基于载荷谱的电动汽车传动构件疲劳寿命与系统可靠性研究

Transmission system is one of the core of the electric vehicle powertrain, which directly impact the reliability and safety of vehicles. Currently, China has the world’s largest production and sales volume of electric vehicles, however, there is still no complete theoretical method in the electric vehicle transmission system design, especially in the aspects of life prediction and reliability design, which becomes important problems needed to be settled urgently. In view of this, this project refines three common theoretical issues including the electromechanical coupling dynamics of underdamped system, the fatigue damage of transmission components under the non-proportional multi-axial stress state as well as the failure-related dynamic time-varying reliability. Accordingly, this propose the research on coupling dynamics of electric vehicle transmission system, the multi-axial stress-strain response, damage mechanism and the high-cycle fatigue life prediction, and the failure evaluation and the relevant reliability design criteria. This project will starts from the construction of electric vehicle transmission system coupling dynamics model to get the dynamic load spectrum of the cycle condition transmission system; The transmission components fatigue damage model considering the time varying multi-axial stress state and the material gradient mechanical parameters will be developed to propose a damage evolution mechanism oriented method of predicting the high-cycle fatigue life of transmission components; The failure-related dynamic time-varying reliability model of transmission system will be established to form the transmission system-structural reliability design guidelines. The expected outcomes will provide strong theoretical and methodological support for the design of electric vehicle transmission system.

传动系统是电动汽车动力总成的核心之一，直接影响到汽车的可靠性与安全性，尽管我国电动汽车产销量世界第一，但在电动汽车传动系统设计上，尤其是寿命预估与可靠性设计方面还未形成完整的理论方法，亟待深入研究。为此，本项目提炼了欠阻尼系统多重机电耦合动力学、构件多轴时变非比例应力疲劳损伤和系统失效相关动态时变不确定可靠性三个共性的基础理论问题，开展电动汽车传动系统机电耦合动力学、构件时变力学响应与损伤机理、构件高周超高周疲劳寿命预估和系统强相关动态时变不确定可靠性的研究，构建电动汽车传动系统机电耦合动力学模型，得到循环工况传动系统载荷谱；建立考虑时变多轴应力状态和材料力学参数梯度特征的传动构件疲劳损伤模型，提出面向损伤演化机理的传动构件高周超高周多轴疲劳寿命预测方法；构建传动系统的失效相关动态时变不确定可靠性分析模型，形成电动汽车传动系统可靠性优化设计准则。为电动汽车传动系统设计提供理论方法支撑。

本项目以电动汽车传动系统为研究对象，针对传动系统高转速、高循环次数等特征带来的新的理论与技术问题，开展了传动系统机电耦合动力学、传动构件时变力学响应与损伤机理、传动构件高周超高周疲劳寿命预估、传动系统强相关动态时变不确定可靠性等内容研究。.项目提出了包含永磁同步电机-传动机构-轮胎的电动汽车传动系统建模方法，构建了电动汽车传动系统机电耦合动力学模型，揭示了电动汽车欠阻尼传动系统多重机电耦合机理，实现了电动汽车传动构件载荷的精确计算模拟。.建立了宏微观几何的齿轮界面接触数值模型，实现了齿轮表面微观形貌、润滑状态作用下的多场耦合接触分析，提出了基于多轴疲劳准则和细观损伤力学的齿轮疲劳分析方法，建立了考虑时变多轴应力状态和材料力学参数梯度特征的电动汽车传动构件疲劳损伤模型，定量描述了齿轮材料服役过程中的多轴应力状态与损伤演化规律，阐明了多轴时变非比例应力状态下传动构件疲劳损伤与性能退化机制。.提出了电动汽车传动构件高周超高周疲劳寿命预测方法，定量揭示了残余应力、硬度梯度等表面完整性参数的影响规律，建立了综合考虑运转工况与构件强度不确定影响以及不同失效形式与构件相互作用的系统可靠性分析模型，开发了面向高可靠与轻量化的电动汽车传动系统结构参数优化方法，获得重量减轻、可靠性提高的传动系统结构参数优化方案，实现了电动汽车传动系统多模式强相关动态失效表征与可靠性设计。.为克服载荷实车试验工况不全面、周期长等局限性，提出了电动汽车传动系统仿真载荷与试验载荷融合的载荷谱分析方法，结合载荷的时域融合，编制了程序载荷谱，并进行了典型电动汽车传动系统疲劳寿命试验，形成了减速器总成疲劳寿命试验企业规范。.项目发表论文46篇，其中SCI论文44篇，申请或授权发明专利6项，获省部级奖励1项。项目骨干获国家级青年拔尖人才、重庆英才青年拔尖人才各1人次，培养毕业研究生11名、在读研究生2名，其中博士研究生7名、硕士研究生6名。