【作者】 郭磊；

【导师】 郝志勇；

【作者基本信息】 浙江大学 ， 动力机械及工程， 2009， 博士

【摘要】 数字化仿真技术和试验识别方法是开展车辆和发动机系统振动噪声分析和控制的有力手段。本文对发动机和变速箱组成的动力总成结构的重要运动系统,曲柄连杆机构和齿轮传动系统采用虚拟样机技术进行动力学特性的分析,在此基础上对结构重要运动部件和固定件进行强度、振动和噪声特性的深入细致的研究。建立曲轴系与缸体系统三维耦合弹性体动力学模型,通过轴系扭振响应仿真和试验结果验证了轴系动力学模型,主轴承动载中考虑轴颈倾斜和弹性耦合效应,探讨了弹性耦合及轴承间隙对气缸体振动噪声特性的影响。在轴系耦合动力学结果基础上,使用直接瞬态法和模态应力合成法分析曲轴结构的动态强度。提出了位移-应力场的精细有限元方法,来分析曲轴油孔和圆角处的动态强度,并校核曲轴圆角高周疲劳设计准则下动态疲劳安全性。使用龙格库塔数值积分方法求解活塞体二阶运动的动力学方程,分析活塞二阶运动的时域特性及对缸套的动态敲击机理,并分析了活塞二阶运动的敏感参数影响,通过试验方法识别缸体上部的振动特性,验证仿真模型的准确性。在整车转毂试验台对变速箱和油底壳结构的表面振动测量,并换算了出结构的辐射噪声声功率,分析了油底壳结构中各侧面板振动对整体辐射噪声的贡献量。建立变速箱齿轮传动系的多体动力学模型,从内部与外部激励的角度研究齿轮传动系的动力学特性,并分析壳体结构的动态响应和辐射噪声特性。建立动力总成结构的全弹性振动响应模型,其800Hz内振动响应与试验结果吻合较好。同时为缩短建模和分析时间,开发出动力总成装置的双质量振动模型,与全弹性体振动响应结果对比,验证了双质量模型的有效性,为动力总成振动分析提供了新的计算模型。结构轻量化设计利用镁合金AZ91D材料开发出油底壳和变速箱壳体结构,提出镁合金结构的声-振特性及结构强度分析方法,并对镁合金结构进行声振特性的优化设计。本文从工程学设计分析角度推动了数字化仿真技术在动力总成结构领域的应用,从技术角度开拓出相关的新方法和技术流程,取得了一系列具有工程实用价值的成果,对汽车和发动机企业具有实际的工程意义。更多还原

【Abstract】 Numeric simulation technology and experimental identification method are two effective ways for analyzing vibration and noise of vehicles and engine systems. With the processes of virtual forcasting, this paper analyzes dynamic characteristics of the important motion sub-system of the powertrain, consist of engine and gearbox, crank-connecting rod mechanism and gear transmission system. Furthermore, research topics are worked on the strength, vibration and noise characteristics of important structural motion parts and fixing parts.By comparing simulated and tested results of torsional vibration response of the crankshaft system, an elastical dynamic model, which is built by coupling the crankshaft system and cylinder system, is verified valid. Main bearing dynamic loads has taken the effects of journal tilt and elastic coupling into account, and the effects of elastic coupling and bearing clearance on the vibration and noise behavior of cylinder body are discussed. Based on the shaft coupling dynamics, dynamic strength of the crankshaft system is analyzed both by direct transient method and modal stress synthesization method. With the fine FEM in the displacement-stress field, the dynamic strength of the crankshaft oil orifices is researched. Meanwhile the dynamic fatigue safety of the crankshaft fillets is checked under the high-cycle fatigue designing principle. The R-K numeric integration method is used to solve the dynamics equation for the secondary motion of the piston. The time-domain characteristic of the secondary motion, dynamic slap force of the piston on the cylinder liner, and the influence of the sensitive parameter are discussed as well. With experiments results, the vibration characteristic of the cylinder surface is identified, in order to verify the accuracy of the simulation model.Measurement has been made on the surface vibration of the gear box and oil pan on a vehicle roller testbed, calculating out the structural noise radiation power and analyzing the variant contribution of each side plate vibration to the whole radiated noise. A multi-body dynamic model is built for the gear train, to study the dynamical characteristics of the gear train by the perspectives of both the internal and external excitations. Dynamic response and radiated noise characteristics are analyzed for the gearbox shell structure. The vibration response of a full elastic model built for the power train agrees well with the experiments within 800 Hz. Meanwhile, to shorten modeling and analyzing time, a double-mass vibration model has been developed for the power train. Compared with the full elastic model, the double-mass model is validated, providing a new calculation model for the power train vibration analysis. The magnesium alloy AZ91D is used to design out a lighter oil pan and gearbox shell structure. And an analyzing method for the noise-vibration characteristic and structural strength is presented for the magnesium structure, and for the optimization of its noise-vibration characteristic.The paper promotes the application of the numeric simulation technology in the domain of powertrain, by a way of engineering design and analysis, and developed the related new method and technical process. It has gained a series of results with practical engineering value for the vehicle and engine companies.更多还原