Abstract: The front engine hood of an automobile is one of its important components, and its thinwalled stamped sheet metal structure can easily lead to insufficient stiffness, resulting in abnormal noises during vehicle operation. This study investigates the issue of abnormal noises in the front engine hood of a certain brand of commercial vehicle. Firstly, finite element modeling is conducted on the front engine hood, and finite element analysis is performed under two loading conditions 400 N and 300 N applied in the Z-direction. The analysis results show that the calculated stiffness is 124.4 N/mm and 140.4 N/mm respectively, both of which do not meet the target. Subsequently, maximum deformation tests are carried out at weak positions of the hood. The test results show that the actual calculated stiffness peaks at weak sheet metal positions are 156.31 N/mm and 152.9 N/mm respectively, indicating that insufficient stiffness at the hinge locations of the front engine hood is the main cause of the abnormal noises. Finally, through design optimization, the thickness of the sheet metal at the hinges of the front engine hood is increased by 2 mm, and the improved front engine hood is subjected to finite element analysis again. The analysis results demonstrate that the stiffness is increased by 258.73 N/mm and 288.78 N/mm respectively compared to before optimization, effectively improving the stiffness and deformation of the front engine hood. This study provides empirical reference for addressing issues of abnormal noises and insufficient hinge stiffness in the front engine hood during automobile development.

Key words: Front hood; Finite element analysis; Stiffness optimization; Deformation; Optimal design

摘要： 汽车前引擎盖是车辆重要零部件之一，其薄壁冲压钣金结构容易导致其刚度不足，引 发车辆行驶异响，文章针对某品牌商用车前引擎盖行驶异响问题开展研究。首先对前引擎盖 进行有限元建模，采用 Z 向施加 400 N 和 300 N 两种载荷工况对其开展有限元分析，分析结 果显示，计算刚度分别为 124.4 N/mm 和 140.4 N/mm，均不达目标。然后对引擎盖薄弱位置开 展最大形变量测试试验，试验结果显示，薄弱钣金位置的实际计算刚度峰值分别为 156.31 N/mm 和 152.9 N/mm，分析前引擎盖铰链处刚度不足是导致前引擎盖异响的主要故障原因。最后通 过设计优化，将前引擎盖铰链钣金厚度增加 2 mm，并对改进后的前引擎盖再次进行有限元分 析，分析结果表明，与优化前相比刚度分别提升 258.73 N/mm 和 288.78 N/mm，改进后前引 擎盖的刚度及变形量得到有效提升。该研究能够对汽车开发过程中车辆前引擎盖异响及铰链 刚度不足问题提供经验参考。

关键词: 前引擎盖；有限元分析；刚度优化；变形量；优化设计