Papers by Keyword: Failure Dependence

Abstract: With the development of Condition-Based Maintenance, there is an urgent need for failure dependence of redundant components in parallel system. In this paper, Markov maintenance cost decision analysis based on failure dependence of components was put forward, moreover, maintenance cost optimal model of parallel system with cost rate was established, meanwhile, the minimum cost rate as well as corresponding optimal detection interval was obtained. Finally, failure dependence and dependent failure rate to parallel system maintenance cost optimal model were studied and realized to prove this theory.

Abstract: Taking into account the uncertainty in material property and component quality, a complex mechanical component such as a gear should be treated as a series system instead of a component when evaluating its reliability, since there exist many sites of equal likelihood to fail. Besides, conventional system reliability model is not applicable to such a system because of the statistical dependence among the failures of the every element (damage site). The present paper presents a model to estimate complex mechanical component reliability by incorporating order statistic of element strength into load-strength interference analysis, which can deal with multiple failure mechanisms, reflect statistical dependence among element failure events and that among different failure modes.

Abstract: Mechanical systems is vulnerable to be influenced of its structure and human factors for its subsystems, components and the complex relationship between each unit, causing the mechanical systems to be failed, which severely affects the reliability of the mechanical systems. based on Petri nets models of mechanical systems analysis, from safety, intermediate and failure three aspects, 3-level working model of “safety-intermediate-failure” is introduced to reflect the reliability (functioning fully) of mechanical systems, intermediary transition between reliable and failure, failure (can not work). Through using the union and intersection operation of stochastic event, and considering the different values of the related failure parameters among basic events which impacts on the reliability of mechanical system, eventually the calculation of mechanical system reliability vector with the intermediate state is established.

Abstract: With the scenario of reliability estimation, a geometrically complex mechanical/structural component with multiple damage sites should be treated as a system, since there are many links (damage sites) of similar failure probabilities on any of such a component and the failures of the individual damage sites are not perfectly dependent of each other. Conventional system reliability model is not applicable to such a system because of the statistical dependence among the element (damage site) failures. To estimate the reliability of a mechanical system (or a complex component) in which element (damage site) failure dependence plays an important role, a model capable of reflecting the effect of element failure dependence is necessary. The present paper develops models which can deal with multiple damage sites and multiple failure mechanisms, reflect the dependence among element failure events and that among different failure modes. Such models are applicable to both typical mechanical systems and various components.

Abstract: As a new tool of statistical analysis, Copula is introduced to build reliability model for structural system consisting of identical components, by which the complex feature of failure dependence can be depicted. Aiming at symmetric structure systems, typical failure-dependence mechanism of components is discussed firstly. Considering the failure-dependence mechanism, modeling steps based on Gauss Copula and Archimedean Copulas are put forward, in which the twin stress, components strength are chosen as the basic variables and the safety margins are chosen as the analytic variables. Compared with Gauss Copula, Archimedean Copulas have powerful capability of describing the failure-dependence mechanism owing to the adjustable parameters can be determined according to the rank correlation coefficient and the information about the critical failure point. Archimedean Copula-based reliability models are applicable to non-normal situations. A numerical example is given to show that the new method is reasonable and feasible. Copula-based reliability models can give a new path for reliability analysis of complex systems with failure-dependence.

Abstract: The reliability of a mechanical system is not simply determined by the reliabilities of components composing the system. For a specified system configuration, system reliability depends on not only component reliability, but also the degree of the dependence among component failures, which can be characterized by load roughness in an extent. In the same way, system complexity depends on not only the number of components that the system contains but also the dependence among component failures. This paper analyzes the main factors that affect the relationship between system reliability and component reliabilities in term of component failure dependence. The factors include load uncertainty, component strength uncertainty, and load roughness as well. Traditional parameter describing system complexity is modified, new parameter to describe component complexity is defined. These parameters play important rule for system reliability design or system reliability allocation.