Based on the structure principle and control strategy of EHPS system, a controller with STM32F103zet6 chip as its core is designed and manufactured. Hardware design includes MCU minimum system circuit, power supply circuit, signal acquisition circuit, power module circuit, CAN communication circuit, fault and high temperature alarm circuit, etc. In terms of control strategy, a vector control method with id=0 is used to control sensorless permanent magnet synchronous motor. In the aspect of software implementation, the control decision-making part, motor drive control part, fault diagnosis and transmission part are mainly designed. The design of power steering system mainly includes: resistance torque of in-situ steering, output torque of steering gear, pressure of steering system, working flow of steering pump and power of steering motor. Finally, the bench test and EHPS system test of the controller are carried out, and the control effect of the controller is tested. The control effect of the controller on the motor is tested in the bench test. The results show that the target speed of the motor responds quickly and the output is stable. The controller developed in this paper realizes the control of the permanent magnet synchronous booster motor. EHPS system test has tested the effect of the controller on the passenger car steering assistance. The EHPS system test results show that: when the self-developed EHPS system controller works, the torque of steering wheel control is significantly reduced, and the steering assistance system has good performances. With increasing vehicle speeds, the steering wheel power moment decreases, which realizes the dynamic change of powers, and meets the requirements of the bus conventional power mode.
    2021,19(3):31-37, DOI: 10.6052/1672-6553-2021-006
    Abstract:
    The electro-mechanical braking system of distributed driving multi-axis vehicles can apply the regenerative braking energy of its wheel motors to improve the vehicle’s braking performance. The deformation coordination model of suspension of the multi-axle vehicle is used to calculate the axial load transfer with different braking strengths, and the braking force distribution coefficient among the axles of the multi-axle vehicle is designed based on ECE regulations. A co-simulation model of electro-mechanical hybrid braking system is established which includes hysteresis characteristics of the air brake system. The rule-based braking control strategy is formulated to discuss the possible topological configuration of the electro-mechanical hybrid braking system. The braking performance of removing air brake component on some axes and the reduction of gas capacity is studied under the premise of ensuring the vehicle’s safety. Thus, the braking system of the vehicle can be simplified, and the available space of the vehicle chassis can be enlarged.
    2021,19(3):38-45, DOI: 10.6052/1672-6553-2021-007
    Abstract:
    The vehicle collision avoidance control system is a key active safety configuration. It can work correspondingly to ensure the driving safety when the vehicle encounters an emergency. In this paper, a hierarchical controller based on the fuzzy and PID algorithms is presented to simulate the vehicle emergency collision avoidance control. A detailed vehicle dynamic model and a driving safety distance model are used for the vehicle safety control. Afterwards, the co-simulation of longitudinal vehicle collision avoidance control with different initial speed conditions is performed. The simulation results show that the vehicle controller based on the fuzzy PID algorithm meets the collision avoidance requirements in a large range of vehicle speeds.
    2021,19(3):46-52, DOI: 10.6052/1672-6553-2021-008
    Abstract:
    The vehicle electronic stability program (ESP) is a critical active safety configuration. It can work correspondingly to ensure the driving stability when the vehicle corners with high speeds. It is necessary to compare and improve the stability control algorithm to evaluate and enhance the vehicle stability in different conditions. In this paper, traditional and fuzzy PID algorithms are presented to simulate the vehicle high speed cornering. A vehicle dynamic model built up Carsim is used for the vehicle stability control. The lateral displacement, vehicle side slip angle, yaw rate and lateral acceleration are selected as parameters for stability evaluations. Afterwards, the co-simulation of vehicle stability control in double shifting, sine and angle step conditions are performed. The simulation results show that the fuzzy PID algorithm based vehicle controller employing the fuzzy PID algorithm meets the stability requirements in different conditions.
    2021,19(3):53-59, DOI: 10.6052/1672-6553-2021-009
    Abstract:
    The torque reduction and torque recovery of the clutch-less AMT used in electric vehicles will cause torsional vibration of the transmission system. Improper torque reduction adjustment will also adversely affect subsequent shift control. In order to improve the shift quality, the dynamic mechanism and control method of the two stages of torque reduction and torque recovery in the shifting process are studied. A torsional vibration model of the transmission system and a synchronizer meshing gear model are established, with the excitation law of torsional vibration during the shifting process being analyzed, and the influence mechanism of the inadequate torque reduction effect on vehicle dynamics and damage to the actuator during the gear shifting process being revealed, A torque controller according to the characteristics of the second-order system and a virtual system based on the initial state assumptions of the system are designed, with and the system torsional vibration suppression and initial state estimation of the torque control process being realized. Finally, the torque reduction and torque recovery control effects simulation are completed. The research shows that the designed controller can configure the damping ratio of the system by adjusting the control rate coefficient to obtain different torque control characteristics. When the damping ratio coefficient is close to 1, it can effectively reduce the torsional vibration during the torque reduction phase and the torque recovery phase.
    2021,19(3):60-68, DOI: 10.6052/1672-6553-2021-010
    Abstract:
    The simulation of the contact relationship between the tire and road surface affects accuracy of the vehicle's suspension response and control.A three-dimensional pavement model is constructed using fractal theory. Based on the three-dimensional road surface model, a three-dimensional dynamic contact relationship between the tire and road surface is established.Aiming at the 1/4 vehicle suspension model, passive suspension, fuzzy PID control and ceiling damping control algorithms are established, respectively. The time and frequency domain responses of the vehicle suspension vertical acceleration, suspension dynamic deflection and tire force, built by employing the passive suspension and the two control algorithms, are compared under two contact conditions. The calculation results show that the fuzzy PID control algorithm is superior to the passive suspension and ceiling damping control algorithms in terms of vehicle ride comfort. When the vehicle takes into account three-dimensional contact between the tire and road, the peak values of body acceleration, suspension deflection, and tire force response under the surface contact conditions are lower than those under the point contact conditions.
    2021,19(3):69-73, DOI: 10.6052/1672-6553-2021-011
    Abstract:
    The steering knuckle is a key component to connect automobile steering system and suspension system, and the performance of steering knuckles affects the incidence rate of road traffic accidents directly. In this paper, in view of the shortcomings and deficiencies of the defect detection methods and technologies of automobile steering knuckle, a new defect detection method of automobile steering knuckle based on Lorentz force is proposed. The new method generates Lorentz force in steering knuckle by controlling electromagnetic signal coupling. Explicitly, Lorentz force excites ultrasonic signals by vibrating solid particles in the steering knuckle, and then the ultrasonic signals are reconstructed to detect the defect distribution in the steering knuckle. In this paper, the basic principle of Lorentz force detection and the process of generating Lorentz force by controlling electric and magnetic signals are studied,and the plane model of the detection method is analyzed and simulated. The results show that the current density distribution, Lorentz force distribution and Lorentz force dispersion distribution in the steering knuckle can reflect the conductivity distribution of the steering knuckle in the coupled imaging detection method with Lorentz force being the sound source. The research work provides a foundation for application of the new method, which is beneficial to development of new detection technologies and applications of new detection methods in the automotive safety inspection industry.
    2021,19(3):74-82, DOI: 10.6052/1672-6553-2021-012
    Abstract:
    A rigid flexible coupled dynamic model of a special vehicle is established with flexibility of the gun tube being considered. Coupling effects on the responses of gun tube are analyzed by comparison with the rigid body model. Then the limit height of the vehicle passing through the vertical boss obstacle road is calculated,and the driving dynamics of the rigid flexible coupled special vehicle under different obstacle conditions is investigated. Furthermore, the suspension system is optimized regarding the suspension stiffness and damping, with the vertical acceleration of the vehicle mass center being the optimization objective. The results indicate that, it is important for coupled modelling to take into account flexibility of gun tube for accurate prediction of vehicle responses, as notable effects on gun's vertical and horizontal displacements, velocities and angular velocity are induced by the flexibility of gun tube. Low vehicle speed and small obstacle height are beneficial to reducing vibration, and the gun tube vertically vibrates more seriously than the vehicle body in different driving conditions. Also, impacts on the vehicle can be reduced for obstacle crossing with single-sided wheel, while vehicle stability can be improved and gun tube's vibration can be weakened for obstacle crossing with two-sided wheels. After optimization of the suspension system, vertical accelerations of both the vehicle and gun tube are notably reduced with the ride comfort being improved.
    2021,19(3):83-88, DOI: 10.6052/1672-6553-2021-013
    Abstract:
    Vehicle mass and road slope are important parameters of active safety control system. This paper presents a serial estimation algorithm for vehicle mass and road slope. The vehicle mass and road slope are estimated in a hierarchical and serial manner according to changing speed. The slowly varying vehicle mass is taken as the estimated output of the first layer, and the rapidly varying road slope is taken as the estimated output of the second layer. The estimation algorithm is based on longitudinal dynamics. Firstly, the vehicle mass of the first layer is estimated through recursive least squares (RLS) algorithm based on tire driving moment and angular velocity, and then the estimated vehicle mass is substituted into the second-layer Newton iteration method for road slope estimation. Compared with the traditional adaptive estimation method, the proposed algorithm can reduce the coupling effect of real-time estimation parameters and does not require additional sensors. Finally, the algorithm is verified through simulation and electric control model vehicle road test, and the simulation and test results show that the proposed identification algorithm can accurately estimate vehicle mass and road slope in a real-time manner.
    2021,19(3):89-94, DOI: 10.6052/1672-6553-2021-014
    Abstract:
    Suspension, as a connection structure system among the body, frame and wheels, has a great effect on vehicle ride comfort, handling stability, and driving comfort. As the new active suspension system can improve driving comfort, prevent fatigue of the driver, and ensure vehicle control authority under extreme working conditions, a quarter active suspension model of in-wheel-drive electric vehicles is established. A sliding mode controller(SMC) of an electromagnetic actuator-based active suspension is also designed, in which stability of the system is proved using Lyapunov criterion and the chattering in SMC is reduced by adopting the reaching law method. Simulations on B-level road and bump excitations are implemented to verify the performance of the designed controller-based the active suspension system, regarding the vertical acceleration of the vehicle body, the suspension dynamic deflection, and the tire dynamic load. The results show that the SMC can reduce the impact on the vehicle body and significantly enhance the vehicle driving comfort and ride comfort.
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    2014,12(3):193-200, DOI: 10.6052/1672-6553-2014-046
    [Abstract] (1947) [HTML] (0) [PDF 748.46 K] (3611)
    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.
    2014,12(1):18-23, DOI: 10.6052/1672-6553-2013-068
    [Abstract] (1985) [HTML] (0) [PDF 1.13 M] (3537)
    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.
    2015,13(5):361-366, DOI: 10.6052/1672-6553-2014-064
    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.
    2017,15(5):385-405, DOI: 10.6052/1672-6553-2017-039
    [Abstract] (1059) [HTML] (0) [PDF 1.91 M] (3330)
    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.
    2014,12(3):243-247, DOI: 10.6052/1672-6553-2014-054
    [Abstract] (1729) [HTML] (0) [PDF 1.07 M] (3299)
    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.
    2014,12(3):269-273, DOI: 10.6052/1672-6553-2014-043
    [Abstract] (2336) [HTML] (0) [PDF 336.30 K] (3122)
    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.
    2014,12(3):225-229, DOI: 10.6052/1672-6553-2014-051
    [Abstract] (1473) [HTML] (0) [PDF 1.38 M] (3076)
    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.
    2012,10(1):21-26, DOI:
    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.
    2008,6(4):301-306, DOI:
    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.
    2016,14(2):97-108, DOI: 10.6052/1672-6553-2015-009
    [Abstract] (1267) [HTML] (0) [PDF 1.87 M] (2651)
    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.
    2013,11(4):357-362, DOI: 10.6052/1672-6553-2013-041
    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.
    2013,11(1):12-19, DOI: 10.6052/1672-6553-2013-003
    [Abstract] (1367) [HTML] (0) [PDF 530.95 K] (2541)
    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.
    2014,12(3):253-258, DOI: 10.6052/1672-6553-2014-056
    [Abstract] (1398) [HTML] (0) [PDF 1.00 M] (2445)
    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.
    2014,12(2):183-187, DOI: 10.6052/1672-6553-2014-025
    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.
    2014,12(3):283-288, DOI: 10.6052/1672-6553-2014-061
    [Abstract] (1875) [HTML] (0) [PDF 479.50 K] (2404)
    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.
    2016,14(3):247-252, DOI: 10.6052/1672-6553-2015-052
    [Abstract] (1140) [HTML] (0) [PDF 2.18 M] (2400)
    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.
    2014,12(1):36-43, DOI: 10.6052/1672-6553-2013-110
    [Abstract] (1160) [HTML] (0) [PDF 2.22 M] (2379)
    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.
    2014,12(3):205-209, DOI: 10.6052/1672-6553-2014-059
    [Abstract] (1539) [HTML] (0) [PDF 467.15 K] (2334)
    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.
    2014,12(3):201-204, DOI: 10.6052/1672-6553-2014-048
    [Abstract] (1616) [HTML] (0) [PDF 296.79 K] (2301)
    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.
    2014,12(1):62-66, DOI: 10.6052/1672-6553-2013-097
    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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