Failure Modes Of System Research Articles

Analysis of seismic damage process of high concrete dam-foundation system

In the anti-seismic analysis of concrete high dams, only the damage cracking of the dam concrete is usually considered, and the nonlinear characteristics of the dam foundation rock during the earthquake are not considered. Taking the Koyna gravity dam in India and Shapai arch dam in China as examples, this paper adopts the nonlinear time-history analysis method and takes into account the comprehensive influence of the radiation damping of infinite foundation, the hydrodynamic interaction between dam and reservoir, the nonlinear dynamic contact between various joints in the dam body and foundation, and the damage of dam concrete and foundation rock mass in the damage evolution process, analyzes damage evolution process of dam body-foundation system under earthquake action and the influence of foundation rock mass damage on seismic failure mode of concrete dam-foundation system, and compares the numerical simulation results with the actual earthquake situation. The calculation results show that after considering the damage of the dam foundation rock mass, the rock mass of the dam heel firstly appears to be damaged under the action of the earthquake and gradually expands into the interior of the foundation. The dam heel and the foundation surface are not damaged. The numerical simulation results are more in line with the actual situation of earthquake.

Health diagnosis of nuclear power plant

At present, nuclear power plant is developing rapidly, and its application has been involved in many aspects including life, military, industry and many other important fields, bringing benefits to people’s life. However, the nuclear power plant has a relatively special structure. Once a safety accident occurs, the consequences will be unimaginable, and the cost of its operation and maintenance will be relatively high. Therefore, how to effectively diagnose the health status of the nuclear power plant is an urgent problem to be solved. On the above-mentioned research background, we need to study nuclear power plant health diagnosis method. Considering the characteristic of the nuclear power plant system and special failure mode, both the safety and economy, a health condition diagnosis method based on analytic hierarchy process and fuzzy comprehensive evaluation method is proposed for the structural characteristics and functional characteristics of nuclear power plants. According to the special failure mode and complex system structure of nuclear power plant, the evaluation index system based on failure mode is constructed by laying the system using the hierarchical analysis method, and the system is scored by fuzzy comprehensive evaluation method. The health status makes a coarse-grained diagnosis and provides a reference for the development of the operation and maintenance strategy.

Simulation of the nonlinear mechanical behaviors of jointed rock masses based on the improved discontinuous deformation and displacement method

This study further develops the discontinuous deformation and displacement (DDD) method to model the nonlinear deformation and failure behaviors of jointed rock masses. The improved DDD (IDDD) method is then proposed to provide a unified formulation for solving the transformation of rock materials from continuum to discontinuum. By embedding finite elements into model blocks, the deformation ability and stress distribution within blocks are refined, and the fracture of an intact block is permitted. Namely, the rock blocks containing a number of finite elements are deformable and can be broken into several smaller parts during calculation. The edges of damaged elements are new joints and mechanical interaction between neighboring blocks along these new interfaces is therefore allowed. A series of numerical tests are conducted to validate the correctness and effectiveness of the IDDD model in terms of bending deformation, frictional contact, strength characteristics, crack propagation, etc. Meanwhile, the failure mode of a block system and flexural toppling of a jointed rock slope are further analysed. The results are in good agreement with the theoretical analyses, previous studies and experimental data. Overall, the proposed IDDD method is effective and reliable to model the nonlinear mechanical behaviors of jointed rock masses and it has shown particular advantages over the conventional numerical methods.

Failure Mode and Effect Analysis in a Linguistic Context: A Consensus-Based Multiattribute Group Decision-Making Approach

Failure mode and effect analysis (FMEA) is an effective risk-management tool, which has been extensively utilized to manage failure modes (FMs) of products, processes, systems, and services. Almost all FMEA models are concerned with how to get a complete risk order of FMs from highest to lowest risk. However, in many situations, it may be sufficient to classify the FMs into several ordinal risk classes. Meanwhile, generating a consensual decision is crucial for the FMEA problem because 1) reaching consensus will enhance the connections among FMEA participants, and 2) a highly accepted group solution to the FMEA problem can be generated. Thus, this study proposes a consensus-based group decision-making framework for FMEA with the aim of classifying FMs into several ordinal risk classes in which we assumed that FMEA participants provide their preferences in a linguistic way using possibilistic hesitant fuzzy linguistic information. In the FMEA framework, a consensus-driven methodology is presented to generate the weights of risk factors. Following this, an optimization-based consensus rule guided by a minimum adjustment distance policy is devised, and an interactive model for reaching consensus is developed to generate consensual FM risk classes. In order to justify its validity of the proposal, our framework is applied for the risk evaluation of proton beam radiotherapy.

Strength and stability in architectured spine-like segmented structures

Architectured and segmented material designs have recently emerged as a powerful approach to increasing the strength and toughness of brittle materials. Architectured materials are made of regular building blocks that can collectively slide, rotate, separate or interlock, providing a wealth of tunable mechanisms and properties. In this work we have used experiments and modeling to explore the mechanical response of idealized segmented systems made of a linear array of cubes subjected to axial pre-compression and to a transverse force. From simple tabletop experiments with playing dice with instrumented tests on 3D printed cubes and simple models, we highlight the effects of axial pre-compression, number of blocks, friction coefficient and surface morphology on strength, energy absorption (toughness) and stability (catastrophic vs. graceful failure). We identified two failure modes in this segmented system: a sliding mode where one or more blocks slide on one another, and a “hinging” mode where some interfaces open and rotate about hinge points. The failure mode transition between hinging and sliding was established, to assist the design of modern architectured structures and materials. Finally, we demonstrate that enriching the morphology of the cubes with curved interfaces (akin to the vertebrae in the spine of reptiles) delays hinging and improves stability.

Water Distribution Networks Resilience Analysis: a Comparison between Graph Theory-Based Approaches and Global Resilience Analysis

The structure and connectivity of infrastructure systems such as water distribution networks (WDNs) affect their reliability, efficiency and resilience. Suitable techniques are required to understand the potential impacts of system failure(s), which can result from internal (e.g. water hammer) or external (e.g. natural hazards) threats. This paper aims to compare two such techniques: Graph Theory (GT) and Global Resilience Analysis (GRA). These are applied to a real network – L’Aquila (central Italy) – and two benchmark networks – D-Town and EXNET. GT-based metrics focus on the topology of WDNs, while GRA provides a performance-based measure of a system’s resilience to a given system failure mode. Both methods provide information on the response of WDNs to pipe failure, but have different data requirements and thus different computational costs and precision. The results show that although GT measures provide considerable insight with respect to global WDN behavior and characteristics, performance-based analyses such as GRA (which provide detailed information on supply failure duration and magnitude) are crucial to better understand the local response of WDNs to pipe failure. Indeed, particularly for complex networks, topological characteristics may not be fully representative of hydraulic performances and pipe failure impacts.

Seismic Behavior Effect of Knee Braced Frames Considering Different Type of Geometry under Non-Linear Analysis

The design and behavior of a ductile structural system called a knee-braced moment frame are presented in this paper. The design of this structural system is based on a capacity-design concept that results in ductile behavior. The knee part is a fuse-like component that dissipates energy by the formation of plastic flexural and/or shear hinges at its ends and mid-span, when the building is subjected to severe lateral loads. However, the diagonal brace component, on the other hand, provides the required level of lateral stiffness and remains in the elastic range without buckling at any time. Attempts have been made, in the present study, to investigate the non-linear seismic behavior of Knee-Braced Frame systems for various influencing factors, and to formulate the effects of the number of building stories, the length of the knee element, and moment of inertia of the bending members on the seismic behavior, the drift of the stories, and the failure mode of these systems. Finally, based on the results of the study, some recommendations have been offered for the effective range parameters for the optimal performance of these systems.

Combining Model-Based Testing and Failure Modes and Effects Analysis for Test Case Prioritization: A Software Testing Approach

Due to The complexity of modern software projects and the increasing size of software systems, it becomes difficult to manually perform tests with limited resources. Also, manual testing cannot assure that the software is tested using all possible combinations of inputs. Therefore, automate software testing activities have become primordial in the Software Development Life Cycle (SDLC). Model-based testing is a prominent validation technique in software testing that uses models of the system under test to automatically generate test cases; this generation leads to a large number of test cases; which cannot exhaustively be executed, due to time and cost constraints. Moreover, the test-cases execution order has an influence on the rate at which faults can be detected. Therefore, it is essential to prioritize test cases in order to execute the most important with limited time and cost. On the other hand, The Failure Mode and Effects Analysis (FMEA) considered as one of the formal techniques to do risk based testing. It offers a structured methodology to identifying the system failure modes, analyzing their effects and setting up controls to risk reducing and improve the quality of systems or products. By applying such a technique to Model-based testing projects, we can benefit from FMEA analysis and the automating in same project. Through this paper, we introduced a new model based testing approach for prioritizing and ranking test cases according to the requirements and failure modes. In the suggested approach we used the Failure Mode and Effect Analysis methodology in model based testing way to automatically generate a set of pair {test case, priority number} to prioritize test cases. It differs from existing approaches in that it generates two types of test cases; requirement-based test cases and failure mode-based test cases. For the purpose of experimental evaluation and analysis, we will compare the suggested approach with some well-known prioritization methods and we will present a case study to illustrate the potential application of the proposed approach in a future work.

Fragility analysis of the roof structure of low-rise buildings subjected to tornado vortices

The fragility curves of roof failures for wood-frame low-rise building were developed in this study with the focus on the roof sheathing panels and roof-to-wall connections. Two different nail spacings for roof sheathing panels and three types of roof-to-wall connections were considered. This study focused on the first failure of roof sheathing panels without considering the sequential loss of the sheathing panels, and the unit failure of effective wind zones containing different numbers of roof-to-wall connections. The tornado simulator-based dataset was used for determination of the statistics of wind loads, without considering the translational motion effects of tornado vortices. The results show that the failure probability of roof is dependent on the proximity of a tornado to a building and the opening azimuth on walls. Additionally, the combined effects of pressure drop and aerodynamic interactions dominate the failure modes of roof system. The obtained fragility curves in this study can be used to estimate the maximum tangential wind speed of the tornado vortices and the local oncoming tangential wind speed at roof height. The estimation of tornado intensity using the present results is likely to approach the lower-bound of wind speed estimation in WSEC (2006) report.

Reliability model for switchgear failure analysis applied to ageing

AbstractThe failure analysis for each component is the biggest problem for maintenance task for switchgears. It should consider the redundant mechanical and electrical systems, in circuit breakers for the analysis. In recently researches, they are often described innumerable system failure modes, according to the methodology applied: RCM plus, RCM 2, among others. Nevertheless, in these methodologies, the specific effects are independently considered (for example the IEEE standard) has proposed 11 failures modes, furthermore CIGRE has proposed 4 evolutionary failures modes however The effects are independent for the failure mode, there is no interaction between them. On the other hand, this research proposes a new perspective with combinations between them and the degradation sequence for ageing process. A proficient method is used to recognize main failure modes, according to IEC 62271–100 (2011) and IEC 62271-1 (2007), later, in the space of arbitrary components, it accomplishes system reliability analysis to calculate the system failure probability, due to reliability analysis, this research proposes a new proposal to complement the IEC standards. To establish the main failure and to propose in decreasing in order their influence. This new proposal to model the searching technique uses the Weibull and gamma distribution. Finally, the authors have done a case study with the new proposal, to prove the reliability goal for contending failure modes under the faster circumstances than traditional methods. In the section 1, the main aspect for the failure analysis in switchgear is described, in the section 2 a system reliability is analyzed with the failure modes criteria: A classical approach and a reliability scope in the analysis. In the section 3 a new proposal is described for a framework, it considers the failure mode analysis and reliability studies, later, in the section 4, the case study is developed with thirty-four hydraulic switchgear and 3201 site acceptance test for preventive maintenance and a section 5, for a discussion about the new proposal in the international standards.

Cost, Schedule and Safety Benefits of Early System Safety Involvement

System safety engineering is the application of engineering and management principles, criteria and techniques to achieve acceptable mishap risks. System safety typically reduces mishap risks through analyses that identify and address potential system failure modes. Studies indicate that when system safety is involved early in the product lifecycle, schedule slippage and cost escalation resulting from design changes can be substantially reduced. Development programs often face the dilemma of whether to apply funding to perform thorough, intensive system safety analyses in the conceptual design phase or wait until later, when designs are more complete, parts are being manufactured or testing is underway. Performing the analyses earlier consumes funds that might be needed later, while performing the analyses later increases the likelihood of expensive and time-consuming redesigns. This paper provides examples that encourage involving system safety engineering earlier in the process, by demonstrating the cost and schedule advantages, as well as the expected safety risk reduction. In addition, involving system safety earlier permits corrective actions to be implemented at a higher level in the system safety order of design precedence, which increases the effectiveness of corrective actions and reduces residual risk.

Modified failure mode and effects analysis under uncertainty: A rough cloud theory-based approach

Failure mode and effect analysis (FMEA) has been commonly utilized for recognition of failures, causes and influences in a system/process. However, the traditional FMEA method has been subjected to a lot of criticisms, e.g., equal importance of risk factor, lack of mechanism in manipulating imprecise information; Although the traditional FMEA is improved by various approaches based on fuzzy set theory, it still suffers from several limitations, such as requirement of prior information, construction of many fuzzy rules, and ignoring randomness in risk evaluation. Therefore, this study integrates the advantage of rough set theory in flexibly and objectively expressing vagueness without extra information and the merit of cloud model theory in taking randomness of experts’ risk assessments into account. Meanwhile, an integrated weighting method considering both subjective and objective aspects is employed to estimate risk factor weights. Then, the failure modes are ranked by an extended TOPSIS (technique for order performance by similarity to ideal solution) method. To finish, a case study about risk evaluation of failure modes in a steam valve system is analyzed to show the effectiveness of the proposed method.

Analysis of a tunnel failure caused by leakage of the shield tail seal system

This paper presents an analysis of a tunnel failure accident during shield tunnel construction on Foshan Metro Line 2 in China. The failure is caused by the leakage of the multilayer seal system, which consists of several brush seals at the tail of the shield. Four different failure modes for the multilayer seal system are discussed. A simple structural analysis of the brush seals is then conducted, and failure mode 4 (failure due to brush seal deformation) is identified as a major reason for the Foshan tunnel accident. A finite element method (FEM) analysis is employed to validate the conclusions drawn from the simple structural analysis of the brush seals.

Performance assessment of bridge-soil-foundation system with irregular configuration considering ground motion directionality effects

Highway bridges with piers of unequal height crossing irregular topographical surfaces have potential complexities in terms of component vulnerability evaluations. This paper investigates the seismic behavior of a five-span concrete girder bridge with three coefficients of pier height and two different types of irregular configurations. Moreover, soil-structure interaction is taken into account by modeling a typical deep foundation, including piles and the surrounding soil, in order to examine the effect of pier base flexibility compared to the equivalent fixed-base model. For this purpose, incremental dynamic analyses are performed on the three-dimensional analytical finite element models using a set of ground motion pairs each rotated about the vertical axis of bridge producing seven angles of seismic incidence. The results obtained from the dynamic analyses and fragility assessment of the selected bridge models illustrate that substructure irregularity, support condition of piers, and directionality of seismic excitations are three interdependent factors in vulnerability assessment of highway bridges. Variation in each of the above-mentioned factors leads to change in the fragility characteristics of a bridge at global system failure mode or individual component limit states.

Experimental and numerical analysis of fully grouted long rockbolt load-transfer behavior

As a simple supporting structure, rockbolts are responsible for maintaining the integrity and stability as well as controlling the deformation, displacement, and crack development in the surrounding rock mass. Knowledge of rockbolt load-transfer behaviors constitutes valuable information, as the rockbolt functionality is affected by load-transfer processes. A series of pullout tests was conducted on a rockbolt with a long embedment length (1500 mm). The critical rockbolt embedment length at which yielding or necking occurs together with the friction coefficient at the residual axial stress was analyzed numerically. Additionally, the failure modes of rockbolt-grouted systems and the effects of several parameters, including the rockbolt diameter (18, 20, and 25 mm) and cement mortar strength, were assessed. The rockbolt strain and energy absorption during the pullout process were also investigated. The identified rockbolt failure modes, which are dependent on the cement mortar strength and rockbolt diameter, include pullout accompanied by partial concrete splitting failure parallel to the rockbolt. Under the same cement mortar strength, the maximum load increases and the rockbolt displacement at the maximum load decreases as the rockbolt diameter increases. When diameter is held constant, the maximum load and corresponding displacement increase as the cement mortar strength increases, but the residual load is irregular. The energy absorbed by the rockbolt in the pullout test is related to the cement mortar strength and failure mode. With an increasing embedment length, the failure process is converted from a completely damaged interface with little simultaneous damage to the cement mortar at the free end to the expansion of the cracks at the loaded and free ends toward each other. The interface is completely damaged when the cracks at both ends become connected.

Failure interaction models for multicomponent systems: a comparative study

Classical reliability models consider the failure modes of a multicomponent system as independent phenomena, even if these modes concern only one component or neighbouring components. In fact, when a failure mode occurs on a given system, causes may be related to external events or to the physical degradation of any component in the system. In both cases, failure modes can partially or totally share some root causes, which may compromise the principle of independence of failure modes. This paper reviews the failure interaction models that characterise the effect of any failure mode of a component on the failure modes of its neighbors and on the entire system. Three relevant groups of interaction models are reviewed: reliability indexes’ interaction, state-based interaction and copula-based interaction. All these models share the hypothesis of stochastic dependence between failure modes, also referred to as failure interaction. They differ in their fundamental modeling concepts. Advantages and limits of each of them are emphasized in a comparative study dealing with dependency concepts, modeling methods and application domains.

Reliability analysis of road networks in disaster waste management

The condition of road networks which connect disaster affected areas and final disposal sites has a critical role in the management of disaster waste. In this paper, we present a two-stage framework to estimate the overall reliability and failure modes of a disaster waste management system considering the reliability of each route involved in the road network. In the first stage, first order reliability method and Ditlevsen bounds are applied to estimate system reliability. In the second stage, an event tree approach is implemented to analyse the failure modes of the system. The methodology is demonstrated with an artificial case study considering three different scales of disasters. The results obtained from the case study can provide information to decision makers regarding the priority of the routes in the system and the most likely failure mode.

A simplified method to evaluate the flexural capacity of lightweight cold-formed steel floor system with oriented strand board subfloor

Lightweight floors built with cold-formed steel C-shape joists and oriented strand board sheathing is one of the primary floor systems in cold-formed steel residential construction. In order to investigate the flexural capacity with accounting for the composite action of the floor system, two tests on the flexural capacity of the floor system were carried out. The test results indicated that the load-carrying capacity of the floor system was significantly affected by the spacing of the screws that connect the joist and oriented strand board sheathing. The primary failure mode of the floor system was the local buckling at the critical section of the C-shape joist although there was tendency of lateral-torsion buckling of the joist. The wavelength of the buckling mode was approximately equal to the screw spacing. A finite element mode was established to simulate the structural behaviour of the floors by commercial software ANSYS and it was found that the numerical results agreed well with the test data. Parametric studies were carried out based on numerical analysis to investigate how the flexural capacity of the floors was influenced by different factors such as screw spacing, joist spacing and sheathing thickness, etc. Finally, based on the test data and numerical analysis results, a simplified design method was proposed to predict the flexural capacity of the floors with accounting for the composite action. The results obtained from the proposed method were validated by both experimental and numerical investigations of two full-scale lightweight floors built with cold-formed steel C-shape joist and oriented strand board subfloor.

RAMS Analysis of Train Air Braking System Based on GO-Bayes Method and Big Data Platform

The RAMS (reliability, availability, maintainability, and security) of the air braking system is an important indicator to measure the safety performance of the system; it can reduce the life cycle cost (LCC) of the rail transit system. Existing safety analysis methods are limited to the level of relatively simple factual descriptions and statistical induction, failing to provide a comprehensive safety evaluation on the basis of system structure and accumulated data. In this paper, a new method of safety analysis is described for the failure mode of the air braking system, GO-Bayes. This method combines the structural modeling of the GO method with the probabilistic reasoning of Bayes methods, introduces the probability into the analysis process of GO, performs reliability analysis of the air braking system, and builds a big data platform for the air braking system to guide the system maintenance strategy. An automatic train air braking system is taken as an example to verify the usefulness and accuracy of the proposed method. Using ExtendSim software shows the feasibility of the method and its advantages in comparison with fault tree analysis.

Generalized thermoelastic analysis of thermo-optic switch multi-layer structure

Delaminating failure is the fatal failure mode of Micro Electro Mechanical Systems(MEMS) multi-layer membrane structures and severely affects the reliability of MEMS devices. In this work, a multi-layer membrane structural model of a thermo-optic switch is established under the framework of generalized thermoelastic theory, and the distribution of interlayer temperature, thermal mismatch stress and core refractive index is calculated. The effect of relaxation time on thermal mismatch stress and refractive index is discussed, and numerical results show that the thermal mismatch stress increases with the heating power. When the relaxation time rises to 10−3s magnitude, the thermal mismatch stress decreases, the core layer reaches a high steady-state temperature and the refractive index of the core layer expands. These results provide a new idea for the research and development of new devices; that is, the adoption of core layer materials with long relaxation time can improve the reliability of MEMS devices.