磁流变减振器阻尼力分析

根据剪切模式和流动模式共同作用机理,分析了磁流变减振器的工作原理;基于Navier-Stokes方程,分析了轴对称模型的流变学方程;利用Bingham模型,描述了磁流变液的本构方程,得出了减振器阻尼力方程;基于阻尼力的表达式,分析了间隙、长度、半径、磁场强度和活塞速度对阻尼力的影响.结果表明:间隙的减小或磁场强度的增加会使阻尼力迅速增加;其它因素对阻尼力的影响相对较小.     

基于振动信号分析的齿轮故障诊断方法研究

本文介绍了齿轮振动信号的时域分析与频域分析的理论基础。针对齿轮常见故障原因和类型,引出了齿轮故障诊断的常用方法,并选用经典的振动分析法,利用MATLAB信号分析功能,对齿轮故障信号的时域和频域分析进行了详尽的阐述。本文对齿轮故障诊断有一定的指导意义。     

透平机械实际应用中的动力学问题

从动力学的角度分析了透平机械转子的临界转速、临界敏感性、振动物理量选择、转子的冷热变形及控制、转子稳定性以及转子的振动评价等问题 ,为透平机械运行、维护、检修及故障分析提供依据     

SFS-1型湿法振筛机在煤粉筛分试验中的应用

例举对比试验数据说明湿法预先脱泥的必要性,重点介绍SFS-1型湿法振筛机的结构,工作原理、主要技术参数以及在煤粉(泥)筛分试验中的应用。     

大型水泥磨减速箱故障诊断

针对某水泥公司一台大型水泥磨机减速箱存在的剧烈振动和强烈噪音，进行现场振动测试，提取相关数据并加以分析，准确查明了故障的主要原因，提出的维修建议被用户认同。     

振动力场作用下温度对超临界CO2/PS微孔塑料气泡形态的影响

以超临界CO2为发泡剂,用自行研制的动态发泡模拟机将机械振动力场引入到PS微孔塑料成型过程中,初步研究了振动力场作用下温度对微孔塑料气泡形态的影响.实验发现,发泡温度越高,气泡核长大的速度越快,导致气泡合并甚至破裂.但发泡温度过低时,超临界CO2在PS熔体中的扩散速率较低,最终制品的泡孔密度小,气泡分布也不均匀.在微孔塑料成型过程中施加振动,有利于发泡剂在熔体中的分散和混合,从而在较低的温度(130℃)下制备出泡孔直径为18μm、泡孔密度为7×107个/cm3的微孔塑料.     

Fault detection on robot manipulators using artificial neural networks

Nowadays, gas welding applications on vehicle’s parts with robot manipulators have increased in automobile industry. Therefore, the speed of end-effectors of robot manipulator is affected on each joint during the welding process with complex trajectory. For that reason, it is necessary to analyze the noise and vibration of robot’s joints for predicting faults. This paper presents an experimental investigation on a robot manipulator, using neural network for analyzing the vibration condition on joints. Firstly, robot manipulator’s joints are tested with prescribed of trajectory end-effectors for the different joints speeds. Furthermore, noise and vibration of each joint are measured. And then, the related parameters are tested with neural network predictor to predict servicing period. In order to find robust and adaptive neural network structure, two types of neural predictors are employed in this investigation. The results of two approaches improved that an RBNN type can be employed to predict the vibrations on industrial robots.     

无机房电梯的振动信号远程监测系统

针对无机房电梯检修维护困难以及人工成本较高的现状,根据无机房电梯测试环境特点和要求,设计了电梯振动信息监测系统.该系统以MCU、ADS8361模数芯片和USB芯片为核心,结合前端信号调理等模块,完成了电梯振动和噪声信号的采集.同时,通过USB方式将采集信号数据传输给上位系统,完成信号数据的处理、存储和分析,为无机房电梯故障诊断和健康状态的分析提供了网络化的信息服务.     

Multivariable predictive control for vibrating structures: An application

This paper proposes the use of Model Predictive Control (MPC) to control a fast mechanical system. In particular an MPC strategy is applied to a laboratory flexible arm to perform a fast positioning of the end-effector with limited oscillations during the maneuver. The on-line implementation of a fast MPC is obtained with an ad hoc platform based on C++ and MATLAB while the MPC tuning is based on a non-linear model identified and validated with experimental data. The effectiveness of the proposed method is highlighted with some suitable experiments performed on the plant. In particular the comparison with a Linear Quadratic Regulator stresses the advantage of the MPC capability to explicitly handle input and state constraints.This feature guarantees smaller displacements that imply a structure stress reduction.     

Postural stability effects of random vibration at the feet of construction workers in simulated elevation

The risk of falls from height on a construction site increases under conditions which degrade workers’ postural control. At elevation, workers depend heavily on sensory information from their feet to maintain balance. The study tested two hypotheses: “sensory enhancement” – sub-sensory (undetectable) random mechanical vibrations at the plantar surface of the feet can improve worker’s balance at elevation; and “sensory suppression” – supra-sensory (detectable) random mechanical vibrations can have a degrading effect on balance in the same experimental settings.Six young (age 20–35) and six aging (age 45–60) construction workers were tested while standing in standard and semi-tandem postures on instrumented gel insoles. The insoles applied sub- or supra-sensory levels of random mechanical vibrations to the feet. The tests were conducted in a surround-screen virtual reality system, which simulated a narrow plank at elevation on a construction site. Upper body kinematics was assessed with a motion-measurement system. Postural stability effects were evaluated by conventional and statistical mechanics sway measures, as well as trunk angular displacement parameters.Analysis of variance did not confirm the “sensory enhancement” hypothesis, but provided evidence for the “sensory suppression” hypothesis. The supra-sensory vibration had a destabilizing effect, which was considerably stronger in the semi-tandem posture and affected most of the sway variables.Sensory suppression associated with elevated vibration levels on a construction site may increase the danger of losing balance. Construction workers at elevation, e.g., on a beam or narrow plank might be at increased risk of fall if they can detect vibrations under their feet. To reduce the possibility of losing balance, mechanical vibration to supporting structures used as walking/working surfaces should be minimized when performing construction tasks at elevation.