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1、 电 子 科 技 大 学 UNIVERSITY OF ELECTRONIC SCIENCE AND TECHNOLOGY OF CHINA 硕士学位论文 MASTER THESIS (电子科技大学图标) 论文题目 考虑载荷动态分配机制的多状态系统 可靠性建模及优化 学 科 专 业 机械设计及理论 学 号 201121080308 作 者 姓 名 张小虎 指 导 教 师 刘 宇 副教授 分类号 密级 UDC注1 学 位 论 文 考虑载荷动态分配机制的多状态系统可靠性建模及优化 (题名和副题名) 张小虎 (作者姓名) 指导教师 刘 宇 副教授 电子科技大学 成 都 (姓名、职称、单位名称) 申请学
2、位级别 硕士 专业学位类别 机械设计及理论 提交论文日期 2014.03 论文答辩日期 2014.05 学位授予单位和日期 电子科技大学 2014 年 06 月 日 答辩委员会主席 评阅人 注 1:注明国际十进分类法 UDC的类号。 MULTI-STATE SYSTEM RELIABILITY MODELING AND OPTIMIZATION WITH CONSIDERING DYNAMIC LOAD DISTRIBUTION STRATEGY A Master Thesis Submitted to University of Electronic Science and Technolo
3、gy of China Major: Mechanical Design and Theory Author: Zhang Xiaohu Advisor: Associate Prof. Liu Yu School: School of Mechatronics Engineering 独创性声明 本人声明所呈交的学位论文是本人在导师指导下进行的研究工作及取得的研究成果。据我所知,除了文中特别加以标注和致谢的地方外,论文中不包含其他人已经发表或撰写过的研究成果,也不包含为获得电子科技大学或其它教育机构的学位或证书而使用过的材料。与我一同工作的同志对本研究所做的任何贡献均已在论文中作了明确的说明
4、并表示谢意。 作者签名: 日期: 年 月 日 论文使用授权 本学位论文作者完全了解电子科技大学有关保留、使用学位论文的规定,有权保留并向国家有关部门或机构送交论文的复印件和磁盘,允许论文被查阅和借阅。本人授权电子科技大学可以将学位论文的全部或部分内容编入有关数据库进行检索,可以采用影印、缩印或扫描等复制手段保存、汇编学位论文。 (保密的学位论文在解密后应遵守此规定) 作者签名: 导师签名: 日期: 年 月 日 摘要 I 摘 要 随着工业和科技的飞速发展,系统和设备的结构越来越庞大,功能日益复杂。可靠性作为产品的基本属性,是衡量产品质量的重要指标,而且可靠性应用的范围越来越广泛,设备对可靠性的要
5、求也越来越高。系统和设备的精密化、大型化、复杂化使传统的二态系统可靠性理论已经不能够准确地描述系统复杂的失效过程和失效规律。多状态系统可靠性理论的出现为学术界和工业界带来了新的活力。与二态系统可靠性理论相比,多状态系统可靠性理论能更好地揭示复杂系统的特征,客观准确地体现工程系统在设计阶段和工作阶段复杂的演变规律,能定性和定量地评估复杂系统的性能和可靠度等重要指标。 然而,现在大部分研究多状态系统可靠性的工作都假设系统中单元之间的失效规律是相互独立的,而这样的假设并不总是符合系统和设备的失效演变规律。事实上,在实际工业和设备中,系统中的单元与单元之间存在着相关性。本论文主要研究载荷动态分配机制下
6、的多状态系统单元间的失效相关性。本论文的主要内容和创新点包括以下几个部分: (1)利用马尔可夫模型对存在载荷动态分配机制的多状态系统进行可靠性建模,详细地介绍存在载荷动态分配机制的多状态系统的建模和求解方法,分析系统组成结构、单元的载荷分配方式与系统的可靠度之间的影响。 (2)提出两层遗传算法对存在载荷动态分配机制的多状态系统同时进行结构和载荷分配策略的优化,得到系统的最优结构和对应的载荷分配策略,并对不同目标函数下的系统结构和载荷分配策略进行比较。采用非劣分层遗传算法(NSGA-II)对系统进行多目标载荷分配策略的优化,得到载荷分配策略的 Pareto解集。 (3)研究同时存在单元失效不完全
7、覆盖和载荷动态分配机制的多状态系统的可靠性建模方法,并对这类多状态系统的结构和载荷分配策略的优化问题进行了研究。 关键字:关键字:多状态系统,可靠性建模,马尔可夫模型,动态载荷分配,不完全覆盖ABSTRACT II ABSTRACT With the development of advanced industrial techniques, systems and devices are designed with diverse functionalities and complexities. Reliability as a critical measure of products q
8、uality becomes a basic attribute of products nowadays, and it is oftentimes strictly required in engineered system design and operation. Nevertheless, the traditional binary-state reliability methods fail to provide an accurate characterization of complex degradation/failure patterns manifested by e
9、ngineered systems with high accuracy, large physical scale, and complexity. The multi-state system reliability methods enrich the reliability theory since it outperforms the traditional binary-state reliability methods in terms of revealing the multi-state nature of complex systems. Most reported wo
10、rks on multi-state system reliability modeling and assessment are developed on the premise the failure processes between any pair of components are statistically independent. However, such hypothesis may not be always held. Components in a system may influence one another during their failure proces
11、ses, making the deterioration process of the entire system even more complicated. This thesis aims at studying the failure dependency between components under the dynamic load distribution strategy. The major contributions of the thesis include: (1) Constructing a new reliability model for multi-sta
12、te systems with dynamic load distribution strategy. A general Markov model is built to characterize the mechanism of dynamic load distribution for multi-state systems. The relation between the load imposed on units, reliability of the entire system, and system structure is studied. (2) Jointly optim
13、izing the dynamic load distribution strategy and system configuration to achieve a higher system reliability/performance. A two-level genetic algorithm is put forth to jointly optimize the dynamic load distribution strategy and system configuration with the aim of maximizing the mean time to failure
14、 or the expected cumulative performance rate of the entire multi-state system. As the mean time to failure and the expected cumulative performance rate are two conflicting objectives, the non-dominated sorting genetic algorithm is employed to seek a set of Pareto optimal solutions for the resulting
15、multi-objective optimization problem. (3) Taking account of the imperfect fault coverage in multi-state system reliability models. The reliability model for multi-state systems with jointly considering the ABSTRACT III dynamic load distribution strategy and the imperfect fault coverage is developed. The optimal load distribution strategy and system configuration in this case are also investigated. Keywords: multi-state system, reliabilit