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动力链部件的耐久性不仅取决于曲柄机构激扰力,而且还受结构部件振动的影响,但这一点往往被人们忽略。本文中介绍了混合分析法,其特点是不把动态负荷看作离散的静负荷,而是根据包括动态结构性能的实时运行条件计算部件耐久性。研究工作是针对一台GE机车的GEVO16型柴油机动力链展开的,其包括一台V16型柴油机和一台由它直接驱动的交流发电机。对油底壳和集成式前端(IFE)进行了模拟,并通过测量对模拟结果加以确认。混合分析法综合利用两种广为采用的分析形式——多体分析(MBA)和有限元分析(FEA),以模拟部件动态负荷、组装负荷和热-机械负荷。基于有限元法导出的简缩模型,在多体分析环境下,将相关动力链部件(发动机机体、油底壳、集成式前端、曲轴以及交流发电机壳体)作为挠性体加以模拟。采用这种MBA模型,对若干燃烧循环进行模拟,其中动力链组件的挠性体承受气体力、活塞侧向力、轴承力和交流发电机反作用力矩的激扰。这种模拟方法可以将发动机机体变形和激扰力之间的相互影响加以考虑。还对动力链各部件之间的相互影响给予了足够重视,以逼近实测的发动机振动性能。部件变形可利用模型尺寸系数由动态MBA模拟导出,通过叠加到有限元模型进行转换,结果生成包含三维应力分布(以时间为自变量)的有限元模型。三维应力分布用于深入的动态疲劳分析,计算应力幅值和平均应力,再求出疲劳安全系数和/或疲劳寿命。为验证计算结果,对测定值和模拟结果进行了对比。动力链在曲轴箱和交流发电机壳体上配有一组加速度计,在油底壳和集成式前端安放应变片。对比结果表明,不论是总变形还是局部应变,都可达到良好的吻合。
The durability of the power chain components depends not only on the crank mechanism but also on the vibration of the structural components, but this is often neglected. In this paper, a hybrid analysis method is introduced, characterized by not considering the dynamic load as a discrete static load, but calculating the durability of the part based on real-time operating conditions including dynamic structural performance. The research was carried out on a GEVO16 diesel power chain for a GE locomotive that includes a V16 diesel engine and an alternator directly driven by it. Oil pan and integrated front-end (IFE) were simulated and the results of the simulation were verified. Hybrid analysis combines two widely used forms of analysis, the Multibody Analysis (MBA) and the Finite Element Analysis (FEA), to simulate the dynamic loads, assembly loads and thermo-mechanical loads on components. Based on the simplified model derived from the finite element method, the relevant power train components (engine block, oil pan, integrated front end, crankshaft, and alternator housing) are modeled as flexures in a multi-body analysis environment. Using this MBA model, a number of combustion cycles were simulated in which the flexure of the power train assembly was exposed to gas forces, piston lateral forces, bearing forces and alternator reaction torque. This simulation method considers the interaction between the deformation of the engine body and the force of the disturbance. Also paid attention to the interaction between the various components of the power chain in order to approximate the measured vibration performance of the engine. Component deformations can be derived from dynamic MBA simulations using model size coefficients, converted by overlaying finite element models, and as a result, a finite element model containing three-dimensional stress distributions (time-dependent) is generated. The three-dimensional stress distribution is used for in-depth dynamic fatigue analysis, calculating stress amplitude and average stress, and then calculating the fatigue safety factor and / or fatigue life. To verify the calculation results, the measured values and simulation results were compared. The power chain is equipped with a set of accelerometers on the crankcase and alternator housings, with strain gauges placed on the oil sump and integrated front end. The comparison results show that both the total deformation and the local strain can reach a good match.