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。

外部冲击下的液压阻尼作动器位置控制策略研究

为了提高液压伺服系统在外部负载突变时的控制性能,提升核心元件和传感单元的使用寿命,创新提出液压作动器与磁流变阻尼器串联的液压阻尼作动器,以实现主动阻尼补偿。首先,针对系统的抗冲击需求,定制开发了多级堆叠式流道结构的磁流变阻尼器,并将其与液压作动器串联组成液压阻尼作动器;然后,采用基于力内环和位置外环的阻尼补偿控制方法,且设计磁流变阻尼器与液压作动器的耦合控制器,确保液压作动器位移跟踪精度的同时快速抑制外部振动冲击;最后,构建位移激励和变负载冲击实验,活塞杆的综合位移控制精度提高了38%以上,验证了液压阻尼作动器在耦合控制器下具备良好的动态响应性能和冲击抑制效果。

大型液压阻尼器结构优化设计

液压阻尼器通过利用液压油的阻力来消耗振动或冲击造成的动能,从而保护设备免遭振动破坏,因此被广泛应用于核电厂作为安全运行的重要保障。为了确保所设计的阻尼器能够满足要求,首先采用有限元法对其进行了静力学分析,确定了初步设计存在的问题。然后,以刚度和强度为主要考核指标对相关的影响因素进行了分析,在此基础上对阻尼器的活塞缸、缸盖、活塞、活塞杆等零件的相关参数进行了优化。最后,进行了静态试验,试验结果表明优化后阻尼器的刚度和强度均能满足工作要求,优化方法的可行性与有效性得到了验证。

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。

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.

混合脱氢装置热泵压缩机振动过大的原因分析及解决措施

通过分析30万t/a丙烷/异丁烷混合脱氢装置热泵压缩机振动值超标问题,开展频谱分析和仿真计算,发现主要是热泵压缩机进口和一级出口管线支撑梁刚度不足,恒力弹簧支架在水平方向上对管道约束力不够及管道内丙烯流速和方向变化等原因造成的,然后进行了针对性的改进,如新建型钢框架、安装动力管卡替换恒力弹簧支架,新增液压阻尼拉杆和液压阻尼器以及更换加固支撑梁等。最终,使得管道钢结构基础稳固性得到了有效增强,管线振动得到了有效的控制,使得热泵压缩机进、出口的振动得到了明显的改善,管线振动振幅最大值由5.4 mm降至1.16 mm,消除了装置运行安全风险,保障了热泵压缩机的安全平稳长周期运行周期。

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。

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。

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。

双筒式液压减振器阻尼力建模与灵敏度分析

为提高减振器阻尼力输出的准确性及减振器性能可靠性,定量分析双筒式液压减振器尺寸参数及其公差、油液黏度等对阻尼力的影响。根据阻尼力的产生机理,建立了减振器复原行程中复原阀开启前、后的阻尼力模型和压缩行程中压缩阀开启前、后的阻尼力模型,利用MATLAB仿真得到了其示功图和速度特性图,并通过台架性能试验进行了验证。考虑到阻尼力模型的复杂性,采用ANSYS中的Design Exploration模块,利用响应面法得到了减振器各个参数的灵敏度,并针对油液黏度、阀系开启高度等影响较大的参数,考虑其随机性,利用蒙特卡洛抽样方法得到了减振器阻尼力的分布,从而为双筒式液压减振器的设计提供了依据,为进一步研究减振器的阻尼力退化及寿命评估奠定了基础。

液压伺服式减振器试验台测控系统设计与开发

为提高油压减振器的制造与检修质量,研制开发新型油压减振器,迫切需要稳定性好、精度高的新型油压减振器试验台。该文简单介绍了新研制的液压伺服式减振器试验台,并结合此类试验台重点介绍了测控系统的原理、硬件设计、软件开发,对在WINDOWS系统中如何精确定时、数字滤波等问题进行了深入研究,解决了如何基于WINDOWS开发实时系统的关键问题。