一类液固混合介质隔振系统的非线性动力学行为与设计方法研究

发布时间：2018-06-07 10:48

本文选题：隔振 + 液固混合介质　；参考：《南京航空航天大学》2014年博士论文

【摘要】：波纹管式液固混合介质隔振器是一类主要用于低频重载动力机械隔振的非线性隔振装置,由波纹管弹性单元体和油液工作介质混合密封于多层波纹管容器组成。目前,在隔振工程领域,低频重载隔振仍是研究难点与焦点问题之一,现有被动隔振技术主要在承载能力、低频隔振、疲劳寿命和气密性等方面存在诸多不足,无法满足日益严苛的隔振需求。波纹管式液固混合介质隔振器的提出可提升现有隔振技术的承载能力与低频隔振性能,在舰船、重型车辆、轨道交通的隔振与潜艇水声辐射的线谱隔离等方面颇具应用前景。波纹管式液固混合介质隔振器具有分段非线性的刚度特征,以这类隔振器为核心组成的隔振系统本质上属非光滑动力学系统,除具有传统光滑隔振系统的动力学特性外(如主共振幅值跳跃),还具备特有的非光滑动力学行为(如擦边失稳),因此其动力学行为的理论分析较为复杂;而在工程意义上,人们主要关心的问题是:如何利用这些非线性动力学行为来提升隔振性能,以及如何屏蔽不利动力学现象的影响。因此,本文以波纹管式混合介质隔振系统为对象,利用非线性动力学理论与方法研究其动力学行为与设计方法,并结合低频隔振与主动隔振开展相关动力学分析与设计工作。主要研究内容和学术贡献如下:1.建立波纹管式混合介质隔振器的弹性力学模型并导出其刚度特性。首先,基于曲梁和板壳模型两种弹性力学模型,分别推导了弹性单元体在外部油液压力与内部气体压力作用下的轴向变形规律;其次,考虑波纹管结构的几何非线性,基于圆环板的大挠度卡门方程与圆环壳的线性控制方程,通过参数摄动法推导了单元体在外部油液压力作用下的非线性刚度;最后基于单元体的压力刚度,推导了隔振器的轴向刚度特性。研究结果表明:液固混合介质隔振器具有分段线性-非线性的刚度特性,并得到了准静态试验验证,而单元体数量与波纹管结构参数可以有效地调整隔振器的刚度及其不连续点的位置。这部分研究内容为隔振器的刚度设计提供了理论依据。2.利用非光滑动力学理论研究波纹管式液固混合介质隔振系统的响应与稳定性。对于轨线与位移分界面横截情形,首先利用接缝法求解系统的单穿越周期n运动响应;继而基于定相位Poincaré截面,引入不连续映射建立横截轨道的频闪映射,随之基于分界面Poincaré截面及其辅助截面,分段构建了横截轨道邻域内的Poincaré映射并导出了其Jacobi矩阵。针对轨线与分界面擦边情形,类似地,通过引入不连续映射构造了周期轨道的Poincaré映射并导出了擦边分岔的规范型。这部分研究为隔振器的动力学设计提供了理论基础。3.研究波纹管式液固混合介质隔振器的非线性动力学设计方法。针对主共振幅值跳跃现象,首先利用奇异性理论对主共振幅频曲线的分岔进行了分类,发现幅值跳跃可由鞍结分岔或者非光滑诱导的擦边分岔所导致,而幅频曲线上的尖角为系统发生了擦边分岔的特征;进而依据频响曲线的拓扑特征给出了避免跳跃发生的参数设计方法,研究结果表明,增大单元体数量可避免分段非线性因素带来的跳跃冲击。针对隔振有效区内的倍周期分岔行为,通过周期轨道Poincaré映射的Jacobi矩阵的特征值分析给出了抑制倍周期分岔产生的参数条件,研究结果表明,增大系统阻尼可以有效抑制倍周期分岔的产生。4.研究柔性基础上波纹管液固混合介质隔振器的隔振性能,并提出提升其低频隔振性能的高静态低动态刚度隔振设计方案。针对运动轨线未穿过分界面的小振幅振动情形,实测了隔振器在柔性基础试验平台上的能量传递率,并通过实测振级落差分析了激振环境与隔振器参数对隔振性能的影响;在大振幅情况下,主要给出主共振区的隔振设计原则,并理论了分析隔振器参数对隔振性能的影响。最后,给出了一种悬置式波纹管液固混合介质隔振设计方案,该方案具备高静态低动态刚度特性。比对结果显示,悬置式隔振器可使显著提升低频隔振性能,若设计合理,甚至可实现小于2Hz的低频隔振。5.将主动隔振与波纹管式液固混合介质隔振技术结合,提出基于时滞立方非线性速度反馈的主动隔振方法。首先采用多尺度法对受控系统进行了主共振分析,考察了时滞对主共振响应及其稳定性的影响,发现在一定时滞范围内,立方非线性速度反馈不仅起到调节阻尼的作用,还可调节系统刚度;继而通过数值仿真讨论了反馈参数对隔振效果的影响,研究结果表明立方非线性速度反馈控制能够有效控制共振区的响应及改善隔振效果,同时不影响高频区的隔振;而后主要从系统稳定性角度给出了反馈参数的设计方法。
[Abstract]:Bellows type liquid solid mixed medium isolator is a class of nonlinear vibration isolation device mainly used for low frequency heavy load dynamic mechanical isolation. It is composed of bellows elastic element and oil liquid medium in multi-layer bellows container. At present, low frequency heavy load vibration isolation is still one of the difficult and focal problems in the field of vibration isolation engineering. Passive vibration isolation technology has many shortcomings in bearing capacity, low frequency vibration isolation, fatigue life and air tightness, which can not meet the increasing demand of vibration isolation. The proposed method of bellows type liquid solid mixture isolator can improve the bearing capacity and low frequency vibration isolation performance of existing vibration isolation technology, and be separated from ships, heavy vehicles, and rail traffic. The corrugated pipe type liquid solid mixed medium isolator has the characteristics of piecewise nonlinear stiffness. The vibration isolation system consisting of this type of isolator is essentially a non smooth dynamic system with the exception of the dynamic characteristics of the traditional smooth vibration isolation system (such as the main resonance amplitude, such as the main resonance amplitude. The theoretical analysis of its dynamic behavior is more complicated, and in engineering significance, the main concern is how to use these nonlinear dynamic behaviors to improve the vibration isolation performance and how to shield the effect of adverse dynamics. In this paper, the dynamic behavior and design method of the bellows type mixed medium vibration isolation system is studied by nonlinear dynamics theory and method, and the related dynamic analysis and design work is carried out in combination with low frequency vibration isolation and active vibration isolation. The main research contents and academic contributions are as follows: 1. the projectile of the bellows type mixed medium vibration isolator is established. The mechanical model and its stiffness characteristics are derived. First, based on two elastic mechanics models of curved beam and plate and shell model, the axial deformation law of the elastic element under the action of external oil pressure and internal gas pressure is derived respectively. Secondly, the geometric non linear of the bellows structure is considered, and the large deflection Carmen equation and the ring based on the circular plate are based on the circular plate. The linear control equation of the shell is used to derive the nonlinear stiffness of the element under the external oil pressure by the parameter perturbation method. Finally, based on the pressure stiffness of the element, the axial stiffness characteristics of the isolator are derived. The results show that the stiffness characteristic of the liquid solid medium isolator is linear to nonlinear, and the quasi-static is obtained. The state test proves that the number of elements and the structural parameters of the bellows can effectively adjust the stiffness of the isolator and the position of the discontinuous point. This part of the study provides a theoretical basis for the stiffness design of the isolator. The response and stability of the bellows type liquid solid mixed medium isolation system are studied by using the non smooth dynamics theory.2.. For the cross section of the rail line and displacement interface, first of all, the joint method is used to solve the N motion response of the single crossing period of the system. Then based on the fixed phase Poincar e section, the stroboscopic mapping of the cross section is established by the discontinuous mapping, and then the Poinc in the neighborhood of the cross section is subsection based on the interface Poincar section and the auxiliary section. Ar e maps and derives its Jacobi matrix. According to the boundary condition of the rail line and interface, the Poincar e mapping of periodic orbits is constructed by introducing discontinuous mappings and the standard type of edge bifurcation is derived. This part of the study provides a theoretical basis for the dynamic design of the isolator by.3. to study the vibration isolation of the bellows type liquid and solid medium. For the nonlinear dynamic design method of the device, the bifurcation of the main resonance amplitude frequency curve is classified according to the singularity theory. It is found that the amplitude jump can be caused by the saddle node bifurcation or the non smooth induced edge bifurcation, and the sharp angle on the amplitude frequency curve has the characteristics of the edge bifurcation of the system. According to the topological characteristics of the frequency response curve, a parameter design method to avoid jumping is given. The results show that the increase of the number of units can avoid the jump impact caused by the piecewise nonlinear factors. According to the characteristic value analysis of the Jacobi matrix of the periodic orbit Poincar e mapping, the behavior of the period doubling bifurcation in the effective isolation zone is given. The study results show that increasing system damping can effectively suppress the generation of multiple period bifurcations, and the vibration isolation performance of the bellows liquid solid mixed medium isolator on the.4. research flexible foundation is effectively suppressed, and a high static and low dynamic stiffness isolation design scheme is proposed to improve the low frequency vibration isolation performance. The energy transfer rate of the isolator on the flexible foundation test platform is measured without the small amplitude vibration on the interface, and the effect of the excitation environment and the isolator parameters on the vibration isolation performance is analyzed by the measured vibration level drop. In the case of large amplitude, the principle of vibration isolation design is mainly given and the vibration isolator is analyzed. The effect of parameters on vibration isolation performance. Finally, a suspension type bellows liquid solid mixed medium isolation design scheme is given. The scheme has high static and low dynamic stiffness characteristics. Comparison results show that the suspension isolator can significantly improve the low frequency vibration isolation performance. If the design is reasonable, even the low frequency vibration isolation.5. of less than 2Hz will be actively separated. The active vibration isolation method based on the time-delay cubic nonlinear velocity feedback is proposed by the combination of vibration and bellows liquid solid mixed medium vibration isolation technology. Firstly, the multi-scale method is used to analyze the main resonance of the controlled system, and the effect of time delay on the main resonance response and its stability is investigated. The cubic nonlinear velocity inverse within a certain time delay range is given. It not only regulates the effect of damping, but also regulates the stiffness of the system. By numerical simulation, the effect of feedback parameters on the vibration isolation effect is discussed. The results show that the cubic nonlinear velocity feedback control can effectively control the response of the resonance region and improve the vibration isolation effect, without affecting the vibration isolation of the high frequency region, and then mainly from the stability of the system. The design method of feedback parameters is given in the qualitative angle.
【学位授予单位】：南京航空航天大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB535.1

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