Reliability Of Components Research Articles

Analisis Pemeliharaan Menggunakan Metode Reliability pada Sistem Gas Turbine Engine untuk Mengetahui Kinerja Engine Turbofan CFM56-3 pada Pesawat Boeing 737-500

In carrying out structured maintenance, a method is needed to increase the durability of an aircraft component, one of the methods used is the reliability method. The reliability of aircraft components is very necessary to ensure that each aircraft component is serviceable and runs according to its function in the aircraft system, so to increase the reliability of an aircraft component, the reliability method is very important to do. This study aims to determine the critical life time limit of the asset or system or equipment function and identify the failure mode that occurs in the Gas Turbine Engine component of the Boeing 737-500 aircraft because if this engine fails, it can result in flight delays and if not handled immediately can cause the aircraft to experience Aircraft on Ground (AOG) conditions, because it has the potential to disrupt airworthiness and threaten safety. This study uses exploratory research which aims to simplify problems to make them easier to solve. This study uses the Pareto diagram method to determine the highest type of failure in components, then analyzes it using the failure mode effect analysis (FMEA) method. Based on FMECA and FTA analysis, there are 3 failure modes, the failure modes include mechanical system (Bleed Valve), pneumatic system (Butterfly Shaft), electrical system (actuator). The failure was due to the occurrence of the top event part consumable, namely the bleed valve part with an RPN value of 192, followed by the butterfly shaft part with an RPN value of 75 and the Actuator part with an RPN value of 72. The pneumatic system and electrical system categories are prioritized to carry out preventive maintenance, which means it is a solution from industry players in an effort to maximize maintenance of the turbofan engine system accompanied by technical or economic analysis to ensure a system in extending the service life of parts in the aircraft system.

Reliability optimization of reliability-redundancy allocation problems based on K-mixed strategy

In a reliability-redundancy allocation problem (RRAP), system reliability is maximized by selecting component reliabilities and finding the most suitable redundancy of subsystems. The advantages of a K-mixed strategy were introduced by modeling, so as to better improve system reliability. Compared with other existing redundancy strategies, the performance of a K-mixed strategy was verified using redundancy allocation problems (RAP). In this study, for the first time, a reliability calculation model under the new structure ( [Formula: see text] = 2 and [Formula: see text] = 1) is proposed, and the K-mixed strategy under the new structure is used in the reliability-RAP (RRAP), which is more complex than the RAP and further saves the production cost. In practical optimization, there was a complex decision-making problem to ensure optimal system reliability while minimizing system volume, weight, and cost. Then, this K-mixed strategy was adopted for modeling three benchmark problems in RRAP to seek a better and more flexible system structure. A powerful evolutionary algorithm (NSGA-II) was used to solve the new RRAP model to obtain the best system structure and reliability. The advantages of this model were confirmed by comparison with results from previous reliability optimization studies. The results show that the cost-saving advantages of the new structure in ensuring maximum reliability are significant. All the optimized remaining costs are noticeably higher than those of other methods, with the cost savings of the series-parallel system being the greatest. The difference in remaining costs compared to previous optimizations remains in the tens. Moreover, in more complex systems (Complex bridge system), the advantage in remaining volume is very significant, with the improvement being three times that of the optimization results of other methods.

Parameter Optimization and Flaw Type Dependent Tensile Properties of 15‐5PH Stainless Steel Manufactured by Laser Powder Bed Fusion

Careful consideration of processing parameters to mitigate defect formation is crucial to ensure reliability of components produced by laser powder bed fusion (LPBF). In this work, additive manufacturing parameter optimization and flaw type dependent tensile properties of 15‐5 precipitation hardened (PH) stainless steel produced by LPBF is examined to understand the correlation among processing parameters, flaw types, and corresponding tensile mechanical behavior. It is reported that LPBF samples with keyhole (KH) pores exhibit superior mechanical properties compared to those induced with lack‐of‐fusion (LOF) flaws, for a given relative density level. Diminished mechanical properties in samples with LOF flaws is correlated to the flaws’ irregular shapes and sharp corners, causing stress concentration. Minimal improvements to the mechanical properties of LOF‐induced samples, despite increasing relative density, indicate even small amounts of LOF flaws cause stress concentration and crack initiation. Conversely, KH pores exhibit high circularity and lower curvature values, and samples with KH pores demonstrate a strong correlation between tensile properties and relative density. Findings from this study suggest that when suboptimal LPBF processing is inevitable, favoring excessive energy input to induce KH pores over LOF flaws can lead to more predictable mechanical behavior of LPBF components.

Study on the tightening scheme of electronic component screw assemblies based on finite element simulation

Abstract To improve the fastening effect of electronic components in mechatronic equipment, the tightening sequence and frequency have a significant impact on the structural performance of these components. This study identifies an optimal fastening method through experimental verification, although some measurement errors were noted; the method remains highly reliable. First, theoretical calculations and experimental analyses were conducted to determine the torque values under different conditions. Then, simulations were performed to study the impact on the stress of each screw. Finally, experimental validation of the simulation results was carried out, and a linear relationship (with a value of 0.82) between the measured and theoretical values was explored. Consequently, an optimized screw group fastening method is proposed, and the torque calculation process is simplified, thereby enhancing the reliability and lifespan of electronic components in mechatronic systems.

Thermal management and heat transfer enhancement of electronic devices using integrative phase change material (PCM) and triply periodic minimal surface (TPMS) heat sinks

This study focuses on the thermal management of electronic components using phase change materials (PCM) with triply periodic minimal surface (TPMS) structures. Three PCM-TPMS heat sinks (PCM-Gyroid, PCM-IWP, and PCM-Primitive) are examined, compared to pure PCM heat sinks. The heat sinks are evaluated under pulsed power sources with passive and active cooling. The effect of varying TPMS relative densities (10 %, 20 %, and 30 %) is also analyzed. The results indicate that PCM-TPMS heat sinks significantly accelerate the melting interfaces of PCM and provide improved heat transfer paths. They effectively scatter and reduce the base temperature of electronic components, with average values of 61.9 °C and 34.9 °C, compared to higher temperatures for pure PCM heat sinks under passive and active cooling, respectively. Increasing the relative density of TPMS structures from 10 % to 30 % leads to a slight improvement in base temperature reduction for the different TPMS structures. Among the three TPMS configurations, the PCM-Gyroid heat sinks are found to be the most effective in reducing base temperatures compared to PCM-IWP and PCM-Primitive heat sinks. Additionally, the use of PCM-TPMS significantly enhances the reliability and durability of electronic components by mitigating thermal cycling. Overall, the study demonstrates the potential of PCM-TPMS heat sinks in improving the thermal management and performance of electronic components.

A Review on Tribological Considerations in the Transition from IC Engines to Electric Vehicles

The shift from internal combustion (IC) engines to electric vehicles (EVs) marks a significant transformation in the automotive industry, prompting a comprehensive reassessment of various engineering considerations. Among these, tribological factors play a critical role in ensuring the performance, reliability, and longevity of vehicle components. This review examines the tribological challenges and opportunities posed by the transition to EVs, focusing on key components such as bearings, gears, and braking systems, which face unique operating conditions in electric powertrains compared to their IC counterparts. The paper addresses how electric vehicles encounter distinct tribological scenarios, such as lower operating temperatures but higher torque loads, which demand new materials and lubrication strategies. It also explores how the near absence of internal combustion in EVs affects component wear and the mechanisms of friction reduction. Additionally, the tribological challenges in IC engines are revisited to provide a comparative understanding of how they differ from those in EVs, particularly regarding energy efficiency and frictional losses. This review emphasizes the importance of minimizing wear and friction to maximize energy efficiency, which is crucial for extending vehicle range and improving performance in EVs. By synthesizing the latest research findings and industry advancements, the review offers valuable insights for researchers and engineers involved in the design and optimization of tribological systems for the next generation of electric vehicles.

Mechanical characterization of FDM components made of polyaryletherketone (PAEK) for aerospace applications: a comparison of direct printing and box-cut sample manufacturing strategies

This study delves into the manufacturing strategies employed for fabricating tensile samples utilized in the mechanical characterization of material extrusion (MEX) components constructed with polyaryletherketone (PAEK) for aerospace applications. Two distinct methods were investigated for obtaining tensile test samples: direct cutting and extraction from a box. These methods were examined under both as-printed and annealing conditions. Quasistatic tensile tests were conducted along the building direction to evaluate the impact of processing conditions on the adhesion of overlying layers. The results unveiled significant disparities in mechanical behavior and crystallinity between directly printed samples and those derived from the box. The Young’s modulus exhibited marginal influence; however, the tensile strength of directly printed samples measured at 30 MPa (prior to annealing), corresponding to 50% of the strength observed in samples cut from the box (60 MPa). Moreover, the elongation at rupture of directly printed samples was found to be less than 2%, while that of cut samples exceeded 8%. Notably, directly printed samples exhibited a significant degree of incipient crystallization (12.18%), contrasting with the lower level of crystallinity observed in samples cut from the box (3.27%). These findings underscore the importance of recognizing the limitations associated with direct sample printing, emphasizing its crucial role in accurately characterizing components destined for the aerospace industry. Furthermore, this understanding is pivotal for optimizing the performance and reliability of MEX-printed PAEK components in aerospace engineering applications.

Fatigue damage assessment of a large rail-cum-road steel truss-arch bridge using structural health monitoring dynamic data

Structural health monitoring (SHM) system provides valuable information for the fatigue assessment of existing rail-cum-road bridges. This paper aims to develop an effective fatigue assessment approach for the rail-cum-road bridge, Jiujiang Yangtze River Bridge, by utilising the SHM data, focusing on dynamic modal analysis, finite element model updating and fatigue assessment. First, the traffic load spectrum and modal characteristics of the bridge are investigated from the SHM data. A three-dimensional finite element model is constructed and then updated by using the measured modal data through the proposed regularised model updating method. Then, the updated numerical model is verified with the measured dynamic response data, which can be utilised for calculating stress response at critical structural components of the rail-cum-road bridge. Finally, an improved Corten-Dolan’s model is proposed to analyse the fatigue damage and structural reliability of the critical structural components of the bridge, taking into account the combined effects of train and highway vehicle loads. The results demonstrate that the proposed fatigue assessment method provides more reliable results for the rail-cum-road bridge by considering the combined effect of multi-level traffic loads and the non-linear fatigue damage accumulation. It is concluded that the short H-shaped suspender is identified as the most vulnerable structural member of the rail-cum-road bridge, and the remaining fatigue service life of the typical components of the bridge should meet the design requirement.

Phase nonlinearity–weighted optical flow for enhanced full-field displacement measurement and vibration imaging

In this study, we developed a technique to utilize phase nonlinearity as a quantifiable confidence measure of the reliability of component displacement vectors extracted from multi-scale and multi-direction phases. The proposed approach includes three novel concepts. First, relative confidence values are established based on phase nonlinearity to quantify the reliability of the displacement components across various environmental conditions. Second, by analyzing the distribution of the relative confidence values, adaptive confidence measures are extracted and are used to reject unreliable displacement components; these confidence measures can dynamically adapt to various environmental conditions, such as varying image noise and large amplitudes of motion. Third, phase nonlinearity–weighted motion integration is conducted to ensure accurate estimation of the full displacement vector from the component vectors. By integrating these three approaches, a remarkable enhancement was achieved in full-field displacement measurement in terms of accuracy, robustness, and signal-to-noise ratio, especially in environments with high noise levels. The capability of the proposed technique was evaluated through numerical experiments using artificial patterns that simulate identical motions under varying noise levels. Experimental validation was also performed on an air compressor to substantiate the accuracy and robustness of the proposed technique. The findings verify its improvements over conventional techniques for full-field displacement measurement.

Prediction of the keyhole TIG welding-induced distortions on Inconel 718 industrial gas turbine component by numerical-experimental approach

Welding technologies represent a paramount joining process for ensuring the quality and reliability of critical industrial components; therefore, their innovation constitutes a driving force in realizing increasingly competitive products. A recently developed technology is the keyhole TIG welding, a new high energy–density alternative to the conventional TIG process. A key role in improving innovative manufacturing processes such as the keyhole TIG is covered by numerical simulation; indeed, it allows the development of a process digital twin able to support decisions and work as a predictive tool. Within this framework, the paper deals with the numerical-experimental investigation of the keyhole TIG technology, successfully employed on a simplified mock-up of an industrial gas turbine component consisting of two 6.5-mm-thick Inconel 718 rings. Numerical analysis aimed at predicting welding-induced distortions was performed employing two different computational approaches, namely the moving heat source and the simplified imposed thermal cycle methods. The numerical-experimental comparison of the results demonstrates an innovative approach in the field of the current keyhole TIG numerical simulation since, besides verification of numerical thermal analysis, further substantial validation of the post-weld distortion predictions is provided through comprehensive three-dimensional experimental data. Moreover, the comparative assessment of the two computational approaches and experimental evidence revealed that the imposed thermal cycle method implementation does not compromise the accuracy of welding distortion forecasting in industrial applications such as that investigated. Therefore, it can be regarded as a valuable tool for supporting the process engineer in designing the ideal set-up to comply with a variety of industrial requirements, among them strict design tolerances.

Modelling of Reliability Indicators of a Mining Plant

The evaluation and prediction of reliability and testability of mining machinery and equipment are crucial, as advancements in mining technology have increased the importance of ensuring the safety of both the technological process and human life. This study focuses on developing a reliability model to analyze the controllability of mining equipment. The model, which examines the reliability of a mine cargo-passenger hoist, utilizes statistical methods to assess failures and diagnostic controlled parameters. It is represented as a transition graph and is supported by a system of equations. This model enables the estimation of the reliability of equipment components and the equipment as a whole through a diagnostic system designed for monitoring and controlling mining equipment. A mathematical and logical model is proposed to calculate availability and downtime coefficients for different structures within the mining equipment system. This analysis considers the probability of failure-free operation of the lifting unit based on the structural scheme, with additional redundancy for elements with lower reliability. The availability factor of the equipment for monitoring and controlling the mine hoisting plant is studied for various placements of diagnostic systems. Additionally, a logistic concept is introduced for organizing preventive maintenance systems and reducing equipment recovery time by optimizing spare parts, integrating them into strategies aimed at enhancing the reliability of mine hoisting plants.

Reliability dependent production-inventory model for redundancy allocation via fuzzy logic

This study deals with a reliability dependent production-inventory model in two scenarios: a redundancy allocation with crisp structure and the other with fuzzy logic. Here, a manufacturer purchases some raw-materials/components in variable cycles and arranges them as series-parallel system to produce a single item with production cost dependent on system reliability. In this model, a retailer gets the opportunity of warranty period and credit period offered by the manufacturer. Also, the retailer’s demand is dependent on system reliability, credit period and selling price. In the crisp model, the component reliability is exponentially dependent on known failure rate and failure time. However, there is no dependent relationship between these two parameters. Actually, the real world is full of uncertainty and these two parameters may depend on each other following some uncertain nature which can be expressed as fuzzy logic. So, in the fuzzy model, failure time has been considered as dependent on failure rate following fuzzy logic and these fuzzy relations are defuzzified by using three fuzzy inference techniques: Mamdani, Sugeno and Tsukamoto. Main goal of this article is to determine the optimum number of cycles and components to maximize manufacturer’s profit and system reliability with some constraints. The model is solved by using elitist non-dominated sorting genetic algorithm (NSGA-II) and some numerical examples closed to real-world have been executed. Comparative analyses are done for different cases; different fuzzy inference techniques and for active and mixed strategies. Finally, some sensitivity analyses and managerial insights are drawn.

Non-destructive evaluation of additively manufactured superalloy IN718 via integrating microfocus X-ray computed tomography and non-linear acoustics

Superalloy IN718 components manufactured by laser powder bed fusion (PBF-LB/M) were non-destructively evaluated by the sideband peak counting (SPC) nonlinear acoustics method and suitably validated by microfocus X-ray computed tomography (XCT). A wide-band chirp acoustic wave was used to inspect the microstructures of IN718 samples with five distinct process parameters, and the results reveal that the number of sidebands, which result from the non-linearity induced by porosity, is significantly influenced by the distribution and size of pores, in addition to the volume fraction. There was a clear correlation between extent of porosity and the corresponding value of the SPC index. XCT analysis corroborated these findings, providing quantitative insights into the porosity characteristics that affect the ensuing acoustic responses. The findings demonstrated that the porosity with varying sizes and distributions generate different SPC profiles, which were correlated to XCT results to quantitatively assess the size and spatial distributions of the porosity. Fusion of SPC and XCT characterization techniques provides a new strategic approach for non-destructive testing, where the SPC method offers rapid, qualitative evaluation, while XCT provides detailed spatial resolution for defect quantification. The integration of SPC could lead to the development of more cost-effective and advanced quality control protocols, ensuring the reliability of AM-manufactured components regardless of their geometry and composition.

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.

Analisis Kerusakan Diafragma Suling Pada Lokomotif Menggunakan Metode Fishbone Diagram

The analysis of the flute diaphragm damage in the locomotive was carried out using the Fishbone Diagram method to identify and group the main cause of the damage. This method visualizes the various factors that contribute to the problem through fishbone diagrams, allowing for an in-depth understanding of the relationship between causative factors such as design, materials, operational processes, and maintenance. The results of the analysis show that the damage to the distilled diaphragm is affected by a combination of internal and external factors, including material wear, excessive operational load, and lack of regular maintenance. These findings provide a basis for formulating more effective repair and prevention strategies, thereby improving the reliability and longevity of components in locomotives.

Optimization of Pyroshock Test Conditions for Aerospace Components to Enhance Repeatability by Genetic Algorithms

Electronic components assembled in satellites should be able to withstand the vibration, noise, and impact loads generated by space vehicles during launch. To simulate the impact loading in a laboratory environment, a pyroshock test simulates an impact load resulting from explosions during the stage and pairing separation of launch vehicles, which imposes significant stress on the components, potentially leading to failures and damage. To ensure component reliability before the flight model (FM) stage, where components are mounted on the actual launch vehicle and sent into orbit, a pyroshock test is conducted during the qualification model (QM) stage using identical parts and specifications. This process involves measurements of the acceleration induced by pyroshock to calculate the shock response spectrum (SRS) and evaluate the components’ reliability against the required SRS to confirm their ability to endure the shock and operate normally in post-tests. The aerospace developer determines the SRS requirements based on the space launch vehicle and the installation location of the electronic components. Configuring a suitable pyroshock test to meet these requirements typically involves extensive trial and error. This study aims to minimize such trial and error by examination of SRS changes through a numerical approach by table structural vibration analysis. The structure is subjected to in-plane impacts using a steel ball via a pendulum method. Various SRS profiles are calculated by test factors such as the weight of the steel ball, the pendulum angle, and the installation position of the test specimen. Furthermore, a genetic algorithm is utilized to derive the optimal test conditions that satisfy the required SRS. An automated pyroshock test system is developed to enhance repeatability and reduce human errors.

Evaluation of the psychometric properties of the homophobia scale in religious-based university students in Indonesia

This study aims to evaluate the psychometric properties of the homophobia scale in students attending religion-based universities in Indonesia. This research is important as homosexuality is a controversial issue in the country and is still a topic of debate. The Homophobia Scale is a tool that assesses attitudes towards homosexuality through 17 items measuring positive affirmation, negative cognition, and the perceived threat of homosexual behavior. The scale was adapted for the Indonesian context, which is predominantly religious, based on The Heterosexual Attitudes Towards Homosexuality (HATH) Scale and Items, originally translated by bilingual experts. The translated scale was then reviewed for content by psychologists and communication experts, and field-tested for reliability and validity. Data from 327 students aged 18–35 from both state and private religion-based universities were analyzed using Rasch model analyses, including principal component analysis (PCA), reliability analysis, and differential item functioning (DIF) assessment. The study found that the homophobia scale accounted for 42.4 % of the raw variance, indicating its unidimensionality. The scale demonstrated an acceptable level of personal reliability and excellent reliability for individual items. Results revealed significant demographic effects, with age and study program showing more differential item functioning (DIF). Male students were more tolerant towards homosexuals than females. Additionally, students at state universities tended to be more tolerant but held negative views of homosexuality when associated with AIDS. In conclusion, the homophobia scale assessed in this study exhibits promising construct validity and sufficient psychometric properties. The findings indicate that negative stigma towards homosexuals and homophobia still persist among students at religion-based universities in Indonesia, despite limited interaction with homosexuals.

Effects of different momentum ratios and Reynolds number in a T-junction with an upstream elbow

This study focuses on analysing thermal mixing in T-junctions with varying momentum and Reynolds number ratios, utilizing computational fluid dynamics (CFD) simulations. The T-junction is a critical component of the primary nuclear thermal–hydraulic circuit within a pressurized water-cooled reactor (PWR). The T-junction connects the pressurizer (PRZ) with the steam generator (SG) and the reactor pressure vessel (RPV). Water from the PRZ and the SG are at different temperatures and incomplete thermal mixing occurs when these two fluid streams meet at the T-junction. This incomplete thermal mixing can induce thermal stratification of the water within the T-junction as well as thermal striping phenomena. Thermal striping phenomena can lead to fluctuations of the temperature at the inner pipe wall of the T-junction. Thermal stratification and thermal striping phenomena can induce thermo-mechanical fatigue and eventual pipe failure which can affect the safety of the reactor. Therefore, a high-fidelity, mechanistic understanding of the turbulent thermo-fluid mixing within T-junctions of PWRs might lead to improvements in component reliability and safety within nuclear power plants (NPPs).The primary aim of the research, presented in this paper, is to understand and quantify the effect of variations in the momentum ratio on the turbulent fluid flow within T-junctions. This is achieved by either varying the branch pipe diameter while keeping the inlet velocity constant (part one) or by adjusting the branch pipe inlet velocity while maintaining a constant diameter (part two). Despite the different variations in momentum ratios, the specific momentum ratios under consideration in both parts of the study remain consistent (namely 98 and 66.4). It is also noteworthy that the momentum ratios considered in the paper can be classified as wall-jet and impinging-jet, according to the definition in (Hosseini, Yuki, & Hashizume, 2008). It should be noted that the momentum ratio is manipulated by adjusting the flow parameters, leading to variations in the Reynolds number ratio between the main pipe inlet and the upstream branch pipe at the T-junction. The turbulent flows in the cases that are considered are simulated using the Improved delayed detached eddy simulation (IDDES-SST) model. The numerical results from these simulations indicate, for the considered momentum ratios, that maintaining the same momentum ratio does not produce similar mean flow behaviour and turbulent quantities of interest (QoI). For instance, the size of the flow recirculation zone is more likely linked to the diameter of the branch pipe. Moreover, the turbulent QoI and temperature fluctuations at the determined locations are likely affected by the changed flow recirculation zone as well as the Reynolds number of the branch pipe flow.

Assessing the reliability of natural gas pipeline system in the presence of corrosion using fuzzy fault tree

The corrosion encountered within natural gas pipelines can precipitate significant ramifications. Numerous internal and external factors contribute to incidents of gas leakage. A multitude of factors influencing pipeline failure underscore the imperative need for a safety system intricately linked to the operation process. The absence of this systematic process for detecting factors contributing to failure detrimentally impacts the efficiency of pipelines. In this context, this paper has devised a risk assessment and warning model utilizing multi-factor monitoring data, employing the fuzzy fault tree analysis (FFTA). The fuzzy fault tree is constructed to assess the impact of individual factors and parameters influencing corrosion on the reliability of the grid. Moreover, a performance diagram illustrating this mechanism is crafted, elucidating the system's reliability relationship based on each component's reliability. The findings showed that 14 basic and 10 intermediate events play a role in the corrosion of natural gas pipelines. The failure probability of the top event was identified to be 22%. Employing the proposed method, the system's reliability was estimated with lower and upper limits of [0.6825, 0.8859]. The obtained results demonstrate the effectiveness and efficiency of the proposed method in addressing the uncertainty inherent in the input data.

Application of the Rosenblatt transformation in First-Order System Reliability approximations

The reliability assessment of structural systems presents a significant challenge in structural engineering. A commonly employed approximation is the First-Order System Reliability Method (FOSRM), which estimates system reliability using the FORM component reliabilities and sensitivity factors. An essential step in FORM involves transforming the random vector X into the standard vector U, often using the Rosenblatt transformation (RT). Several studies demonstrated that different conditioning orders in the RT yield different FORM component results. This study investigates how these differences on component level propagate into the FOSRM system level. We conducted several typical engineering case studies with various failure probabilities, system sizes, and dependency structures (Gaussian and Frank Copula). For the Frank Copula, different Rosenblatt conditioning orders systematically yielded different FOSRM results, with most cases showing differences between 10% and 30% in estimated failure probability. For some systems, these differences increased with system size, suggesting that greater variations might be observed for larger systems. Notably, systems with Gaussian Copula functions also proved vulnerable to the Rosenblatt conditioning order when different components were assessed with different conditioning orders. The observed differences were larger than previously reported and should be carefully considered in uniform safety assessments.