中文摘要：

针对车身内腔电泳膜厚不足导致生锈,而传统试错方法耗费大量成本、电泳工艺开孔缺乏科学依据等问题,提出了一种能实现车身电泳工艺孔正向设计的新方法——基于电泳仿真的区域分析法。首先基于法拉第电沉积理论,获取电泳过程中的电场、流场信息,搭建电泳电化学仿真环境,建立电泳过程数学模型;构建电泳基础试验模型及其仿真模型,通过试验和仿真结果对比以及参数迭代修正,反求得到对涂料沉积量影响较大的基本沉积参数数值;基于工程上对车身电泳关键区域的划分,确定大梁局部区域典型3层钣金结构为研究对象,构建了大梁局部区域简化结构的电泳电化学全耦合仿真模型,并验证了该模型的准确性。在此基础上,以工艺孔形状、大小为变量,以电化学分析为手段进行研究发现：开孔形状对电泳膜厚几乎无影响,而开孔面积对电泳膜厚有较大影响,分析得到膜厚衰变的数值规律,导出了大梁区域内腔电泳膜厚的安全系数。通过对加强板上双孔叠加效果的分析,进一步推导出该区域孔间距设计的安全系数。最后将量化的研究结果应用于某车大梁区域的结构更改,成功解决了该区域内腔生锈问题。

英文摘要：

According to the fact that thin e-coating films in vehicle body cavities result in corrosion while the traditional trial and error method costs a lot and the design of e-coating holes is always unsubstantiated,a regional analysis strategy based on e-coating simulation was proposed which can achieve forward design of vehicle body e-coating holes.Firstly the electric field and the flow field information in e-coating process were obtained and the electrochemical simulation environment was established based on Faraday electro deposition theory.Then the mathematic model of e-coating process was built.Basic e-coating experiment models and its simulation models were established and the basic deposition parameters which were critical to paint depositionquantities were also obtained by comparing experiment results and simulation results and iteratively refining the parameters.The typical three-layered sheet metal structure of the regional frame was taken as the research object based on the division of the critical regions of vehicle body e-coating in engineering.Then a fully coupled electrochemical e-coating simulation model of the simplified regional structure of frame was built and verified.Based on these works,the areas and shapes of e-coating holes were taken as variables to do the research by electrochemical analysis method.The results show that hole area has a great effect on film thickness while hole shape almost has no influence on film thickness.Numerical disciplines of film decay are found,and the safety factor for e-coating film thickness in a regional frame cavity is then deduced.The safety factor of spacing design of holes is further deduced by analyzing the overlay effects of two holes on the stiffening plate.By applying the quantitative results to structure improvement of a frame in vehicle,corrosion in cavities can be successfully eliminated.