A Novel Strategy for Probability-Based Failure Avoidance of Operating Technical Systems

2001 ◽  
Author(s):  
Dirk Söffker
Keyword(s):  
Failure Rate ◽  
Operating Conditions ◽  
Fault Detection And Isolation ◽  
Reliability Engineering ◽  
Reliability Characteristics ◽  
Safety And Reliability ◽  
Reliability Control ◽  
Technical Systems ◽  
Novel Strategy ◽  
Dependent Failure

Abstract Failure and fault avoidance techniques are becoming important methodologies due to economical and ecological risks of modern technologies. The basic methodologies and techniques developing safe systems are connected with reliability engineering technologies or fault detection and isolation (FDI) approaches. The contribution introduces into the ideas of the 1997 firstly published SRCE (Safety and Reliability Control Engineering)-concept. Core of the approach is the development of a history- and load-dependent failure rate, which allows the online-calculation of reliability characteristics, which can be monitored or controlled. The classical definitions of reliability engineering characteristics are unfit due to the fact that they are only ‘driven’ by the time, so effects of changing operating conditions etc. can not be considered directly. The proposed approach solves this problem by introducing a new definition of a failure rate by introducing load- and lifetime-dependent failure rate. This also includes the possibility to consider regenerating/recovering effects of technical systems or components. As an example the determination is illustrated and applied to the monitoring of an automotive tire.

scholarly journals Reliability Simulation of Two Component Warm-Standby System with Repair, Switching, and Back-Switching Failures under Three Aging Assumptions

Mathematics ◽  
2021 ◽  
Vol 9 (20) ◽  
pp. 2547
Author(s):  
Kiril Tenekedjiev ◽  
Simon Cooley ◽  
Boyan Mednikarov ◽  
Guixin Fan ◽  
Natalia Nikolova
Keyword(s):  
Failure Rate ◽  
Primary Component ◽  
The Other ◽  
System Failures ◽  
First Case ◽  
Reliability Characteristics ◽  
Two Component ◽  
Standby System ◽  
Dependent Failure ◽  
Warm Standby

We analyze the influence of repair on a two-component warm-standby system with switching and back-switching failures. The repair of the primary component follows a minimal process, i.e., it experiences full aging during the repair. The backup component operates only while the primary component is being repaired, but it can also fail in standby, in which case there will be no repair for the backup component (as there is no indication of the failure). Four types of system failures are investigated: both components fail to operate in a different order or one of two types of switching failures occur. The reliability behavior of the system is investigated under three different aging assumptions for the backup component during warm-standby: full aging, no aging, and partial aging. Four failure and repair distributions determine the reliability behavior of the system. We analyzed two cases—in the First Case, we utilized constant failure rate distributions. In the Second Case, we applied the more realistic time-dependent failure rates. We used three methods to identify the reliability characteristics of the system: analytical, numerical, and simulational. The analytical approach is limited and only viable for constant failure rate distributions i.e., the First Case. The numerical method integrates simultaneous Algebraic Differential Equations. It produces a solution in the First Case under any type of aging, and in the Second Case but only under the assumption of full aging in warm-standby. On the other hand, the developed simulation algorithms produce solutions for any set of distributions (i.e., the First Case and the Second Case) under any of the three aging assumptions for the backup component in standby. The simulation solution is quantitively verified by comparison with the other two methods, and qualitatively verified by comparing the solutions under the three aging assumptions. It is numerically proven that the full aging and no aging solutions could serve as bounds of the partial aging case even when the precise mechanism of partial aging is unknown.

Is high-altitude mountaineering Russian roulette?

2013 ◽  
Vol 9 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Edward K. Cheng
Keyword(s):  
High Altitude ◽  
Failure Rate ◽  
Rate Model ◽  
Reliability Engineering ◽  
Significant Difference ◽  
Inference Techniques ◽  
Decreasing Failure Rate

AbstractWhether the nature of the risks associated with climbing high-altitude (8000 m) peaks is in some sense “controllable” is a longstanding debate in the mountaineering community. Well-known mountaineers David Roberts and Ed Viesturs explore this issue in their recent memoirs. Roberts views the primary risks as “objective” or uncontrollable, whereas Viesturs maintains that experience and attention to safety can make a significant difference. This study sheds light on the Roberts-Viesturs debate using a comprehensive dataset of climbing on Nepalese Himalayan peaks. To test whether the data is consistent with a constant failure rate model (Roberts) or a decreasing failure rate model (Viesturs), it draws on Total Time on Test (TTT) plots from the reliability engineering literature and applies graphical inference techniques to them.

Analysis of risk concept for technical systems using digital twins

2020 ◽  
pp. 99-113
Author(s):  
Анатолий Михайлович Лепихин ◽  
Николай Андреевич Махутов ◽  
Юрий Иванович Шокин ◽  
Андрей Васильевич Юрченко
Keyword(s):  
Risk Management ◽  
Risk Analysis ◽  
Risk Model ◽  
Computer Modelling ◽  
Product Lifecycle Management ◽  
Operating Conditions ◽  
Digital Twins ◽  
Real Objects ◽  
Technical Systems ◽  
Active Research

Рассмотрены основные методологические аспекты анализа рисков технических систем с использованием цифровых двойников. Сформулирована концепция рисканализа и предложена базовая модель для ее реализации. Рассмотрены информационные аспекты анализа неопределенностей модели риска. Показано, что технологии цифровых двойников позволяют эффективно сочетать результаты компьютерного моделирования с данными мониторинга реальных объектов, обеспечивая более глубокий анализ объектов, с учетом множества вариантов конструкции, технологий и условий эксплуатации Development of technology and technical systems significantly increases in the volume of information. Traditional methods for designing, manufacturing and operating of technical systems do not allow processing such volumes of information. In this regard, the modern strategy for creating technical systems is based on the use of digital twins. Solving the problems of risk analysis and risk management for technical systems at all stages of the life cycle appears to be one of the promising areas for application of the digital twins technology. Despite of active research, using digital twins in risk analysis currently do not have appropriate methodological justifications and technical solutions in a number of key aspects. In particular, effective reductions of the order of risk models and quantifying uncertainty factors of various types have not been solved. The concept of the risk-informed decision making in product lifecycle management has not been implemented. In fact, there are very few publications on the risk analysis and risk management methodology using digital twins. The article discusses the main methodological aspects of risk analysis of technical systems using digital twins. The concept of risk analysis is formulated and a basic model for its implementation is proposed. The informational aspects of the analysis of uncertainties of the risk model are considered. It is shown that digital twin technologies allow effective combination of the results of computer modelling with the data monitoring of real objects, providing a deeper analysis of objects, taking into account a variety of design options, technologies and operating conditions.

Root cause identification approach using decomposition of QFD and extended RPN for product manufacturing reliability degradation

2021 ◽  
pp. 1748006X2110436
Author(s):  
Anqi Zhang ◽  
Yihai He ◽  
Chengcheng Wang ◽  
Jishan Zhang ◽  
Zixuan Zhang
Keyword(s):  
Quality Function Deployment ◽  
Degradation Mechanism ◽  
Product Reliability ◽  
Root Cause ◽  
Reliability Characteristics ◽  
Identification Technique ◽  
Reliability Control ◽  
Product Manufacturing ◽  
Identification Approach ◽  
Root Cause Identification

Reliability is reflected in product during manufacturing. However, due to uncontrollable factors during production, product reliability may degrade substantially after manufacturing. Thus, root cause analysis is important in identifying vulnerable parameters to prevent the product reliability degradation in manufacturing. Therefore, a novel root cause identification approach based on quality function deployment (QFD) and extended risk priority number (RPN) is proposed to prevent the degradation of product manufacturing reliability. First, the connotation of product manufacturing reliability and its degradation mechanism are expounded. Second, the associated tree of the root cause of product manufacturing reliability degradation is established using the waterfall decomposition of QFD. Third, the classic RPN is extended to focus on importance to reliability characteristics, probability, and un-detectability. Furthermore, fuzzy linguistic is adopted and the integrated RPN is calculated to determine the risk of root causes. Therefore, a risk-oriented root cause identification technique of product manufacturing reliability degradation is proposed using RPN. Finally, a root cause identification of an engine component is presented to verify the effectiveness of this method. Results show that the proposed approach can identify the root cause objectively and provide reference for reliability control during production.

scholarly journals Intelligent Fault Diagnosis Techniques Applied to an Offshore Wind Turbine System

2019 ◽  
Vol 9 (4) ◽  
pp. 783 ◽  
Author(s):  
Silvio Simani ◽  
Paolo Castaldi
Keyword(s):  
Fault Diagnosis ◽  
Wind Turbine ◽  
Operating Conditions ◽  
Fault Detection And Isolation ◽  
Offshore Wind ◽  
Data Driven ◽  
Offshore Wind Turbine ◽  
Wind Turbine System ◽  
High Degree ◽  
Offshore Plants

Fault diagnosis of wind turbine systems is a challenging process, especially for offshore plants, and the search for solutions motivates the research discussed in this paper. In fact, these systems must have a high degree of reliability and availability to remain functional in specified operating conditions without needing expensive maintenance works. Especially for offshore plants, a clear conflict exists between ensuring a high degree of availability and reducing costly maintenance. Therefore, this paper presents viable fault detection and isolation techniques applied to a wind turbine system. The design of the so-called fault indicator relies on an estimate of the fault using data-driven methods and effective tools for managing partial knowledge of system dynamics, as well as noise and disturbance effects. In particular, the suggested data-driven strategies exploit fuzzy systems and neural networks that are used to determine nonlinear links between measurements and faults. The selected architectures are based on nonlinear autoregressive with exogenous input prototypes, which approximate dynamic relations with arbitrary accuracy. The designed fault diagnosis schemes were verified and validated using a high-fidelity simulator that describes the normal and faulty behavior of a realistic offshore wind turbine plant. Finally, by accounting for the uncertainty and disturbance in the wind turbine simulator, a hardware-in-the-loop test rig was used to assess the proposed methods for robustness and reliability. These aspects are fundamental when the developed fault diagnosis methods are applied to real offshore wind turbines.

Investigations to Arrive at a Stable Start-Up Procedure for AHWR

2008 ◽  
Author(s):  
R. K. Bagul ◽  
D. S. Pilkhwal ◽  
P. K. Vijayan ◽  
D. Saha
Keyword(s):  
Natural Circulation ◽  
Heat Removal ◽  
Operating Conditions ◽  
Type I ◽  
Stable Regime ◽  
Start Up ◽  
Safety And Reliability ◽  
Heavy Water Reactor ◽  
Tube Type ◽  
Operating Points

Natural circulation is being adopted as a mode of core heat removal in several nuclear reactors that are under development. This is due to the passive nature of natural circulation that enhances the system safety and reliability. However, major concern in the design of natural circulation based reactor systems is to avoid the flow instabilities that may occur under certain operating conditions, i.e. unstable operational regime. Therefore various reactor operational transients such as start-up, power raising, setback and also the steady state operating points must fall within the stable regime. The choice of operating procedures needs to be made judiciously and which also needs to be validated and supported by experiments. Advanced Heavy Water Reactor (AHWR) being developed in India is a pressure tube type natural circulation boiling water-cooled reactor, wherein major part of the power is generated by thorium. Experiments and analytical studies have been performed to arrive at a rational start-up procedure for AHWR. Experimental results obtained in simple rectangular natural circulation loops as well as in a scaled down facility have revealed the importance of external pressurization to avoid the flashing and Type-I instabilities that occur at low pressure during start-up.

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