基于非线性能量阱的深海柔性张力腿的振动抑制

本文研究了基于非线性能量阱的深海柔性张力腿的振动抑制问题.考虑端部参数激励和非线性能量阱(NES)作用下的张力腿力学模型,采用哈密顿变分原理推导出非线性振动控制的运动微分方程,利用伽辽金法进行离散化.通过参数分析和数值仿真计算,得到柔性张力腿的横向位移模态振动响应,同时还对比分析了NES与调谐质量阻尼器的减振性能.结果表明,相同情况下NES具有更为显著的减振效果,并且可以通过调整NES吸振器的参数,达到最优振动控制效果.     

压电复合梁高阶有限元模型与主动振动控制研究

大型柔性空间结构的振动控制问题引起了广泛的关注.压电材料以其低质量、宽频带和适应性强等特点,非常适合于柔性空间结构的振动控制.本文针对上下表面粘贴有分布式压电传感器和作动器的智能层梁结构,提出了一种考虑压电材料对结构质量、刚度影响的高阶有限元模型.考虑到空间结构可能承受较大的热载荷,在模型中计及了压电材料的热电耦合效应.采用常增益负反馈控制方法、常增益速度负反馈控制方法、Lyapunov反馈控制方法和线性二次型调节器方法(LQR)设计主动控制器,实现了智能层梁结构脉冲激励下的振动主动控制.仿真结果表明,LQR方法更能有效的实现结构振动控制,并且具有更低的作动器峰值电压,但不能消除热载荷引起的结构静变形.     

基于DSP的振动信号检测系统的设计

为了对机械设备的振动情况进行实时的检测和分析,防止不良振动现象的产生,或改变振动参数提高机械设备的性能,采用了TI的DSP芯片TMS320VC5402对机械振动信号进行实时分析处理,设计了一种实时监测机械振动情况的检测系统;该系统能将机械振动的频率、振幅及相位信息传输给PC机,利用VB软件绘出振动信号的时域或频域图形,并且可以通过PC机发送分频系数给DSP,控制其采样频率,从而达到精确采样振动信号及调整振动参数的目的;实验表明该系统能提高振动信号的测量精度,具有现场应用的价值。     

双钢轮振动压路机错峰控制技术研究

双钢轮振动压路机作业过程中由于要从静止到匀速行驶,同时振动轮要经历从静止到高速旋转振动,均会产生较大的载荷冲击,严重影响作业质量.为了提高压路机的作业质量,减少冲击载荷,提出了错峰控制技术,给出了控制方法和控制流程,使得振动系统在行驶系统作业一段时间后再启动,使功率配置合理;进行了现场实验,验证了错峰控制技术的合理性.     

电磁轨道发射过程中导轨的振动特性研究

针对电磁轨道发射过程中存在的导轨的振动响应问题,将电磁轨道装置简化为固定在弹性支撑上的伯努利-欧拉梁,并将导轨受到的移动载荷简化为均布载荷与集中力的组合形式,建立导轨的通用动力学方程,运用模态叠加法求解得到了振动响应解析解.借助参数化分析语言APDL,仿真不同速度的移动载荷作用下导轨的振动响应,与理论求解进行对比分析,验证了理论计算方法的可行性,并分析了系统的物理特性、结构参数等对临界速度及导轨挠度的影响.研究结果表明,临界速度时导轨的挠度变形最大.研究工作可为电磁轨道装置的结构设计提供参考.     

随机载荷的远程参数控制实现的模型

远程参数控制技术(RPC)利用计算机输出的数字信号经系统传递函数控制系统输出,忽略输入、输出信号的具体量纲,通过模拟迭代的方法逐步消除误差和非线性因素的影响.在对随机过程远程模拟控制理论进行研究的基础上,建立了一个严谨离散化的,便于工程应用的RPC模型.该模型主要用于对高频随机载荷的高精度模拟.     

超1-依赖贝叶斯信号智能分类算法

通过计算每个超1-依赖分类器与其相对应的朴素贝叶斯分类器的差异性来对超1-依赖分类器进行加权,提出了一种新的超1-依赖智能分类方法,利用4层小波包分解提取缸盖振动信号的特征向量,采用基于信息熵最小化的多区间离散化分析确定离散区间后,利用改进的超1-依赖贝叶斯分类器对模拟故障状态下的离散数值进行分类诊断。实验证明,该方法对于柴油机振动信号在不同工况下均表现出了较高的识别准确率。     

烟草供料成条机导轨滑块结构离散化滞后控制研究

烟草供料成条机在控制过程中存在延迟滞后的问题,难以满足不同种类烟草供料的成条需求,导致烟草供料成条机卷制烟支质量较差,难以保证烟丝束密度均控制标准范围内。研究烟草供料成条机导轨滑块结构离散化滞后控制方法。分析供料成条机结构,设计由导轨滑块结构组成的集流装置,能够在离散化和成束阶段降低机器共振幅度,提高烟丝束质量。设计离散化滞后控制算法,通过气-液信息放大重量装置,放大卷制前烟丝束瞬时质量信号,精准控制平准器进行气-电升降改变修剪位置,改善控制滞后问题,平衡每一支烟的烟丝束密度。利用离散化模糊PID技术模糊化内部机械振动和外界环境干扰,实现导轨滑块结构离散化滞后控制。实验证明,通过这种技术改造的供料成条机能够解决控制滞后问题,提高烟支质量,降低烟支碎丝率和空头率。     

滚动轴承故障诊断优化仿真研究

研究提高滚动轴承故障诊断准确率问题,滚动轴承故障振动信号具有非平稳,造成系统不稳定,针对传统方法难以提取故障信息的不足,提出一种小波包和最小二乘支持向量机的滚动轴承故障诊断方法(WP-LSSVM)。首先采用小波包对滚动轴承振动信号进行降噪处理,消除背景和噪声信息,然后小波包对去噪后振动信号分解并计算能量特征值,最后采用最小二乘支持向量机对能量特征值进行学习,建立滚动轴承故障诊断模型。仿真结果表明,滚动轴承故障诊断训练和测试时间减少,且故障诊断准确率得到提高。     

高冲击载荷下磁流变阻尼器的控制系统设计

针对工程领域中高冲击环境下的阻尼特点,采用了一种能够缓冲高冲击载荷的磁流变阻尼器,并设计了延时模糊PID的控制算法,通入实时改变阻尼器中电磁线圈的控制电流,实现了对高冲击载荷的有效缓冲控制.整个控制方法是基于TMS320F2812来实现的.实验结果表明,通过延时模糊PID控制算法的实时精确控制,能够明显提高阻尼器控制系...     

Comparative studies of perceived vibration strength for commercial mobile phones

A mobile phone, also known as cell phone or hand phone, is among the most popular electrical devices used by people all over the world. The present study examines the vibration perception of mobile phones by co-relating the relevant design parameters such as excitation frequency, and size and mass of mobile phones to the vibration perception survey by volunteers. Five popular commercially available mobile phone models were tested. The main findings for the perception surveys were that higher vibration frequency and amplitude of the peak acceleration would result in stronger vibration perception of the mobile phones. A larger contact surface area with the palms and figures, higher peak acceleration and the associated larger peak inertia force may be the main factors for the relatively higher vibration perception. The future design for the vibration alert of the mobile phones is likely to follow this trend.     

一个结构振动仿真系统的实现

本文介绍的结构振动的数值和图形仿真系统是我们所研究的振动控制仿真系统的一个模块。介绍了振动的仿真的基本方法和实现过程中的几个关键问题，并概略介绍了作者在微机上实现的仿真系统（ＳＤＳＳ）的主要功能。     

Technical Note Human hand-transmitted vibration measurements on pedestrian controlled tractor operators by a laser scanning vibrometer

A first application of a new measurement technique to detect vibration transmitted to the human body in working conditions is presented. The technique is based on the use of a laser scanning vibrometer. It was previously developed, analysed and tested using laboratory test benches with electrodynamical exciters, and comparisons with traditional measurement techniques based on accelerometers were made. First, results of tests performed using a real machine generating vibration are illustrated. The machine used is a pedestrian-controlled tractor working in a fixed position. Reference measurements by using the accelerometer have been simultaneously performed while scanning the hand surface by the laser-based measurement system. Results achieved by means of both measurement techniques have been processed, analysed, compared and used to calculate transmissibility maps of the hands of three subjects.     

基于虚拟仪器的旋转设备振动监测与分析系统设计

针对旋转设备振动监测的改造升级项目的用户需求,采用虚拟仪器技术,设计开发了一种分布式的振动监测与分析系统,可对多个设备进行监测并提供多种振动分析图形。系统保留了原有监视仪表的使用,从其BUFFER口或串口采集振动信号,降低了改造费用,实现了平稳升级。LabWindows/CVI软件开发平台的使用,使显示界面和仪表相类似,便于操作人员使用,还大大缩短了开发周期。本文论述了该系统的总体结构和软件功能开发,系统已在工业现场进行了初步测试,效果良好,具有实用价值。     

轿车动力总成主动隔振最优控制研究

介绍压电作动器与被动悬置串联组成的轿车动力总成主动悬置系统,分析了隔振系统的数学模型,采用最优控制原理提出了实施方法。     

钻柱纵向振动时钻头钻进计算机仿真

国内在研究钻头钻进岩石时着重研究钻头与岩石相互作用,没有考虑因钻柱振动带来的影响;而国外没有考虑钻头与岩石作用来研究钻柱振动,而且假设激振源为周期性的,都偏离实际。该文从建立符合实际的下端边界条件入手,着重研究了钻柱的纵向振动。用有限单元法,求出整体质量、整体刚度,整体阻尼矩阵采用的是比例阻尼矩阵,利用牛顿法得到钻柱的振动方程。并利用Houbolt数字解法模型求解了振动微分方程。根据上述模型编制了用于分析钻柱纵向振动的计算机仿真软件,并进行了大量仿真实验,通过对实验结果分析得到了有意义的结论。     

基于DSP的风机振动监测系统

介绍了基于DSP的风机振动实时在线监测系统的设计、组成环节、功能及应用效果。研究了风机系统振动监测点、传感器的选择、振动信号的A／D采样、系统各个模块的硬件构成和软件功能的实现等几个问题。系统具有实时振动幅值直观显示、故障提前预警、测量精度高、抗干扰能力强、软件操作界面灵活等特点。风机监测系统设计新颖、美观坚固、操作简单、整体性稳定可靠，具有较高的性价比，值得推广。     

Recognizing the viscoelastic safe area of work shoe sole in the sitting posture with vibration transmissibility in the vertical direction

Work shoe soles are a useful tool for decreasing the amplitude of vibration transmissibility to the human body for subjects exposed to foot-transmitted vibration (FTV) in the workplace. The main objective of this paper is to identify the viscoelastic safe area of work shoe soles in the sitting posture using a biomechanical model. To identify the model parameters, twelve young males participated in the experimental test. Moreover, to identify the viscoelastic parameters of the shoe sole model, three different work shoe soles, i.e., soft sole (Shore scale: A25), fairly soft sole (Shore scale: A42), and hard sole (Shore scale: A70), were used, whose mechanical parameters were extracted by establishing the experimental test based on vibration transmissibility. Afterward, the viscoelastic safe area of work shoe soles was determined based on vibration power absorption (VPA) for subjects exposed to vibration. The numerical simulation demonstrates that the soft shoe soles can decrease the maximum value of VPA up to two times compared to barefoot conditions. Furthermore, the maximum value of VPA in the hard sole is up to 14% more than that of the soft sole. Furthermore, the experimental test shows that the amplitude of vibration transmissibility to the hard sole is 15% more than that of the soft sole (p < 0.01), which is in line with the results of the numerical simulation. Moreover, increasing the mass of the shoe sole from 0.3 to 0.6 kg leads to a reduction in the viscoelastic appropriate area of the work shoe sole up to nine times.     

A reanalysis of spinal motion during vibration

Calibrated film of the motion of the lumbar spine during vibration was reanalysed, making use of a number of computer based techniques to improve accuracy and reduce measurement noise. The results demonstrated resonant behaviour at about 4 Hz and indicated that at vibration levels of the order of 1 m/s2 there exists bending of the order of 1° (peak to peak) between adjacent vertebrae in the lumbar spine. The bending is complex and involves phase differences along the spine and possibly a rocking motion of the pelvis.     

Ergonomic analysis of fastening vibration based on ISO Standard 5349 (2001)

Hand-held power tools used for fastening operations exert high dynamic forces on the operator's hand-arm, potentially causing injuries to the operator in the long run. This paper presents a study that analyzed the vibrations exerted by two hand-held power tools used for fastening operations with the operating exhibiting different postures. The two pneumatic tools, a right-angled nut-runner and an offset pistol-grip, are used to install shearing-type fasteners. A tri-axial accelerometer is used to measure the tool's vibration. The position and orientation of the transducer mounted on the tool follows the ISO-5349 Standard. The measured vibration data is used to compare the two power tools at different operating postures. The data analysis determines the number of years required to reach a 10% probability of developing finger blanching. The results indicate that the pistol-grip tool induces more vibration in the hand-arm than the right-angled nut-runner and that the vibrations exerted on the hand-arm vary for different postures.