Fault Tree Analysis of the Reliability of Electric Vehicles in India

Innovations for electric vehicles have advanced quickly in latest decades. Large-scale business use of these vehicles is still constrained by reliability-related issues. By utilising fault tree (FT) and Monte Carlo simulation, a mathematical prototype is created that includes the reliability traits of all major electrical parts of the vehicle system, including the battery, motor, drive, controllers. The research demonstrates that by raising the component restoration rates, the vehicle’s survivability can be raised. A thorough discussion of this paradigm is provided, along with a presentation and analysis of the reliability estimations based on an electric vehicle. This research on the reliability design and maintenance of an electric vehicle can be supported by the ideas that are outlined in the paper. Additionally, the findings of this study may be helpful to those who build electric vehicle, especially when upgrading the components efficiency and planning for reliability increase.

Methodology for reliability allocation based on fault tree analysis and dualistic contrast

Reliability allocation is a difficult multi-objective optimization problem. This paper presents a methodology for reliability allocation that can be applied to determine the reliability characteristics of reactor systems or subsystems. The dualistic contrast,known as one of the most powerful tools for optimization problems,is applied to the reliability allocation model of a typical system in this article. And the fault tree analysis,deemed to be one of the effective methods of reliability analysis,is also adopted. Thus a failure rate allocation model based on the fault tree analysis and dualistic contrast is achieved. An application on the emergency diesel generator in the nuclear power plant is given to illustrate the proposed method.

A SIMULATED ANNEALING METHOD FOR FAULT TREE ANALYSIS

采用模拟退火方法解最大的最小割集发生概率，同时在寻优过程中找出近优的最小割集，最后确定基本事件的重要性顺序．通过计算机模拟，本算法得到较满意的结果．

Fault Tree Analysis of CNC Machine Tool Based on BDD Technology

CNC machine tool is a large complex system which contains both mechanical and electrical components.As one of these components,the spindle is crucial for the performance of CNC machine tool.To improve the quality of CNC machine,the reliability of spindle was evaluated in this paper using a fault tree analysis(FTA)method.The FTA method is a set of calculation methods based on Boolean algebra.However,it is difficult to analyze a large and complex fault tree with inaccurate results and low efficiency as well as the complexity of time and space.Both of them will result in the so-called "combinatorial explosion".To overcome this problem,the analysis method based on binary decision diagram(BDD)was introduced in our works,and a sorting method about bottom events was also recommended which can reduce the size of the BDD effectively.

Revised Fault Free Analysis Method for Reliability Evaluation of Smart Grids

Smart grid was proposed as a practical form of future power distribution system. Evaluating the reliability of smart grids was of great importance and significance. A revised fault tree model was proposed to distinguish and separate grid-connected operation mode and islanded operation mode of smart grids,focusing on the perspective of the consumers. A hierarchical Monte Carlo simulation method for reliability evaluation was also proposed based on the proposed fault tree model. A case of reliability evaluation for the future renewable electric energy delivery and management( FREEDM) system was carried out and analyzed. The proposed methods can be applicable to other forms of smart grids.

APPLICATION OF FUZZY SET THEORY IN FAULT TREE ANALYSIS

Based on the fuzzy set theory and the expand principle, using fuzzy number as the boundary condition of fault tree analysis, a new method of analyzing fuzzy fault probability of the top event is developed. Fuzzy importance analysis of the basic event is proposed as well. A practical example is given. This method is a new way to solve the obscure problems of fault tree analysis and has great value in engineering practice.

RELIABILITY ANALYSIS OF THE PRIMARY CYLINDER OF THE 10MN HYDRAULIC PRESS

According to the demand of high reliability of the primary cylinder of the hydraulic press, the reliability model of the primary cylinder is built after its reliability analysis. The stress of the primary cylinder is analyzed by finite element software—MARC, and the structure reliability of the cylinder based on stress strength model is predicted, which would provide the reference to the design.

Reliability Analysis for Complex Systems Based on Dynamic Evidential Network Considering Epistemic Uncertainty

Fault tolerant technology has greatly improved the reliability of modern systems on one hand and makes their failure mechanisms more complex on the other.The characteristics of dynamics of failure,diversity of distribution and epistemic uncertainty always exist in these systems,which increase the challenges in the reliability assessment of these systems significantly.This paper presents a novel reliability analysis framework for complex systems within which the failure rates of components are expressed in interval numbers.Specifically,it uses a dynamic fault tree(DFT)to model the dynamic fault behaviors and copes with the epistemic uncertainty using Dempster-Shafer(D-S)theory and interval numbers.Furthermore,an approach is presented to convert a DFT into a dynamic evidential network(DEN)to calculate the reliability parameters.Additionally,a sorting method based on the possibility degree is proposed to rank the importance of components represented by interval numbers in order to obtain the most critical components,which can be used to provide the guidance for system design,maintenance planning and fault diagnosis.Finally,a numerical example is provided to illustrate the availability and efficiency of the proposed method.

基于T-S模糊故障树的驱动电机冷却系统可靠性分析

车用驱动电机液压冷却系统存在故障机理不确定等问题。本文应用模糊数描述其故障概率和故障程度,建立驱动电机冷却系统的T-S模糊故障树模型,计算系统模糊可能性,分析各部件的概率重要度和关键重要度,找出影响系统可靠性的关键部件。

故障树自动建树及分析软件的实现

故障树分析(Fault Tree Analysis)在系统可靠性评估中起着至关重要的作用。然而,作为故障树分析的核心故障树(FT)的构建,传统构建故障树的方法存在耗时长且容易出错等缺点。为了解决这些问题并应对复杂系统自动建造故障树的困难,该文提出一种基于元部件模型及系统结构模型的规范化描述方法,并以此为基础,通过建立元部件模型库、复杂标识符库,设计出故障树自动建树及分析软件,实现系统结构模型搭建、自动建树、复杂结构识别处理及可靠性分析过程的全自动化。详细阐述了故障树自动建树软件自动建树及分析的基本步骤,并通过一个简化的汽车ABS系统应用实例验证了该软件的有效性和可行性。实例应用结果表明,该故障树自动建树及分析软件不仅能够实现自动构建和分析故障树,提高工作效率,而且能够识别处理具有复杂结构的故障树,对复杂系统的自动建树及可靠性分析的推广具有重要意义。

考虑不确定性情况下的故障树重要度分析方法及应用

为了度量底事件发生概率不确定性对顶事件的影响程度,在建立故障树概率组成函数的基础上,基于矩独立重要性测度提出了考虑底事件发生概率不确定性情况的故障树重要度分析方法。以某飞机结冰探测系统为例,利用所提出的重要度方法分析了底事件发生概率不确定性对该系统故障的影响程度,设计者可根据重要度结果更有针对性地开展分析与设计,同时也验证了所提方法的合理性。

基于故障树和贝叶斯网络的履带车辆行星变速机构可靠性分析

行星变速机构作为履带车辆传动系统的核心部件,其可靠性直接影响履带车辆的正常运行。以履带车辆行星变速机构为研究对象,基于实测试验结果建立故障树,将故障树转化为贝叶斯网络(Bayesian Network,BN)模型,并考虑行星变速机构正常、普通故障、严重故障3种状态进行可靠性分析。研究结果表明,行星变速机构失效概率为89.34×10^(-8)h^(-1),其工作400 h的可靠度为0.99964,符合设计要求;利用贝叶斯网络双向计算的功能,可知当行星变速机构发生失效,由主轴断裂或摩擦片烧蚀、翘曲、断裂或齿轮疲劳断齿引起的可能性较大。为后续装备检修、改进设计提供理论依据。

SMA驱动尿道阀可靠性的蒙特卡罗仿真分析

形状记忆合金(SMA)驱动尿道阀是应对尿道功能障碍设计的机电装置,若临床应用一旦发生失效,将被迫取出更换。为研究尿道阀的可靠性,依据尿道阀组成原理建立了尿道阀故障树和可靠性数学模型,提出了一种基于蒙特卡罗法的尿道阀仿真算法,仿真分析了尿道阀的可靠性指标。实验结果表明:该仿真算法简单有效,尿道阀平均寿命达10000次的失效概率为0.012。该仿真算法也可为克服膀胱功能障碍的SMA驱动人工逼尿肌系统可靠性设计提供理论指导。

基于模糊综合评价的水下采油树结构可靠性分析

针对水下采油树结构可靠性分析,提出一种基于模糊综合评价理论的水下采油树结构可靠性分析方法。首先,通过分析不同厂家水下采油树构型,确定水下采油树的典型结构构型及组成,分析水下采油树在运行过程中所受的外载荷;其次,采用专家打分以及模糊综合评价法求得故障树底事件失效率,通过定量分析求解顶事件失效率、可靠度及可靠寿命曲线等可靠性指标;最后,对故障树进行重要度分析及失效率变化对系统结构可靠性的影响,结果表明:“树本体内磨损”的关键重要度最高,对系统结构可靠性的影响最大,是结构中的薄弱环节,应予以关注。研究成果可为水下采油树结构的风险评估提供技术参考,对水下采油树的设计制造提供一定的指导意义。

基于故障树分析的电缆故障诊断可靠性评估方法研究

提出了一种基于故障树分析的电缆故障诊断方法。介绍了故障树分析技术的基本概念和方法。深入探讨了电缆故障的类型和成因。基于故障树构建了电缆故障诊断模型,并通过案例分析进行了验证。最后,对电缆故障的可靠性进行了评估。为电缆系统的可靠性评估提供了一种新的方法,对电缆故障的预防和处理具有重要意义。

煤矿皮带运输系统可靠性分析研究

结合煤矿皮带运输系统的原煤运输流程,对系统中关键设备的故障进行分析,建立基于流程的故障树分析模型。进一步通过故障树定性和定量分析,得出故障树顶事件发生的最小割集,同时通过不同角度分析出系统的关键底事件,发现系统的薄弱环节。

基于FMEA的自动扶梯故障模式危害度研究

本文采用FMEA方法对自动扶梯各系统及部件的失效模式及故障原因进行了分析,建立了自动扶梯驱动主机、梯级链、导轨系统、扶手带等关键部件故障树模型,提出了重要部件故障危害度评估方法,研究了基于RCM的自动扶梯维护与检验技术,有利于实现自动扶梯科学维修,降低事故发生频率,对提高设备使用安全可靠性和智能运维管理能力具有参考作用。

某电动车低温散热器排气管断裂分析

本文以某电动车低温散热器排气管在路试过程中断裂为例进行故障分析,通过对排气管断口电镜分析确定了裂纹性质及断裂初步原因。然后使用故障树分析法(FTA)工具,通过生产过程排查,确定了外力磕碰风险原因;通过对原材料进行红外光谱检测、灰分检测及电镜分析,确定使用了回用料原因;通过对散热器排气管应力模拟分析、轴向强度检测试验,确定了结构不良原因。针对以上原因制定了相应的整改措施,解决了散热器通气管断裂的故障问题。对汽车从业人员在同类尼龙结构在整车上的设计、原材料使用及故障分析工作有一定指导意义。

Numerical Simulation to Reliability Analysis of Fault-Tolerant Repairable System

In the traditional method for the reliability analysis of fault-tolerant system,the system structure is described by means of binary decision diagram (BDD) and Markov process,and then the reliability indexes are calculated.However,as the size of system augments,the size of state space will increase exponentially.Additionally,Markov approach requires that the failure and repair time of the components obey an exponential distribution.In this study,by combining dynamic fault tree (DFT) and numerical simulation based on the minimal sequence cut set (MSCS),a new method to evaluate reliability of fault-tolerant system with repairable components is proposed.The method presented does not depend on Markov model,so that it can effectively solve the problem of the state-space combination explosion.Moreover,it is suitable for systems whose failure and repair time obey an arbitrary distribution.Therefore,our method is more flexible than the traditional method.At last,an example is given to verify the method.