Dynamics of Vibroprotective Systems with Roller Dampers of Low-Frequency Vibrations

We study low-frequency vibrations of a vibroprotective system of solid bodies formed by a roller damper and a moving load-carrying body under the action of external harmonic excitations. The dynamic equations of combined motion of the working body of the damper over the hinged roller without sliding and the load-carrying body are deduced and numerically analyzed. A new procedure is proposed for the evaluation of the optimal parameters of adjustment of roller dampers in nonlinear systems.     

基于吸振器控制的两自由度轧机辊系特性研究

考虑四辊轧机液压缸非线性弹簧力的影响因素,引入吸振器控制装置,建立带吸振器的两自由度轧机辊系模型,通过分析轧机耦合系统平衡点,得出增大吸振器的刚度系数能有效避免Hopf分岔和混沌动力学行为的产生;通过分析频谱曲线、时域曲线,得出吸振器装置可以增大谐振频率与主共振频率之间的距离,缩短轧机辊系从不稳定状态收敛于稳定周期的时间;通过幅频特性曲线,得出在一定范围内减小吸振器的质量可以提高系统的稳定性,增大吸振器弹簧力可以缩小系统不稳定区域,增大吸振器摩擦力可以降低系统的振动幅值。     

Determination of the amplitude-frequency characteristic of a vibroprotective system with two-mass pendulum damper in the linear statement

We study the dynamic behavior of a vibroprotective system with a two-mass pendulum damper. By using the Ritz averaging method, we deduce the equations for the amplitude-frequency characteristics of this system in the linear statement. A numerical method for the evaluation of the damper adjusted parameters is proposed. Translated from Problemy Prochnosti, No. 6, pp. 100–109, November–December, 2008.     

Analytic Determination of the Amplitude-Frequency Characteristic of a Nonlinear Vibroprotective System with Roller Damper

We consider the dynamic behavior of a nonlinear vibroprotective system with roller damper of low-frequency oscillations. By using the Ritz averaging method, we deduce the equation of the amplitude-frequency characteristic of the nonlinear system. A new graphic method is proposed for the determination of the parameters of adjustment of the roller damper.__________Translated from Problemy Prochnosti, No. 2, pp. 136 – 150, March – April, 2005.     

一类高阶中立型偏微分方程系统解的振动性

本文获得了一类中立型偏微分方程系统解振动的若干充分条件。     

一类非线性脉冲中立型时滞抛物方程组的振动准则

本文研究一类非线性脉冲中立型时滞抛物方程组的振动性,利用一阶脉冲中立型微分不等式,获得了该类方程组在两类不同边界条件下所有解振动的若干充分条件。所得结果充分反映了脉冲和时滞在振动中的影响作用。     

板式膜反转降膜吸收器设计与性能研究

板式膜反转降膜吸收器是一种将板式降膜吸收和膜反转技术相结合而开发的新型吸收器,合理设计与掌握其吸收性能对今后这种吸收器的工程应用十分重要.为此,通过建立、求解板式膜反转降膜吸收过程的数学模型,确立了设计条件下最佳吸收器结构;对于所设计的板式膜反转吸收器进行了不同吸收压力、溶液流量、进口浓度、进口温度及冷却条件下传热传质性能的计算,并与竖板降膜吸收器进行了比较.     

一类非线性多时滞脉冲抛物型方程解的振动性质

本文研究一类非线性多时滞脉冲抛物型方程在齐次Dirichlet和Neumann边界条件下解的振动性质.利用分析技巧,给出一个脉冲微分不等式无最终正解(或最终负解)的条件.然后,利用平均法,将该方程解振动性问题转化为相应脉冲时滞微分不等式有无最终正解(或最终负解)问题,进而在两类齐次边界条件下获得了判别该类方程解振动的充...     

带限位倒摆的实验与数值研究

设计研制一个带限位的倒摆实验系统,建立 该系统的力学模型,通过实验与数值分析的研究,讨论周期与随机激励情况下的各种响应,证实所建立模型的正确性,揭示该系统存在复杂的非线性动力学行为,并指出噪声对系统非线性动力学行为的影响。研究结果将为带有间隙结构的设计和间隙结构动力学分析提供参考。     

Oscillation behavior of a high-temperature silicon droplet by the electromagnetic levitation technique superimposed with a static magnetic field

When a static magnetic field was applied to a Si droplet levitated by an electromagnetic force, only one peak was observed to remain in the frequency spectrum. It was the objective of this work to clarify whether this peak can be assigned to the m = ± 2 oscillation or to the rotation of the droplet. By analyzing the behavior of the deflection angle of the droplet in a top view, we conclude that this peak is not due to the surface oscillation of the droplet but to the droplet rotation.     

时间尺度上具有次线性中立项的三阶 Emden-Fowler 时滞动力方程的振动性

判定时间尺度上时滞动力方程的振动性和渐近性在数学物理、自动控制理论及工程、传染病模型分析和桥梁设计等诸多领域具有重要作用。针对时间尺度上具有次线性中立项的三阶 Emden-Fowler 时滞动力方程的振动性和渐近性开展研究,利用时间尺度上的微积分理论,广义 Riccati 变换和不等式技巧,获得了该方程两个振动定理,改进和推广了已有文献的相应结果,并给出了两个实例验证了新定理的有效性。     

高速振荡脉冲射流振荡腔内涡旋—碰撞壁相互作用的模拟分析与实验

本文利用离散涡旋模型模拟了振荡腔内涡旋与碰撞壁的相互作用,讨论了三种碰撞壁的保角变换。通过数值计算得出了锥形碰撞壁对自激振荡压力影响最大和椭圆形碰撞壁影响较低的结论,并进行了间接的对比实验验证。实验结果与理论分析相一致。     

Dynamics analysis of distributed parameter system subjected to a moving oscillator with random mass, velocity and acceleration

The problem of calculating the response of a distributed parameter system excited by a moving oscillator with random mass, velocity and acceleration is investigated. The system response is a stochastic process although its characteristics are assumed to be deterministic. In this paper, the distributed parameter system is assumed as a beam with Bernoulli–Euler type analytical behaviour. By adopting the Galerkin's method, a set of approximate governing equations of motion possessing time-dependent uncertain coefficients and forcing function is obtained. The statistical characteristics of the deflection of the beam are computed by using an improved perturbation approach with respect to mean value. The method, useful to gathering the stochastic structural effects due to the oscillator–beam interaction, is simple and leads to results very close to Monte Carlo simulation for a wide interval of variation of the uncertainties.     

开孔结构内压传递方程的孔口特征参数识别

对开孔结构内压传递方程的孔口特征参数识别进行理论和实验研究。基于通用双参数内压传递方程,探讨了在正弦波激励下考虑非线性阻尼的孔口特征参数提取方法,并采用时程计算方法对参数提取的精度进行了详细分析,设计并制作了专用的实验装置用于孔口特征参数提取。研究结果表明,基于正弦波激励的孔口特征参数提取方法在共振峰附近的提取精度较为可靠,而发生共振反应是保证孔口参数提取精度的前提。