一次风机启停瞬间轴承箱振动速度值超标的原因分析及处理方法

陕西省韩城第二发电厂2×600WM机组，2号锅炉A侧一次风机安装工作结束后，风机进行单体调试运行阶段。首次启动失败，风机轴承箱上的热控轴振保护动作跳闸停机。从计算机上显示，一次风机承力端轴承箱上传来振动速度值瞬间达21．25mm／s、与保护定值7mm／s比较，超出上限值3倍。显然问题出在振动上。为了进一步探明振动原因，决定暂时解除轴振保护（顺控解除）。将风机启动全速后就地用测振仪测量风机轴承箱体振动速度值，其结果有效振动速度值仅为3．1mm／s、小于风机厂家原设计值4．6mm／s，如何解决启、停瞬间轴振速度超标问题，从制造厂家到安装单位是一个新的课题。

一次风机振动故障诊断及分析

针对某厂锅炉侧一次风机检修后出现的振动大问题,通过进行振动参数测试,并对测试结果综合分析,找出振动故障的原因,提出了改进方案。分析结果表明:风机轴承的振动幅值、振动速度值,振动频谱中的高频分量,均呈现滚动轴承的故障频率特征。从而断定振动故障的原因为轴承失效。

振动监测在轮盘低循环疲劳试验中的应用

振动加速度值在轮盘低循环疲劳试验中 ,是判断轮盘是否产生较长裂纹的一个重要指标。燃气涡轮研究院在其SB80 4轮盘低循环疲劳试验器上进行过多个轮盘的低循环疲劳试验 ,其中有 2个压气机盘和 3个涡轮盘产生了较长的裂纹。根据这 5次疲劳试验中实际记录的振动加速度的变化值说明 :在轮盘的低循环疲劳试验中 ,可以通过监测振动峰值的变化来判断轮盘是否产生较长的裂纹。

基于快速傅里叶分析法的油浸式变压器绕组振动特性分析

变压器外壳的振动信号是反应变压器运行状态的有效信息。为研究正常运行变压器绕组的振动信号特征,在分析变压器绕组振动原理的基础上,对振动频率及加速度幅值两大特征量进行了讨论。并采用短路电流法进行变压器绕组振动信号测试,统计分析了不同型号、不同容量变压器绕组振动信号的频率分布和振动加速度幅值特点。测试结果与理论分析一致,正常状态下变压器绕组的振动信号频率集中在100 Hz;B相绕组所受电动力大于A、C两相,B相振动加速度幅值最大。结果可对进一步研究基于振动信号的变压器故障诊断技术提供参考。

热模态试验系统高温振动校准测试装置设计

针对平板式热模态试验系统用激光测振系统原位校准需求,开展试验系统高温环境振动加速度幅值原位校准测试方法研究。基于振动标准法校准技术提供标准振动加速度幅值信号,研建能够将常温下振动信号传递到高温环境的陶瓷传递杆,研制能够有效隔绝高温对标准振动信号影响的隔热装置,组建高温环境加速度幅值原位校准测试装置。通过对陶瓷传递杆的热变形分析,以及陶瓷传递杆传递系数的标定,确保校准测试装置满足校准要求,扩展不确定度优于3%。利用装置对平板式热模态试验系统开展原位校准测试试验,结果表明,该装置可以实现对平板式热模态试验系统高温环境振动加速度幅值测量的量值溯源,保障试验数据的准确可靠。

振动检测仪在电动机状态监测和润滑管理中的应用

电动机振动监测由于数据可靠性差,缺乏判断标准,只能靠维护人员手摸或耳听来判断电机的运行状况,因而电动机轴承烧毁、转子损伤等故障时有发生,电动机的检修也存在大量的过修现象,通过对影响监测数据可靠性的因素进行分析,总结了振动检测仪在电动机状态监测中的基本要求和注意事项,并通过对电动机检修后补充润滑脂前后振动加速度高频值的对比分析,找出了运用振动加速度高频值判断电动机轴承润滑状况的方法,总结了电动机连续运转加油间隔时间,并以此指导电动机的润滑管理,将监测电动机的平均轴承使用寿命从78.5天延长至210天,效果比较显著。因此,运用振动监测仪进行电动机状态监测,根据振动加速度高频值来判断轴承的润滑状况,能大幅度提高电动机轴承的使用寿命。

土石方爆破振动测试与分析

本文结合几个爆破振动测试的工程实例，对土石方深孔爆破引起的振动强度特征及传播规律进行了分析与总结，首先采用回归分析求出各点的K、α值，结果表明随着测试地点不同，K值变化大；质点振速和振动频率都随着距离的增大而变小，其中在近处，一般垂直方向振速大，而在远处则相反；最后对频率预测的公式进行了验证，证明该公式可行。所得成果可为今后工作提供帮助。

基于振动信号的热辊运行监测方法

为了减少热辊轴承损坏造成化纤设备故障,提出一种基于振动信号的热辊运行监测方法,对热辊轴承寿命状况及受损状况进行监测;通过振动传感器定期采集热辊的振动信号,采用随机子空间方法对振动信号进行计算,并提取计算结果中对应的振动频率和振动加速度幅值参数,对热辊的运行状态进行判断。指出:随机子空间法能够比较准确地计算出热辊总体振动中各振动分量的频率,但振动分量较多时计算精度会下降;对比多阶计算结果,能够去除非稳定频率,提高频率和振动加速度的计算精度;当两阶振动频率接近时,计算振动加速度与傅里叶变换后的频谱幅值存在较大误差;取随机子空间方法计算振动加速度幅值的130%弥补计算结果误差,判断结果为部分试验样本的振动偏大,但符合试验样本未做整机平衡的情况,说明该振动监测方法有效。

Experimental study on concrete columns hybrid reinforced by steel and FRP bars under seismic loading

In order to study the dynamic behavior of hybrid reinforced concrete columns, shaking table tests of three concrete columns with equal initial stiffness were conducted.The longitudinal reinforcements include an ordinary steel bar,a steel-fiber reinforced polymer（FRP） composite bar（SFCB）, and hybrid reinforcement（steel bar and FRP bar, CH）. Test results show that the peak ground acceleration（PGA） responses of different columns are similar to each other. For an ordinary reinforced concrete（RC） column, the plastic strain of the steel bar develops rapidly after the PGA of the input ground motion reaches 100 cm / s^2, and the corresponding residual strain develops dramatically. For a SFCB column, even after the peak strain reaches 0. 015, the residual strain is below 5 × 10^- 4. For the hybrid column C-H,the residual strain of the FRP bar is similar to that of the SFCB column. In general, concrete columns with hybrid steel and FRP bar reinforcement can achieve smaller residual deformation, and the SFCB reinforced columns can be constructed in extreme environments, such as offshore bridges, due to good anti-corrosion performance.

激光扫描设备的隔振设计

由于某些精密仪器测量时对环境要求非常严格,特别是在振动及噪声方面有较高要求,针对这种问题分析了产生噪声及振动的原因,并提出了关于相应的隔振及降噪措施。

蜡油加氢热高分液能量回收透平运行分析

主要对蜡油加氢裂化装置热高分液能量回收透平使用情况进行了分析说明,对透平的基本原理和该液力透平的基本参数做简单的介绍,对投用过程中出现的问题提出相应的解决措施。通过现场对液力透平、离合器、电机和反应进料泵的水平与垂直方向振动进行实测,对相应频谱和趋势进行分析。同时对液力透平的节能效果进行粗略计算。

汽机基础振动速度与振动位移的转换及对比

国内外汽轮发电机基础设计规范有着很大差别,特别是在进行强迫振动分析过程中,不同规范的振动限定指标和限值不同,为此着重对强迫振动的不同振动限定指标之间的转换进行推导,并对不同规范关于振动限值的要求进行对比,以便工程设计人员在今后的设计过程中能够熟练地使用不同规范,做出合理的设计.

Seismic response of tunnel under normal fault slips by shaking table test technique

Mountain tunnel crossing a normal fault in seismically active zone is easily affected by normal fault slip and earthquake. It is necessary to study tunnel dynamic response under action of normal fault slip and earthquake. In this paper, a three-dimensional normal fault sliding device was designed, and a shaking table test was carried out to study tunnel seismic performance under normal fault slip. The results show that peak acceleration of lining is dominated by an existence of fault and direction of seismic excitation, not normal fault slip. And the incremental strains of lining in critical zone with 1.7 times fault thickness and centered in faults induced by normal fault slip and seismic excitation are larger than ones only by seismic excitation. And the incremental strains in critical zone increase with the increase of normal fault slip magnitude ranging from 0 to 2 mm. And normal fault slip results in a significant reduction of overall tunnel stiffness subjected to an earthquake. These experimental results provide a scientific reference for prevention and control measurement of tunnel damage under earthquake and normal fault slip.

Effect of Radial Depth on Vibration and Surface Roughness During Face Milling of Austenitic Stainless Steel

This paper studies the influence of radial depth on vibration, chip formation and surface roughness during face milling of AISl3O4 austenitic stainless steel with indexable cemented carbide milling cutters. The amplitude of vibration acceleration increased with the increasing radial depth up to 80 mm. And the domain vibration frequency varied with the radial depth. In this paper, three types of chips were found： C shape, long shape and spiral shape. The minimum surface roughness value occurred when the radial depth equalled 40 mm in the experiment. Irregular changes of chip curl radius and chip thickness could be attributed to different numbers of alternately engaged teeth when the feed and speed were fixed. Surface roughness is related to forced vibration and chip formation. Radial depth with different numbers of alternately engaged teeth could significantly influence the forced vibration, chip formation, and surface roughness.

Investigation on the threshold control of safety blasting vibration velocity for the extraction of complicated orebody under railway

The threshold control of safety blasting vibration velocity is a significant process for the underground mining of complicated ore deposit under construction,road,and water.According to the equivalent principle of displacement and velocity of mass point,differential evolution is put forward based on 3DEC dynamic analysis,making the calculation more efficient and accurate.The 3DEC model of the complicated orebody under railway is established according to the topographic maps and geological data of the eastern Pyrite Mine.The stimulus-response distribution of internal stress and displacement fields are demonstrated by analyzing the on-site monitoring vibration displacement and velocity data of the mass point.The reliability of parameter selection,such as blasting simulation waveforms,rock damping,is identified.The safety vibration velocity of railway is set to 4.5 cm/s in line with the requirement of safety blasting rules.Thus,the maximum amount of single-stage explosive in this region is 44.978 kg.The simulation result is in good agreement with the on-site monitoring datum.No displacement and settlement of the 701 railway special line was achieved by choosing the critical amount of the single-stage explosive.

Human Comfort Evaluation of a Steel-Concrete Composite Building Subjected to Aerobics

The current steel-concrete composite floors design might be susceptible to the resonance phenomenon, causing undesirable vibrations in the frequency range that is the most noticeable to humans, i.e., 4 Hz to 8 Hz. This way, the main objective of this work is to investigate the dynamic structural behaviour of a steel-concrete composite multi-storey building when subjected to human rhythmic activities （aerobics）. The studied structural model represents a typical interior floor bay of a commercial building used for gym and is composed by three floor levels spanning 20 m by 20 m, with a total area of 3×400 m2. An extensive parametric study was developed aiming to obtain the peak accelerations, RMS （root mean square） accelerations and VDV （vibration dose value） values, based on two different mathematical formulations. The human comfort of the building was analysed and the vibration transmissibility related to the steel columns was verified. Based on the found results, the investigated structural model presented high vibration levels that compromise the human comfort.

Experimental and Numerical Procedures of a Sonar Platform with a Sound Absorption Wedge

Experiments involving a sonar platform with a sound absorption wedge were carried out for the purpose of obtaining the low frequency acoustic characteristics. Acoustic characteristics of a sonar platform model with a sound absorption wedge were measured, and the effects of different wedge laid areas on platform acoustic characteristic were tested. Vibration acceleration and self-noise caused by model vibration were measured in four conditions: 0%, 36%, 60%, and 100% of wedge laid area when the sonar platform was under a single frequency excitation force. An experiment was performed to validate a corresponding numerical calculation. The numerical vibration characteristics of platform area were calculated by the finite element method, and self-noise caused by the vibration in it was predicted by an experiential formula. The conclusions prove that the numerical calculation method can partially replace the experimental process for obtaining vibration and sound characteristics.

单轴承主发电机试验安装方式改进

针对单轴承主发电机试验安装系统分析了主发电机振动速度值超差的原因,对原试验安装方式进行了结构改进,改进后的安装方式作为典型结构应用到其他单轴承主发电机的试验中。

下肢外骨骼的新型足部机构舒适性优化

为减小在高负重的情况下穿戴下肢外骨骼时足部与地面接触产生的冲击,本文设计了一种用于提高足部舒适性的外骨骼足部机构,并对其影响舒适性的关键指标进行了优化。首先,本文基于步态周期的足底受力特点建立了足部机构物理模型,进而抽象出振动数学模型,并用有限元分析软件ANSYS仿真验证了模型的正确性。然后,本文基于振动数学模型分析了振动参数对绝对传递率的影响,并用数学计算软件MATLAB遗传算法工具箱优化振动参数。最后,本文以白噪声模拟路面高程作为振动输入,利用MATLAB中的可视化仿真工具Simulink并结合振动方程构建加速度仿真模型,进而计算足部的振动加权均方根加速度值。研究结果表明,该足部舒适性机构能够满足减振性与足底压力的舒适性指标。本文为外骨骼足部机构的设计提供了一套较为完整的设计方法,对于其他外骨骼的足部设计以及踝关节康复机构的设计具有借鉴意义。