基于疲劳损伤累积理论的结构寿命预测与时变可靠性分析方法研究

发布时间：2018-05-02 13:12

本文选题：疲劳损伤累积理论 + 载荷相互作用效应　；参考：《电子科技大学》2017年博士论文

【摘要】：随着航空航天、轨道交通、船舶海洋、机械制造等工业技术水平的提高,现代机械装备正逐步向大型化、高速化和高性能方向发展。许多机械装备关键零构件或结构的服役环境复杂,运行条件恶劣,导致各类破坏事故频繁发生。腐蚀、磨损和疲劳是机械结构破坏的主要表现形式,其中以疲劳破坏尤为突出。针对长期承受交变循环载荷作用的机械结构,疲劳断裂是其最主要的失效模式,占机械结构失效总数的50%~90%。疲劳破坏具有很强的隐蔽性和突发性,破坏前无明显的征兆,对机械装备的安全运行构成了严重威胁,一旦发生破坏易于造成重大事故和生命财产损失。机械装备零构件或结构的疲劳寿命及其可靠性是制约装备整机寿命和系统可靠性水平的关键因素。因此,精确地预测和评估机械结构的寿命和可靠性,是确保其在服役期内安全、可靠运行的重要保障,对合理制定维修决策和健康管理计划,最大限度地发挥装备的使用价值,提高经济效益和抗疲劳设计等方面均具有重要的理论价值和现实意义。由于疲劳失效过程的复杂性和随机性,传统的寿命预测理论和可靠性分析方法还不够完善,仍存在诸多尚未解决的难题和不足。针对此,本文以有限寿命设计方法和疲劳损伤累积理论为基础,深入开展疲劳损伤失效机理、寿命预测技术以及可靠性分析方法的研究,采用机械装备关键零构件的金属材料试件和焊接结构件的疲劳试验数据进行模型和方法验证,使现有疲劳分析理论日臻完善,拓展其应用范围。论文主要研究内容和成果如下:(1)提出了考虑载荷相互作用效应的疲劳损伤等效法则与剩余寿命预测方法。针对变幅加载载荷历程效应的复杂性以及Miner法则的内在缺陷,从损伤累积的角度出发,系统地研究了载荷加载顺序及载荷交互效应的作用机制。根据疲劳失效的“二元判据”,引入了疲劳损伤状态的概念定性地表征材料的受损程度。针对传统损伤等效方法的缺陷,提出了考虑载荷相互作用效应的疲劳损伤等效法则。在此基础上,结合韧性耗散模型,建立了改进型剩余寿命预测模型,该模型能综合考虑载荷顺序及载荷间交互作用对损伤发展和疲劳寿命的影响。(2)提出了基于疲劳驱动能损伤参数的非线性损伤累积模型与剩余寿命预测方法。针对传统损伤变量在描述上难以揭示失效过程能量耗散的本质,以疲劳驱动力模型为基础,运用能量准则,提出了一种描述疲劳失效全过程的驱动能损伤参数。从失效的能耗过程出发,建立了以驱动能耗散为状态参量的疲劳损伤定量方法和非线性损伤累积模型。在此基础上,运用损伤等效原理,推导出剩余寿命预测模型表达式以及考虑载荷相互作用效应的改进模型,并通过试验设计研究了两种模型的典型非线性特征。(3)提出了基于动态剩余S-N曲线与材料记忆性能退化的修正线性损伤累积准则。针对非线性损伤理论计算量大的缺陷以及Miner法则在工程应用上的优势,从剩余寿命和S-N曲线的角度出发,研究了动态剩余S-N曲线和材料记忆性能的退化规律,通过引入材料记忆退化参数定量地表征动态剩余S-N曲线的斜率比,提出了一种修正的线性损伤累积准则。该准则保留了传统Miner法则形式上的简易性,便于疲劳损伤定量分析和寿命估算。通过对比三种线性损伤模型并结合试验设计,详细阐述了四种模型存在的共有属性以及线性损伤增长行为。(4)提出了基于双线性损伤累积理论的概率模型以及时变疲劳可靠性分析方法。疲劳失效是一个损伤不断累积的动态过程,传统的基于静态的可靠性分析方法无法体现载荷历程的时变特征,而基于动态的可靠性分析方法难以揭示失效过程裂纹萌生和裂纹扩展的两阶段特性。针对此,以双线性损伤累积理论为依据,分别在正态分布和对数正态分布假设下,构建了概率损伤累积模型。在此基础上,运用应力-强度干涉理论,建立了基于“累积损伤-临界损伤”时变可靠度模型,实现了疲劳全寿命周期内的可靠度预测。
[Abstract]:With the improvement of industrial technology level, such as aeronautics and Astronautics, rail transportation, marine and mechanical manufacturing, modern mechanical equipment is gradually developing to large, high speed and high performance direction. The service environment of key components or structures of many mechanical equipment is complicated and its operating conditions are bad, causing various types of damage accidents to occur frequently, corrosion, wear and tear. Fatigue is the main form of mechanical structure failure, especially the fatigue failure. The fatigue fracture is the most important failure mode for the mechanical structure which bears the alternating cyclic loading for a long time. The 50%~90%. fatigue failure, which accounts for the total number of mechanical structures, has a strong concealment and sudden appearance, and there is no obvious sign before the damage. It is a serious threat to the safe operation of mechanical equipment. Once the damage occurs, it is easy to cause major accidents and loss of life and property. The fatigue life and reliability of the components or structures of the mechanical equipment are the key factors that restrict the life of the equipment and the reliability level of the system. Therefore, the life and the life of the mechanical structure are accurately predicted and evaluated. Reliability is an important guarantee to ensure the safety and reliable operation of the service during the service period. It has important theoretical value and practical significance for the rational making of maintenance decision and health management plan, maximizing the use value of equipment, improving the economic benefit and anti fatigue design. The traditional life prediction theory and the reliability analysis method are still not perfect, and there are still many unsolved problems and shortcomings. Based on the finite life design method and fatigue damage accumulation theory, this paper develops the fatigue damage failure mechanism, the life prediction technology and the reliability analysis method, and adopts the study of the fatigue damage failure mechanism, the life prediction technique and the reliability analysis method. The fatigue test data of the metal materials and welded structures of the key components of the mechanical equipment are verified by model and method. The existing fatigue analysis theory is perfected and its application scope is expanded. The main contents and achievements of this paper are as follows: (1) the fatigue damage equivalence principle and the residual life consideration considering the interaction effect of load phase are proposed. In view of the complexity of the loading process effect of variable amplitude loading and the inherent defects of the Miner rule, the mechanism of the loading sequence and the interaction effect of load is systematically studied from the point of view of damage accumulation. Based on the "two element criterion" of fatigue failure, the conceptual qualitative surface material of fatigue damage state is introduced. In view of the defects of the traditional damage equivalent method, the equivalent law of fatigue damage considering the interaction effect of load is proposed. On this basis, an improved residual life prediction model is established by combining the ductile dissipation model. The model can take into account the damage development and fatigue life of the load sequence and the interaction between the loads. (2) the nonlinear damage accumulation model and the residual life prediction method based on the fatigue driving energy damage parameters are proposed. It is difficult to reveal the essence of energy dissipation in the failure process according to the description of the traditional damage variables. Based on the fatigue driving force model, an energy criterion is used to describe the whole process of fatigue failure. On the basis of the damage equivalence principle, the expression of residual life prediction model and the improved model considering the interaction effect of load are derived, and the experiment is carried out. The design studies the typical nonlinear characteristics of the two models. (3) a modified linear damage accumulation criterion based on the dynamic residual S-N curve and the degradation of material memory performance is proposed. The defects of the nonlinear damage theory and the advantages of the Miner rule in engineering application are studied, from the angle of the residual life and the S-N curve. The dynamic residual S-N curve and the degradation law of material memory performance, by introducing the material memory degradation parameters to quantitatively characterize the slope ratio of the dynamic residual S-N curve, a modified linear damage accumulation criterion is proposed. This criterion preserves the simplicity of the traditional Miner rule form, and facilitates the quantitative analysis of fatigue damage and the life estimation. After comparing three linear damage models and combining with experimental design, the common properties and linear damage growth behavior of the four models are described in detail. (4) the probability model based on the bilinear damage accumulation theory and the time-varying fatigue reliability analysis method are proposed. The fatigue failure is a dynamic process of continuous damage accumulation, and the traditional method is traditional. The static reliability analysis method can not reflect the time-varying characteristics of the load history, and the dynamic reliability analysis method is difficult to reveal the two stage characteristics of crack initiation and crack propagation in the failure process. On this basis, based on the stress intensity interference theory, a time-varying reliability model based on cumulative damage critical damage is established to predict the reliability of fatigue life cycle.

【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TH140

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