高速列车转向架构架损伤、等效应力及寿命分布特性研究

为分析高速列车转向架构架损伤、等效应力及寿命分布特性,对构架疲劳关键测点进行动应力线路实测并对测点实测时域数据波形进行解析;基于实测应力时间历程及雨流计数法编制二维应力谱,利用Goodman等寿命方程将二维应力谱等效转换为一维应力谱;阐述线性累积损伤及非线性累积损伤模型的建立方法并对实测数据的线性累积损伤及非线性累积损伤进行了计算及对比分析;分别基于线性累积损伤理论及非线性累积损伤理论推导出各理论下的等效应力,基于实测数据对两种等效应力进行了计算及对比分析;通过结合非线性累积损伤及线性累积损伤理论计算的等效应力及不同可靠度下的材料S-N曲线计算并对比分析构架结构的疲劳寿命。研究结果表明,与非线性疲劳分析理论相比,线性疲劳分析理论对高速列车转向架构架的疲劳特性评估偏于保守。     

不同焊缝类型对宽轮距转向架构架疲劳分析的影响

转向架是单轨车辆核心的部件之一,承担着车辆的牵引、制动和承载作用,直接影响到车辆运行的安全性和可靠性。其中构架又是转向架的承载主体,传递并衰减轮轨与车体的振动。宽轮距转向架构架通过焊接和大量螺栓连接,事实上,在复杂的动载荷作用下,疲劳破坏主要从焊缝和螺栓连接处开始。对于焊接结构,由于焊接接头部位存在较大的应力集中,且常伴随有各种焊接缺陷,因而是最容易发生疲劳破坏的区域。所以焊缝结构疲劳分析及优化在设计阶段尤为重要。     

Theoretical research and experimental validation of elastic dynamic load spectra on bogie frame of high-speed train

When a train runs at high speeds, the external exciting frequencies approach the natural frequencies of bogie critical components, thereby inducing strong elastic vibrations. The present international reliability test evaluation standard and design criteria of bogie frames are all based on the quasi-static deformation hypothesis. Structural fatigue damage generated by structural elastic vibrations has not yet been included. In this paper, theoretical research and experimental validation are done on elastic dynamic load spectra on bogie frame of high-speed train. The construction of the load series that correspond to elastic dynamic deformation modes is studied. The simplified form of the load series is obtained. A theory of simplified dynamic load–time histories is then deduced. Measured data from the Beijing–Shanghai Dedicated Passenger Line are introduced to derive the simplified dynamic load–time histories. The simplified dynamic discrete load spectra of bogie frame are established. Based on the damage consistency criterion and a genetic algorithm, damage consistency calibration of the simplified dynamic load spectra is finally performed. The computed result proves that the simplified load series is reasonable. The calibrated damage that corresponds to the elastic dynamic discrete load spectra can cover the actual damage at the operating conditions. The calibrated damage satisfies the safety requirement of damage consistency criterion for bogie frame. This research is helpful for investigating the standardized load spectra of bogie frame of high-speed train.     

基于SIMPACK仿真分析的高速列车蛇行失稳识别方法

高速列车的横向运动稳定性不仅会影响列车的运行品质,还影响车辆的运行安全。现有的高速列车失稳在线监测方法大多是对高速列车大幅蛇行失稳状态进行识别,然而高速列车的小幅蛇行失稳状态很难被准确有效地识别出来。为此,提出了一种基于信号分析的蛇行失稳识别方法,不但可以识别出大幅蛇行失稳,而且可以识别出小幅蛇行失稳。首先通过SIMPACK软件建立高速列车动力学仿真模型,再现高速列车运行过程中出现的稳定、小幅蛇行失稳和大幅蛇行失稳状态;再对仿真结果的构架横向加速度进行分析,利用信号的周期性差异,计算其自相关系数并设定阈值,以此来识别小幅蛇行失稳状态和大幅蛇行失稳状态;最后通过实验数据验证了所提出的监测方法的有效性。     

二维随机载荷作用下疲劳寿命的研究

基于Goodman公式和Miner损伤定则,提出了一种考虑载荷均值影响的二维随机载荷作用下疲劳寿命的计算方法。在此基础上以幅值和均值均符合正态分布的随机载荷为研究对象,推导出了其当量载荷的概率密度函数和等效载荷的数学模型,采用Gauss-Legendre求积公式进行积分运算,对该载荷作用下的疲劳寿命进行了研究。分析了等效载荷随载荷均值和幅值不同分布参数变化而变化的规律,并与不考虑载荷均值的一维随机载荷作用下的等效载荷进行了对比。研究结果表明：载荷均值μm的正负变化对等效载荷产生明显的影响,负的μm导致等效载荷降低,甚至低于一维随机载荷作用下的等效载荷;而正的μm会导致等效载荷迅速增大以至到远大于一维随机载荷作用的等效载荷;当μm=0时,二维随机载荷则略高于一维随机载荷作用的等效载荷。     

随机载荷下焊接结构疲劳寿命的一种有效计算方法

随机载荷下的疲劳寿命估算方法通常涉及两个方面,循环计数和损伤累积。本文研究了一种用于随机载荷下焊接构件疲劳寿命预测的有效计算方法。按照这种方法,只要求已知应力历程的功率谱密度和常规疲劳试验数据,就可以对承受随机载荷的焊接构件作出疲劳寿命计算。利用结构系统的复频响应函数,可以由已知的输入功率谱求出结构响应的谱密度。这就使得结构设计者即使在设计阶段不知道结构承受的应力历程,而只知道结构系统的输入,也同样可以对所设计的结构作出疲劳寿命预测。本文所述方法被用于某超重型矿用汽车车架的疲劳寿命计算,计算结果与实际情况基本吻合。     

基于简化模型的头车转向架气动噪声特性研究

由于高速列车气动噪声形成的机理和分析较为复杂,目前的检测系统还不能从列车高速运行状态下噪声测试中做出清楚的分辨,通过计算流体力学方法研究高速列车头车转向架气动噪声特性。建立经过简化的转向架、头车未安装转向架的简化车身和头车安装简化转向架的车身三种计算模型,分析列车运行200 km/h,300 km/h速度下简化转向架周围流场与气动声场特性,进一步分析此速度下简化转向架对头车车外气动噪声的影响。分析结果显示转向架周围有周期性的漩涡生成、脱落现象,气动噪声在其周围的辐射规律呈现偶极子分布。转向架车轴和构架横梁的上、下表面为偶极子声源集中的部位。前轮对在垂直与气流方向的竖直平面上和平行于气流方向的竖直平面上引起的噪声比后轮对大,在平行于气流的水平平面上比后轮对小。两个速度下,转向架气动噪声分布规律大致相同,幅值有差别。转向架使头车车外噪声显著增高,转向架附近噪声增幅尤为明显。行车速度200 km/h时,简化转向架能使头车车外气动噪声幅值增大3~5 d BA,行车速度300 km/h时,增幅为5~8 d BA。     

柔性构架的动应力仿真研究

在 ANSYS 有限元分析软件中建立了转向架构架的柔性体模型,在 SIMPACK 多体动力学软件中建立了完整的车辆系统动力学模型,把 SIMPACK 中计算得到的构架载荷-时间历程引入 ANSYS 中得到构架各部位的应力分布以及关键部位的应力-时间历程,从而为构架的疲劳强度评估和疲劳寿命预测奠定了基础.这一方法不仅实现了有限元计算与多体动力学分析之间的有效结合,而且完成了多体系统动力学研究中刚体与柔性体之间的耦合,是构架设计新方法的尝试.     

Fatigue life estimation of MD36 and MD523 bogies based on damage accumulation and random fatigue theory

Bogies are one of the multifunctional parts of trains which are extremely subjected to random loads. This type of oscillating and random excitation arises from irregularities of the track including rail surface vertical roughness, rail joints, variance in super-elevation, and also wheel imperfections like wheel flats and unbalancy. Since most of the prementioned sources have random nature, a random based theory should be applied for fatigue life estimation of the bogie frame. Two methods of fatigue life estimation are investigated in this paper. The first approach which is being implemented in time domain is based on the damage accumulation (DA) approach. Using Monte-Carlo simulation algorithm, the rail surface roughness is generated. Finite element (FE) model of the bogie is subjected to the generated random excitation in the first approach and the stress time histories are obtained, and consequently the fatigue life is estimated by using the rain-flow algorithm. In the second approach, the fatigue life is estimated in frequency domain. Power spectral density (PSD) of the stress is obtained by using the FE model of the bogie frame and the fatigue life is estimated using Rayleigh technique in random fatigue theory. A comprehensive parametric study is carried out and effects of different parameters like the train speeds and level of the rail surface vertical roughness on the estimated fatigue life are investigated. This paper was recommended for publication in revised form by Associate Editor Hong Hee Yoo Davood Younesian received his MSc and PhD in Mechanical Engineering, both from Sharif University of Technology, Iran. He joined the Iran University of Science and Technology in 2005 as an Assistant Professor in the School of Railway Engineering. Dr Younesian’s research area is mainly focused on non-linear and random vibrations, optimal control of vibrations, dynamics and vibration of structures and railway vehicle systems. He has published more than 75 papers in international journals and conference proceedings in the areas of his research. Ali Solhmirzaei received his BSc in Railway Engineering (Rolling Stock) from Iran University of Science and Technology and his MSc in Mechanical Engineering from K.N.T University of Technology, Iran. His research is mainly focused on finite elements, railway vehicle dynamics and fatigue analysis of railway structures. Alireza Gachloo received his BSc in Railway Engineering (Rolling Stock) from Iran University of Science and Technology, Iran. His research is mainly focused on random vibration, railway vehicle dynamics and random fatigue.     

Sound Source Localisation for a High-Speed Train and Its Transfer Path to Interior Noise

Noise is one of the key issues in the operation of high-speed railways, with sound source localisation and its transfer path as the two major aspects. This study investigates both the exterior and interior sound source distribution of a high-speed train and presents a method for performing the contribution analysis of airborne sound with regard to the interior noise. First, both exterior and interior sound source locations of the high-speed train are identified through in-situ measurements. Second, the sound source contribution for di erent regions of the train and the relationships between the exterior and interior noises are analysed. Third, a method for conducting the contribution analysis of airborne sound with regard to the interior noise of the high-speed train is described. Lastly, a case study on the sidewall area is carried out, and the contribution of airborne sound to the interior noise of this area is obtained. The results show that, when the high-speed train runs at 310 km/h, dominant exterior sound sources are located in the bogie and pantograph regions, while main interior sound sources are located at the sidewall and roof. The interior noise, the bogie area noise and the sound source at the middle of the coach exhibit very similar rates of increase with increasing train speed. For the selected sidewall area, structure-borne sound dominates in most of the 1/3 octave bands.     

磁悬浮列车转向架疲劳寿命功率谱预测法

本文简要讨论了随机振动疲劳寿命分析中应力功率谱的获取，不规则性的描述及各种疲劳分析模型，并结合磁悬浮列车转向架的疲劳分析情况，得出了用Dirlik法进行疲劳寿命预测是相对最优的结论。最后利用有限元软件和Dirlik法相结合对磁悬浮列车转向架进行疲劳寿命预测，并与时域中的名义应力法所得结果相比较，证明了该法的最优性和有效性。     

重型燃气轮机叶片离心载荷下应力特性的研究

针对重型燃气轮机叶片疲劳寿命研究的需要,通过设计和搭建的全尺寸叶片疲劳试验装置,模拟离心载荷工况下的低周疲劳试验,开展离心载荷下叶片应力分布和疲劳寿命预测的研究。该全尺寸叶片疲劳试验装置能够模拟低周疲劳中的等效离心载荷工况,为叶片试验提供必要的条件和手段。同时,对叶片进行网格划分和有限元仿真计算后,得到叶片Von mises应力分布结果,发现叶身应力最大处位于中部偏下边缘薄壁侧。然后将有限元仿真及应力试验相结合,提出叶片疲劳试验的离心载荷等效方法。在此基础上完成叶片的动应力试验,获得应力时间历程数据,并且给出离心载荷应力谱。结果表明,叶身中部边缘的应力水平最高,动应力谱幅值与频数概率的分布服从6阶麦克劳林拟合函数,用等效离心载荷疲劳寿命进行叶片寿命预测的结果是偏安全的,该结论可作为优化设计和试验研究的参考依据。     

基于UIC标准的转向架构架强度评估

介绍了某型动车转向架焊接构架的结构特征,建立了其有限元模型;根据国际铁路联盟标准UIC615-4详细计算了构架强度分析所需的载荷条件,其中包含超常载荷、运营载荷、及附加载荷;对得到的载荷进行了组合,确定了强度分析的载荷工况,载荷工况又分为静强度评价载荷工况和疲劳强度评价载荷工况;对构架静强度进行了计算与评定,并用Goodman疲劳强度极限图对构架疲劳强度进行了评定。结果表明该转向架焊接构架能够满足标准规定的静强度及疲劳强度的要求。     

估算谱载下疲劳裂纹起始寿命的等寿命法

提出了一种新的估算谱载下疲劳裂纹起始寿命的方法，即等寿命法。该算法主要依赖于等幅试验结果，简便实用；同时能够反映变幅疲劳的基本特性。试验评估结果表明，该方法的预测能力明显优于当量损伤等其他十三种方法。     

底盘构件多轴随机载荷下高周疲劳准则研究

为探明汽车底盘构件在随机载荷下多轴高周疲劳准则的应用方法与寿命预测规律,以某品牌B级轿车为研究对象,通过采集试验场强化路轮心六分力信号,建立了整车多体动力学模型,应用虚拟迭代法获取转向节与其他零件连接点的载荷时间历程;建立转向节有限元模型,通过模态仿真与试验验证了有限元模型的准确性;提取了von Mises应力下寿命值最小节点的应力分量时间历程;研究了8种高周疲劳准则所基于的3种类型临界平面的计算方法,通过多轴循环计数提取临界面上正应力幅与剪应力幅,并计算不同准则对应的等效应力幅,总结幅值分布与寿命预测规律。研究结果表明,在幅值分布与寿命预测方面,Zhang-Yao准则的等效剪应力幅值整体偏大,预测寿命为1.09×105周次,较其他准则偏于保守;McDiarmid准则的大应力幅仅占3.4%,预测寿命为1.25×106周次,明显大于其他准则的预测寿命值,而改进的McDiarmid准则预测寿命值明显减小。在计算成本方面,von Mises准则无需提取临界面与多轴循环计数,应用最为便捷;Findley准则提取临界面过程需要计算所有平面的正应力与剪应力数据,故计算成本最高。     

高速铁路钢轨剩余疲劳寿命预测研究

利用断裂力学理论建立高速铁路钢轨剩余寿命的预测模型;首先对特定线路上钢轨的动载弯曲应力、温度应力、残余应力进行计算,然后利用预测模型估算高速钢轨的疲劳剩余寿命,分析钢轨材料、列车速度系数、钢轨基础弹性系数对钢轨剩余寿命的影响。结果表明:相同营运条件下,U71Mn钢轨剩余寿命比PD3钢轨长;钢轨剩余寿命随列车速度系数的增加而降低,随钢轨基础弹性系数的增长而延长。     

动态载荷峰值分布及在疲劳损伤分析中的应用

通过研究随机信号峰值分布的规律,提出了使用应力响应信号自功率谱密度函数来分析和预测零部件疲劳寿命的新方法。首先．由响应应力随机信号的自功率谱密度函数导出响应信号的峰值分布规律,然后通过计算损伤率并采用高周疲劳线性累计损伤理论来分析零部件的寿命。采用本文提出的方法,在摩托车车架可靠性试验中,通过计算机对车架进行了动载荷疲劳强度分析,取得了较好的工程效果。     

应用焊接头P—S—N曲线估算结构疲劳强度的若干问题

根据疲劳寿命的分散性规律，本文探索了Ｐ—Ｓ—Ｎ曲线的合理描述模型；考虑平均应力和焊接头与结构相似性的影响，提出了Ｐ—Ｓ—Ｎ曲线的当量对称循环应力幅化的方法和确定疲劳影响系数的相对疲劳影响系数法。实际结构的试验结果与估算结果的比较表明，本文的工作是有效的和合理的。     

车轮多边形对高速列车车轴疲劳强度影响研究

车轮多边形是铁道车辆一种常见的非圆化病害,对轮对振动和车辆运行安全有明显的影响。在建立刚柔耦合拖车和动车车辆系统动力学模型基础上,将车轮多边形简化为简谐波并将其考虑为车轮轮径的变化,研究20阶车轮多边形对拖车和动车车轴疲劳强度的影响。结果表明,等效应力幅比值与速度呈非线性关系,且拖车和动车峰值出现位置有所不同,拖车峰值位置出现在速度为225 km/h,对应多边形激励频率432.7 Hz;动车不同截面分别在300 km/h、375 km/h时存在峰值,对应多边形激励频率分别为576.5Hz、721.2Hz。在各峰值位置处,多边形幅值的变化对拖车和动车部分截面的等效应力幅比值均有显著影响。拖车和动车车轴等效应力最大值均位于C截面,并且随着车轮多边形幅值的增加,其等效应力显著增大,超过车轴疲劳强度限值,降低车轴使用寿命。研究结果有助于改善20阶车轮多边形对高速列车车轴疲劳强度及弹性振动的影响。     

基于等效结构应力法的镁合金接头疲劳寿命预测

针对镁合金焊接结构疲劳强度评估方法不全面的问题,在等效结构应力法的研究基础上,提出了镁合金焊接接头疲劳寿命预测方法。基于 200 余个包含不同特征的镁合金接头疲劳试验数据,采用有限元数值模拟,计算试件接头焊趾处的等效结构应力。结合 ASME 标准中对曲线拟合的规范,进行镁合金接头寿命曲线拟合,得出了预测疲劳寿命的常系数 C d 和 h 。将拟合结果与铝材的疲劳寿命曲线进行对比,结果表明,镁合金接头在 1×10^7?次循环下的疲劳强度约为 31.6 MPa ,同等条件下约为铝材疲劳强度的 82% 。该镁合金接头疲劳寿命预测方法可用于评估镁合金结构疲劳强度是否满足轨道车辆车体结构使用需求。