Simulation Research on an Active Anti-Roll System for an Air Spring Passenger Car

To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing research between the passive and active system, a two-track vehicle model and a co-simulation model of air spring system are built. For the simulation research on the linear movement of the actuator, a mathematical model is considered as dynamical subsystem in the co-simulation model. To active control the roll angle of vehicle body, a sliding-mode controller with optimized control parameters for the test vehicle is introduced into the model. The characteristics of sliding-mode controller is discussed and the validation of active antiroll control is proved by comparison with other control methods. The results show that the roll angle of air spring vehicle is reduced obviously with the active anti-roll actuator in comparison with that of the passive system. Compared with other control methods, sliding-mode controller has an advantage of shortest switching times, which leads to a longer lifetime of actuator and valves.

The error research on vertical rigidity theory’s formula of airborne air spring

On the basis of analyzing the result of numerical simulation and that of theoretical analysis,the systematic error of some air spring's theoretical formula is researched. The result shows that the vertical stiffness's theoretical formula of air spring owes the systematic error. And the systematic error is relative to the three supposed conditions which are used in the process of theoretical deduction. However,the systematic error is small enough so that the supposed conditions of theoretical formula are reasonable. Moreover,with the increase of initial inner pressure,the systematical error increases.

Dynamic frequency response characteristics of a compound regulative quasi-zero stiffness air spring system

Quasi-zero stiffness(QZS) device is widely studied for their better performance in low-frequency and micro-vibration isolation due to the high-static and low-dynamic(HSLD) stiffness characteristics.The previous QZS isolator with determined parameters is not suitable for variable isolated mass.In this study,a novel compound regulative quasi-zero stiffness air spring(CRQSAS)has been proposed and designed by introducing a bidirectional regulator for the horizontal air springs.The CRQSAS could change the quasi-zero region depending on the payload.To identify the parameters of the convoluted air spring(CAS) and novel rubber air spring(NRAS),the air spring testing system is established.The stiffness functions of air springs are obtained by the multi-parameter fitting method.According to the structure of the CRQSAS,the dynamic model of the system is analyzed and simplified by Taylor Expansion.The harmonic balance method(HBM) is applied to calculate the frequency response and absolute displacement transmissibility.An experimental prototype has been set up to verify the theoretical model and simulation.Compared with the single NRAS,CRQSAS performs better in low-frequency and micro-amplitude vibration.The research proves that CRQSAS is a passive device widely applied for improving isolation precision under low-frequency vibration.

An Air Mass Based Approach to the Establishment of Spring Season Synoptic Characteristics in the Northeast United States

The Northeast United States spring is indicative of major meteorological and biological change though the seasonal boundaries are difficult to define and may even be changing with global climate warming. This research aims to obtain a synoptic meteorological definition of the spring season through an assessment of air mass frequency over the past 60 years. The validity of recent speculations that the onset and termination of spring have changed in recent decades with global change is also examined. The Spatial Synoptic Classification is utilized to define daily air masses over the region. Annual and seasonal baseline frequencies are identified and their differences are acquired to characterize the season. Seasonal frequency departures of the early and late segments of the period of record are calculated and examined for practical and statistical significance. The daily boundaries of early and late spring are also isolated and assessed across the period of record to identify important changes in the season’s initiation and termination through time. Results indicate that the Northeast spring season is dominated by dry air masses, mainly the Dry Moderate and Dry Polar types. Prior to 1975, more polar air masses are detected while after 1975 more moderate and tropical types are identified. Late spring is characterized by increased variability in all moist air mass frequencies. These findings indicate that, from a synoptic perspective, the season is dry through time but modern springs are also warmer than those of past decades and the initiation of the season is likely arriving earlier. The end of the season represents more variable day-to-day air mass conditions in modern times than detected in past decades.

A Hybrid Structure of Dual Stators and a Pneumatic Spring for Resonance Control in an Air Mount

An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to –10 dB.

仿猫类落地姿态的准零刚度隔振器

对设备加装隔振装置是保证其高效工作的重要方法之一.本文从仿生学的角度,根据猫科动物落地时优秀的抗冲击能力,通过观察其落地动作姿态,利用非线性补偿原理,以空气弹簧作为正刚度结构,设计出一种具有非对称刚度特性的高静低动刚度隔振器.以其为研究对象,建立了动力学模型,利用特定的方法对非对称刚度系统进行分析求解,并与数值结果和有限元仿真结果进行对比.结果表明,在较低阻尼以及较高激励幅值下,还会出现倍周期响应甚至混沌响应.同时,通过将本文设计的隔振结构和单一空气弹簧的隔振性能对比,可以得到隔振效果明显优于单一空气弹簧的结论,从而验证了所设计隔振结构的有效性和可行性.

Local intraseasonal air-sea relationship over the North Indian Ocean and western North Pacific during the spring-to-summer transition

该工作研究了1998-2013年春夏转换期间的两种主要模态的局地季节内海气相互作用。大气要素场和海表热通量在高频尺度上(10-20天)显示出更大的变率。在北印度洋,南海和菲律宾海,30-60天的海温和海表热通量的显著相关区域更大,并且相关系数更高。结果表明在两个时间尺度上在北印度洋,南海和西北太平洋存在强烈的局地海气相互作用,然而海气相互作用的强度取决于区域和要素的选取方式。

大跨度钢桁架隔震结构隔震性能及影响规律分析

由于大跨空间结构竖向振动问题突出,水平隔震支座难以有效控制结构的竖向地震响应。将摩擦摆水平隔震支座和空气弹簧-摩擦摆三维隔震支座应用于大跨度钢桁架中,分析钢桁架水平隔震结构和三维隔震结构的隔震控制效果。结果表明,水平隔震和三维隔震均延长了结构自振周期,隔震后一阶振型为上部桁架结构沿水平方向的整体平动。时程分析显示,在普通地震动、近断层脉冲型地震动和远场长周期地震动作用下,水平隔震支座对桁架水平和竖向节点峰值加速度的平均隔震率分别为43.4%和9.2%,三维隔震支座对桁架水平和竖向节点峰值加速度的平均隔震率分别为43.8%和24.4%,水平隔震支座和三维隔震支座对桁架峰值等效应力的平均隔震率分别为4.2%和17.7%。水平隔震支座和三维隔震支座对桁架水平地震响应控制效果基本相同,三维隔震支座对结构的竖向地震响应控制效果更好。

低频非线性浮筏隔振装置设计及特性研究

低频振动噪声影响水下装备声隐身性能。在原气囊隔振装置基础上,通过结构改进设计,使得侧向气囊能够为系统提供负刚度,通过与垂向气囊并联,设计了一种新型非线性浮筏隔振装置,提升了隔振装置的低频隔振能力。新型隔振装置由“侧向气囊-万向节-垂向气囊”非线性隔振器组和浮筏组成。分析了侧向气囊为系统提供负刚度原理,建立了非线性浮筏隔振装置六自由度动力学模型,设计了新型隔振装置样机并开展了相关性能试验。理论分析和试验结果表明,新型非线性浮筏隔振系统垂向一阶固有频率约为原系统的50%,垂向隔振性能提升了约6 dB,侧向隔振性能与原系统相当。此外,也研究了非线性浮筏隔振系统的摇摆稳定性。研究结果表明,在重载情况下,新系统能够具备较好的摇摆稳定性。

基于非线性空气弹簧模型的整车仿真与主客观评价

应用非线性空气弹簧模型,研究了空气悬架整车的动力学仿真和主观评价。结合空气弹簧频率、振幅相关性模型与Simulink仿真,给出了空气悬架整车7自由度模型,对比了不同路面情形下悬架动行程和簧上加速度的均方根值和功率谱密度。从时域和频率2个角度分析了不同速度、路面及减振器阻尼情形下空气悬架整车的动态特性。对装有不同空气弹簧的整车进行主、客观试验测试。结果表明:悬架动行程预测误差小于7%,簧上位置加速度共振峰值预测误差小于6%,共振频率预测误差小于6%;从而验证了所提模型的普适性和精确性;反映了带空气悬架整车的动态特性,解释了平顺性主客观试验的机理。

基于精细传递矩阵法的气囊隔振器横向刚度特性分析

构建并求解了预载条件下气囊隔振器的囊体力学模型,提出了一种气囊隔振器横向刚度特性的参数化计算方法。在考虑囊体预应力的条件下构建了囊体力学模型,引入位移中间向量并采用精细积分法推导了囊体状态向量间的传递矩阵,利用迭代法解析了囊体状态向量、内部压力以及结构参数之间的耦合变化关系,基于边界条件完成了囊体刚度的参数化求解,结合理想气体刚度模型完成了气囊隔振器横向刚度特性的计算分析。对比试验结果,验证了横向刚度特性计算方法的正确性,探究了主要设计参数对刚度特性的影响规律。

减振制品用天然橡胶在存储过程中结构与性能的演变

采用长期储存和加速老化相结合的方法对减振制品用天然橡胶(NR)在存储过程中结构与性能的演变进行研究。结果表明,随着老化温度的升高和老化时间的延长,NR硫化胶的硬度、100%定伸应力、300%定伸应力、储能模量和损耗模量均逐渐增大且总体变化趋势与交联密度的变化趋势相近,拉伸强度和扯断伸长率的变化率均呈现整体下降趋势,而损耗因子则迅速降低并趋于稳定,动静刚度比呈现先降低后缓慢上升的趋势;热空气老化对NR硫化胶减振性能的影响较小。

高速列车空气弹簧二系悬挂垂向振动规律研究

建立空气弹簧系统垂向非线性动力学模型和某高速列车动力学模型,根据空簧垂向振动传递试验结果,验证空簧非线性动力学模型的准确性,采用数值仿真分析空簧的垂向动刚度特性和振动传递规律。研究二系抗侧滚扭杆刚度、空簧节流孔直径和二系垂向减振器阻尼对振动传递规律的影响,对比不同二系悬挂结构对车辆动力学指标的影响,发现节流孔直径对空簧动刚度和传递率影响很大,减小节流孔直径会增大空簧垂向动刚度;采用节流孔方式有利于改善高频减振效果,采用二系垂向减振器有利于低频减振。研究结果表明:采用合适直径的节流孔可以实现和二系垂向减振器近似的振动传递率,且减小垂向平稳性指标值及车体垂向加速度值。

轨道交通车辆空气弹簧智能监测系统

针对轨道交通车辆空气弹簧在劣化过程中本体高度变化难以检测,压力测量精度不高,缺乏智能预警功能等问题,设计了轨道交通车辆空气弹簧智能监测系统。对这一监测系统的结构、硬件、软件、工作过程进行了介绍,并分析了技术创新点。这一监测系统应用智能传感技术、数据转储技术、智能预警技术,可以精确测量空气弹簧内部间隙变化、内压值变化,实现智能预警提示检修,进而能够提高检修效率,节约检修成本。

山东一次春季冷空气10级大风的天气成因

2020年3月18日中午至夜间,山西、河北、北京、天津和山东等地先后出现阵风10级及以上强风天气。利用风廓线雷达、国家级地面气象观测站和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts, ECMWF)第五代大气再分析数据(ECMWF Reanalysis v5,ERA5)等资料,对强风过程的天气学成因进行了分析。结果表明:强风发生在低空暖脊异常发展的热力环境条件下,冷锋自黄土高原下到华北平原,中层锋消,垂直方向上发生“断裂”,低层冷锋先行侵入热低压,在锋生过程中发生。强风具有显著的非地转瞬变特征,低层强冷平流是强变压梯度产生的主要因素,变压风叠加在快速移动的冷锋系统中诱发大风,变压风是重要组成部分;低空动量下传效应引起低层风速波动,但不足以直接诱发强风。

2020年-2023年春节期间重庆城区空气质量对比研究

为明晰实行烟花爆竹管控措施后重庆城区空气质量变化成因,文章基于PM_(2.5)质量浓度、PM_(2.5)组分及气象观测数据,对比分析了2020年-2023年春节期间重庆城区污染物浓度变化趋势。结果表明,气象条件对于燃放高峰期和春节期间大气污染物浓度具有重要影响。春节期间PM_(2.5)主要来源为二次源、机动车尾气、工业排放、烟花爆竹和生物质燃烧、扬尘源。2023年新冠疫情“乙类乙管”后经济复苏,机动车尾气、工业等排放增加,叠加烟花爆竹燃放影响,在气象不利条件下,春节期间PM_(2.5)出现明显反弹。

我国铁路车辆空气弹簧试验方法分析

采用TB/T 2841—2019 《铁路车辆空气弹簧》规定的Ⅰ类、Ⅱ类空气弹簧试验方法和Ⅲ类空气弹簧试验方法开展试验,得到的空气弹簧性能指标值存在较大差异。为便于统一铁路车辆空气弹簧试验方法,分析2种空气弹簧试验方法的差异。选定8种主型动车组空气弹簧,按2种试验方法分别进行试验研究。试验结果表明:Ⅰ类、Ⅱ类空气弹簧试验方法的试验工况更贴近空气弹簧的实际使用条件,比Ⅲ类空气弹簧试验方法更合理。通过统计分析,得到动车组空气弹簧垂向静态刚度、垂向动态刚度、水平静态刚度和水平动态刚度2种试验方法的参考转换系数。

客车舱门气弹簧选型设计与运动仿真

为了提高客车舱门气弹簧选型的设计质量、效率及可视性,文章采用三维软件进行客车舱门气弹簧的选型设计,通过作图法得到气弹簧的安装位置,然后理论计算确认该安装位置的舱门支撑力和关闭力满足设计要求。通过CATIA中的数字样机(DMU)模块的运用,实现气弹簧运动仿真,直观观测舱门开启角度、干涉情况等,从设计源头校核确认,保证气弹簧自锁有效。气弹簧三维选型设计与运动仿真分析的使用,提高了客车舱门气弹簧选型设计的效率与设计水平,在设计源头避免气弹簧选型不当导致舱门开启角度不对、舱门开启力度偏大或偏小、气弹簧寿命短等问题。

特高压直流GIL运行可靠性设计与研究

特高压直流GIL运行可靠性取决于内绝缘设计的可靠性。此外,导电元件直流电流密度的取值、弹簧触头的定位设计、GIL各元件中的绝缘件与金具连接处的楔形气隙的处理以及母线中支撑件的结构设计细节,都会对产品运行可靠性产生重大影响,不能忽视。对于运行环境十分严酷的UHV DC GIL为保证内绝缘工作可靠性和减少气体维护工作量,文中还提出了高气密性结构设计。为适应-50℃低温运行要求,产品选用了液化温度很低的N_(2)/SF_(6)混合气体,对两种气体的配比,压力特性和绝缘特性进行了讨论与计算。还有产品的局放、气体密度及微水含量的监视系统的可靠性设计,都会对产品运行可靠性产生直接影响。文中对上述问题的研究成果作了介绍,可供高压直流产品设计使用。对其中未解的新技术如基于冷镜露点测试原理、微机电技术制作的智能气体湿度和密度监测装置、高压直流复合绝缘套管伞面局放起始场强提出了研究方案。文中提出的诸多GIL运行可靠性设计要点,对于其他超/特高压直流气体绝缘电器可参考选用。

输煤皮带秤技术的优化与应用研究

在传统煤矿测量过程中,容易出现精确度低、稳定性差等问题。因此通过分析传统输煤皮带秤技术,提出了输煤皮带秤技术的优化方法。该方法深入剖析了影响计量皮带秤测量准确度和稳定性的因素,提出了提高计量皮带秤测量准确度和稳定性的电气仪表技术优化改进措施。结果表明,优化后的输煤皮带秤技术能够提高称重准确度和效率,为相关行业的生产和管理提供了有效的建议和改进空间。