共查询到20条相似文献，搜索用时 156 毫秒
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针对振动和冲击对车载设备的危害,分析了车载电子设备机箱、机柜、印制板等的抗振措施,及隔振系统的选型和合理布局。 相似文献
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斜拉索的振动分类及振动机理探讨 总被引：1，自引：0，他引：1
对斜拉桥拉索的振动类型,不同学者有不同的分类方法,文献[1]及文献[2]对斜拉轿拉索的各类振动进行了分析.至今发现的斜拉索可能发生的振动类型有以下几类:涡激振动;尾流驰振;抖振;空气动力失稳;风雨振动和参数振动. 相似文献
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针对振动对光纤陀螺性能的影响,提出改善机械结构与信号处理相结合的抗振技术。根据机械振动机理,应用有限元理论对结构的分析,改善光纤环骨架的设计,提高其共振频率,达到了舰船使用环境的要求;分析了振动对光纤环的调制机理,采用小波滤波的方法对受振动噪声污染的陀螺输出进行信号处理,比较不同小波基的滤波效果,得到适合实际使用的最优选择。 相似文献
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汽轮机振动是多种现象综合作用的结果。将其振动按振动性质划分为普通强迫振动、电磁振动、拍振、气流激振、随机振动、轴瓦自激振动、参数振动、汽流激振、摩擦涡动等共11类。其中,普通强迫振动,其振幅与机组运行工况、运行时间无明显关系时,排除了轴承座连接刚度、共振影响之后,采用正向推理可以判断出振动故障的原因是激振力过大。引起普通强迫振动的激振力有转子不平衡、固定式联轴器连接的轴系同心度和平直度偏差等原因,主要谈一下影响普通强迫振动的几点原因。 相似文献
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振动舒适性是车辆性能的重要方面,动力传动系统的振动对整车振噪舒适性具有重要影响。系统分析了动力传动系统的弯曲振动问题,从模型的搭建、试验研究、影响因素及控制方法四个方面进行分析,对研究车辆的振噪舒适性具有重要意义。 相似文献
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露天矿山爆破开采过程中会产生一系列的危害,严重威胁地表建筑物及人员的安全.通过现场实时监测采集了露天矿山远距离建筑物的质点振动速度及主振频率,并且根据萨道夫斯基公式对监测结果进行线性回归,推导出爆破振动波的衰减规律.试验结果表明:爆破振动质点振速与爆心距有关,随着爆心距的增大,质点振动速度逐渐减小;质点振动的三向振速中,水平径向振速最大;监测点的峰值振速均在安全允许范围之内,一般情况下对周围建筑物没有影响;爆破地震波衰减系数K=248.05,α=1.52,即爆破振动质点振速衰减规律公式为:V=248.05(3√Q/R)1.52.爆破振动监测结果和衰减规律对类似地形和地质的露天矿爆破开采具有一定的参考价值. 相似文献
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An efficient planar micromixer based on multidirectional vortices in a curved channel with radial baffles is proposed and examined in this work. The curvature of the microchannel and the radial baffles induce vortices in different directions. The multidirectional vortices and the converging-diverging flow caused by the baffles contribute together to the enhancement of mixing. The micromixer is fabricated with polydimethylsiloxane by a single planar microlithography process and the mixing behaviors are observed by a confocal spectral microscope imaging system to validate the simulation obtained by a commercial code. The simulation and experimental results are in reasonable agreement. The concentration distributions and flow patterns obtained reveal the following trends. (i) The mixing efficiency of the basic C-shaped micromixer with the first baffle attached to the internal cylinder and the second attached to the external cylinder is better than that of the C-shaped micromixer with inverted arrangement of baffles. (ii) When the radius of the curved channel and the width of the passage between the baffle and the cylindrical wall are small enough and the Reynolds number (Re) is large enough, an extra separation vortex develops in the downstream of the second baffle. This phenomenon is one of the reasons of trend (i). (iii) A micromixer consisting of a few basic C-shaped micromixers connected by straight channels may generate a high degree of mixing for the case with a large Re. 相似文献
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《Journal of The Franklin Institute》2022,359(10):4699-4726
The vibration of a railway car body is a superposition of the vibrations of its various modes. It is typically easy to obtain the physical vibration of the car body using sensors in an in situ or a simulated test vehicle. However, it is difficult to determine the modal vibration of the body and its contribution. There are no effective multi-mode vibration control methods for the car bodies. This study proposes a modal vibration decomposition method (MVDM) based on singular value decomposition (SVD) and least squares fitting (LSF). Accordingly, the physical vibration of a railway car body is decomposed into modal vibrations. A method for calculating the modal contribution factor (MCF) is presented, and the dominant flexible modes of the car body are determined and considered the target for the vibration control method. Several pieces of equipment are considered as dynamic vibration absorbers (DVAs) to control the multi-mode vibration of the car body using the dynamic vibration absorption theory and determine the installation parameters of the individual equipment. Finally, the effectiveness of vibration control is verified through dynamic simulations. The results demonstrate the effective decomposition of the physical vibration of the car body into various modal vibrations using the MVDM. This provides accurate data for the MCF calculation and determination of the flexible modes of the car body. The proposed method reduces the vibration of the target modes and improves the ride quality of the railway vehicle. At the optimal damping ratio, the vibration of the DVA-based equipment itself is acceptable. This allows for multi-mode vibration control without requiring extensive modification to the car body structure or suspension system parameters of the vehicle. 相似文献
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This study proposes a novel cell collection method based on collagenase treatment and ultrasonic vibration. The method collects calf chondrocytes from a reusable metal cell culture substrate. To develop our concept, we calculated the natural vibration modes of the cell culture substrate by a finite element method, and conducted eigenvalue and piezoelectric-structural analyses. Selecting the first out-of-plane vibration mode of the substrate, which has a single nodal circle, we designed and fabricated the cell collection device. The excited vibration mode properly realized our intentions. We then evaluated the cell collection ratio and the growth response, and observed the morphology of the collected cells. The collagenase and ultrasonic vibration treatment collected comparable numbers of cells to conventional trypsin and pipetting treatment, but improved the proliferating cell statistics. Morphological observations revealed that the membranes of cells collected by the proposed method remain intact; consequently, the cells are larger and rougher than cells collected by the conventional method. Therefore, we present a promising cell collection method for adhesive cell culturing process. 相似文献
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以Iwan改进的尾流振子模型为基础，给出了剪切流中水中悬浮隧道锚索横向涡激振动的工程分析方法，分析了悬浮隧道重浮比以及剪切流特性对锚索涡激响应的影响。计算结果表明，悬浮隧道重浮比的改变，使锚索各阶模态的频锁区域分布发生变化，从而改变了结构的涡激振动响应；剪切流陡度参数的增大会使锚索涡激响应的幅值减小，若使用均匀流场代替剪切流场计算悬浮隧道锚索的涡激振动，会过高估计其响应幅值。 相似文献
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重载的铁路货车滚动轴承极易出现损伤类故障,因故障的突发性使得振动信号具有非线性、非平稳的特性,且振动信号极易受非检测部位振动的干扰,而使得有效信号不易被提取,传统的基于傅里叶变换的检测方法无法有效将非平稳的振动信号中的干扰去除,造成最终的检测准确率不高的问题。为了提高检测准确率,提出基于小波包的检测方法,首先针对振动信号的非平稳特性采用小波滤波有效去除其中的干扰,然后通过最小二乘支持向量机提取出非平稳振动信号中的故障特征信号并完成故障检测。实验表明,这种方法能够有效去除振动信号中的干扰,并准确检测重载铁路货车上的滚动轴承损伤故障。 相似文献
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基于线性二次型最优控制在结构振动控制中的研究 总被引：1，自引：0，他引：1
动力设备在工作过程中引起的振动对设备运行的可靠性、安全性及周围环境都会产生重要影响,因此寻求抑制振动有效控制方法具有重要意义。本文介绍了线性二次型（LQR）最优控制方法,以三层振动体为研究对象,采用数值计算和仿真相结合的方法,分析探讨了线性二次型最优控制在振动控制中的明显优势。 相似文献
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Cheng-Hung Huang 《Journal of The Franklin Institute》2005,342(7):793-813
The conjugate gradient method (CGM), or the iterative regularization method, is applied to a generalized inverse nonlinear force vibration problem, (i.e. system parameters are function of displacement), to simultaneously estimate the unknown time-dependent external forces for a multiple-degree-of-freedom damped system by using the measured displacements. The system parameters of the present study are considered function of displacement, thus it is classified as a genuine nonlinear inverse vibration problem. The numerical experiments are performed to test the validity of CGM by using different types of system parameters, external forces and measurement errors in this study. 相似文献
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对于飞行试验中非平稳振动信号,进行时频分析后仅可定性的观察到频率值随时间发生变化的趋势,为了确定振源机理,需要进一步寻求频率变化与飞行参数变化之间的相关性.提出了一种把所关注频率值的变化曲线从时频分析图中提取出来的方法,以定量的研究引起频率值变化的原因.针对某型机平飞状态出现的垂尾尖部振动较大现象,运用此方法提取频率变化线,通过与发动机参数的对比与拟合,确认了该振动产生的振源来自发动机的高压转子. 相似文献
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《Journal of The Franklin Institute》2022,359(7):3238-3290
The space debris removal system (SDRS) of tethered space tug is modelled as a cable dragged flexible spacecraft. The main goal of this paper is to develop a dynamic modeling approach for mode characteristics analysis and forced vibration analysis of the planar motion of a cable dragged flexible spacecraft. Solar arrays of the spacecraft are modelled as multi-beams connected by joints with additional rotating spring where the nonlinear stiffness, damping and friction are considered. Using the Global mode method (GMM), a novel analytical and low-dimensional nonlinear dynamic model is developed for vibration analysis of SDRS to enhance the design capacity for better fulfillment of space tasks. The linear and nonlinear partial differential equations that governing transverse vibration of solar arrays, transverse and longitudinal vibrations of cable are derived, along with the matching and boundary conditions. The natural frequencies and analytical global mode shapes of SDRS are determined, and orthogonality relations of the global mode shapes are established. Dynamical equations of the system are truncated to a set of ordinary differential equations with multiple-DOF. The validity of the method is verified by comparing the natural frequencies obtained from the characteristic equation with those obtained from FEM. Interesting mode localization and mode shift phenomena are observed in mode analysis. Dynamic responses of the system excitated by fluctuation of attitude control torque and short-time attitude control torque are worked out, respectively. Nonlinear behaviors are observed such as hardening, jump and super-harmonic resonances. Residual vibration of the overall system with considering the varous values of nonlinear stiffness, damping coefficient and friction coefficient has shown that the nonlinearity of joints has a great influence on the vibration of the overall system. 相似文献