【作者】 张帆；

【导师】 刚宪约；

【作者基本信息】 山东理工大学 ， 车辆工程， 2012， 硕士

【摘要】 车身骨架作为客车的主要承载结构,其结构安全性是客车被动安全性能的重要指标,也是保证客车可靠运行的关键因素。与此同时,车身骨架的质量在客车整备质量中占有较大的比重,对其进行轻量化设计既能减少客车的能源消耗,又能降低其碰撞能量,是提高客车的能源利用效率和结构安全性的重要措施。采用有限元技术对客车的车身骨架进行静、动态的结构校核和轻量化设计在提高客车的安全性、舒适性、降低能源消耗和减少排放等方面具有重要意义。目前,基于有限元技术的空气悬架客车结构特性分析在车身骨架的典型工况分析、拓扑优化设计和侧翻安全性仿真三方面尚存在以下不足：基于简化悬架法的典型工况建模方法难以准确模拟空气悬架的耦合承载特性,且忽略了高度阀组合控制方式的作用,与空气悬架的实际承载特性有一定差异。拓扑优化设计中,车身骨架有限元模型较为庞大,需要耗费大量的计算资源；且边界条件设置过于简化,拓扑优化结果的可靠性较低。进行全试验周期的客车侧翻安全性仿真,计算规模庞大,不利于缩短设计周期。针对以上不足,本课题开展了如下相关理论研究和工程运用工作：1、建立了基于载荷等效法和辅助约束法相结合的空气悬架客车典型工况有限元建模方法：通过力学分析与数值求解,建立了空气悬架系统耦合承载特性的分析计算方法；建立了基于载荷等效法和辅助约束法相结合的有限元建模方法。基于上述方法,课题进行了Corp612A、Corp612B两型空气悬架客车的典型工况结构校核和轻量化改进。Corp612A型客车实车减重170Kg,并已通过可靠性试验,Corp612B型全承载式客车设计减重250Kg。2、建立了基于子结构技术和载荷等效法的客车车身骨架拓扑优化方法：在拓扑优化分析中引入子结构技术,将非拓扑区域结构凝聚为超单元,达到节约计算资源的目的；同时,采用基于载荷等效法和辅助约束法相结合的建模方法,提高拓扑优化结果的可靠性。基于上述建模方法,课题进行了客车顶棚、侧围和底架格栅的单工况和综合工况拓扑优化分析,子结构技术的引入使拓扑优化分析效率提高了两个数量级以上3、建立了基于刚体预处理的客车侧翻安全性有限元建模方法：基于翻转、跌落阶段的刚体车身假设,进行了客车模型与地面碰撞的初始条件分析,获得碰撞瞬时客车模型参数；通过修改原始的客车侧翻安全性有限元模型生成了客车碰撞阶段的有限元模型。基于上述建模方法,课题进行了Corp612B型全承载式客车碰撞阶段的侧翻安全性仿真分析,验证了该建模方法的可行性,同时对客车的上部结构进行了改进设计,提高了其侧翻安全性。更多还原

【Abstract】 As the main bearing structure of bus, structure security of the body frame, as an iMPortant index of passive safety performance, is a key factor for reliable operation. Meanwhile, the quality of body frame takes great part of the bus equipment quality. Therefore, lightweight design for body frame is an iMPortant measurement for developing energy-saving and safe bus. Processing static and dynamic structure safety analysis and lightweight design though finite element analysis has a vital significance in iMProving passive safety performance, traveling comfort, smooth operation, reducing energy consuMPtion and emissions, etal.At present, deficiencies of finite element analysis technique of air suspension bus in structure characteristic analysis under typical working conditions, topology optimization design and rollover crashworthiness simulation are as follows:Traditional modeling method of finite element analysis under typical working conditions can not accurately simulate the bearing characteristics of air suspension system, the altitude valve control mode of air spring has also been ignored, which means the bearing characteristics of FEA model have certain differences with actual bearing characteristics of the body frame. Topological optimization design take too much coMPuting resources because dimensions of FEA model is too large; and also boundary conditions are always too siMPlified, reliability of the analysis results is low. The FEA size it too large in rollover crashworthiness simulation of the whole test cycle, which is not conducive to shorten the design cycle.For the shortages above, this topic proceeded the following theoretical research and engineering application work:Based on equivalent load method and assistant constraint method, modeling method of air suspension bus FEA analysis under typiacl working conditions has been established. Combing theoretical analysis and numerical calculation method, analysis and calculation method of bearing properties of the air suspension system has been established; based on equivalent load method and assistant constraint method, FEA modeling method of air suspension bus has been established. Based on method above, finite element analysis and lightweight design of Corp612A, Corp612B air suspension bus has conducted. The quality of Corp612A bus reduced170kg and passed through the reliability test. After lightweight design Corp612B bus reduced250kg.Topology optimization modeling method based on substructure and equivalent load method has been established, substructure method has been introduced in the topological optimization analysis which greatly saves analysis time. Meanwhile, boundary conditions based on equivalent load method and assistant constraint method are set to accurately simulate the actual stress state of the body frame which iMProves the reliability of topology optimization analysis. Based on method above single and multiple conditions topology optimization of ceiling、side panel and chassis grid of bus has been conducted, validity of the modeling method is verified.A new rollover crashworthiness modeling method has been established. Take the bus model of rollover crashworthiness in the flip and falling phase as a rigid body, crash initial conditions of the bus model were obtained though theoretical calculation. A new bus rollover crashworthiness model of crash phase was generated though modifying the original key file. Based on method above, rollover crashworthiness simulation of Corp612B bus was carried out which verified the feasibility and efficiency of the modeling method. The upper structure of the bus was modified according to the simulation result which iMProved the crashworthiness of the bus.更多还原