基于柔性部件载荷提取的前副车架疲劳分析

宋自力+刘俊红+张雷+芦伟

摘 要：以准确的耐久道路谱作为动力学分析的边界条件，分别建立刚性和柔性部件的多体模型，提取前副车架连接点载荷谱。分别以两种载荷谱为输入，对前副车架的本体和焊缝进行疲劳分析。研究发现，基于刚性和柔性部件提取的载荷数据在幅值、均值、离散性和相对伪损伤方面均有很大差别。载荷二轴性分析显示，前副车架应选择多轴疲劳分析方法。相比而言，基于柔性部件提取载荷，本体多轴疲劳分析结果与试验情况更吻合，焊缝损伤最大位置和循环次数也与试验结果非常接近。

关键词：前副车架；柔性部件；寿命预测；多轴疲劳

中图分类号：O346.2文献标文献标识码：A文献标DOI：10.3969/j.issn.2095-1469.2016.03.11

Abstract：A dynamics analysis was conducted under the boundary conditions of accurate load spectrums of durable roads.Two multi-body models were built respectively for flexible and rigid parts. Load spectrums of front subframe were extracted at all connection points. With these two load spectrums as the inputs， fatigue analysis on main parts and seam welds of front subframe was carried out. The results show that loads extracted based on rigid and flexible parts have a large difference in amplitude， the average value， discrete properties and the relative pseudo damage. A multiaxial fatigue analysis is proposed for the front subframe according to the biaxial analysis of loads. By contrast， for the loads based on flexible parts， the results of multiaxial fatigue analysis for the main part are more consistent with the test results. And also the predicted damage area and life cycles of the seam welds agree with the test results.

Keywords：front subframe； flexible parts； life prediction； multiaxial fatigue

采用计算机辅助工程（Computer Aided Engi-neering，CAE）的方法在汽车产品设计阶段进行疲劳寿命预测，能有效发现结构中的薄弱位置，并优化改进直到满足客户使用要求，是提高汽车可靠性和安全性的重要手段。由于材料本身具有疲劳寿命离散性特征，产品寿命往往难以精准预测，但经CAE 分析后一定程度上可以减少疲劳失效的发生。部件疲劳寿命不仅与材料特性有关，还受到载荷、加工工艺和表面状态等因素的影响，这就使准确预测疲劳寿命的难度更大。如何提高疲劳仿真精度一直是研究的重要课题。疲劳仿真分析包括三个基本要素：几何模型、载荷和材料疲劳特性，其中正确的边界载荷是准确预测的关键[1]。车轮力传感器可以准确测量车辆行驶过程中的轮心载荷，为汽车产品的寿命预测提供了重要的技术支撑。……