【作者】 钟智攀；

【导师】 陈科；

【作者基本信息】 合肥工业大学 ， 机械电子工程， 2009， 硕士

【摘要】 发动机曲轴是发动机中最重要的部件之一,它承受复杂、交变的冲击载荷,是发动机设计的重点和难点。传统设计、分析方法的简化难以满足实际的需要,而多体动力学和有限元法的发展使得精确地分析曲轴动力学响应问题成为可能。本文探讨用数字样机技术,通过多体动力学仿真手段和有限元分析对发动机曲轴力学性能进行了研究。主要的研究工作概括如下:〔1〕结合现代机械设计的应用理论,系统介绍了现代内燃机设计开发过程的重要技术——数字样机技术;介绍了应用数字样机技术开展曲轴系统动力学研究的主要流程。〔2〕在对曲轴强度的研究中,应用ADAMS软件,建立曲轴连杆和机体模型,进行了基于数字样机技术的曲轴系的动力学分析,模拟了曲轴的实际工作状况,得到曲轴的主轴颈及连杆轴颈受力情况,从而为进一步研究分析曲轴强度奠定了基础。〔3〕应用Pro/E软件建立曲轴的三维实体模型,通过Pro/E与ANSYS的接口将其转换成ANSYS有限元模型,对曲轴进行网格划分和边界条件的施加,进行了基于有限元方法的曲轴静态强度分析,分析了曲轴的变形和应力状态,并完成了曲轴的疲劳强度计算,结果表明,该曲轴的强度满足设计和运行工况的要求。〔4〕基于上述有限元模型对曲轴进行模态分析,计算了曲轴前6阶自由振动模态,分析了模态的振型及固有频率。通过模态实验和有限元计算相结合的方法来验证有限元模型的准确性。数据表明,有限元计算模态结果与实验测试结果吻合较好,表明曲轴有限元模型在一定频率范围内能较好地表征各自物理模型的动态特性。曲轴的模态频率能够用来预测发动机各部件之间动态干扰的可能性,通过合理的结构设计可以避开共振频率。这为发动机曲轴优化、改进设计提供了有价值的理论依据。研究结果表明,利用数字样机技术,结合有限元分析手段可以完成发动机曲轴的动力学响应分析工作,获得了很好的仿真结果,同时对于发动机曲轴的改进设计,提高发动机设计水平及提高发动机整机性能有着重要意义,是既经济又有效的科学化手段。更多还原

【Abstract】 Crankshaft is one of the most important parts in engine, which bears the complicated and alternant of the impact load and is the focus and difficult in engine design. The simplified analytical methods can not meet the actual needs by traditional design, and multi-body dynamics and finite element method allows the development of more accurate analysis of the crankshaft in response to the question of dynamics possible.This paper discusses the use of digital prototyping technology, mechanical properties of the engine crankshaft are studied by means of multi-body dynamics simulation and finite element analysis. The main research work is summarized as follows:(1) Combining with the application of modern mechanical design theory, modern internal combustion engine system design and development indispensable technology - digital prototyping technology is introduced; the application of digital technology to carry out the crankshaft system dynamics on the main steps is also introduced.(2) Establishment of the crankshaft connecting rod the body model with ADAMS on the study of crankshaft intensity. Based on digital prototyping technology of the crankshaft dynamics analysis, the actual working conditions of the crankshaft is accurately simulated to gain the main axis of the crankshaft carotid and connecting rod journal forces, providing the foundation for further research and analysis of the strength of crankshaft.(3) The three-dimensional solid model of the crankshaft is established with Pro/E. Through the Pro / E and ANSYS interface to convert the ANSYS finite element model, the crankshaft meshes and boundary conditions imposed are realized. The finite element method based on the crankshaft static strength analysis of the crankshaft of the deformation and stress state calculates the fatigue strength of the crankshaft, and the results show that the strength of the crankshaft design and operating condition meet the requirements of working conditions perfectly.(4) Modal analysis were finished based on the above finite element model of crankshaft, the crankshaft before the 6-order free vibration modal analysis of vibration mode shapes and natural frequencies were calculated. By modal experiments and the combination of finite element method, the accuracy of finite element model is verified. Datum show that the finite element method and experimental modal test results agree well, indicating that finite element model of the crankshaft in a certain frequency range can better characterize their dynamic characteristics of the physical model. Modal frequency of the crankshaft can be used to predict the engine components of the possibility of dynamic interference, so the rational structural design could avoid the resonance frequency. Optimize for the engine crankshaft to improve the design based on valuable theoretical basis.With digital prototyping technology, the results combining with finite element analysis tools to complete the engine crankshaft dynamic response analysis show that a very good simulation results can be obtained. It is of great significance for improving the design of the engine crankshaft, improving the level of engine design engine performance, which is both economical and effective scientific means.更多还原