【作者】 李欣冉；

【导师】 陈无畏；

【作者基本信息】 合肥工业大学 ， 车辆工程， 2012， 博士

【摘要】 随着国民经济的快速发展和人们生活水平的不断提高,汽车的保有量越来越大。在这种形势下,汽车的NVH性能(NVH即是噪声Noise,振动Vibration和声振粗糙度Harshness三个英文单词的首字母)得到了越来越多的关注,也被认为是衡量现代汽车工业水平的重要指标。由于该性能和人们的身心健康密切相关,很多国际组织都制定了相应法规来明确对汽车NVH性能的要求。同时学术界和工业界投入了大量的人力物力财力进行了研究。目前汽车的NVH研究主要集中在汽车的动力总成,进排气系统,传动系统等方面,本学位论文旨在研究在不同路面工况激励下的悬架系统的NVH性能,针对悬架关键参数对NVH性能的影响和改善进行了理论分析,仿真和试验研究。论文首先在查阅大量文献的基础上,回顾了汽车NVH技术发展历程和研究现状。然后采用有限元理论和方法,对悬架构件进行模态分析和柔性化处理。分析了路面不平垂向激励经过悬架传递到车身的传递路径,设定汽车NVH性能参数指标,并建立了刚柔耦合的汽车动力学模型。研究了不同工况条件下,前后悬架刚度阻尼对汽车NVH性能指标的影响。采用试验设计(DOE)方法,匹配优化改善汽车NVH性能。论文从理论上分析了悬架橡胶衬套的结构和材料特性,采用有限元方法分析其各向弹性变形,与厂商提供的试验数据对比。对比了衬套安装前后,汽车NVH性能指标变化,然后研究了不同方向刚衬套度对该指标影响的灵敏度。选择较敏感的参数进行试验设计(DOE),经过优化改善NVH性能。建立考虑衬套影响的半车模型,将其不同工况条件下的仿真结果与不考虑衬套影响的半车模型,刚柔耦合汽车动力学模型进行对比。论文从理论上分析了轮胎的结构和材料特性,建立了子午线轮胎滚动分析的三维有限元模型。在模型中充分考虑到轮胎材料和结构的复杂性,以及轮胎与轮辋、地面的接触摩擦,研究了轮胎转向状态下的不同车速和转向角对轮胎变形、接地区应力的影响。研究了轮胎的充气压力和径向刚度之间的关系。轮胎的径向刚度进而影响悬架刚度,建立其与悬架刚度的数学关系,并对比不同轮胎刚度时的整车仿真响应曲线分析其对汽车NVH性能的影响。论文进而分析了半主动悬架相较与传统被动悬架在改善汽车NVH性能方面的作用。对影响汽车NVH性能的时域指标进行了频域加权处理,考虑了不同频段对NVH性能指标影响的敏感度不同,同时在控制方法设计中兼顾了行驶安全性。通过仿真,对比不同工况下半主动悬架对汽车NVH性能的改善。论文进行了大量试验,测试了不同工况条件下的汽车NVH性能,验证了仿真模型的准确性。将半主动悬架安装到试验车上,通过台架和实车道路测试,验证了其对汽车NVH性能的改善。更多还原

【Abstract】 With the great improvement of economics and people’s living standard, the number of retained vehicles is becoming more and more huge.In this situation, the vehicle NVH performance(NVH, just the three initial characters of noise, vibration and harshness)is drawing more and more concerns, and it is also considered as one important index for judging the level of the modern vehicle industry.Because the performance is closely related to the physical and metal health of human beings, many international organizations have established according laws and regulations to confirm the requirements of the vehicle NVH performance.In the meanwhile,the academia and industria have invested a lot of money, materials and manpower for the vehicle NVH researches.At present, the vehicle NVH researches are centered on the vehicle power assembly, intake and exhaust system, and transmission assembly. This dissertation aims at studying the suspension NVH performances under different road conditions, and carries out theoretical analyses, simulation and tests of the effects of the key suspension parameters on the NVH performance.Firstly, the dissertation reviews the vehicle NVH technology development and research status on the basis of looking up many papers.After that, this dissertation uses the finite element theory and method for the modal analyses and flexible treatments of some suspension parts.The dissertation analyses the path of the road irregularity vertical excitations transferred to the vehicle body, establishes the vehicle NVH performance index and builds up the rigid-flexible coupling vehicle dynamical model.Under different work conditions,the effects of the suspension stiffness and damping on the vehicle NVH performance are studied.The DOE(Design of Experiments) method is applied for improving the vehicle NVH performance by fitness-optimization.dissertation analyzes the structural and material properties of the suspension rubber bushings.The flexible deformations in every direction are analyzed, and compared with the test data supplied by the manufacturers.The vehicle NVH performance are compared, before and after the suspension bushings are installed.Then the sensitivities of different suspension bushing stiffness on the NVH index are studied.Some rather sensitive parameters are choosed for the DOE,in order to improve the vehicle NVH performance.The dissertation establishes up the half vehicle model including the bushing effects, and compares the simulation results with those of the half vehicle model without the bushing effects and rigid-flexible coupling model.The dissertation analyzes the structural and material properties of the vehicle tires in theory, and builds up the three-dimensional(3D) finite element method(FEM) model for the analysis of the radial tire roll. In the FEM model,the complexity of the tire materials and structures are taken into account adequately, and the contact frictions among the tires,rim and ground are also studied.The dissertation studies the effects of different vehicle speeds and steering angle on the tire deformations and ground area stress distribution.The relations between the tire pneumatic stress and radial stiffness are studied.The tire radial stiffness would affect the suspension stiffness furthermore.and the mathematical relations between it and the suspension stiffness are also built up.By comparing the full vehicle simulation response curves of different tire stiffness, the vehicle NVH performance is studied.And then, the dissertation analyzes the effects of semi-active suspensions on the vehicle NVH performance,as compared to traditional passive suspensions.On those vehicle NVH time-domain indices,frequency weightings are carried out.When taking into account of the different sensitivities of diverse frequency bands towards the NVH performance indices,the driving safety is also considered in the control method design. Through simulation,the effects of the semi-active suspension on the vehicle NVH improvement are verified.Many tests are carried out in the dissertation, and by testing the vehicle NVH performances under different work conditions,the exactness of simulation models are verified.The semi-active suspensions are installed on the test vehicle,through rig and real vehicle road tests,those suspension effects on the vehicle NVH performance improvements are verified.更多还原