基于BP神经网络的船用柴油机振动状态监测

通过监测柴油机表面振动信号,用时间序列分析方法提取柴油机故障的振动特征参数,以此建立相应的神经网络,用于船用柴油机的状态监测,提高诊断的准确性。试验研究在中速四冲程增压柴油机上进行。文中以柴油机气阀间隙异常的诊断和柴油机负荷状态的识别为例阐述了该方法的实现过程,并给出了振动信号的特征参数与柴油机工作状态之间的关系。研究表明,利用神经网络监测柴油机运行状态的变化是可行的和有效的。     

剪切来流下柔性立管涡激振动抑制装置试验研究

文章针对柔性立管螺旋列板抑制装置在剪切流场中的涡激振动响应特性进行了试验研究,试验过程中通过旋转臂架从而形成相对剪切来流。通过测试得到的应变数据,基于模态叠加法,可得到立管的位移响应等参数。试验中针对螺旋列板的螺距和鳍高的变化进行了分析,系统地研究了不同螺旋列板状态下立管的主导频率、主导模态、无量纲振幅比以及疲劳损伤等参数。研究结果表明：螺旋列板可以很好地抑制立管的涡激振动响应;与螺距相比,鳍高对立管涡激振动响应会带来更大的影响;剪切流场中立管螺距恒定为5.0D（D为立管外径）时,鳍高为0.15D时的立管具有最好的抑制效果。     

汽车内外饰系统级试验的相关概述

为了解决汽车内外饰件由于频繁使用和自然环境影响产生的老化问题,产品开发部门需要在研发阶段对产品进行一系列的验证试验。其中,系统级试验具有测试件零件模块化、适应测试种类多样化、安装状态准确及研发成本低效率高的优点,在研发阶段正在被日益广泛的应用。文章介绍了系统级试验所涵盖的环境老化试验,振动试验,耐久试验,刚度试验和安全性试验,并阐述了对应的试验目的和试验方法。     

减振型无砟轨道轨枕结构对比分析

减振型无砟轨道形式较多,典型的有弹性支承块式轨枕和SAT S312双体轨枕,以及一种新型的减振型轨枕——弹性长枕。为了给无砟轨道设计中轨枕形式及参数的选取提供参考,通过建立弹性长枕的三维有限元模型,考虑避免弹性长枕结构与线路激振发生共振,从弹性长枕的枕下胶垫刚度、侧面套靴刚度、埋深及支撑长度4个方面进行模态分析,给出弹性长枕合理的参数匹配,再对3种轨枕做出对比分析。结果表明:3种减振型轨枕中,弹性长枕的结构最优,SAT S312双体轨枕次之,弹性支承块式轨枕最差。     

滚子轴承状态监测技术中基本振动的评价

通过已受损伤滚子轴承产生振动的方法,阐述如何测量这种振动和怎祥将这种振动从机器其它零件所产生的振动中分离出来,如何分析和评价这种振动以及怎样检验各种缺损的部位和轴承的工作状态,由此来预测轴承的剩余寿命。     

发动机悬置刚度优化设计

利用多体动力学软件ADAMS(Automatic Dynamic Analysis of Mechanical System)建立了某动力总成悬置系统6自由度刚体动力学模型。通过线性模态提取的方法,结合某发动机实际,以力传递率最小为目标函数,悬置刚度值作为设计变量,在强迫激励下,利用二次序列规划法SQP(Sequential Quadratic Programming)进行优化,针对对隔振影响较大的参数进行调整,最终提出悬置刚度设计方案,达到了使传递力有效值降低30%左右的良好效果。     

铁道车辆振动控制技术--有源与半有源悬挂分析

分析利用有源悬挂和半有源悬挂方法对铁道车辆振动控制的原理和技术。对日本最新型700系列高速列车上采用的可变阻尼减振器进行研究分析,认为其基本原理是通过高速电磁阀切换阻尼孔(节流孔),从而改变减振器的阻尼力达到控制振动的目的。指出在隧道内,车体的横向振动加速度可减少30%左右。介绍日本新开发的可以自动调整动力学性能的减震器的进展情况。给出横向用可变阻尼减振器和垂向用可变阻尼减振器内藏型空气弹簧的结构和特点。     

磁流变液减振控制应用的研究动态

磁流变流体与电流变流体相比工程应用特性优异,在振动半主动控制中的作用倍受关注。根据减振控制设备中磁流液不同的流动模式、电极的布置及运动方式从功能原理的角度将其归类;从参数与非参数的角度分析研究比较了现有模型的特点;并就国内外工程应用现状说明磁流变液的振动控制领域的广阔应用前景,最后总结出应继续深入的理论及工程应用研究方向。     

Guidance for new policy developments on railway noise and vibration

Noise and vibration are two of the main problems associated with railways in residential areas. To ensure quality of life and well-being of inhabitants living in the vicinity of railway paths, it is important to evaluate, understand, control and regulate railway noise and vibration. Much attention has been focused on the impact of noise from railway traffic but the consideration of railway-induced vibration has often been neglected. This paper aims to provide policy guidance based on results obtained from the analyses of relationships estimated from ordinal logit models between human response, railway noise exposure and railway vibration exposure. This was achieved using data from case studies comprised of face-to-face interviews (N = 931), internal vibration measurements (N = 755), and noise calculations (N = 688) collected within the study “Human Response to Vibration in Residential Environments” by the University of Salford, UK. Firstly, the implications of neglecting vibration in railway noise policies are investigated. The findings suggest that it is important to account for railway induced vibrations in future noise and transport policies, as neglecting vibrations results in an underestimation of people highly annoyed by noise. Secondly, implications of neglecting different types of railway sources are presented. It was found that the impact of noise and vibration form maintenance operations should be better understood and should be taken into account when assessing the environmental impact of railways in residential environments. Finally, factors that were found to influence railway vibration annoyance are presented and expressed as weightings. The data shows that factors specific to a particular residential area should also be taken into account in future vibration policies as the literature shows that attitudinal, socio-demographic and situational factors have a large influence on vibration annoyance responses. This work will be of interest to researchers and environmental health practitioners involved in the assessment of vibration complaints, as well as to policy makers, planners and consultants involved in the design of buildings and railways.     

柴油机周期双层隔振系统振动特性

舰船对动力设备的隔振性能要求越来越高,基于柴油机双层隔振系统,利用周期结构对弹性波的带隙特性,将双层隔振系统的筏体设计成周期结构。在ANSYS中对双层隔振系统进行谐响应计算,通过对比分析,斜方柱周期筏体在200-1000Hz内具有更好的隔振效果,在410.5 Hz、807 Hz处出现带宽分别为15Hz、29.5Hz带隙。采用缩减周期数的斜方柱周期筏体建立双层隔振实验系统,验证了斜方柱周期结构的带隙特性。