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This paper investigated the mechanical performance, progressive failure process, and failure modes of riveted joints, bonded joints, and hybrid joints with different adhesive layer thicknesses connecting carbon-fiber-reinforced plastic (CFRP) and aluminum alloy subjected to quasi-static tensile loading. The 2D digital image correlation technique was used to record the deformation and strain of the overlap area. The results show that the thickness of the adhesive layer had a negative effect on the mechanical properties of the hybrid joints, and when the thickness of the adhesive layer was increased from 0.2 to 0.8 mm, the peak load and the energy absorption (EA) values of the hybrid joints were reduced by 14.38 and 23.22%, respectively. Compared with the bonded and riveted joints, hybrid joints showed better performances in peak load and EA values, and rivets were able to continue carrying loads when the adhesive layer failed. The typical failure modes of the hybrid joints included CFRP compressive failure, adhesive failure, fiber-tear failure, and light-fiber-tear failure. It was further found that the adhesive could disperse the stress around the rivet holes and effectively reduce the stress concentration around the rivet holes. [ABSTRACT FROM AUTHOR]

The Gumbel-Hougaard family's invention of copula distribution paved the way for new research, and it has been widely applied in recent years to a range of series–parallel multi-state complicated engineering systems, but not to agricultural applications. Recent study undertaken by a variety of organizations reveals that food grain production is not keeping up with population growth. Many technocrats use wireless sensing networks to collect and analyze data to increase production; nevertheless, by focusing on general repair, they fall short of their goal. To avoid this problem and restore the broken system as soon as achievable, in this paper we have developed a reliability formula in a way that numerical solutions can be obtained systematically in a reasonable computational time for precision agriculture that makes use of the copula distribution. This paper aims to analyze the various reliability measures such as availability, reliability, mean time to failure, and cost analysis of a wireless computer network for precision agriculture made up of three subsystems in series configuration. Hazard rates of all the units are assumed to be constant and follow exponential distribution, while repair supports general distribution and copula distribution. The system is analyzed by supplementary variable technique, Laplace transformation and Gumbel-Hougaard copula distribution. This paper we have used a significant feature of copula distribution under catastrophic failure by assuming two different forms of failure between neighboring transitions from which one can check the behavioral analysis of the designed system. This research may be beneficial for precision agriculture whereas a k-out-of-n-type configuration exists. [ABSTRACT FROM AUTHOR]

The ubiquitous deployment of Li-ion batteries (LIBs) in more demanding applications has reinforced the need to understand the root causes of thermal runaway. Herein, we perform a forensic simulation of a real-case failure scenario, using localised heating of Li(Ni0.5Mn0.3Co0.2)O2 versus graphite 18650 cylindrical cells. This study determined the localised temperatures that would lead to venting and thermal runaway of these cells, as well as correlating the gases produced as a function of the degradation pathway. Catastrophic failure, involving melting (with internal cell temperatures exceeding 1085 °C), deformation and ejection of the cell componentry, was induced by locally applying 200 °C and 250 °C to a fully charged cell. Conversely, catastrophic failure was not observed when the same temperatures were applied to the cells at a lower state of charge (SOC). This work highlights the importance of SOC, chemistry and heat in driving the thermal failure mode of Ni-rich LIB cells, allowing for a better understanding of battery safety and the associated design improvements. [ABSTRACT FROM AUTHOR]

The critical power-law acceleration of response quantities has been widely accepted and validated as an effective way to predict the failure time. However, in practical applications, only the data in the vicinity of the failure time exhibit critical power-law behaviour, which cannot describe the entire acceleration stage. In this study, it is shown that by using experimental results from the catastrophic failure of rocks under uniaxial compression, the acceleration of the mean strain presents two typical phases, and the final data in close proximity to the catastrophic time conform to the critical power-law trend. The early part of the acceleration stage is dominated by an exponential relationship with time to failure. Thus, the entire acceleration stage can be described using a combination of exponential and power-law functions. A prediction method based on a combined description of the entire acceleration failure process is proposed to forecast the failure time and is validated by experimental results. This combined description allows for an earlier warning of catastrophic failure than the power-law alone.

Liquefied natural gas (LNG) storage tanks are usually equipped with bunds to provide an additional layer of protection. However, the catastrophic failure of an LNG storage tank usually results in a bund overtopping. The overtopped LNG will evaporate rapidly at ground surface to form the flammable gas cloud. Previous studies have developed computational fluid dynamics (CFD) models to investigate the ability of bunds to retain liquids; However, the models were developed based on ambient liquid, ignoring the evaporation phenomena and vapor dispersion of LNG. In this work, a multiphase CFD model which integrated with the evaporation model was proposed to simulate the complete overtopping process (including LNG overtopping, LNG spread, LNG evaporation and vapor dispersion). The data from two field experiments were used to validate the model. In addition, this paper studied a case of catastrophic failure that derived from an industrial LNG Tank. The effect of the bund configurations on the wind flow field, the overtopping fraction, the spread of LNG and the dispersion of LNG vapor cloud was analyzed. The present work can help relevant personnel to better assess the engineering risks associated with catastrophic failure of storage tanks for decision making in the process safety framework. [ABSTRACT FROM AUTHOR]

We propose a stochastic dynamical model to simulate slope secondary and tertiary creep phenomena. The slope secondary creep is represented by the Kesten process defined as a stochastic affine auto‐regressive process involving both multiplicative and additive random variables. The Kesten process can realistically capture the co‐existence of a background deformation and intermittent displacement bursts, which are together well characterized by an inverse gamma velocity distribution. The slope tertiary creep is modeled by a nonlinear stochastic dynamical equation embodying a nonlinear feedback mechanism and a nonlinear random effect, which can mimic the development of slow or catastrophic landslides. For catastrophic landslides, the probability density function of slope velocities tends to deviate from the inverse gamma distribution by populating the "dragon‐king" regime, although sometimes they may grow undetectably in the "black‐swan" regime. Our model provides a quantitative framework to understand, simulate, and interpret complex landslide displacement time series. Plain Language Summary: Landslides that threaten life and property often exhibit complex temporal evolutions. Some landslides may creep slowly over a long period of time, while others can accelerate rapidly or even collapse catastrophically. It remains difficult to understand and/or predict their behavior. In this work, we develop a novel stochastic dynamical formulation that can realistically reproduce the displacement time series of landslides in natural systems. It can simulate the progressive deformation of a slowly creeping slope as well as mimic its rapid acceleration with/without catastrophic failure. The ever‐present fluctuations in natural systems can also be captured in this stochastic modeling framework. By conducting synthetic numerical simulations capable of resembling many of the observed essential features of real landslides, we develop quantitative insights into the mechanisms that drive their complex temporal evolutions. Recommendations for landslide hazard forecasting and mitigation are further provided. Key Points: A slope approaching failure tends to exhibit a phase transition from secondary to tertiary creepThe stochastic Kesten process reproduces the phenomenology of intermittent bursts and inverse gamma velocity distribution of secondary creepA nonlinear stochastic dynamical process captures the tertiary creep of a slope evolving into a slow or catastrophic landslide [ABSTRACT FROM AUTHOR]

The ubiquitous deployment of Li-ion batteries (LIBs) in more demanding applications has reinforced the need to understand the root causes of thermal runaway. Herein, we perform a forensic simulation of a real-case failure scenario, using localised heating of Li(Ni0.5Mn0.3Co0.2)O2 versus graphite 18650 cylindrical cells. This study determined the localised temperatures that would lead to venting and thermal runaway of these cells, as well as correlating the gases produced as a function of the degradation pathway. Catastrophic failure, involving melting (with internal cell temperatures exceeding 1085 °C), deformation and ejection of the cell componentry, was induced by locally applying 200 °C and 250 °C to a fully charged cell. Conversely, catastrophic failure was not observed when the same temperatures were applied to the cells at a lower state of charge (SOC). This work highlights the importance of SOC, chemistry and heat in driving the thermal failure mode of Ni-rich LIB cells, allowing for a better understanding of battery safety and the associated design improvements.

Abstract We propose a stochastic dynamical model to simulate slope secondary and tertiary creep phenomena. The slope secondary creep is represented by the Kesten process defined as a stochastic affine auto‐regressive process involving both multiplicative and additive random variables. The Kesten process can realistically capture the co‐existence of a background deformation and intermittent displacement bursts, which are together well characterized by an inverse gamma velocity distribution. The slope tertiary creep is modeled by a nonlinear stochastic dynamical equation embodying a nonlinear feedback mechanism and a nonlinear random effect, which can mimic the development of slow or catastrophic landslides. For catastrophic landslides, the probability density function of slope velocities tends to deviate from the inverse gamma distribution by populating the “dragon‐king” regime, although sometimes they may grow undetectably in the “black‐swan” regime. Our model provides a quantitative framework to understand, simulate, and interpret complex landslide displacement time series.

Catastrophic landslides characterized by runaway slope failures remain difficult to predict. Here, we develop a physics‐based framework to prospectively assess slope failure potential. Our method builds upon the physics of extreme events in natural systems: the extremes so‐called "dragon‐kings" (e.g., slope tertiary creeps prior to failure) exhibit statistically different properties than other smaller‐sized events (e.g., slope secondary creeps). We develop statistical tools to detect the emergence of dragon‐kings during landslide evolution, with the secondary‐to‐tertiary creep transition quantitatively captured. We construct a phase diagram characterizing the detectability of dragon‐kings against "black‐swans" and informing on whether the slope evolves toward a catastrophic or slow landslide. We test our method on synthetic and real data sets, demonstrating how it might have been used to forecast three representative historical landslides. Our method can in principle considerably reduce the number of false alarms and identify with high confidence the presence of true hazards of catastrophic landslides. Plain Language Summary: Catastrophic slope failures that pose great threats to life and property remain difficult to predict due to the strong variability of slope behavior. As a result, only a limited number of large rock slope failures have been so far successfully forecasted with associated risks mitigated. Here, we propose a novel predictive framework to prospectively and quantitatively detect slope failure precursors with high confidence. Our research sheds light on one of the most challenging questions in landslide prediction: Would an active landslide slowly move or catastrophically fail in the future? Our method adds a new conceptual framework and operational methodology with a significant potential to support existing early warning systems and hence reduce landslide risks. Key Points: Tertiary creeps of catastrophic landslides accommodate dragon‐kings showing statistically different properties than secondary slope creepsA predictive framework is developed to forecast catastrophic landslides by detecting signatures typical of the emergence of dragon‐kingsA phase diagram characterizes the detectability of dragon‐kings against black‐swans and discriminates catastrophic and slow landslides [ABSTRACT FROM AUTHOR]

Fracture of the tibial component can be a devastating complication after primary total knee arthroplasty. While fractures of the tibial baseplate have been reported, failure at the junction between the baseplate and stem has not been well-described. We present a 49-year-old male who developed progressively worsening left knee pain and an effusion 7-8 years after an index total knee arthroplasty. Radiographs revealed component subsidence and subtle asymmetry between the baseplate and stem. At the time of revision, the tibial component was found to be fractured at the junction of the baseplate and stem, with complete dissociation between the two pieces. Clinicians should maintain a high index of suspicion for catastrophic failure, as this rare phenomenon can be subtle on radiographs and requires close monitoring for signs of component subsidence.

The burgeoning demand for land resources in cities has spurred the development of intricate underground infrastructure networks. Therefore, evaluating the performance and stability of entire existing underground complexes in the event of construction-related disturbances becomes increasingly crucial for ensuring overall urban resilience. This paper adopts a coupled modeling technique of the Finite Element Method (FEM) and Smoothed Particle Hydrodynamics (SPH) for the analysis of catastrophic failure mechanisms in underground complexes, with a focus on disturbances due to nearby tunneling. Two-dimensional centrifuge model experiments were used to thoroughly calibrate the coupled FEM-SPH method, validating its accuracy and suitability for the simulation of soil–structure interaction problems. Subsequently, a full-scale integrated model of the underground complex and formation in a given area was established, including the subway network and highway system. Taking into account the longitudinal connections of the tunnel segments, the catastrophic coupling mechanisms related to construction disturbances in deep tunneling were investigated. The results indicate that collapsed soil caused by deep construction disturbances spreads through the gaps between the tunnels towards the ground, acting as a force-transmitting medium to correlate the deformations of the different structures. The response of the structures was evaluated using five different patterns of deformation, including tunnel settlement, dislocation, opening, rotation, and ovalization. In addition, the evolution of the performance of the underground complex during construction disturbances was analyzed using three types of indicators. Finally, the assessment of the catastrophic failure degree and the identification of vulnerable areas within the complex were carried out. [ABSTRACT FROM AUTHOR]

Abstract Catastrophic landslides characterized by runaway slope failures remain difficult to predict. Here, we develop a physics‐based framework to prospectively assess slope failure potential. Our method builds upon the physics of extreme events in natural systems: the extremes so‐called “dragon‐kings” (e.g., slope tertiary creeps prior to failure) exhibit statistically different properties than other smaller‐sized events (e.g., slope secondary creeps). We develop statistical tools to detect the emergence of dragon‐kings during landslide evolution, with the secondary‐to‐tertiary creep transition quantitatively captured. We construct a phase diagram characterizing the detectability of dragon‐kings against “black‐swans” and informing on whether the slope evolves toward a catastrophic or slow landslide. We test our method on synthetic and real data sets, demonstrating how it might have been used to forecast three representative historical landslides. Our method can in principle considerably reduce the number of false alarms and identify with high confidence the presence of true hazards of catastrophic landslides.

In this paper, a finite element-based framework is presented to model the probabilistic progressive failure of fiber-reinforced composite laminates with high fidelity and efficiency. The framework is based on the semidiscrete modeling approach that can be seen as a good compromise between continuum and discrete methods. The enhanced semidiscrete damage model (ESD2M) tool set comprises a smart meshing strategy with failure mode separation, a new version of the enhanced Schapery theory with a novel generalized mixed-mode law, and a novel probabilistic modeling strategy. These three joined components make the model efficient in capturing failure modes such as matrix cracks, fiber tensile failure, and delamination, as well as their interactions with high fidelity, while taking material nonuniformities into account. The model capabilities are demonstrated using single-edge notched tensile cross-ply laminates as an example. The ESD2M was not only capable of capturing the complex damage progression but also provided insights and explanations for some of the failure events observed in the laboratory. The presented framework efficiently integrates failure mode predictions with probabilistic modeling and enables Monte Carlo simulations to predict the ultimate failure strength with good accuracy, as well as its scatter. [ABSTRACT FROM AUTHOR]

In this paper, a finite-source retrial queueing system with twoway communication is investigated with the help of a simulation program of own. If a randomly arriving request from the finite-source finds the single server idle its service starts immediately, otherwise it joins an orbit from where it generates retrial/repeated calls after a random time. To increase the utilization of the server when it becomes idle after a random time an outgoing request is called for service from an infinity source. Upon its arrival if the server is busy, it goes to a buffer and when the server becomes idle again its service starts immediately. requests arriving from the finite-source and orbit are referred to as primary or incoming ones while requests called from the infinite source are referred to as secondary or outgoing requests, respectively. The service times of the primary and secondary requests are supposed to be random variables having different distributions. However, randomly catastrophic failures may happen to all the requests in the system, that is from the orbit, the service unit, and the buffer. In this case, the primary requests return to the finite-source, and the secondary ones are lost. The operation of the system is restored after a random time. Until the restoration is finished no arrivals and service take place in the system. All the above-mentioned times are supposed to be independent random variables. The novelty of this paper is to perform a sensitivity analysis of the failure and restoration/repair times on the main characteristics to illustrate the effect of different distributions having the same average and variance value. Our aim is to determine the distribution of the number of requests in the system, the average response time of an arbitrary primary request without successful service, also the average response time of an arbitrary and successfully served primary request, the total utilization of the service unit, or the probability that a primary request leaves the system without successful service because of a catastrophic event. Results are illustrated graphically obtained by our simulation program. [ABSTRACT FROM AUTHOR]

Catastrophic failure of ceramic-on-polyethylene total hip arthroplasty is still occasionally described. We report on a new case of complete atraumatic penetration of an intact ceramic head through the titanium cup in a cementless total hip arthroplasty due to dramatic polyethylene and metal wear. We reviewed the literature for similar cases and analyzed potential risk factors. Most importantly, revision of radiologically worn liners should not be postponed, especially in young and active patients with conventional liners, because the time to dramatic failure could be shorter than expected.

Abstract Background To evaluate the clinical features and results of the revision total hip arthroplasties (THA) in patients with catastrophic failures and metallosis. Methods Fifteen hips of 14 patients with catastrophic failure and metallosis in hip arthroplasties were evaluated. They were followed for at least 4.2 years after the revision THA. Clinical evaluation was performed using Harris hip score. Osteolysis, loosening or presence of metallosis was evaluated with standard radiographs. Metallosis was evaluated intraoperatively according to the metallosis severity classification. Results The mean time from failure until revision surgery was 9.4 years. It was observed that in the primary THA, metal-on-ceramic (MoC), ceramic-on-ceramic (CoC) and metal-on-conventional polyethylene (MoCPE) bearings were used in 1, 3 and 11 hips, respectively. Grade III metallosis was observed in all patients during revision surgeries. The mean Harris hip score increased from 55 points before revision THA to 75 points at the final follow-up. In revision arthroplasty, MoCPE and CoC bearings were used in 13 and 2 hips, respectively. The femoral stem was replaced in 5 hips. All acetabular cups, except that of one hip, were revised. Conclusions Revisions of THAs with catastrophic failures and metallosis are quite challenging. Routine follow-up of arthroplasty patients is beneficial to examine for osteolysis, loosening, and asymmetric wear.

In this study, a data-driven methodology for the reliability analysis of natural gas compressor units is developed, and both the historical failure data and performance data are employed. In this methodology, firstly, the reliability functions of the catastrophic failure and degradation failure are built. For catastrophic failure, the historical failure data are collected, and the rank regression model is utilized to obtain the reliability function of the catastrophic failure. For degradation failure, a support-vector machine is employed to predict the unit's performance parameters, and the reliability function of the degradation failure is determined by comparing the performance parameters with the failure threshold. Finally, the reliability of the compressor unit is assessed and predicted by integrating the reliability functions of the catastrophic failure and the degradation failure, and both their correlation and competitiveness are considered. Furthermore, the developed methodology is applied to an actual compressor unit to confirm its feasibility, and the reliability of the compressor unit is predicted. The assessment results indicate the significant impact of the operating conditions on the precise forecasting of the performance parameters. Moreover, the effects of the value of the failure threshold and the correlation of the two failure modes on the reliability are investigated. [ABSTRACT FROM AUTHOR]

We examine how catastrophic innovation failure affects organizational and industry legitimacy in nascent sectors by analyzing the interactions between Virgin Galactic and stakeholders in the space community in the aftermath of the firm's 2014 test flight crash. Following catastrophic innovation failure, we find that industry participants use their interpretations of the failure to either uphold or challenge the legitimacy of the firm while maintaining the legitimacy of the industry. These dynamics yield two interesting effects. First, we show that, in upholding the legitimacy of the industry, different industry participants rhetorically redraw the boundaries of the industry to selectively include players they consider legitimate and exclude those they view as illegitimate: detracting stakeholders constrain the boundaries of the industry by excluding the firm or excluding the firm and its segment, whereas the firm and supporting stakeholders amplify the boundaries of the industry by including firms in adjacent high-legitimacy sectors. Second, we show that, in assessing organizational legitimacy, the firm and its stakeholders differ in the way they approach distinctiveness between the identities of the industry and the firm. Detracting stakeholders differentiate the firm from the rest of the industry and isolate it, whereas the firm and supporting stakeholders reidentify the firm with the industry, embedding the firm within it. Overall, our findings illuminate the effects that catastrophic innovation failure has over high-order dynamics that affect the evolution of nascent industries. [ABSTRACT FROM AUTHOR]

In today's era, the embedded system plays a very keen role in every field. However, the possibilities of errors occur in that system is so common, due to which the degradation of the system takes place or the system gets crash. The various types of errors that can be occurred in the embedded system are deliberated in its mathematical modelling. The interaction of the software with each system's component and interaction of system software to application software are also considered. In this study, Markov process, Laplace Transformation and supplementary variable technique have been used to analyse the reliability measures of embedded system with its sensitivity and also discussed the effects of various failure rates on system performance. At last, a numerical example has been take to illustrate the results and their graphical representation are also given. [ABSTRACT FROM AUTHOR]

A cusp catastrophic model was developed for the pillar-and-roof support system based on the simplified mechanical model of the support system and the improved stress-strain relationship for gypsum. Then, the catastrophic failure mechanism was investigated for the gypsum support system by considering the influence of relative humidity (RH). Meanwhile, the failure criterion for catastrophic instability in the gypsum support system was deduced, and the expression for the safety factor of the pillars was improved by considering the shape and size effects on the strength of gypsum. The results indicate that the RH exerts a significant influence on the catastrophic control parameters for the gypsum support system: with the increase of the RH, the catastrophic control parameters are more prone to cross the bifurcation set and meet the conditions of catastrophic instability for this system. For the input parameters used in the failure criterion, the RH mainly degrades the uniaxial compression strength and then causes catastrophic instability. According to the stability analysis for the mined-out area of the Jingmen Gypsum mines, the lower limit (about 1.60) of the value of factor k relating the size effect to the uniaxial compression strength was obtained. [ABSTRACT FROM AUTHOR]

The n‐i‐p type perovskite solar cells suffer unpredictable catastrophic failure under operation, which is a barrier for their commercialization. The fluorescence enhancement at Ag electrode edge and performance recovery after cutting the Ag electrode edge off prove that the shunting position is mainly located at the edge of device. Surface morphology and elemental analyses prove the corrosion of the Ag electrode and the diffusion of Ag+ ions on the edge for aged cells. Moreover, much condensed and larger Ag clusters are formed on the MoO3 layer. Such a contrast is also observed while comparing the central and the edge of the Ag/Spiro‐OMeTAD film. Hence, the catastrophic failure mechanism can be concluded as photon‐induced decomposition of the perovskite film and release reactive iodide species, which diffuse and react with the loose Ag clusters on the edge of the cell. The corrosion of the Ag electrode and the migration of Ag+ ions into Spiro‐OMeTAD and perovskite films lead to the forming of conducting filament that shunts the cell. The more condensed Ag cluster on the MoO3 surface as well as the blocking of holes within the Spiro‐OMeTAD/MoO3 interface successfully prevent the oxidation of Ag electrode and suppress the catastrophic failure. [ABSTRACT FROM AUTHOR]

The gas produced from an oil field is used to inject into the well for enhanced recovery of oil and gas. The injected gas flows through a pipeline called a header to individual wells for gas injection. One such 6" gas injection header at an offshore process complex experienced a leakage during operation just after 2 years of service. The operating pressure of the pipeline was normal, and there was no process disturbance at the time of the failure. There was no localized corrosion and thinning of the header. The material of construction of the header sample was reported to be ASTM A106 Gr B specification. Laboratory investigations revealed that the material did not conform to ASTM A106 Grade B standard. In the present case, the H2S partial pressure was 0.09 psi; this comes under sulfide stress cracking (SSC) region 2 as per ISO 15156-2:2015; therefore, the environment is prone to SSC. During metallography and SEM analysis, cracks filled with corrosion product typical of SSC were observed which propagated intergranularly. Zigzag cracks typical of hydrogen-induced cracking that branched out from the main SSC crack were also observed. As the metal was too brittle in nature, the gas injection header cracked at many sites. When the crack grew to the extent that the pipe could not withstand the operating pressure anymore, it failed in a brittle manner and the header was shattered into pieces. [ABSTRACT FROM AUTHOR]

Hazardous materials are stored in the large tanks in the industry, e.g., a single LNG tank can be as large as 230,000 m3. Therefore, a catastrophic tank failure can cause a disastrous incident. A secondary containment, such as a bund, is required by regulations to control the risk; however, the released liquid may overtop from the bund due to its high kinetic energy converted from potential energy. Computational Fluid Dynamic (CFD) is a proper tool for the bund overtopping study, but there has been significant discrepancy among previous CFD studies. This work developed 2D CFD models of bund overtopping using the axisymmetric approach. A screening study on several turbulence models was performed, and RNG k-ε Standard Wall Functions (RNG k-ε SWF1) and Large Eddy Simulation WALE (LES WALE) were selected for a detailed comparison in terms of overtopping fraction and flow dynamic behaviour. Both RNG k-ε and LES models were systematically validated against experimental data, and the results indicate that LES model is slightly better than RNG k-ε model, and both models are acceptable based on the criteria of statistical performance measures. [ABSTRACT FROM AUTHOR]

Under certain conditions, Lithium‐ion (Li‐ion) batteries can produce flammable and/or explosive atmospheres and pose related risks. Battery Energy Storage Systems are composed of large quantities of Li‐ion batteries. This article uses basic concepts of combustion to describe the flammable hazards associated with BESS failures. [ABSTRACT FROM AUTHOR]

In this paper, a physics of failure-based prediction method is combined with statistical models to consider the impact of current crowding and current droop effects on the reliability of LED arrays. Electronic-thermal models of LEDs are utilized to obtain the operation conditions under the influences of current crowding and current droop. A Markov chain-based model is used to calculate the probability distribution of each failure mode, including the lumen decay and catastrophic failure. Two types of LEDs were selected for a numerical study. The proposed prediction method provides the realistic reliability prediction results. It is found that the properties of LEDs have a great impact on their hazard rates of LED arrays. The equivalent resistance, third-order non-radiative coefficient, and radiative coefficient of LEDs are critical to the reliability of an LED array.

In practical engineering, uncertain failure modes can result in the system failure. To evaluate and enhance the reliability of multi-component systems, a general model is developed in this study, which considers two competing failure, the nonfatal failure and the catastrophic failure. The nonfatal failure is due to internal degradation damages from external uncertain shocks and the catastrophic failure is due to external extreme random shocks. The system is considered to be out of work in the situation that either the damage from random shocks or the total degradation exceeds the thresholds. Moreover, the uncertainty analysis theory for multi-state system is utilized to calculate the effect of uncertain shocks in the process of degradation. Two numerical examples are proposed to show the application. To demonstrate the influence of parameters on reliability, the sensitivity analysis is performed. Meanwhile, to verify the accuracy of the proposed model, the Monte Carlo Simulation is utilized here. The results of the proposed model are compared, and they accord well with the Monte Carlo Simulation.

This paper discusses the reliability analysis of repairable complex system comprising of two subsystems in series configuration together with the controllers. The two subsystems, consisting of three undistinguishable units in a parallel arrangement and functioning under 1-out-of-3: G operational policy. Controllers control both the subsystems and can be unstable, and the malfunction result in the controller prevents system operation. The system may have an unforeseeable catastrophic failure due to which the system may not perform its function once the situation arises. The failure rate of the units is constant, and the exponential distribution is assumed to obey. The two forms of repair namely general repair and Goumbel-Hougard copula repair are used to restore the existing failed units of the system. The supplementary variable technique with Laplace transformation is used to evaluate the output of the system. Using Stochastic theory, differential equations are derived to obtain essential features of reliability such as availability of the system, reliability of the system, MTTF, and profit analysis. Graphs were drawn to highlight the behavior of the results. Tables and figures display the findings and suggest that copula repair is a more efficient repair policy for the improved performance of repairable systems. It brings a different aspect to the research world to adopt multi-dimensional repair in the form of the copula. Besides, the findings of the model are useful for system engineers and maintenance managers. [ABSTRACT FROM AUTHOR]

Background: To evaluate the clinical features and results of the revision total hip arthroplasties (THA) in patients with catastrophic failures and metallosis. Methods: Fifteen hips of 14 patients with catastrophic failure and metallosis in hip arthroplasties were evaluated. They were followed for at least 4.2 years after the revision THA. Clinical evaluation was performed using Harris hip score. Osteolysis, loosening or presence of metallosis was evaluated with standard radiographs. Metallosis was evaluated intraoperatively according to the metallosis severity classification. Results: The mean time from failure until revision surgery was 9.4 years. It was observed that in the primary THA, metal-on-ceramic (MoC), ceramic-on-ceramic (CoC) and metal-on-conventional polyethylene (MoCPE) bearings were used in 1, 3 and 11 hips, respectively. Grade III metallosis was observed in all patients during revision surgeries. The mean Harris hip score increased from 55 points before revision THA to 75 points at the final follow-up. In revision arthroplasty, MoCPE and CoC bearings were used in 13 and 2 hips, respectively. The femoral stem was replaced in 5 hips. All acetabular cups, except that of one hip, were revised. Conclusions: Revisions of THAs with catastrophic failures and metallosis are quite challenging. Routine follow-up of arthroplasty patients is beneficial to examine for osteolysis, loosening, and asymmetric wear. [ABSTRACT FROM AUTHOR]

In this study, a data-driven methodology for the reliability analysis of natural gas compressor units is developed, and both the historical failure data and performance data are employed. In this methodology, firstly, the reliability functions of the catastrophic failure and degradation failure are built. For catastrophic failure, the historical failure data are collected, and the rank regression model is utilized to obtain the reliability function of the catastrophic failure. For degradation failure, a support-vector machine is employed to predict the unit’s performance parameters, and the reliability function of the degradation failure is determined by comparing the performance parameters with the failure threshold. Finally, the reliability of the compressor unit is assessed and predicted by integrating the reliability functions of the catastrophic failure and the degradation failure, and both their correlation and competitiveness are considered. Furthermore, the developed methodology is applied to an actual compressor unit to confirm its feasibility, and the reliability of the compressor unit is predicted. The assessment results indicate the significant impact of the operating conditions on the precise forecasting of the performance parameters. Moreover, the effects of the value of the failure threshold and the correlation of the two failure modes on the reliability are investigated.

Light-emitting diode (LED) lighting has, compared to other types of lighting, a significantly lower energy consumption. However, the perceived service life is also important for customer satisfaction and here there is a discrepancy between customers’ experience and manufacturers’ statements. Many customers experience a significantly shorter service life than claimed by the manufacturers. An experiment was carried out in the Pehr Högström Laboratory at Luleå University of Technology in Skellefteå, Sweden to investigate whether voltage disturbances could explain this discrepancy. Over 1000 LED lamps were exposed to high levels of voltage disturbances for more than 6000 h; the failure rate from this experiment was similar to the one from previous experiments in which lamps were exposed to normal voltage. The discrepancy thus remains, even though some possible explanations have emerged from the project’s results. The lamps were exposed to five different types of voltage disturbances: short interruptions; transients; overvoltage; undervoltage; and harmonics. Only overvoltage resulted in failure of the lamps, and only for a single topology of lamp. A detailed analysis has been made of the topology of lamps that failed. This lamp type contains a different internal electronics circuit than the other lamp types. Failures of the lamps when exposed to overvoltage are due to the heat development in the control circuit increasing sharply when the lamps are exposed to a higher voltage. Hence, it is concluded that there are lamps that are significantly more sensitive to voltage disturbances than other lamp types. Manufactures need to consider the voltage quality that can be expected at the terminal of the lamp to prevent failure of lamps due to voltage disturbances. This paper therefore contains recommendations for manufacturers of lighting; the recommendations describe which voltage disturbances lamps should cope with.

Identifying precursory trends in acoustic/seismic observations allows the forewarning/prediction of catastrophic events. However, rupturing across multiple scales leaves it unclear whether features of small events are applicable predictors of the larger ensemble final collapse. To resolve this issue, we present a multiscale heterogeneous model that straightforwardly characterizes the duration and mechanism of multiscale catastrophic failures. Our results identify four distinct classes of failure including random single breaks, small catastrophic failure (SCF) events, large catastrophic failure (LCF) events that consist of subordinate SCF and random break events, and a culminating macroscopic catastrophic failure (MCF) event resulting from the coalescence of subordinate LCF events. Only the local response quantities, recorded at their corresponding position, show an accelerating precursory trend to an SCF event. LCF events can appear in stages both before and after the maximum load in the system. Our findings highlight that although cumulative LCF event and deformation rates for the entire system always exhibit singular accelerating precursors as MCF is approached, this is not true at all individual event points. This may explain why no clearly accelerating precursor is observed before some catastrophic events. Thus, these results suggest a methodology for recognizing and distinguishing effective precursory information from monitoring signals across scales and in eliminating false predictions. [ABSTRACT FROM AUTHOR]

Reliability prediction in power electronic converters is of paramount importance for converter manufacturers and operators. Conventional approaches employ generic data provided in handbooks for random chance failure probability prediction within useful lifetime. However, the wear-out failures affect the long-term performance of the converters. Therefore, this article proposes a comprehensive approach for estimating the converter reliability within useful lifetime and wear-out period. Moreover, this article proposes a wear-out failure prediction approach based on a structural reliability concept. The proposed approach can quickly predict the converter wear-out behavior unlike conventional Monte Carlo-based techniques. Hence, it facilitates reliability modeling and evaluation in large-scale power electronic-based power systems with huge number of components. The proposed comprehensive failure function over the useful lifetime and wear-out phase can be used for optimal design and manufacturing by identifying the failure prone components and end-of-life prediction. Moreover, the proposed reliability model can be used for optimal decision-making in design, planning, operation, and maintenance of modern power electronic-based power systems. The proposed methodology is exemplified for a photovoltaic inverter by predicting its failure characteristics. [ABSTRACT FROM AUTHOR]

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• Strain concentration decreases ductility of deformation. • Parameters defining strain concentration degree. • Higher ductility leading to larger catastrophic failure. • Longer depth precuts resulting in higher strain concentration. • Strain concentration degree should be an intrinsic cause of some origins influencing ductility and failure modes. The physical control of ductile deformation and failure behaviors of aluminum alloys is still open to investigation, although this is a central problem for material design and safety evaluation. In this study, 6061 aluminum alloy sheets with different pre-cut depths were uniaxially stretched, and the evolution of strain fields was monitored to reveal the relationship between the strain concentration and failure process. The average strain/strain fluctuation ratio and the strain propagation velocity were defined to quantify the strain concentration degree. The strain concentration degree is an intrinsic factor hosting deformation ductility, maximum bearing load, and failure modes. The underlying mechanism of this changing ductility and failure process is the increased strain/stress concentration degree due to increased pre-cut depth. The experimental results indicated that higher ductility resulted in a larger catastrophic failure in the 6061 aluminum alloy. A lower deformation ductility led to a more gradual macroscopic failure. Our findings suggest that various origins inducing different strain concentration degrees can cause various effects on ductility and failure modes of 6061 aluminum alloy. [ABSTRACT FROM AUTHOR]

Previous studies show that the total volume of fractures increases non-linearly during loading as rocks approach failure in triaxial compression at stress and temperature conditions representative of the upper crust. However, the factors that control the critical volume of fractures or the critical spatial organization of the fracture network that trigger macroscopic failure remain unclear. To identify the fracture characteristics that determine the timing of macroscopic failure and localization of the fracture networks, we analyze data from six X-ray tomography experiments on Westerly granite with varying confining stress, fluid pressure, and amounts of preexisting damage. We develop machine learning models to predict 1) the timing of failure, 2) the localization of the fracture networks as measured with the Gini coefficient of the fracture volume, and 3) the change in localization from one differential stress step to the next. When the models only have access to individual fracture characteristics, the fracture length produces the best predictions of the distance to failure. When the models have access to the fracture length and sets of other characteristics, the fracture volume, aperture, and distance between fractures produce the best predictions of the distance to failure. The characteristics that describe the time or loading in the experiment, the axial strain and differential stress, produce some of the best predictions of the Gini coefficient. The results are generally consistent among the different experiments, suggesting that the fracture characteristics that determine the timing of macroscopic failure, and the localization of the fracture network, are independent of the range of confining stress, fluid pressure, and amount of preexisting damage tested here. Our results are consistent with the idea that monitoring the spatial distribution of deformation and changes in the seismic wave properties indicative of fracture growth may improve forecasting efforts of failure in the crust. • Predicting localization, delocalization, and the timing of catastrophic failure. • The fracture length, volume, aperture, and clustering predict the timing of failure. • The macroscopic strain and stress predict fracture localization. • The models struggle to predict delocalization. [ABSTRACT FROM AUTHOR]

The complicated seismic response of earth slopes and the transition mechanism from progressive to catastrophic motion of landslides have long been recognized as one of the most challenging research topics in geotechnical earthquake engineering. In this paper, this fundamental conundrum will be tentatively unveiled from a new perspective combining the seismic slope displacement analysis with (mechanical) dynamic porewater pressure feedback of the shear band soils against the earthquake excitation. We present both the conceptual scheme and the calculation framework to numerically study the dynamic changes of porewater pressure, shear strength parameters, and hydraulic properties of the shear band soils. Their significant influences to the change of earthquake-induced landslide movement modes are systematically investigated. Different dilation angles are chosen to characterize the shear dilation and shear contraction processes in the shear band soil, while the dynamic porewater pressure feedback in the shear band soil during the continuous seismic displacement is investigated. The results show that the seismic slope displacement and failure strongly depend on the mechanical feedback of the shear band soil. When the dilation angle is positive, the porewater pressure feedback in the shear band during the slope movement is negative, and the effective resistance stress increases, which is not susceptible to catastrophic motion. On the other hand, when the dilation angle is negative, the positive porewater pressure feedback may lead to catastrophic failure. At last, the effects of shear softening/hardening combined with dilation angle evolution on the ultimate slope movement mode are also put forward. [ABSTRACT FROM AUTHOR]

It is known that cell concretes are almost immediately destroyed under load, having reached certain critical stresses. Such kind of destruction is called a “catastrophic failure”. Process of crack formation is one of the main factors, influencing process of concrete destruction. Modern theory of crack formation is mainly based on the Griffith theory of destruction. However, the mentioned theory does not completely correspond to the structure of cell concrete with its cell structure, because the theory is intended for a solid body. The article presents one of the possible variants of modelling of the structure of cell concrete and gives some assumptions concerning the process of crack formation in such hollow, not solid environment.

We consider the Equal-Load-Sharing Fiber Bundle Model as a model for composite materials under stress and derive elastic energy and damage energy as a function of strain. With gradual increase of stress (or strain) the bundle approaches a catastrophic failure point where the elastic energy is always larger than the damage energy. We observe that elastic energy has a maximum that appears after the catastrophic failure point is passed, i.e., in the unstable phase of the system. However, the slope of elastic energy vs. strain curve has a maximum which always appears before the catastrophic failure point and therefore this can be used as a reliable signal of upcoming catastrophic failure. We study this behavior analytically for power-law type and Weibull type distributions of fiber thresholds and compare the results with numerical simulations on a single bundle with large number of fibers.

The critical power-law acceleration of response quantities has been widely accepted and validated as an effective way to predict the failure time. However, in practical applications, only the data in the vicinity of the failure time exhibit critical power-law behaviour, which cannot describe the entire acceleration stage. In this study, it is shown that by using experimental results from the catastrophic failure of rocks under uniaxial compression, the acceleration of the mean strain presents two typical phases, and the final data in close proximity to the catastrophic time conform to the critical power-law trend. The early part of the acceleration stage is dominated by an exponential relationship with time to failure. Thus, the entire acceleration stage can be described using a combination of exponential and power-law functions. A prediction method based on a combined description of the entire acceleration failure process is proposed to forecast the failure time and is validated by experimental results. This combined description allows for an earlier warning of catastrophic failure than the power-law alone., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Recent severe burn injuries and at least one death have been attributed to the sudden explosion of a particular type of tabletop fuel oil-burning torch when moved by or somehow affected by the user while lit. An investigation was performed to determine the variables involved in the design and operation of the subject torch that provided the necessary and sufficient conditions for the occurrence of the above explosions. The investigation findings strongly suggest that the explosions were caused by a faulty design of the tabletop torch that failed to separate the fire (ignition source) from a fuel that had too low of a flashpoint. [ABSTRACT FROM AUTHOR]