ON INFLUENCE OF KINEMATICS TO EQUIVALENT LINEAR DAMPING OF HELICOPTER BLADE HYDRAULIC DAMPER

An analytical model of hydraulic damper was presented in forward flight accounting for pitch/flap/lag kinematic coupling and its nonlinear force-velocity curve. The fourth order Runge-Kutta was applied to calculate the damper axial velocity in time domain. Fourier series based moving block analysis was applied to calculate equivalent linear damping in terms of transient responses of damper axial velocity. Results indicate that equivalent linear damping will be significantly reduced if pitch/flap/lag kinematic coupling introduced for notional model and flight conditions.

Peculiarities of Calculating Bridges with Seismic Isolation Including Spherical Bearings and Hydraulic Dampers in Russia

The peculiarities of calculating isolated structures with spherical bearings are analyzed in this paper. Some of peculiarities are caused by the lack of data at the moment when engineering solutions had to be made, Other peculiarities are connected with physical peculiarities of the device behaviour. To provide the analysis of structure hehaviour under the condition of the lack of input information, two types of design models of seismic protection devices were considered. They are the dampers linearization and the modelling of real dampers by dry friction ones. The dampers linearization makes it possible to use the existing software for calculating linear strongly-damped systems. To calculate structures with dry friction dampers, a new software was worked out. In this case, the structure is described as a piecewise-linear system of a relay-type. The investigations of the structure oscillations take into account both horizontal and vertical components of earthquake input. Under this condition, horizontal oscillation equations of structures are the MaRie-Hill ones. The input and structure parameters which caused the structure instability are estimated. To exclude the structure instability, high damping devices should be used. These methods were used for seismic resistant analysis of bridges with spherical bearings and hydraulic dampers applied in Sochi.

Structure Analysis for a New Type of Vane Hydraulic Damper Using Magneto-rheological Fluid

Over recent years the progress in actuator and microelectronics technology has made intelligent suspension systems feasible.Based on conventional vane hydraulic damper,a new vane magneto-rheological fluid(MRF) damper with fail-safe capability is designed.Firstly,the mathematical model of damping moment is deduced based on the parallel-plate model and Bingham model of MR fluids.Secondly,some influence factors of damping adjustable multiple are analyzed to provide some ways for augmenting the damping adjustable multiple under the condition of keeping initial damping moment invariable.Finally,the magnetic circuit is designed,and magnetic field distribution is simulated with the magnetic finite element analysis software-ANSOFT.The theory and simulation results confirm that the damping adjustable range of vane MRF damper can meet the requirement of heavy vehicle semi-active suspension system.

SOLUTION FOR PRESSURE DISTRIBUTION IN SQUEEZE FILM DAMPER WITH ELECTROHYDRAULIC ACTIVE CONTROL

Aiming at the problems existed in the squeeze film damper of the rotating machinery utilizing traditional passive dynamic pressure film bearing, a project of dynamic pressure and static pressure hybrid oil film bearing with piezoelectric crystal electrohydraulic active control supply orifice hole is proposed. For this kind of hybrid film bearing, the π film assumption can not hold true. In order to solve the pressure distribution, a new kind of solving method is proposed.

基于ADAMS/Hydraulics的减振器设计与特性仿真研究

为深入研究高速列车车辆减振器的性能,更好地改善高速列车的舒适度,建立了高速列车电液比例阀式减振器的数学模型,并通过ADAMS软件的Hydraulics模块对该减振器进行动力学仿真,得出减振器的示功图以及阻尼随速度变化的特性曲线。仿真结果表明:此减振器的阻尼力与阻尼口的开口大小及振动频率有关,同时其可以连续变化,能够满足半主动减振器可调可控的要求。

实验教学用可调阻尼液压减振器的解析设计

现有可调阻尼减振器存在成本高、可靠性难保证等诸多缺陷,故汽车平顺性实验中常采用“更换不同被动阻尼减振器”方法测试阻尼对平顺性的影响,但此方法实验周期长、效率低且易造成减振器连接部件损坏。针对此问题,研制一种可调阻尼液压减振器,通过步进电机驱动芯杆与活塞杆相对转动调控节流孔而实现阻尼调节。提出基于汽车悬架系统最佳阻尼比的可调阻尼液压减振器解析设计方法,设计可调阻尼液压减振器的速度特性曲线、阻尼可调区域及阀系参数,并建立阻尼比、可调节流孔面积及步进电机转角间的函数关系。在此基础上,搭建样机并进行台架实验。结果表明:阻尼力实验值与要求值相对偏差小于2.0%,疲劳寿命是实验标准要求的2.1倍以上,表明此减振器满足性能和可靠性要求,说明所提可调阻尼液压减振器解析设计方法的有效性。此减振器用于汽车平顺性实验中可有效提高实验效率且避免减振器连接部件损坏,且可推广应用到减振特性实验及汽车半主动悬架实验等。

Global hydraulic stability analysis for dynamic regulation in multi-zone variable air volume air-conditioning system

Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation effect.To solve this problem,the index of global hydraulic stability,which takes the physical quantity of the pipe network pressure and the air flow rate as reference,is proposed based on Graph theory,and a pipe network model for the hydraulic calculation is built.Then,the simulation study based on the actual operation data is carried out in MATLAB.The distribution of the pressure and the air flow in the pipe network is obtained,and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy(DP strategy)and fan frequency regulation strategy(FF strategy).Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy,and then the fluctuation of the pressure and the air flow can be reduced.The contribution of this study is to provide an evaluation index of global hydraulic stability,which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.

考虑流体可压缩性的液压阻尼器振幅和动刚度频率依赖性研究

液压阻尼器因其优异的特性在国内被广泛用于各种桥梁、铁路连续梁、桥梁抗震改造。为研究液压阻尼器动刚度和振幅的频率依赖性内在影响机制,搭建了考虑阻尼介质压缩性的阻尼器力数学模型,利用AEMSim软件搭建液压阻尼器仿真模型,并对液压阻尼器进行现场实物试验,将仿真结果和试验结果对比分析。结果表明:液压阻尼器的动刚度随着加载频率的增加而增大;振幅随着加载频率的增加而减小;阻尼介质的压缩特性是影响阻尼器动刚度和振幅的关键因素。

旋翼系统液压阻尼器的工作原理及其对振动的影响分析

主要研究了旋翼液压阻尼器的工作原理及其对旋翼振动的影响,从动力学和动平衡理论对液压阻尼对直升机旋翼系统振动的影响进行了理论分析。并通过现场动平衡的典型问题的解决过程进行总结,得到了旋翼系统液压阻尼器阻尼特性、性能参数的改变,将会影响整个旋翼系统振动水平的结论。

飞灰过滤器反吹阀国产内件的应用与改进

介绍飞灰过滤器反吹阀国产内件的应用情况,对阀座损坏和阀门外漏的原因进行分析,通过改进阀座材质、调整阀座预压缩量、改进阀杆和波纹管结构、增加液压阻尼器、优化仪表气源压力和阀门维修技术等措施,有效提高了阀门及内件的使用寿命,降低了阀门运行、维护成本,提高了飞灰过滤器及煤气化装置的运行稳定性。

装配调节阀的汽车液压阻尼器的结构设计及分析

为了提高汽车行驶过程中平顺性和运行稳定性,设计了一种具有调节阀的液压阻尼器,达到高精度控制与快速响应的功能。该阻尼器中的阀芯在衔铁推动下运动,实现进出油口流量调节,达到阻尼器呈现阻尼特性的效果。研究结果表明:随着电压幅值提高,阀芯触动时间逐渐缩短,改变激励电压并不会造成响应时间变化。随着阀芯移动速度增大,阻尼系数呈线性提高,上升时间逐渐增加。该研究有助于提高汽车液压阻尼器控制精度,为后续的整体性能优化奠定一定的理论基础。

液压阻尼器活塞杆激光熔覆WC/Co06涂层耐磨耐腐蚀性能

目的研究WC添加量对WC/Co06复合涂层耐磨耐腐蚀性能影响,以期应用到液压阻尼器活塞杆表面,增强活塞杆耐磨耐腐蚀性能。方法采用同轴送粉式激光熔覆设备在液压阻尼器活塞杆用42Cr Mo钢表面制备不同WC含量(质量分数为5%、10%、15%、20%)的WC/Co06涂层,用金相显微镜、扫描电镜、X射线衍射仪及维氏硬度显微计,对4组不同WC含量的涂层进行质量检测。用滑动摩擦磨损试验机对涂层进行磨损性能测试。用盐雾腐蚀试验箱对涂层进行耐腐蚀测试。结果熔覆层表面质量良好,稀释率为5%左右。熔覆层显微组织随WC含量的升高越来越致密,WC/Co06涂层生成多种硬质相,如Cr_(23)C_(6)、Cr_(7)C_(3)、WC及Fe_(3)W_(3)C等分布在γ-Co固溶体周围增强其硬度以及耐磨耐腐蚀能力。4组熔覆层中,20%WC含量的熔覆层硬度最高(810HV),是基体的(275HV)2.95倍。摩擦磨损及盐雾腐蚀试验后,熔覆涂层磨损量及腐蚀失重均明显降低,其中20%WC熔覆层的磨损量及腐蚀失重最低,分别为基体的54.7%和21%。结论WC可提高熔覆层硬度,改善熔覆层的耐磨耐腐蚀性能,且WC含量越高,强化效果越明显。通过试验可得20%WC含量的WC/Co06涂层具有更优良的耐磨耐腐蚀性能。

改进型蓄能器设计与分析

为了抑制舰船舵液压系统压力冲击,提出一款新型液压减振降噪装置,将气囊、磁流变液阻尼器、阻尼孔3种常见的消振方法集成在一起。通过查阅液压手册,确定气囊的体积、压力参数;基于AMESim仿真,确定阻尼孔的数量、直径和长度;结合Lord公司生产的磁流变液阻尼器,确定磁流变液阻尼器的参数。基于AMESim,搭建改进型蓄能器仿真模型。结果表明:改进后的蓄能器在冲击模式下的插入损失大于15 dB;流量脉动模式下,当流量脉动频率大于100 Hz时,其插入损失大于10 dB;脉动频率越高,插入损失越大。

某型液压阻尼器启动力差异分析及改进

为解决某型机载液压阻尼器前推与后拉启动力差异较大的问题,对密封结构及阻尼腔排气结构进行改进设计。分析故障机理并确定原因是由密封设置不合理造成的启动力异常以及内部油液未充满造成的伸出方向阻尼性能下降,共同导致了侧杆装置前推后拉启动力差异。验证结果表明:该设计能提高阻尼器的密封性能,满足系统启动力的要求。

铁道车辆油压减振器振动特性研究

油压减振器广泛用于铁道车辆,在以往的的设计过程中,主要用于流体力学模型进行减振器的结构设计。本文首次引入跨学科的模型,基于振动与噪声理论,对减振器的振动特性进行研究。主要介绍了市域平台机车一系垂向油压减振器的结构与工作原理、底阀的结构与工作原理。研究铁道车辆油压减振器底阀止回阀与阀座接触面积对振动特性的影响,主要通过试验对比不同止回阀接触面积的油压减振器在相同工况下振动特性。研究内容对后续油压减振器振动特性评估提高借鉴与参考。

Testing and Modeling for Energy Dissipation Behavior of Velocity and Displacement Dependent Hydraulic Damper

A passive energy-dissipating device, velocity, and displacement dependent hydraulic damper (VDHD), is developed to reduce the seismic response of structure. This device is comprised of a hydraulic jack, check valve, relief valve, and throttle valve. The numerical analysis model for SAP2000 nonlinear analysis program is proposed to simulate the energy-dissipating characteristics of VDHD. The analysis results of this model compared with the seismic resistant tests reveal that this proposed model can accurately describe the actual energy-dissipating behavior of VDHD. The efficiency of VDHD is confirmed using this proposed model for carrying out numerical analyses of bare building, building added with bulking resistant bracing (BBR), and VDHD. The energy-dissipating capabilities of VDHD are performing excellent displacement and acceleration control with various ground magnitudes; being an energy absorber to absorb mechanical energy in the structure and resist structural movement; and gathering the advantage of BRB.

核电站设备用大型液压阻尼器故障分析

“华龙一号”是具有完全自主产权的第三代压水堆核电创新成果,是目前核电站主流堆型。核电站设备用大型液压阻尼器(以下简称“设备阻尼器”)属于核安全1级设备,是蒸发器、主泵等主设备支撑的关键部件,其性能的好坏会影响蒸汽发生器、主泵等的安全运行。在蒸汽发生器、主泵等设备正常运行过程中,必然会受到振动、地震、热位移、温度等因素影响,设备阻尼器性能参数是否满足设计要求尤为重要,一旦失效会引起主设备动态反应的变化,这些影响通过接管、管道传播,对整个系统的设备都有潜在的威胁,给电厂运行带来隐患。文中利用故障分析方法对设备阻尼器性能参数进行故障分析,通过故障原因、故障模式、薄弱环节及失效模式分析,为核电站主要设备安全运行提供强有力的保障,提高整体系统的可靠性。

液压阻尼器动静态性能试验台的设计研究

针对液压阻尼器特性,研制了一种同时满足其动静态性能测试的试验台,解决了该试验台面临的一系列关键技术问题。从节能的角度,采用小泵站大蓄能器组的形式,解决了动静态试验对流量要求差别巨大的矛盾;在回油路上设置蓄能器组解决了大流量对回油管路和低压元件的冲击问题;采用液压夹紧方式,使得试验空间的调节方便可靠;采用上下位机的控制模式,同时满足了数据采集速度和控制界面友好的要求。该试验台的最大输出动态力为1 000 kN,频率范围为0.01～33 H z。试验表明,该试验台较好地满足了设计要求,完全满足阻尼器的试验需求。

高速列车抗蛇行减振器的简化物理参数模型

建立某高速列车单循环作用式抗蛇行减振器的简化物理参数模型,该模型基于Kasteel复杂物理参数模型,但对阻尼阀和单向阀进行了合理简化。针对抗蛇行减振器的静、动态特性,进行仿真和台架试验的对比研究。最后,对比研究了简化物理参数模型和传统Maxwell模型下的车辆蛇行运动稳定性。研究结果表明,传统Maxwell模型无法准确描述液压减振器的动态特性,而复杂物理参数模型虽计算精度高但其效率过低无法用于整车动力学仿真。简化物理参数模型能够准确地模拟抗蛇行减振器的复杂力学行为,计算效率高,适于整车动力学仿真。在高锥度工况下,传统Maxwell模型会过高估计单循环作用式抗蛇行减振器的动态阻尼,导致稳定性预测结果和简化物理参数模型有较大误差。

铁道车辆油压减振器三维流场动态仿真

液压减振器是轨道车辆行走部的重要装置,其阻尼特性由一组特殊结构的阻尼阀来实现。为优化液压减振器缸体的整体流道结构,分析关键阻尼阀在不同开启状态下局部流场对阻尼特性的影响,有必要采用流体三维动态仿真计算方法预估其性能。研究中针对某典型轨道机车垂向减振器的结构和参数,构建相应的数学模型和实体模型。采用CFX自适应动网格技术,对各典型振动条件下阀体及内外缸体内的交变流场进行数值模拟,得到相应流道中的速度场、压力场和流线分布图。进一步地采用基于三维流场的可视化分析方法,清晰而全面地反映了各关键流道流体的流动状况。由此获得的减振器工作特性曲线与实际标准特性曲线相吻合,证实了模型的可行性和方法的有效性。所建立的分析模型和采用的仿真方法,为从机理上分析减振器能量耗散过程提供理论依据,同时,也为流道的结构优化设计提供快速、有效的手段。