【作者】 张帅；

【导师】 王登峰；

【作者基本信息】 吉林大学 ， 车辆工程， 2018， 博士

【摘要】 车轮是汽车行驶系中最重要的承载件和安全件,在工作中承受的载荷和工况复杂。作为非簧载质量和汽车上主要的旋转和移动部件,其轻量化设计对汽车节能减排作用更加显著,更能有效地提高整车的轻量化水平;但同时极易引起车轮力学性能的降低。车轮轻量化的程度和综合性能的优劣直接影响汽车的经济性、动力性、操纵性、舒适性、制动性和行车安全。因此,在车轮轻量化设计时,需考虑车轮结构的改变对车轮的疲劳性能、冲击性能和气动性能等力学性能的影响。同时,采用多种轻合金材料组合应用、改善生产加工工艺和进行结构优化设计三种方法的协同运用是新型轻量化车轮开发的关键技术。因此,综合考虑车轮各项性能的结构-材料-性能一体化多学科多目标轻量化优化方法,是车轮轻量化的核心技术和研究热点。本文以16?61 ₂J型车轮为研究对象,基于联合拓扑优化技术设计一个由镁合金轮辋和铝合金轮辐构成的组装式车轮。基于弹性力学、塑性力学、断裂力学和流体力学的有限元分析方法,结合疲劳理论、冲击理论以及湍流理论,建立组装式车轮的有限元分析模型,研究车轮结构对车轮疲劳性能、冲击性能和气动性能的影响机制。在此基础上,综合考虑车轮的质量、强度、刚度、模态频率、疲劳寿命、13°冲击性能、90°冲击性能和气动性能等指标,基于代理模型方法对组装式车轮进行了多学科、多目标轻量化优化设计,并通过试验验证有限元分析模型的正确性和多学科、多目标轻量化优化设计的有效性。建立了车轮结构研发流程和多学科、多目标优化设计方法,为车轮开发和优化设计提供理论和技术依据。首先,基于车轮动态弯曲和径向疲劳试验工况进行联合拓扑优化,设计出一个组装式车轮。采用有限元分析方法研究组装式车轮的强度、刚度、疲劳寿命和径向疲劳寿命安全系数等性能参数与车轮结构之间的关系。计算和分析动态弯曲疲劳试验下螺栓的疲劳寿命,选定螺栓型号,并对螺栓连接的组装式车轮进行自由模态仿真分析。其次,建立组装式车轮13°冲击试验的有限元模型,分别分析冲锤正对辐条和正对窗口冲击两种工况下车轮的有效塑性应变和超出轮辐材料弹性变形极限的单元分布情况。还进一步建立组装式车轮90°冲击试验的有限元模型,分析冲锤正对窗口冲击时车轮内轮缘的变形量、轮辋和轮辐的有效塑性应变;同时分析冲锤正对气门嘴窗口冲击时车轮的破坏范围以及超出冲击部位圆周25%（90°）范围的轮辋和轮辐的有效塑性应变。并研究结构尺寸对车轮冲击性能的影响。接着,基于计算流体动力学（CFD）方法建立组装式车轮和不同轮辐结构车轮的空气动力学分析有限元模型。采用慕尼黑工业大学的DrivAer标准通用车模及其风洞试验数据来确定CFD仿真分析的计算方案。分析带有组装式车轮的整车和轮腔附近的流场特性以及制动盘的对流传热性能,并分析不同辐条数目、轮辐样式和辐条宽度下车轮的气动性能,研究车轮轮辐结构对整车和车轮流场与气动阻力以及制动盘对流传热性能的影响机制。然后,基于代理模型方法对组装式车轮进行多学科、多目标优化方法研究。利用网格变形技术建立组装式车轮在8种分析工况下的参数化模型,使用Isight软件平台集成各工况性能的计算软件进行优化拉丁超立方设计和中心复合设计,分别用来拟合克里金（Kriging）近似模型并检验其拟合精度。利用所建立的近似模型,采用第二代非劣排序遗传算法（NSGA-II）对组装式车轮进行多学科、多目标轻量化优化设计;得到Pareto多目标优化解前沿,在满足车轮各项性能约束条件要求下,选取车轮结构质量较小的妥协解确定优化方案,验证轻量化车轮多学科、多目标优化设计结果的性能,并研究优化前后车轮结构变化对各项性能指标的影响。最后,采用锻造工艺分别加工出组装式车轮的轮辋和轮辐样件,并对车轮进行动态弯曲疲劳试验、动态径向疲劳试验、13°冲击试验（辐条和窗口）、90°冲击试验（窗口和气门嘴）和模态分析试验。对组装式车轮各个试验的性能指标进行分析和评价,并通过各试验结果与仿真结果的对比验证有限元分析的正确性和多学科、多目标轻量化优化方案的有效性。更多还原

【Abstract】 The wheel is the most important load bearing and safety part in the driving system of a car,and the loads and working conditions are complicated in the work.As an unsprung mass and the main rotating and moving part of car,its lightweight design is more significant for the automobile energy saving and emission reduction,which can more effectively improve the whole car’s lightweight level.But at the same time it is very easy to reduce the mechanical properties of the wheel.The level of lightweight and the comprehensive performance of the wheel directly affect the economy,power,maneuverability,comfort,braking and traffic safety of the car.Therefore,in the lightweight design of the wheel,it is necessary to consider the influence of the change of the wheel structure on the mechanical properties of the wheel,such as the fatigue,impact and aerodynamic performance.At the same time,the key technology for the development of a new lightweight wheel is the collaborative application of the three methods with composite applications of multiple light alloy materials,improving production and processingtechnologyandoptimizingthestructure.Therefore,the structure-material-performance integrated multi-disciplinary and multi-objective lightweight optimization method,which comprehensively considers the performance of the wheel,is the core technology and hotspot of the wheel lightweight research.In this paper,taking a16?61 ₂J type wheel as the research object,based on the united topology optimization technology,an assembled wheel composed of a magnesium alloy rim and an aluminum alloy disc is designed.Based on finite element analysis methods of the elastic mechanics,plastic mechanics,fracture mechanics and fluid mechanics,combined with the fatigue theory,impact theory and turbulence theory,finite element analysis models of the assembled wheel are established to study the influence mechanism of the wheel structure on the wheel’s fatigue performance,impact performance and aerodynamic performance.On this basis,considering the performance indexes of the mass,strength,stiffness,modal frequency,fatigue life,13°impact performance,90°impact performance and aerodynamic performance of the wheel,based on the surrogate model method,multi-disciplinary and multi-objective lightweight optimization design of the assembled wheels is carried out,and the validity and accuracy of the finite element analysis models and the multi-disciplinary and multi-objective optimization design are verified through tests.This paper establishes a wheel structure research and development process and multi-disciplinary and multi-objective optimization design method for the wheel to provide theoretical and technical basis for the development and optimization of a wheel.Firstly,based on the dynamic bending and radial fatigue test conditions of the wheel,a united topology optimization is carried out to design an assembled wheel.The finite element analysis method is used to study the relationship between the performance parameters such as the strength,stiffness,fatigue life and safety factor of radial fatigue life of the assembled wheel and the wheel structure.The fatigue life of bolts under the dynamic bending fatigue test is calculated and analyzed,and then the type of the bolt is selected.And free modal analysis of the bolted assembled wheel is simulated.Secondly,finite element models of the assembled wheel for 13°impact tests are established to analyze the effective plastic strain of the wheel and elements distribution beyond the elastic deformation limit of the disc material under two conditions of the hammer facing the spoke and the window respectively.And establish finite element models of the assembled wheel for 90°impact tests further,analyzed the deformation of the inner wheel flange and the effective plastic strain of the rim and disc when the hammer impacted facing the window,and analyzed the failure range of the wheel and the effective plastic strain of the rim and disc beyond the 25%circumferential range（90°）of the impact position when the hammer impacted facing the valve window.Then research the influence of structure size on the impact performance of the wheel.Then,finite element models of the assembled wheel and wheels with different discs for aerodynamic analysis are established by using computational fluid dynamics（CFD）method.The DrivAer standard car model and its wind tunnel test datas of the Technical University of Munich are used to determine the calculation scheme of CFD simulation analysis and verify the correctness of the results.The flow field characteristics of the car with assembled wheels and wheel cavity and the heat transfer performance of the brake disc are analyzed.And the aerodynamic performance of wheels with different number,styles and widths of spokes are analyzed.The influence mechanism of the wheel disc structure on the flow field,the aerodynamic drag of the car and wheel and the heat transfer performance of the brake disc are researched.Subsequently,a multi-disciplinary and multi-objective optimization method for the assembled wheel is researched based on the surrogate model method.The parametric models of the assembled wheel under eight simulation conditions are established by using the mesh morphing technology.The Optimal Latin Hypercube Design and Central Composite Design are respectively used to fit the Kriging surrogate model and to validate the fitting precision of the surrogate model in Isight software platform where softwares calculating the performance indexes are integrated.Using the established surrogate model,the Non-dominated Sorting Genetic Algorithm-??（NSGA-??）is adopted to perform the multi-disciplinary and multi-objective lightweight optimization design of the wheel.The Pareto frontier is obtained,and a compromise solution with lighter wheel mass is selected as the optimization scheme while meeting the various performance requirements of the wheel.Verify the performance of the lightweight multi-disciplinary and multi-objective optimization design results,and research the influence of wheel structure changes on various performance indexes before and after optimization.Finally,the rim and disc samples of the assembled wheel are processed respectively by forging process.Then,the dynamic bending fatigue test,dynamic radial fatigue test,13°impact tests（spoke and window）,90°impact tests（window and valve window）and modal analysis test are carried out.The performance indexes of each test of the assembled wheel are analyzed and evaluated.And the correctness of the finite element analysis and the effectiveness of the multi-disciplinary and multi-objective lightweight optimization scheme are verified by the comparison of the test and simulation results.更多还原