基于虚拟仪器的舰船动力装置振动测量系统开发

以虚拟仪器LabVIEW为平台选择振动测量系统硬件,研制舰船动力装置振动测量系统,实现对舰船动力装置振动监测与分析的功能。通过与比利时LMS公司振动测试系统的对比振动测量分析试验,验证了基于虚拟仪器振动测量系统在其精度、功能和稳定性等方面均能满足测试分析的技术要求。     

基于改进HHT变换法的波纹补偿器振动信号分析

为解决波纹补偿器产生的非线性、非平稳振动信号处理困难的问题,提出了 一种基于改进HHT变换法的波纹补偿器振动信号分析方法.改进HHT变换法首先是对振动信号进行小波降噪处理,然后通过EMD法分解出若干IMF,最后对每个分解后的IMF分量进行Hilbert变换得到Hilbert谱和Hilbert边际谱.经实验验证,改进HH...     

The stability and mechanical characteristics of heavy haul couplers with restoring bumpstop

To investigate the stability and mechanical characteristics of a type of heavy haul coupler with restoring bumpstop, the geometry and force states of couplers were analysed at different yaw angles and the longitudinal forces. The structural characteristics of this coupler were summarised. To aid in the investigation, a multi-body dynamics model with four heavy haul locomotives and three detailed couplers was established to simulate the process of emergency braking. In addition, the coupler yaw instability and lateral forces were tested in order to investigate the effect of relevant parameters on the locomotive's wheelset lateral forces. The results show that only when the bumpstop force exceeds half of the coupler longitudinal compression force, can the follower be rotated and the yaw angle of the coupler increase. The bumpstop preload is the most important stabilising factor. The coupler lateral force is constant when the coupler longitudinal force is smaller than the critical values of 2000, 1400 and 1150 kN at coupler free angles of 7°, 8° and 9°, respectively, for operation on straight track. The coupler free angle and the locomotive's lateral clearance of the secondary stopper are important in decreasing the wheelset lateral forces of the locomotive. It is advised that a smaller locomotive's secondary lateral suspension stiffness, a free clearance of 35 mm and an elastic clearance of 15 mm from the secondary lateral stopper be selected. If the coupler's free angle is less than the self-stabilising angle which is 5.5° for operation on straight track, the coupler is stable no matter how great the longitudinal force is. The wheelset lateral forces are allowed at the coupler longitudinal force of 2500 kN when the free angle is 6°. These studies establish meaningful improvements for the stability of couplers and match the heavy haul locomotive with its suspension parameters.     

A curving ACC system with coordination control of longitudinal car-following and lateral stability

The paper presents a curving adaptive cruise control (ACC) system that is coordinated with a direct yaw-moment control (DYC) system and gives consideration to both longitudinal car-following capability and lateral stability on curved roads. A model including vehicle longitudinal and lateral dynamics is built first, which is as discrete as the predictive model of the system controller. Then, a cost function is determined to reflect the contradictions between vehicle longitudinal and lateral dynamics. Meanwhile, some I/O constraints are formulated with a driver permissible longitudinal car-following range and the road adhesion condition. After that, desired longitudinal acceleration and desired yaw moment are obtained by a linear matrix inequality based robust constrained state feedback method. Finally, driver-in-the-loop tests on a driving simulator are conducted and the results show that the developed control system provides significant benefits in weakening the impact of DYC on ACC longitudinal car-following capability while also improving lateral stability.     

斜拉桥斜拉索二维涡激振动的数值模拟研究

采用基于RANS方法的SST湍流模型对斜拉桥斜拉索二维（2D）模型涡致振动进行了数值模拟。2D模型建立和网格划分通过专业前处理软件ICEM—CFD来实现。保持2D模型的频率不变,通过改变风速的方法来研究2D模型涡致振动的特性。研究了2D模型涡致振动的幅值,阻力系数以及锁定区域随约减阻尼变化的规律。研究结果表明斜拉索2D模型发生涡致振动时其幅值随着约减阻尼减小而增大,直至稳定到一个常数,同时通过比较发现数值模拟得到的2D模型幅值与试验结果比较接近;锁定区域随约减风速减小而增大;同样2D模型的平均阻力系数在锁定区域随着约减风速减小而增大。     

桁宽对大跨度铁路斜拉桥车-桥耦合振动性能的影响研究

为考虑桁宽对大跨度铁路斜拉桥动力特性及车辆走行性的影响,以某主跨580m双塔斜拉桥为背景,分别建立了3种不同桁宽(15,24,30m)桥梁的有限元模型,对比其固有频率的差异,并通过车-桥耦合振动分析,比较了3种桁宽情况下桥梁、列车的动态响应。分析结果表明,桥梁横向振动和扭转振动的频率随桁宽的增加而明显增大,竖向振动频率随桁宽的增加而略有减小;主梁的横向位移随桁宽的增加而明显变小,桁宽15m出现了规律性的横向振动;3种桁宽情况下车辆响应变化不明显,桁宽15m时动车和拖车的响应(特别是轮轴横向力及减载率)总体上较其他2种桁宽的响应略大,车辆的响应对桁架的宽度变化不敏感。     

不同质量比对刚性圆柱体涡激振动振幅的影响

涡激振动发电装置是一种能够捕获浅海区域低流速海流能的新型能源装置,为了在不同海况下均能高效地对能量进行转换,需要对振动参数进行探讨,因此本文对质量比在振动响应和能量方面进行了分析。结合尾流振子模型和结构振动模型,得到双自由度涡激振动耦合模型,将Stappenbelt实验设置输入该模型,模型计算结果与其实验结果吻合,验证了模型的正确性。通过对中低质量比、超低质量比和高质量比三种条件下的柱体涡激振动响应进行分析,结果表明：中低质量比条件下,振幅和频率锁定区间宽度随质量比增加而减小;超低质量比条件下,顺流向无量纲振幅接近1,无法忽略,双向最大振幅发生约化速度Ur=6附近;高质量比条件下,最大振幅所对应的约化速度随着质量比的增加而增加,顺流向第二次波峰消失,横向出现两次波峰。     

基于横向安全距离模型的主动避障算法

现有的安全距离模型是基于纵向相对车速或减速度值建立的,没有考虑移动目标的横向运动特性。本文利用移动目标横穿马路的速度、相对位置,建立横向安全距离模型,并提出一种基于横向安全距离模型的主动避障算法。首先,根据横向移动目标横穿马路的速度、相对位置和自车的制动距离建立横向安全距离模型,设计主动避障算法。接着,为计及路面条件对制动效果的影响,引入当前行驶路面估算的附着系数峰值估算最大制动减速度,约束目标避障减速度,并调整制动强度,以适应不同路况的安全避障行驶。最后,以典型横向移动目标骑行者作为研究对象,通过PreScan/Simulink/CarSim联合仿真验证避障算法的有效性。结果表明:基于横向安全距离模型的主动避障算法能有效避免与骑行者碰撞,提高行车的主动安全性。     

混凝土腐蚀后列车振动对水下交叉隧道的影响分析

针对联络横通道与主隧道连接形成的交叉隧道结构,利用海蚀条件下衬砌混凝土的经时力学模型和塑性损伤本构模型,考虑高速列车的行驶效应,开展实测高速列车振动荷载作用下,交叉隧道结构在混凝土遭受腐蚀影响后的结构损伤分析。研究表明:列车行驶引起的主隧道压致和拉致损伤主要分布在隧道底部大约130°的区域,且主隧道的拉致损伤程度和范围相对压致损伤更大,拉致损伤最大值约为压致损伤的5.1倍;随着列车行驶速度的增大,隧道的损伤将更加显著,并朝着隧道的中上部位置发展,列车行驶速度从300 km/h提升至350 km/h,压致损伤最大值和拉致损伤最大值分别增加了53%、36%左右;联络横通道的损伤区域主要集中在其边墙和拱部。     

车桥耦合振动分析的数值方法

车桥耦合振动问题是铁路和公路桥梁中十分重要的研究课题， 而目前所采用的数值算法所需的时间比较长， 为了减少计算机时， 本文在对高速铁路曲线梁车 桥耦合振动研究中， 建立了一种基于激励非线性振动的数值计算方法， 并完成了计算程序 Ｂ Ｓ Ｎ Ｄ Ｓ 的编制， 取得了较好的计算结果． 并将其与其他模型进行比较， 在保证精度的前提下， 较大地节省了计算时间