【作者】 赵健；

【导师】 金涛；

【作者基本信息】 浙江大学 ， 化工过程机械， 2013， 硕士

【摘要】 汽车密封条具有良好的密封性和环境隔离作用,安装使用在汽车车身的各个部位。汽车市场的快速发展和消费者对更好乘用体验的追求要求密封条具备更好的使用性能和外观。然而,密封条主要由橡胶类材料构成,在装配和使用过程中会产生材料间的剧烈接触和摩擦,结构的有限元分析涉及高度的非线性问题,包括材料非线性、几何非线性和边界条件非线性,使得现代CAE技术不能获得良好的应用。所以,有必要对此进行深入探索。本文基于上述背景,分析探讨了密封条结构有限元分析中的种种问题,对影响分析准确性的关键因素进行评价,提出试验和分析改进方法,主要研究成果如下：1.设计橡胶材料的单轴拉伸、单轴压缩／等轴拉伸、平面剪切、体积压缩试验以及摩擦系数测定试验,获取丰富的材料特性曲线。分析橡胶材料试验中存在的Mullins效应,并以一结构较为简单的密封条为例,验证材料试验数据、Mullins效应和材料模型的选择对分析结果的重大影响,初步确定了适用于密封条结构分析的材料基础试验方案。2.探索几何非线性问题的有限元描述方法,并讨论了处理接触和摩擦问题的理论方案。以行李箱、头道、门框、导槽等四类密封条为例,使用MSC.Marc软件对密封条使用中可能存在的压缩、插入、拔出、滑动、装配等运动形式进行分析,分析结果获得了后续产品试验的良好印证,同时还对不满足设计要求的密封条进行了有效的结构优化。以上成功应用表明了有限元分析方案的合理性。3.针对密封条弯曲问题,分别开展密封条弯曲抗凹性分析和弯曲起皱分析,前者可以查看密封条按规定半径弯曲后的变形状态,后者使用弧长法追踪弯曲时的失稳路径,获得密封条弯曲起皱的临界载荷以及变形状态。三维弯曲分析有利于设计人员进行结构改进,保证密封条良好的外观。更多还原

【Abstract】 Due to excellent sealing quality and environment-isolation function, weather-strip seals are widely used in various parts of a car. The rapid development of automobile industry, as well as the demand for better using experience from the drivers, leads to requirements for seals with higher quality and better appearance. While, mainly made of rubber materials, weather-strip seals produce intense contact and friction problems in assembly and normal use. Thus the structure analysis involves highly nonlinear problems on materials, geometry and boundary conditions. As a result, modern CAE technique gets poor performance and needs more exploration.Based on this embarrassing situation, this paper focuses on some of the key factors which affect the precision of finite element analysis on weather-strip seals. Improvements on material test and structure analysis are proposed, which can be summarized in three aspects:1. Design various material test devices, i.e., simple tension, simple compression or biaxial tension, planar shear, volumetric compression and friction measurement. Abundant material characteristic curves are gained, which display the famous Mullins effect. Then, conduct analysis on a simple weather-strip seal to test and verify the impact of material data, Mullins effect and different material models. Hence, fundamental material test strategies are determined for subsequent analysis.2. Probe the finite element description of geometric nonlinearity problem and discuss strategies to handle contact and friction in the analysis. At last, conduct analysis on four typical weather-strip seals, i.e., trunk seal, primary door seal, front and back door seal and window seals, which involve various forms of movement like compression, insertion, extraction, slip and assembly process. The calculated results agree well with the experimental value. On top of it, optimization work is continued on structures which fail to meet the design requirements. Both jobs display the effective application of finite element method in structure analysis of weather-strip seal.3. For the bending process of weather-strip seals, analysis on the sinking-resistance and wrinkling problem are respectively done. While the former displays the deformation state after the seal is bent as the radius of the sheet metal, the latter tracks the buckling route with arc length method in the finite element analysis and gets the critical load which leads to the finial buckling mode. Designers could continue effective structure optimization for better appearance of weather-strip seals on the basis of the two jobs.更多还原