Individual Component Failure Research Articles

Estimation for Expected Energy Not Served of Power Systems Using the Screening Methodology of Cascading Outages in South Korea

The uncertainty of complex power systems increases the possibility of large blackouts due to the expectations of physical events, such as equipment failures, protection failures, control actions failure, operator error, and cyber-attacks. Cascading outage is a sequence of dependent failures of individual components that successively weaken the power system. A procedure to identify and evaluate the initiating events and perform sequential cascading analysis is needed. In this paper, we propose a new screening methodology based on sequential contingency simulation of cascading outages, including probabilistic analysis and visualization model. Performance of a detail cascading analysis using practical power systems is suggested and discussed. The proposed screening methodology will play a key role in identifying the uncontrolled successive loss of system elements.

Dynamic response of aluminum corrugated sandwich subjected to underwater impulsive loading: Experiment and numerical modeling

The aluminum sandwich structures with the trapezoidal corrugated core subjected to underwater impulsive loadings are studied experimentally and numerically in the present study. The blast resistance in terms of dynamic deformation, failure modes and associated mechanisms is evaluated in relation to the load intensity, and the core height under air-backed and water-backed conditions. 3D digital imaging correlation and postmortem analysis are employed to investigate the deformation and failure of individual components, focusing on the effects of loading intensities, core height and loaded condition. The discrepancy in bending stiffness along the x-direction and y-direction results in the asymmetrical propagation of plastic hinges and the crack initiates and propagates along the x-direction. Although the core height affects the response rate and the local tendency of deformation greatly as the impulses increase, the core height has a limited influence on the deflection resistance when the corrugated sandwich panels have the same areal mass. The critical impulse for tearing failure of sandwich with higher core height is much smaller than that of panels with lower core height. Due to the resistance and reaction in backwater column, the transverse deflection does not increase monotonously to the increasing core heights and impulses under water-backed condition. The corrugated sandwich panels suffer significantly smaller inner face deflections than the solid plates of identical mass per area under air-backed condition, while all plates involved show approximate blast-resistance performance under water-backed condition.

A Phenomenological Description of the Failure of Nonuniform Threads with Obstruction at Weak Sites

The mechanics of twisted threads with rectilinear core, which serves to describe the failure of both individual components as well as the thread as a whole, is analyzed. The article proposes a hypothesis according to which obstruction of weak sites of the core thread by a contact load from the direction of the winding thread with loading of the composite (core-spun) thread may serve to account for the observed extremal variation in strength.

Enhanced Hazard Analysis and Risk Assessment for Human-in-the-Loop Systems.

The objective of this study was to enhance the existing system hazard analysis (SHA) technique by introducing the concepts of human and automation reliability quantification as well as fuzzy classification of system risks. These enhancements led to formulation of a new overall system risk-reliability score. Many system safety analysis methods focus on individual physical component failure. Some human reliability analyses (HRA) consider human-automation interaction in determining system failure rates. There is no system safety analysis technique that quantifies the impact of human and automation reliability on the risk of hazard exposure. Classification of the probability and severity of hazard exposure is typically made in terms of linguistic rather than numerical variables. Fuzzy sets are applicable for transforming linguistic classifications to numerical quantities. We focused on using fuzzy sets to define overlapping bands of system risk exposure with reference to the hazard risk categories defined in MIL-STD 882B. Fuzzy sets were also used for human-automated system reliability classification. Introduction of human and automation reliability assessment in the SHA allows for definition of a system risk-reliability modeling space. The enhanced SHA (E-SHA) technique yields a mishap risk index, which is projected based on a composite assessment of human-automated system reliability at the time of operation. The E-SHA was compared with one of the most advanced HRA techniques. The E-SHA technique supports broader safety control recommendations and provides comparable, if not more detailed, results than prior systems safety and HRA techniques.

Techno-economic and reliability assessment of solar water heaters in Australia based on Monte Carlo analysis

Monte Carlo analysis is used in this study to estimate the techno-economic benefits and reliabilities of solar water heaters. The study focuses on a product range manufactured by a local company in Australia. The historical data provided by the company forms the basis of this investigation. The inverse Weibull distribution function is a good match for representing the historical data in the model in terms of the number of failures per operating time for each component. The overall system reliability is determined as the sum of individual component failures during the product lifetime. The analysis is carried out for different system configurations using copper, stainless steel and glass-lined storage tanks. All the systems utilise flat plate collectors. The product with glass-lined storage tanks and electric boosters show a good overall reliability if systems are maintained.Based on the probability model, the variable maintenance costs of solar water heaters were estimated over the product lifetime. This together with capital expenditures and fuel charges are used to compute the specific price of hot water supply for different system configurations. Moreover, a sensitivity analysis is implemented to show the impact of auxiliary heating on the economic viability of the products. The results show that solar water heaters can offer significantly better long-term economic viability compared to conventional systems at moderate auxiliary energy consumptions.

Dynamic failure of honeycomb-core sandwich structures subjected to underwater impulsive loads

Abstract The aluminum sandwich structures with hexagonal honeycomb cores subjected to water-based impulsive loading are studied experimentally. The blast resistance in terms of dynamic deformation, failure modes and associated mechanisms is evaluated in relation to the load intensity, core relative density under air-backed and water-backed conditions. 3D digital imaging correlation and postmortem analysis are used to investigate the deformation and failure of individual components, focusing on the effects of loading intensities, core relative density and loaded condition. The failure mode maps of sandwich panels are summarized to study the different regimes of deflection resistance in different experimental cases. The results show that the effect of relative core density significantly influences the blast resistance of sandwich panels under the different loaded conditions. The sandwich panels with denser cores perform better blast resistance at high impulsive loads under air-backed condition. Only slight discrepancy of deflection resistance has been observed under the water-backed condition. The honeycomb sandwich panels suffer significantly smaller backface deflections than solid plates of identical mass per area under air-backed condition, while the discrepancy of deflection is negligible under the water-backed condition.

Dynamic response and failure of PVC foam core metallic sandwich subjected to underwater impulsive loading

Abstract The sandwich structures with metallic facesheets and PVC foam cores subjected to water-based impulsive loads are investigated experimentally. The blast resistance in terms of dynamic deformation, failure modes and associated mechanisms is evaluated in relation to the effect of load intensity, core density and core height under air-backed and water-backed conditions. The plates are subjected to underwater impulsive loads of different intensities with a lab-scaled underwater explosive simulator. 3D digital imaging correlation and postmortem analysis are used to investigate the deformation and failure of individual components, focusing on the effects of loading intensities, structural properties and loaded conditions. The primary failure modes of cores transfer from core crushing and inelastic deformation to cracks and fragmentation with the increasing applied impulse and core density. The distinct trends of deflection shown by front faces and back faces are influenced by the effect of core density significantly. Unlike the air-backed condition, water-backed condition affects the damage and deflection of the sandwich structure in a different way because of the critical intensity of impulsive loads. Quantitative structure-loading-performance relation is carried out to provide guidance for structural design.

Time-Dependent System Reliability Analysis Using Random Field Discretization

This paper proposes a novel and efficient methodology for time-dependent system reliability analysis of systems with multiple limit-state functions of random variables, stochastic processes, and time. Since there are correlations and variations between components and over time, the overall system is formulated as a random field with two dimensions: component index and time. To overcome the difficulties in modeling the two-dimensional random field, an equivalent Gaussian random field is constructed based on the probability equivalency between the two random fields. The first-order reliability method (FORM) is employed to obtain important features of the equivalent random field. By generating samples from the equivalent random field, the time-dependent system reliability is estimated from Boolean functions defined according to the system topology. Using one system reliability analysis, the proposed method can get not only the entire time-dependent system probability of failure curve up to a time interval of interest but also two other important outputs, namely, the time-dependent probability of failure of individual components and dominant failure sequences. Three examples featuring series, parallel, and combined systems are used to demonstrate the effectiveness of the proposed method.

Shutter Technique for Noninvasive Individual Cell Characterization in Sealed CPV Modules

An optical shutter technique for quality control and degradation analysis of concentrating photovoltaic (CPV) modules is presented. Shuttering configurations are described and used to determine individual component degradation or failure in field-exposed commercial modules. Cells are shuttered in specific patterns, intentionally engaging internal bypass diodes, and current–voltage ( I – V ) curves are measured at the housing terminals of the sealed module. Individual cell characteristics may be qualitatively determined by contrasting module I – V responses to different shutter configurations and quantitatively determined by fitting an extended equivalent circuit model to the shutter data.

High-speed digital imaging and computational modeling of dynamic failure in composite structures subjected to underwater impulsive loads

The load-carrying capacity of composite structures under water-based impulsive loads is evaluated in relation to different core materials and load intensity. The analysis focuses on the role of core density and the effect of varying structural attributes and environmental conditions on deformation and failure mechanisms in monolithic as well as sandwich composites. The structures analyzed are simply supported planar composites with PVC foam cores and E-glass/vinylester facesheets. For the analysis carried out, the material properties of the sandwich cores are varied while the total mass is kept constant. The structures are subjected to impulsive loads of different intensities using a novel new projectile-impact-based facility called the Underwater Shock Loading Simulator (USLS). In-situ high-speed digital imaging and postmortem analysis are used to study the deformation and failure of individual components, focusing on the effects of loading intensities, failure modes and material heterogeneity. Depending on the loading rate, shear cracking and/or collapse are the primary failure modes of the polymeric foam cores. Core density and height also significantly influence the response and failure modes. On a per unit weight basis, structures with low density cores consistently outperform structures with high density cores because the former undergo smaller deflections, acquire lower velocities and transmit a smaller fraction of incident impulses. Scaling relations in the form of deflection and impulse transmitted as functions of core density and load intensity are obtained to provide guidance for structural design.

A systems approach to examining disaster response: Using Accimap to describe the factors influencing bushfire response

This article argues that systems theory-based human factors methods have a key role to play in examining and enhancing systems of disaster response. This argument is supported by a first-of-its-kind test application of a popular risk management framework to describe bushfire response activities. Specifically, an Accimap of the response to a recent major Australian bushfire was constructed. The case study is used to test a series of predictions made by the risk management framework in order to test the applicability of this approach in a bushfire response context and to determine whether systems theory-based frameworks are compatible with the analysis of disaster response activities. In conclusion, the output demonstrates that such approaches are suited to the analysis of disaster response efforts. Moreover, it is argued that, compared to the existing individual component failures approach, this holistic systems approach provides a more comprehensive understanding of response performance and better promotes improvements to the overall disaster response system.

Damage of cells and battery packs due to ground impact

The present paper documents a comprehensive study on the ground impact of lithium-ion battery packs in electric vehicles. With the purpose of developing generic methodology, a hypothetic global finite element model is adopted. The force–displacement response of indentation process simulated by the global FE model is cross-validated with the earlier analytical solutions. The punching process after the armor plate perforation, the ensuing crack propagation of the armor plate as well as the local deformation modes of individual battery cells are clearly predicted by the global modeling. A parametric study is carried out, and a few underlying rules are revealed, providing important clues on the design of protective structure of battery packs against ground impact. In the next step, detailed FE models at the level of a single battery cell and shell casing are developed and simulations are performed using boundaries and loading conditions taken from the global solution. In the detailed modeling the failure of individual components is taken into account, which is an important indicator of electric short circuit of a battery cell and possible thermal runaway. The damage modes and the deformation tolerances of components in the battery cell under various loading conditions are observed and compared.

From the Editors

From the Editors

On the Computational Complexity of Measuring Global Stability of Banking Networks

Threats on the stability of a financial system may severely affect the functioning of the entire economy, and thus considerable emphasis is placed on the analyzing the cause and effect of such threats. The financial crisis in the current and past decade has shown that one important cause of instability in global markets is the so-called financial contagion, namely the spreading of instabilities or failures of individual components of the network to other, perhaps healthier, components. This leads to a natural question of whether the regulatory authorities could have predicted and perhaps mitigated the current economic crisis by effective computations of some stability measure of the banking networks. Motivated by such observations, we consider the problem of defining and evaluating stabilities of both homogeneous and heterogeneous banking networks against propagation of synchronous idiosyncratic shocks given to a subset of banks. We formalize the homogeneous banking network model of Nier et al. and its corresponding heterogeneous version, formalize the synchronous shock propagation procedures, define two appropriate stability measures and investigate the computational complexities of evaluating these measures for various network topologies and parameters of interest. Our results and proofs also shed some light on the properties of topologies and parameters of the network that may lead to higher or lower stabilities.

Prognostic Health Management of a RF Transceiver Chain

The impact that modern wireless communications plays in our everyday lives is huge. A great deal of our day to day operation, be it commercial, civil or defence relies on the ability to deploy these technologies reliably, with the minimum of failure. This paper presents a system based Prognostic Health Management (PHM) methodology for health monitoring and prognostics within a RF transceiver chain, with the ability to provide impending detection of individual system component failure. The primary focus of this paper is towards military assets such as radar and electronic warfare (EW) systems, but it is envisaged that it will have other connotations in helping to provide quality of service (QoS) in wireless communications as well as civilian radar systems. Methods of failure modes and degradation in RF devices are examined before suggesting a methodology where parametric data may be extracted for health monitoring by non-linear techniques. This data is then compared to an ideal healthy transceiver by the use of a metric employing the Mahalanobis distance. A prognostic is applied in the form a sequential Monte-Carlo method by the use of a particle filter to give an approximation of remaining useful life (RUL).

Biologically Inspired Networks

Inspired by the nature, the interesting properties of natural organisms can be imitated in many different applications. The nature has been optimizing itself for billions of years and in many cases it simply introduces the most optimal approaches. On the other hand, the task of data collection and aggregation is critical in wireless sensor networks (WSN). The information packets should traverse the network towards the aggregating center i.e. sink node. The problem of finding the best path to route the data has been long under investigation. The authors propose a new method for collecting the data from sensor field based on a biological inspired method adopted from tubular network formation behavior of slime mold where biological organisms efficiently self-organize unreliable and dynamically changing topology, to compensate for the failure of individual components while not relying on explicit central coordination. They show that the emergent network exhibits a widely observed property in natural topologies called scale-free which explains a lot of inherent characteristics in living creatures. At the end the authors show that the data collection time for a biologically inspired network is shorter than uniform channel capacity scheduling.

Aseptic Tibial Debonding as a Cause of Early Failure in a Modern Total Knee Arthroplasty Design

We observed isolated tibial component debonding from the cement in one modern primary TKA design (NexGen LPS 3° tibial tray; Zimmer, Warsaw, IN, USA). This failure mechanism is sparsely reported in the literature. We (1) assessed survivorship of this tibial tray with special emphasis on debonding; (2) described clinical and radiographic features associated with tibial failure; and (3) compared patient and radiographic features of the failures with a matched cohort. A total of 1337 primary TKAs were performed with a cemented NexGen LPS 3° tibial tray over an 11-year period. Twenty-five knees (1.9%) were revised for tibial debonding. BMI and radiographic alignment in the tibial debonding group were compared with a matched control group. Implant survivorship was assessed using tibial debonding as the end point. Survival free of revision from tibial debonding was 100% at 1 year and 97.8% at 5 years. The tibial failures shared a typical radiographic pattern with debonding at the cement-implant interface and subsidence into varus and flexion. We found no link between limb alignment or individual component alignment and failure because 22 of the 25 failures occurred in well-aligned knees. Our standardized followup of patients undergoing TKA at routine intervals allowed us to discover a higher rate of revision resulting from tibial debonding. We have discontinued the use of this particular tibial tray for primary TKA and surveillance for patients undergoing TKA continues to be warranted.

A systems approach to understanding and enhancing disaster response: An Accimap analysis of bushfire response activities

This article argues that systems theory-based human factors methods have a key role to play in understanding and enhancing systems of disaster response. This argument is supported by a first-of-its-kind test application of a popular risk management framework to the analysis of bushfire response activities. Specifically, an Accimap analysis of the response to a recent major Australian bushfire was conducted. The analysis is used to test a series of predictions made by the risk management framework in order to test the applicability of this approach in a bushfire response context and to determine whether systems theory-based frameworks are compatible with the analysis of disaster response activities. In conclusion, the analysis demonstrates that such approaches are highly suited to the analysis of disaster response efforts. Moreover, it is argued that, compared to the existing individual component failures approach, this holistic systems approach provides a more comprehensive understanding of response system performance and better promotes improvements in disaster response.

Analytical modeling and comparison of fault-tolerant message flow control mechanisms in torus-connected networks

In many environments, rather than minimizing message latency or maximizing network performance, the ability to survive beyond the failure of individual network components is the main issue of interests. The nature of Wormhole Switching (WS) leads to high network throughput and low message latencies. However, in the vicinity of faulty regions, these behaviors cause rapid congestion, provoking the network becomes deadlocked. While techniques such as adaptive routing can alleviate the problem, they cannot completely solve the problem. Thus, there have been extreme studies on other types of switching mechanisms in networking and multicomputers communities. In this paper, we present a general mathematical model to assess the relative performance merits of three well-known fault-tolerant switching methods in tori, namely Scouting Switching (SS), Pipelined Circuit Switching (PCS), and Circuit Switching (CS). We have carried out extensive simulation experiments, the results of which are used to validate the proposed analytical models. We have also conducted an extensive comparative performance analysis, by means of analytical modeling, of SS, PCS, and CS under various working conditions. The analytical results reveal that SS shows substantial performance improvements for low to moderate failure rates over PCS and CS, which achieves close to WS performance. PCS can provide superior performance over CS and behaves the same or in some occasions worse than SS, under light and moderate traffic, especially with the same hardware requirements.

Progressive collapse analysis of thin-walled box columns

Box columns are often used as main strength members of various types of thin-walled structures such as ships, ship-shaped offshore structures, and aerospace structures. Until and after the ultimate limit state is reached, box columns exhibit highly nonlinear structural behavior in terms of geometrical and material aspects. In particular, the effects of local buckling, global buckling, and their interaction play a significant role in the resulting consequences of box columns under extreme actions. In order to calculate the maximum load-carrying capacity of box columns, it is thus highly required to perform the progressive collapse analysis to take into account progressive failures of individual components and their interacting effects. The aim of the present study is to demonstrate a method that is useful for the progressive collapse analysis of thin-walled box columns in terms of computational efficiency and accuracy. Theoretical outline of the method is addressed. Short, medium and long box columns in length are studied in terms of interacting effects between local component failure modes and global system failure modes. The effect of unloaded edge conditions of individual plate elements is also studied. A comparison of the method with more refined nonlinear finite element method computations is made.