具有振动边界自激系统的混沌行为

鉴于初轧机轧制过程中振动的非线性和边界可动,本文建立了轧机轧制过程中主传动系统的扭转自激振动模型,通过对所建模的研究表明,该系统具有多种非线性振动模式,且在近共振区出现了混沌行为,这为分析,诊断及控制这一具有混沌行为为系统的振动提供了理论依据。     

消除初轧机系统自激振动的理论分析

在研究初轧机因打滑等因素产生自激振动时,本文考虑了连接轴转动的影响;从而提出一个新的力学模型,建立了具有运动边界问题的微分方程,得到消除自激振动的条件．     

强非线性自激振动问题的瞬态解

用新的改进的L-P法并结合权残法求得了一般情况下(阻尼项可以不是小量)强非线性自激振动问题的一级近似瞬态解。近似解有很好的精度。     

充液旋转壳的流固耦联自激振动

本文根据实验拟事出流固耦联系统的非一函数和模态参数。建立了此系统的非线性振地系统的数值和解析分析，论证了充液旋转壳的流固耦联自激振动特性，求出了流固耦联系统的霍普分叉解，阐明了只结文物鱼洗的振动机理。本文结论对同类自激振动的研究具有重要的参考价值     

平面滑移铰内发生自激振动的充分条件

自激振动是含摩擦机械系统最严重也最具破坏性的运动形式. 目前, 通常以增加润滑的方式 尽可能减少自激振动. 本文以平面滑移铰为研究对象, 假设铰连接的物体为刚体, 并且认为 铰内的间隙为小量, 推导了平面滑移铰内产生不符合物理事实解的条件. 这可看作是导致系 统产生自激振动的一种诱因. 该条件适用于任何含平面滑移铰的机械系统.     

摩擦自激振动引起摩擦面波状磨耗的试验研究

在销-盘摩擦磨损试验机上进行金属干摩擦试验,研究摩擦自激振动对盘试件磨痕表面轮廓的影响,采用激光位移传感器测量盘试件摩擦表面轮廓尺寸,用加速度传感器测量销试件的摩擦自激振动.试验结果表明：在干摩擦状态下,销-盘系统容易发生持续的摩擦自激振动,当摩擦时间达到一定数值后,盘试件的磨痕表面轮廓会出现明显的波浪形磨耗,波浪形磨损机理主要是疲劳磨损.分析表明波浪形磨耗的波长近似等于摩擦自激振动的周期与滑动速度的乘积,由此推断摩擦自激振动引起了摩擦表面的波浪形磨耗.     

多自由度分段光滑非线性系统的近似解——-中华文物龙洗的自激振动

建立了由干摩擦引起的两个弹性体之间自激振动的数学模型. 利用平均法 求出了由干摩擦引起的多自由度分段光滑非线性动力系统的近似解析解，分析了搓动速度、 振动频率与振幅的关系曲线，相位角与搓动速度的关系曲线，分析结果与数值解基本吻合. 为研究多自由度分段光滑非线性系统提供了一种有效的近似解析分析方法.     

消除初轧机系统自激振动的理论分析

 在研究初轧机因打滑等因素产生自激振动时,本文考虑了连接轴转动的影响;从而提出一个新的力学模型,建立了具有运动边界问题的微分方程,得到消除自激振动的条件．     

曾逐东风拂舞筵------再谈自激振动

叙述自激振动的产生机理,以及日常生活和工程技术中存在的各种自激振动.     

多自由度分段光滑非线性系统的近似解——中华文物龙洗的自激振动

建立了由于摩擦引起的两个弹性体之间自激振动的数学模型.利用平均法求出了由干摩擦引起的多自由度分段光滑非线性动力系统的近似解析解,分析了搓动速度、振动频率与振幅的关系曲线,相位角与搓动速度的关系曲线,分析结果与数值解基本吻合.为研究多自由度分段光滑非线性系统提供了一种有效的近似解析分析方法.     

再谈荡秋千——兼谈自激振动

通过荡秋千运动解释自激振动的特征,叙述其在航天技术中的应用。附录中应用相平面方法作定性分析。关键词 秋千, 绳系卫星, 自激振动, 相平面法     

Non-linear control of friction-induced self-excited vibration

The present paper introduces a new method of controlling friction-driven self-excited vibration. The control law is primarily derived using the Lyapunov's second method. A single degree-of-freedom oscillator on a moving belt represents the primary model of the system. The control action is achieved by modulating the normal load at the frictional interface based on the state of the oscillatory system. The basic mechanism of the control action utilises subcritical Hopf bifurcation of the equilibrium followed by cyclic-fold bifurcation (of limit cycle oscillations) to globally stabilise the equilibrium. The basic mechanism is qualitatively independent of the exact model of friction. Different models of friction, like, algebraic model, LuGre model and switch model with time-dependent static friction are considered to substantiate the above claim. An approximate method for estimating the critical value of the control parameter that ensures global stability of the equilibrium is also proposed.     

Wind tunnel experiments on unstable self-excited vibration of sectional girders

In this paper, a wind tunnel analysis of two degrees-of-freedom system represented by sectional girders is carried out. Besides an evaluation of the aeroelastic coefficients, the analysis is focused on the influence of the natural frequency ratio on the initiation of unstable vibration, which can be of practical interest. On the phenomenological level, the paper also discusses experimentally ascertained response regimes, with an emphasis on their stability character. The attention is paid to the memory effect in the response described by the hysteresis loop together with the separation curves determining the stability boundaries. The influence of initial disturbance on the stability is examined. Two types of cross-sections were investigated: (i) rectangular one with the aspect ratio 1:5, and (ii) bridge-like cross-section with comparable principal dimensions. For both types of cross-sections, the limits of the stability are significantly affected by an intentionally introduced initial disturbance. This holds especially with regard to the rectangular profile where the separation curves create very narrow sub-domains between a stable and an unstable response, while the bridge-like cross-section demonstrates much stable behaviour.     

Approximate analytical solution of the self-excited vibration of piecewise-smooth systems induced by dry friction —The vibration mechanism of the Chinese cultural relic Dragon Washbasin

Based on our previous work, a mathematical model of piecewise-smooth systems is established by means of phase-plane orbit analysis, and it is then used to study the intersting phenomena of Chinese cultural relic Dragon Washbasin. The mechanism of nonlinear damping is analyzed; the approximate analytical solution of self-excited vibration of piecewise-smooth nonlinear systems induced by dry friction is derived by means of KB Method, the results of which agree well with that of the numerical solution. Therefore, the method presented in this paper is proved to be very efficient in analyzing the self-excited vibration of piecewise-smooth systems induced by dry friction.     

The effect of parametric excitation on a self-excited three-mass system

This contribution deals with the quenching of self-excited vibrations by means of parametric excitation due to periodic variation of spring stiffness. A three-mass chain system is investigated in detail. It is shown that the self-excitation can be fully or partly suppressed in a particular frequency interval.