轨道梁特性对磁浮车轨相互作用研究

为缓解磁浮系统车轨耦合振动,目前往往采用增大轨道梁质量的方法来降低车轨系统耦合所带来的不利影响,但在研究过程中却忽略轨道梁刚度及车辆运行速度的变化对车桥振动的影响。为此,该文首先介绍磁浮轨道梁结构、特性要求以及车轨相互作用方式;然后采用车辆轨道垂向耦合动力学模型,仿真分析轨道梁刚度和车辆运行速度对磁浮车辆与轨道之间相互作用的影响。研究表明:轨道梁刚度对车轨振动响应影响较大,同时车速的影响也不能忽略。为以后轨道梁设计、安装及分析磁浮车轨相互作用提供一定的参考价值。     

考虑基础结构损伤的无砟轨道-车辆耦合动力模型及其求解

为了探究无砟轨道结构损伤与车轨动态相互作用的相互影响机制,基于经典的车辆-轨道耦合动力学理论,利用混凝土弹性损伤本构考虑无砟轨道结构的损伤效应,将车辆简化为多刚体系统,并假定随机性的轨面不平顺以单节车长为周期重现,利用Hertz非线性接触实现车辆系统与含损伤无砟轨道系统的垂向传力耦合,从而建立考虑轨道结构损伤效应的无砟轨道-车辆垂向耦合周期性动力模型;为了加速该同时包含材料非线性和接触非线性的动力模型求解的收敛速度,采用隐式动力预测-校正算法和轨道-车辆系统交叉迭代的求解策略,实现了含损伤无砟轨道-车辆垂向耦合动力模型的隐式快速求解。     

轨道接头压陷激励下轮轨垂向振动分析

本文基于车辆－轨道耦合大系统的思想，将钢轨简化为弹性点支承有限长的欧拉梁、轮轨接触关系采用弹簧接触，建立了轮轨动力学模型。对车轮匀速行驶过程中，在轨道接头压陷激励下轮轨相互作用产生垂向振动响应作了分析。并得出车速、轨头压陷波深对振动的影响。     

慢起慢落时磁浮车辆与钢轨道框架耦合共振分析

磁浮车辆在钢轨道框架慢起慢落的过程中会发生车轨耦合共振的情况，针对上海磁浮车在调试过程中遇到此类问题，进行了现场测试。测试数据说明：发生共振的频率是33Hz左右，这与钢轨道框架的垂向自振频率相同。理论分析表明，系统过程的稳定与二次悬挂的频率与阻尼、控制器的频带和阻尼、轨道的频率和阻尼及系统的基本参数（额定平衡位置、车轨质量比、线圈电阻及电感）都有关。因此在系统其他参数不变的情况下，通过改变钢轨道框架立柱的侧向刚度，也即改变钢轨道框架的自振频率，可以使系统在慢起慢落过程中稳定。     

小半径曲线中低速磁浮车辆-轨道耦合系统动力响应分析

小半径曲线上中低速磁浮车辆-轨道系统的动力响应对车辆安全运营具有重要意义,但当前研究极少涉及。运用有限元和多体动力学方法,建立了中低速磁浮车辆-小半径曲线段高架轨道耦合动力学模型,考虑空间动态磁轨作用以及轨道关键部件的参振作用,分析了小半径曲线上的车辆-轨道系统动力响应。结果表明：二维磁轨关系会过大地估算曲线段磁轨作用力;曲线段磁浮车辆车体主要为2 Hz以下的低频晃动;曲线段连续梁钢构高架轨道的振动主要由0～20 Hz的轨道整体弯扭变形和80～100 Hz的F轨局部弯扭变形引起;轨道垂向振动加速度缓和曲线段大于圆曲线段,横向振动加速度圆曲线段大于缓和曲线段,缓和曲线段振动加速度对车速变化更为敏感。研究结果可为曲线段磁浮高架轨道设计和车辆安全运营提供理论依据。     

车辆—轨道耦合系统垂横模型及其验证

本文根据车辆－轨道耦合动力学原理,建立车辆－轨道垂横耦合模型,并进行全面的验证：首先与国际著名软件NUCARS进行对比;其次与车辆－轨道垂向耦合模型得到的车辆和轨道系统垂向随机响应对比;然后与鹰厦线小半径曲线试验结果对比;最后与货物列车的线路试验结果对比。对比结果有力地验证了车辆－轨道耦合系统垂横模型及其求解方法的正确性和合理性,为车辆－轨道耦合系统垂横模型的广泛应用奠定了基础。     

不平顺条件下高速铁路轨道振动的解析研究

为了分析不平顺条件下高速铁路轨道结构振动,推导了移动车辆在轮对处和轨道结构在轮轨接触点处的柔度矩阵,考虑移动轴荷载和轨道不平顺,建立了移动车辆-轨道垂向耦合振动的解析模型.模型中,移动车辆考虑为弹簧和阻尼器连接的多刚体系统;有碴轨道结构模拟为连续弹性3层梁;轮轨间考虑为线性赫兹接触.算例分析了单台TGV高速动车引起的有碴轨道结构振动,得到轨道不平顺引起的动态轮轨力和轨道各部分的最大振动加速度,研究了列车速度、轨道不平顺以及轨下垫板及扣件、道床和路基等轨下基础刚度对轨道振动的影响.计算表明:随着列车速度和轨道不平顺的增加,轨道结构的振动响应不断增大;轨下基础刚度对轨枕和道床的振动影响较大,对钢轨振动的影响较小.     

缩尺比例车辆-轨道垂向振动实验系统研究

在分析车辆-轨道垂向耦合振动模型基础上提出基于相似性原理的缩尺轨道垂向振动实验台,具体阐述其关键参数的计算方法;基于轨道车辆运行设计沿轨道纵向运行的加载小车,实现车辆载荷移动加载;基于虚拟仪器技术实现实验台控制及数据采集。通过对缩尺实验台动力学模型数值仿真、实验结果表明,该缩尺轨道垂向振动实验系统能模拟车辆-轨道垂向耦合振动的低频振动特性。     

固定谐振荷载作用下曲线轨道动力响应特性研究EI北大核心CSCD

将曲线轨道视为周期性离散支撑结构,根据周期性结构的振动特性,通过引入移动荷载作用下曲线轨道梁的数学模态以及广义波数,得出曲线轨道梁频域响应的级数表达,进而求解固定谐振荷载作用下曲线轨道梁平面外弯扭耦合振动的响应特性。通过计算不同频率固定谐振荷载作用下曲线轨梁的动力响应,可以求得曲线轨梁垂向位移频响特性。对单层离散点支撑轨道模型进行计算分析可知:曲线轨道梁一阶自振频率受扣件支点垂向支撑刚度、垂向支撑阻尼系数、扣件支点间距变化影响较大,扣件支点垂向支撑刚度增加时轨梁一阶自振频率提高,垂向支撑阻尼系数增加时轨梁一阶自振频率略有减少,扣件支点间距减小时轨梁一阶自振频率提高;扣件支点间距对曲线轨梁频响特性具有显著的影响,跨中处一阶pinned-pinned共振峰幅值及支点处反共振峰幅值随支点间距的增加而变大;曲线半径对地铁轨道轨梁垂向位移频响特性几乎没有影响。     

高速磁浮桥上轨道梁振动特性初步研究

将磁浮车辆、桥上轨道梁及下部桥梁视为整体大系统,建立磁浮车辆-轨道梁-桥梁动力耦合模型,并应用Fortran语言进行程序设计,利用其进行计算机仿真,研究在不同幅值、不同波数和不同波长的正弦不平顺作用下的系统振动响应规律.     

线路不平顺对高速磁浮铁路动力响应特性的影响

基于动力有限元和耦合振动理论建立了高速磁浮列车-轨道梁动力学模型。通过仿真计算得到了高速磁浮线路确定性不平顺及随机不平顺对系统动力指标影响规律,提出了控制磁浮线路不平顺的参考建议。     

轨道梁在磁浮列车以共振速度通过时动力响应分析

该文研究了高速磁浮列车运行引起的轨道梁动力响应问题。采用模态综合技术建立了梁墩体系模型,推导了高速磁浮列车轨道梁运动方程,运用迭代技术求解了列车轨道梁系统动力学方程,计算分析了高速磁浮列车通过24m简支轨道梁引起的动力响应,结果表明:随着运行速度提高,轨道梁动力响应相应提高,在350km/h左右存在一阶二次谐波共振;当列车运行速度超过400km/h时,轨道梁和列车动力响应将被显着放大,为避免轨道梁出现一阶一次共振现象,在设计上,应使轨道梁的一阶自振频率远高于磁浮列车与轨道梁的特征频率(即设计速度与车长比值)。     

磁浮车辆-桥梁耦合系统随机振动分析的时域显式方法研究

轨道不平顺所引起的磁浮车辆-桥梁耦合系统随机振动问题是磁浮列车行驶过程中需要关注的重点问题之一,传统的随机振动方法在解决这类问题时存在工作量大、计算效率低等问题。分别从磁浮车辆系统和桥梁系统出发,建立磁浮车辆系统响应和桥梁系统响应关于车桥相互作用电磁力的时域显式表达式;利用车轨间的电磁力方程及几何相容条件,构建电磁力关于轨道不平顺的时域显式表达式;进一步推导得到轨道不平顺作用下磁浮车辆系统和桥梁系统关键动力响应显式表达式。在此基础上,利用统计矩运算法则,直接获得磁浮车辆系统和桥梁系统关键响应的演变统计矩;也可以利用轨道不平顺的数字生成技术,结合随机模拟法,获得车桥耦合系统关键响应的统计信息。在上述过程中,由于车桥耦合系统关键动力响应的显式表达式已先行构建完毕,因此大幅提升了随机振动分析的计算效率。以二自由度磁浮车辆与桥梁耦合模型为例,阐明了方法列式过程。磁浮列车过多跨简支梁桥的数值算例结果表明,时域显式法具有理想的计算精度和效率。     

弹性轨道上二自由度磁悬浮列车的动力特性分析

通过对弹性变形轨道上二自由度磁悬浮列车耦合系统动力特性的数值研究,给出了系统受控稳定性情形下控制参数G1,G2 的选取方式;讨论了控制参数G1,G2 和系统特征参数(如悬浮体质量Ms、运行速度v、轨道跨长L等)对磁悬浮系统的动力学特性的影响方式,分析了弹性轨道的变形特征等。     

Influence of Thermal Conductivity on Guidance Force Decay of HTS Bulk Exposed to AC Magnetic Field Perturbation in a Maglev Vehicle System

Bulk superconductors have great potential for various engineering applications, especially in a high-temperature superconducting (HTS) maglev vehicle system. In the vehicle system, the stable levitation can be achieved without any complex control system owed to the pinning effect of the bulks. However, the HTS bulks in the vehicle system were always exposed to the time-varying external magnetic field, which was generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, we studied the guidance force decay characteristics of the YBCO bulk over the NdFdB guideway used in the HTS maglev vehicle system by an experiment in which the AC external magnetic field generated by an electromagnet was used to simulate the time-varying external magnetic field caused by the inhomogeneity of the guideway, and calculated the guidance force decay as a function of time based on an analytic model. In this paper, we investigated the influence of thermal conductivity on the guidance force decay of HTS bulk exposed to AC field perturbation in the maglev vehicle system and tried to adopt a method to suppress the decay. From the results, it was found that the guidance force decay rate was higher for the bulk with the lower thermal conductivity. So, we could reduce the guidance force decay of the HTS bulk exposed to the AC external magnetic field perturbation in the maglev vehicle system by improving the thermal conductance of the bulks.     

中低速磁浮列车-低置梁系统竖向耦合振动研究

为了探讨中低速磁浮列车-低置梁系统竖向耦合振动,基于SIMPACK和ANSYS联合仿真,首先建立了中低速磁浮列车-桥梁/低置梁系统竖向耦合振动模型,以某试验线20 m简支梁现场动载试验为依据,验证此方法的可靠性。随后,根据所建立的中低速磁浮列车-低置梁系统竖向耦合振动模型进行动力仿真分析,并探讨了不同参数对低置梁竖向动力响应的影响。结果表明:低置梁自振频率较高,一阶竖弯达32.9 Hz;低置梁框架跨中竖向动位移及加速度均较底板中心大,框架振动属于高频振动（相对于底板振动）,在50 Hz~100 Hz加速度显著大于底板中心;磁浮列车荷载加载频率较高,该加载频率（整数倍）易与低置梁自振频率重合或接近而产生共振效应,显著放大低置梁动力响应;随着支撑脱空长度的增大,低置梁动力响应显著增大,且增速加大,随着路基刚度和底板厚度的增大,低置梁动力响应减小,且减小的幅度变小。     

Influence of Critical Current Density on Guidance Force Decay of HTS Bulk Exposed to AC Magnetic Field Perturbation in a Maglev Vehicle System

Superconducting maglev vehicle is one of the most promising applications of HTS bulks. In such a system, the HTS bulks are always exposed to AC external magnetic field, which is generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, we studied the guidance force decay of the YBCO bulk over the NdFdB guideway used in the High-temperature superconducting maglev vehicle system with the application of the AC external magnetic field, and calculated the guidance force decay as a function of time based on an analytic model. In this paper, we investigated the influence of the critical current density on the guidance force decay of HTS bulk exposed to AC field perturbation in the maglev vehicle system and try to adopt a method to suppress the decay. From the results, it was found that the guidance force decay rate was higher for the bulk with lower critical current density. Therefore, we could suppress the guidance force decay of HTS bulk exposed to AC external magnetic field perturbation in the maglev vehicle system by improving critical current density of the bulk.     

Influence of Work Height on Guidance Force Decay of HTS Bulk Exposed to AC Magnetic Field Perturbation in a Maglev Vehicle System

Bulk superconductors have great potential for various engineering applications, especially in superconducting maglev vehicle systems using high-temperature superconducting bulks. In such a system, the HTS bulks were always exposed to AC external magnetic field, which was generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, it was observed that the guidance force of the YBCO bulk over the NdFdB guideway used in the high-temperature superconducting maglev vehicle system was decayed by the application of the AC external magnetic field. In this paper, we investigate the influence of the work height on the guidance force decay of HTS bulk exposed to an AC field perturbation in the maglev vehicle system and try to adopt a method to suppress the decay. From the experimental results, it was found that the decay rate of the guidance force was smaller at higher work height in the case of the same field-cooled height. So we could suppress the guidance force decay of HTS bulk exposed to AC external magnetic field perturbation in the maglev vehicle system by increasing the work height of the bulk.     

Influence of Vertical Vibrations on an Array of Bulk HTSC Above the Permanent Magnet Guideway

The dynamic response of high-temperature superconducting (HTS) maglev vehicle system, which consists of a high-temperature superconductor (HTSC) array of seven YBa₂Cu₃O_7−x bulks above permanent magnet guideway (PMG), was investigated experimentally. The dynamic stiffness and displacements and the levitation force of the bulk HTSCs were investigated as function of the external excitation amplitudes in the range of 1–4 mm and frequencies in the range of 1–400 Hz. The levitation force and the resonance frequency and the dynamic stiffness of the bulk HTSCs are correlative to reduce with the excitation frequency lower than 30 Hz and the applied excitation amplitude higher than 3 mm due to the energy loss. However, the experimental results show the reduction occurred in the first several cycles, which proves that the array of the bulk HTSCs can sustain the external excitation vibration in the vertical direction due to its strong dynamic stiffness. The experimental results are helpful in the application of the HTS maglev vehicle in the future.