车用增压器涡轮时变可靠性建模与寿命预测方法研究

For the problem of reliability evaluation and life prediction of turbine of turbocharger for vehicle application, and giving prominence to the time-dependence of reliability and the probability characteristics of life, the method for time-dependent reliability modeling and life prediction of turbine of turbocharger for vehicle application is studied in this program. According to the characteristics of turbine of turbocharger for vehicle application, the loading process and stress response of turbine is studied, and the failure behavior and the strength degradation of turbine are analyzed. Then, the characteristics and mechanism of failure dependence among the different failure modes of turbine is studied, and the method for analyzing the failure dependence of turbine is proposed. With the number of miles traveled by a vehicle or the time worked by an engine as the life parameter of turbine of turbocharger, the method for modeling the time-dependent reliability of turbine with multiple failure modes is studied, and the time-dependent reliability and failure rate models of turbine, which can embody the effect of parameters such as failure modes, stress, strength and its degradation, life index, and so on, are developed. Considering the effect of multiple failure modes caused by the over speed failure, rub fatigue, blade vibration, thermal fatigue, and so on, the probability distribution functions of life of turbine are derived, and the method for determining the reliable life is presented. Further, the rules that the parameters of loading process, stress, strength and its degradation, and so on affect the reliability, failure rate and reliable life, are revealed. Finally, taking a turbine of turbocharger of vehicle engine as an example, the methods and models proposed are applied to analyze the reliability and life of this turbine.

本项目针对车用增压器涡轮的可靠性评价与寿命预测问题，突出可靠性的时变特征与寿命的概率特征，研究适用于车用增压器涡轮的时变可靠性建模与寿命预测方法。根据车用增压器涡轮的特点，研究涡轮的典型载荷历程与应力响应；分析涡轮在典型载荷历程下的失效行为与强度退化规律；研究涡轮不同失效模式之间存在的失效相关性特征与失效相关性形成机制，建立起涡轮的失效相关性分析方法。以车辆行驶里程或发动机工作时间为寿命度量指标，研究涡轮在多种失效模式下的时变可靠性建模方法，建立起能够科学体现"多种失效模式、应力、强度及其退化规律、寿命指标"等参数的涡轮时变可靠度与失效率计算模型；综合考虑涡轮超速破坏、轮毂疲劳、叶片振动、热疲劳等多种失效模式的影响，建立起涡轮的寿命概率分布模型，给出涡轮的可靠寿命确定方法；揭示"载荷历程、应力、强度及其退化"等参数对涡轮可靠度、失效率以及可靠寿命的影响规律；并进行应用验证。

项目针对车用增压器涡轮的可靠性评价问题，研究了车用增压器涡轮的失效行为，建立了涡轮的时变可靠性建模与寿命预测方法及模型。首先，研究了车用增压器涡轮工作状态参数的变化特点，分析了涡轮在离心载荷、热载荷和气动载荷作用下的应力响应特征，建立了车用增压器涡轮的载荷与应力响应分析方法。其次，研究了车用增压器涡轮的典型失效模式，揭示了涡轮超速破坏、轮毂疲劳、叶片共振、蠕变疲劳等失效模式的失效机理，通过试验测试的方法获得了涡轮的轮毂疲劳强度性能与高温蠕变性能，建立起了涡轮对应超速破坏、轮毂疲劳、叶片共振、蠕变疲劳等不同失效模式的可靠性与寿命评价模型。考虑多种失效模式对涡轮可靠性的影响，分析了不同失效模式之间存在的失效相关性，建立了多种失效模式条件下涡轮的失效行为表征方法及模型。然后，研究了具有多失效模式时涡轮的时变可靠性建模与寿命评价方法，通过建立与求解概率微分方程和概率差分方程，分别以连续型变量和离散型变量为寿命度量指标，建立了能够体现“多种失效模式及其失效相关性、载荷与应力随机性、强度及其退化规律”等参数影响的可靠度与失效率计算模型以及寿命的概率密度函数与累积分布函数计算模型，给出了涡轮的可靠寿命确定方法。最后，开展了涡轮时变可靠性建模与寿命评价方法的工程应用研究。将研究成果应用于某型增压器涡轮的可靠性增长，分析了涡轮的失效模式及其失效机理，对涡轮进行了结构优化，运用可靠性模型对涡轮的可靠性增长效果进行了评价，并进行了台架试验验证。形成的车用增压器涡轮时变可靠性建模与寿命预测方法，解决了涡轮在研制阶段无足够失效数据时的可靠性与寿命评价问题；成果不仅可以应用于车用增压器涡轮的可靠性设计与分析、寿命评定、可靠性增长、维修保障方案制定等，而且可以推广应用于航空活塞发动机增压器涡轮、船用增压器涡轮等。