Component Failure Research Articles

Prediction of Failure Due to Fatigue of Wire Arc Additive Manufacturing-Manufactured Product

Currently, the focus of production is shifting towards the use of innovative manufacturing techniques and away from traditional methods. Additive manufacturing technologies hold great promise for creating industrial products. The industry aims to enhance the reliability of individual components and structural elements, as well as the ability to accurately anticipate component failure, particularly due to fatigue. This paper explores the possibility of predicting component failure in parts produced using the WAAM (wire arc additive manufacturing) method by employing fractal dimension analysis. Additionally, the impact of manufacturing imperfections and various heat treatment processes on the fatigue resistance of 30CrMnSi steel has been investigated. Fatigue testing of samples and actual components fabricated via the WAAM process was conducted in this study. The destruction of the examined specimens and products was predicted by evaluating the fractal dimensions of micrographs acquired at different stages of fatigue testing. It has been established that technological defects are more dangerous in terms of fatigue failure than microstructural ones. The correctly selected mode of heat treatment for metal after electric arc welding allows for a more homogeneous microstructure with a near-complete absence of microstructural defects. A comparison of the fractal dimension method with other damage assessment methods shows that it has high accuracy in predicting part failure and is less labor-intensive than other methods.

Standardization in Tribology

This paper presents an analysis of standards applied in tribology, especially concerning materials, test methods and failures of machine components, related to exploitation under load and motion. By the help of their own research and based on open literature, the authors justify the use of standards in tribology, but also the researchers’ initiative to develop new and more particular test methods and materials with application in tribology, starting from the already standardized ones. The market asks for products that could be rapidly and efficiently assessed by standards, but laboratory work ask for standards in order to compare old and new, original solutions. Thus, using standards does not block the researchers’ work, but helps to point out the new solution and even to develop new materials and test methods that accelerates the introduction of these new solution in actual applications. There are given examples of applying standards in tribology laboratories and how they are used or extend in order to point out a beneficial aspect of the tribological behavior.

The Influence of the Assembly Line Configuration and Reliability Parameter Symmetry on the Key Performance Indicators

In the context of the demand for mass customization of products, a trade-off between highly efficient automated systems and flexible manual operators is sought. The linear arrangement of workstations made it possible to divide the process into many simple operations, which increases production efficiency, but also results in an increase in the number of workstations and a significant extension of the line. A human operator is usually treated as a quasi-mechanical object, and a human error is considered, similarly, as a failure of a technical component. However, human behavior is more complex and difficult to predict. A mathematical model of a new production organization is presented, including dividing the traditional production line into shorter sections or replacing the serial assembly line with a U-line with cells. Moreover, the reliability of operator and technical means are distinguished. Work-in-progress inventories are located between line sections to improve system stability. The stability of the assembly line is examined based on the system configuration and probabilistic estimates of human failure. The influence of the symmetry of reliability parameters of people on key performance indicators (KPI (headcount), KPI (surface) and KPI (Overall Equipment Effectiveness) is examined. KPI (solution robustness) and KPI (quality robustness) are also presented in order to evaluate the impact of a disruption on the assembly line performance. New rules for assigning tasks to stations are proposed, taking into account the risk of disruptions in the execution of tasks. For comparison of assembly problems, heuristic methods with newly developed criteria are used. The results show the impact of symmetry/asymmetry on assembly line performance and an asymmetric distribution of manual assembly times that is significantly skewed to the right due to human errors. On the assembly line, the effects of these errors are cumulative and lead to longer assembly times and lower KPIs.

Reliability and performance evaluation of weighted [formula omitted]-out-of-[formula omitted]:G system consisting of components with discrete lifetimes

For the k-out-of-n system consisting of components that have different weights, the system is in a good state if the total weight of working components is at least k. Such a system is known to be weighted k-out-of- n:G system. Although the weighted k-out-of-n system that has continuously distributed components’ lifetimes has been extensively studied, the discrete weighted k-out-of-n:G system has not been considered yet. The present paper fills this gap by modeling and analyzing the weighted k -out-of-n:G system that consists of discretely distributed components’ lifetimes. In particular, the behavior of the total capacity/weight of the system with respect to the component failures is evaluated. An optimization problem that is concerned with the determination of optimal number of spare components is also formulated by utilizing the mean lost capacity of the system.

Fabrication of Co-Based Cladding Layer by Microbeam Plasma and Its Corrosion Mechanism to Molten Salt.

Corrosion of the molten salts Na2SO4 and NaCl has become one of the major factors in the failure of steel components in boilers and engines. In this study, CoNiCrAlY cobalt-based cladding layers with different NiCr-Cr3C2 ratios were prepared by microbeam plasma cladding technology. The influence of the NiCr-Cr3C2 content on the microstructure, mechanical properties, and molten salt corrosion resistance of CoNiCrAlY was investigated. The CoNiCrAlY with a 25 wt.% NiCr-Cr3C2 (NC25) cladding layer possessed the highest microhardness (348.2 HV0.3) and the smallest coefficient of friction (0.4751), exhibiting great overall mechanical properties. The generation of protective oxides Cr2O3, Al2O3, and spinel phase (Ni,Co)Cr2O4 is promoted by the addition of 25 wt.% NiCr-Cr3C2, which significantly reduces the corrosion of the cladding layer, and this effect is much more obvious at 950 °C than that at 750 °C. Furthermore, its corrosion mechanism was clarified. From the findings emerge a viable solution for the design and development of new high-temperature corrosion-resistant coatings.

A Novel Data-Driven Approach with a Long Short-Term Memory Autoencoder Model with a Multihead Self-Attention Deep Learning Model for Wind Turbine Converter Fault Detection

The imminent depletion of oil resources and increasing environmental pollution have driven the use of clean energy, particularly wind energy. However, wind turbines (WTs) face significant challenges, such as critical component failures, which can cause unexpected shutdowns and affect energy production. To address this challenge, we analyzed the Supervisory Control and Data Acquisition (SCADA) data to identify significant differences between the relationship of variables based on data reconstruction errors between actual and predicted values. This study proposes a hybrid short- and long-term memory autoencoder model with multihead self-attention (LSTM-MA-AE) for WT converter fault detection. The proposed model identifies anomalies in the data by comparing the reconstruction errors of the variables involved. However, more is needed. To address this model limitation, we developed a fault prediction system that employs an adaptive threshold with an Exponentially Weighted Moving Average (EWMA) and a fixed threshold. This system analyzes the anomalies of several variables and generates fault warnings in advance time. Thus, we propose an outlier detection method through data preprocessing and unsupervised learning, using SCADA data collected from a wind farm located in complex terrain, including real faults in the converter. The LSTM-MA-AE is shown to be able to predict the converter failure 3.3 months in advance, and with an F1 greater than 90% in the tests performed. The results provide evidence of the potential of the proposed model to improve converter fault diagnosis with SCADA data in complex environments, highlighting its ability to increase the reliability and efficiency of WTs.

Corrosion evolution and quantitative corrosion monitoring of Q355 steel for offshore wind turbines in multiple marine corrosion zones

Offshore wind turbines operating in harsh marine environments are at risk of corrosion. Thickness loss and perforation caused by corrosion can lead to component failure or structure collapse. An environmental test setup was constructed to simulate various marine corrosion zones. Several experimental studies were conducted on Q355 steel, commonly used in offshore wind turbines. The mass loss and electrochemical properties of the steel specimens were analyzed, including electrochemical impedance spectra and polarization curves. The results indicate that corrosion remains stable in the immersion and tidal zones, whereas corrosion in the splash zone is the most severe, with a corrosion rate as high as 0.70 mm/a. A significant macroscopic corrosion cell effect was observed on the vertical steel strip, accelerating corrosion in the splash zone and at the low tide line. The corrosion product compositions and corrosion morphology of each corrosion zone were characterized and analyzed. Furthermore, a corrosion monitoring sensor based on electromechanical impedance was proposed. A prediction model for the mass loss rate of vertical steel strips was developed based on the conductance peak frequency. This study elucidates the corrosion evolution of wind turbine structural steel and proposes a comprehensive steel corrosion monitoring solution.

Use of mobile metallography to assess the extent of damage to high temperature components in power plants

Abstract Microstructural replicas are used in recurrent testing of hot, pressuriszed components to detect creep damage. The test location must be representative of the damage development and subsequent component failure. Poor preparation leads to the formation of artefacts which are considered in the damage assessment. The assessment is subject to method and operator variability. When assessing the life of components based on microstructure replicas, these must be taken into account and, if necessary, extended stress calculations for the component must be used.

Design and destructive testing of high-value hook fabricated by laser metal deposition

Laser metal deposition (LMD) provides an emerging opportunity for the economic fabrication of high-value components at low production volume. Despite the technical and commercial opportunities associated with LMD, there exist potential failure-modes that differ from those typical of traditional manufacture; concurrently, LMD is typically applied to high-value components associated with a high consequence of failure. This report contributes to the emerging literature on LMD component design and failure analysis by documenting the design and destructive testing of a high-value tensile loaded hook component, including numerical structural simulation, manufacture characterisation, microstructural analysis and instrumented destructive testing. This systematic design contributes to the understanding of LMD design for structural integrity and supports the application of LMD as a robust commercial additive technology.

A rolling horizon for rolling stock maintenance scheduling problem with cyclical activities

The rolling stock maintenance scheduling problem addressed here involves scheduling a set of cyclical preventive maintenance activities while considering resource capacity and geographically dispersed depots. The objective is to minimize both corrective and preventive maintenance costs using reliability features. We propose to use rolling horizon to decompose the problem into several successive subproblems such that each one tackles the scheduling of only the next cycle of activities instead of all cycles. The scheduled dates to be fixed should be as close as possible to their respective deadlines. Each train can have three status (in service, in maintenance, out of service). The activities deadlines are determined depending on component failure rate which has to be respected otherwise the train becomes out of service. An integer linear programming (ILP) model is proposed to solve the subproblem using a time oriented modeling to get an accurate maintenance cost (preventive and corrective) and respect a minimum of available trains. The rolling horizon allows to build a feasible schedule within a predefined planning horizon for moderate size problems with an interesting trade-off between computation time and solution quality.

The formation mechanism of gradient properties and the regulation mechanism of elastic properties in three‐dimensional tubular braided composites

AbstractThree‐dimensional tubular braided composites (3DTBCs) have mitigated delamination issues typical of laminated composites, gaining wide industrial application. However, their intricate internal fiber architecture, influenced by processing techniques, leads to continuous property variations, resulting in localized stress concentrations that can cause premature component failure and significantly impact performance. This paper introduces a field theory‐based quantitative analysis method for property gradients and investigates their formation mechanism. Additionally, it explores the effects of braiding parameters on property gradients. The described analysis method enables the prediction of gradient structures and associated strength distributions, offering potential pathways for maximizing the strength of 3DTBC.Highlights The mesostructure and mechanical properties of three‐dimensional braided tubular composites inherently exhibit unavoidable gradient distributions. The performance gradient can be quantitatively described using field theory‐based analytical methods. The motion trajectory of the yarn carrier is the primary cause of the property gradient. The property gradient can be controlled by adjusting the braiding process parameters.

Rigid–flexible coupling design and reusable impact mitigation of the hierarchical-bistable hybrid metamaterials

Mechanical metamaterials with multistable unit cells featured by negative stiffness or quasi-zero stiffness is attracting increasing attention owing to their unique mechanical properties and reusable potential. In this paper, a hierarchical-bistable hybrid metamaterial with rigid–flexible coupling design is proposed, demonstrating excellent mitigation performance and protection against multiple impacts. The metamaterial consists of a multi-layer bistable beams with a central honeycomb and is manufactured by 3D printing. Firstly, the negative stiffness characteristics of the curved beams in the metamaterial are theoretically determined, and the convergence of the finite element model under different mesh sizes is analyzed. And the quasi-zero stiffness characteristics of the metamaterial have been confirmed, along with its more stable and uniform deformation pattern, through the quasi-static compression experiment. Then the buffering performance of the metamaterial is studied in ball impact tests, showing an average improvement of about 65% compared to the rigid control group, while verifying the accuracy of the finite element model. With the analysis of the deformation modes and strain energy, the mitigation mechanism of metamaterials is demonstrated to extend the contact time and disperse the impact load through the layered deformation to reduce the peak response, instead of relying on plastic strain. Finally, the reusability of the metamaterial is explored by the ten-times plate impacts simulation. The results demonstrate that the metamaterial decreases the plastic strain of its structure by 60% while reducing impact response, thereby preventing the premature failure of core components. These results demonstrate the great potential of the proposed metamaterials for various engineering applications, including aircraft or spacecraft landing protection, vehicle pedestrian protection, and the transportation protection of fragile objects or precision instruments.

A comparative study on mechanical-electrical-thermal characteristics and failure mechanism of LFP/NMC/LTO batteries under mechanical abuse

Understanding the failure behaviors and failure mechanisms of lithium-ion batteries under mechanical abuse is essential for numerical reconstruction of abuse scenarios for different types of cells. This study investigates the mechanical-electrical-thermal characteristics, components tensile properties and failure mechanisms of LiFePO4 (LFP), Li(Ni0.5Mn0.3Co0.2)O2 (NMC), and Li2TiO3 (LTO) cells through indentation experiments, including ball intrusion, cylindrical intrusion, and out-of-plane compression modes at quasi-static loading rates. Additional ball intrusion experiments were conducted at varying loading rates. This study compares the effects of different material systems on battery performance under standardized mechanical abuse conditions. Post-test examinations analyze surface damage and internal component fracture morphology. Two distinct fracture modes were observed: ductile fracture and brittle fracture. The findings suggest that, under the same loading mode, LTO cells exhibit distinct failure behavior compared to NMC and LFP cells, attributed to differing material properties and resulting fracture modes during intrusion. Based on the analysis of the tensile results of the battery components, the cell fracture mode may be related to the tensile strength of the separator. The loading rate significantly impacts the mechanical-electrical-thermal performance of pouch cells, resulting in increased cell stiffness and shorter internal short circuit duration at higher loading speeds. However, the effect of loading rate is consistent across cells with different material systems.

Analisis Perawatan Heading Machine dengan Metode Reliability Centered Maintenance (RCM)

The heading machine is a critical type of machine used in the production of header tubes. If a failure occurs during the production of header tubes, the product cannot proceed to the next process and must be discarded. However, this machine frequently encounters component failures that require halting the machine for repairs, which is detrimental to the company. This research aims to enhance the machine's reliability by identifying the critical components and scheduling appropriate maintenance based on the heading machine's needs. The research method used is RCM, which includes collecting data on machine downtime and repairs, creating an FMEA table, identifying critical components, calculating TTF and TTR, determining component distribution patterns, establishing parameters, calculating the reliability of critical components, and scheduling maintenance. The research findings identified the critical components as conical spring for orifice and jaw for thread. The calculation of the reliability value using the Weibull distribution equation with scale and shape parameters for the conical spring for orifice components are 1001.78 and 1.12285, respectively. For the jaw for thread component, the scale and shape parameters are 532.083 and 1.33233, respectively, based on values derived from statistical software. As a result, the maintenance schedule should be set when the reliability value of the conical spring for orifice and jaw for thread reaches 0.5 at (t) 720 hours or 30 days, and (t) 390 hours or 17 days, respectively.

Fault diagnosis of the distribution network based on the D-S evidence theory Bayesian network

Relay protection rejection and misoperation exist in the existing distribution network, which will affect the fault diagnosis results. To diagnose faults in distribution networks, this paper presents a fault diagnosis method for the distribution network based on the D-S evidence theory Bayesian network. First, the collected relay protection information is divided into two categories, protection information and circuit breaker information; the corresponding Bayesian network model is established based on their respective action logic, and the corresponding component failure probability is obtained by Bayesian backward inference. Second, the fault probabilities obtained from the two Bayesian networks are fused by the D-S evidence theory, and the obtained fault probabilities are used to diagnose the faulty component. Then, using the Bayesian network corresponding to the faulty component to perform Bayesian forward inference, the protection devices and circuit breakers are identified for misoperation or rejection to achieve the fault diagnosis of the distribution network. Finally, the correctness and reliability of the proposed diagnosis method are verified through the analysis of arithmetic cases.

Enhancing building robustness through a fuse-based segmentation framework

The most widely used design approaches today for improving the robustness of buildings rely on improving continuity within the structural system to ensure that loads supported by failed components can be redistributed to the rest of the system. Although this is effective for small initial failures, it can increase the risk of disproportionate collapse after larger initial failures due to collapsing elements pulling down parts of the structure that would otherwise be unaffected. This form of continuity-enabled collapse propagation can be avoided by dividing a structure into different segments. However, completely separating parts of a building results in lower performance under operational conditions, against lateral loads, and after small initial failures. In fact, the advantages of both continuity and segmentation can be combined through a fuse-based segmentation approach in which predefined segment borders ensure connectivity after small initial failures but separate to isolate collapse after larger initial failures. To ensure that this approach is used effectively to improve the robustness of building structures, a design framework is proposed in this article to systematically consider relevant structural and geometric criteria in order to define suitable segmentation configurations for reinforced concrete and steel framed building structures. An application to a realistic case study is also presented to demonstrate the effectiveness of the proposed framework in enhancing structural robustness.

Reassessment of Thor® 115 parent metal performance including consideration of notch behavior

In recent years, the waning of creep rupture ductility in the long term, and sensitivity to creep damage tolerance of creep strength-enhanced ferritic (CSEF) steels were put under the spotlight. The loss of ductility and damage accumulation at stress concentrations may result in early failures of boiler components, and potentially result in severe economic impact and/or safety concerns. To address the potentially undesirable materials performance, the ASME Boiler and Pressure Vessel Code has recently introduced rules for identification of damage intolerant behavior by means of testing, and for design of boiler components with creep damage-intolerant CSEF steels, as Code Case 3048. As of today, only Grade 91 Type 2 material has been classified as a damage tolerant steel.The Thor® 115 (T115) CSEF steel has entered the market in recent years and has since been used for the construction of several combined cycle power plants. This CSEF steel was developed as an evolution to Grade 91, with chemical composition modifications to enhance the resistance to steam oxidation while ensuring long-term microstructural stability, and therefore permitting its use for the higher temperature boiler components, as an alternative to stainless steels. While chemical composition and manufacturing precautions prescribed for Grade 91 Type 2 also apply to T115, an assessment of the materials’ damage tolerance following design standards criteria, and including extensive metallurgical characterization, has not yet been published.This work presents up-to-date uniaxial creep testing results of T115 CSEF, and the derived creep-rupture ductility and damage tolerance parameter evaluation. In addition, results from notched bar creep testing are presented, illustrating the material's response to multiaxial stress states. Post-test metallographic examination of ruptured specimens was also performed and findings are discussed.

“Knowledge, attitude and reporting practices of ventilator-related errors among nursing professionals"

BackgroundVentilator-related errors (VREs) pose a critical concern for patient safety, necessitating a thorough understanding and mitigation strategies within healthcare settings. This study delves into the prevalence of VREs, while examining the nurse's knowledge of VREs and their reporting attitudes, and practices. Study designCross sectional analytical study. MethodsA cross-sectional study was conducted on 129 nurses working in the Intensive Care Unit (ICU) of a major tertiary care hospital located in the southern part of India. The study involved the administration of a Knowledge, Attitude, and Practice (KAP) survey questionnaire. ResultsThe findings demonstrate a deficiency in the comprehension of VREs among ICU nurses, which subsequently affects their attitudes and reporting practices. Only a small percentage of nurses possess good knowledge (13.2 %), attitude (7 %), and reporting practices (5.4 %). Many nurses identified issues with ventilator performance, including component failure (17 %), design issues (14 %), and alarm problems (14 %). They also reported battery-related problems (9 %), lack of awareness of the instruction manual (7 %), software challenges (6 %), and wear and tear (6 %). A significant association between VRE knowledge and staff experience (p < 0.05) and attitude (P < 0.001) was found. Reporting practices are influenced by staff attitudes (moderate, P < 0.001; good, P < 0.001). ConclusionThis study highlights the significant impact of VRE on patient safety, emphasizing the urgent need for comprehensive understanding and effective preventative measures in healthcare settings.

Bayesian inference for reliability of K-out-of-N: G repairable retrial systems with mixed standbys, switching failure and reboot delay

Existing reliability studies on K-out-of-N: G repairable retrial systems with mixed standbys mainly consider the case where the standby switching is completely reliable and the repair time follows an exponential distribution, and most of them directly analyze the system reliability indices based on probability theory. Given the existence of such phenomenon as standby switching failure in engineering, this paper proposes a novel reliability model of K-out-of-N: G repairable retrial system with switching failure, and performs statistical inference on the reliability to realize the modeling and evaluation of the system. The considered system consists of mixed standbys and a repairer with vacation. When an operating component fails, the warm standby one is switched to the operating one immediately, and the probability of switching failure during the switchover process is p. In the case where the repair time of failed components follows a general distribution, based on the supplementary variable method and recursive algorithm, the steps for calculating the system steady-state availability are presented. In the case of unknown parameters for repair time and retrial time, the Bayesian estimator of the steady-state availability under the squared error loss function and highest posterior density (HPD) confidence interval are obtained. In numerical simulation, the system reliability inference is realized by using the Monte Carlo (MC) method, and the validity of the inference method is analyzed.

On the Concerning Early Failure of a Short Stem Press-Fit Humeral Component

IntroductionAnatomic total shoulder arthroplasty (TSA) is a common surgical intervention for various shoulder pathologies, predominantly glenohumeral osteoarthritis. While generally considered safe and effective, complications remain a challenge. Short stem implants, aim to preserve bone stock and reduce complications. However, concerns about a specific short stem implant (Univers Apex; Arthrex, Naples, FL, USA) have surfaced due to high reported rates relatively early aseptic loosening. MethodsThis retrospective study analyzed 116 consecutive TSA patients with Univers Apex implants from 2004 to 2022. 15 revision cases were assessed for radiographic loosening, and explanted implants were examined for damage using a 0-3 scale. Histopathological analysis evaluated cellular responses to wear debris. ResultsOf the patients, 13% (15/116) required revision at 23.2 months on average. A distinct radiographic loosening pattern was identified, with humeral component subsidence and thinning of the proximal humeral cortex. Histopathology revealed a robust inflammatory response to wear debris, with a potential association between macrophage infiltration, hinge damage, and polyethylene wear. ConclusionThis study reveals a notable rate of early aseptic humeral loosening with the Univers Apex short stem implant, emphasizing concerns raised in previous reports and providing a potential explanation for the high rate of early failure. Surgeons should exercise caution and closely monitor patients with this implant design.