Most current condition‐based maintenance (CBM) systems using proportional hazards model (PHM) assume that enough historical data are available. However, in many practical cases…
Abstract
Purpose
Most current condition‐based maintenance (CBM) systems using proportional hazards model (PHM) assume that enough historical data are available. However, in many practical cases, it is usually costly to collect much historical data prior to real practice (model implementation). This paper aims to focus on the necessity and benefits of updating a PHM with new samples generated in the process of model implementation.
Design/methodology/approach
First, an updating scheme is presented and embedded into the entire cycle of PHM establishment, its application/implementation, and its updating. Next, a simulation evaluation is conducted based on a typical degradation model.
Findings
By updating a PHM using newly generated samples, the precision and reliability of residual life (RL) prediction can be improved, especially close to system failure.
Research limitations/implications
The current version of PHM is typically for non‐repairable systems or those systems only receiving renewal maintenance. Further research should focus on the inclusion of the effect of imperfect maintenance.
Practical implications
The updating scheme enables maintenance practitioners to more precisely and reliably predict the RL of an in‐operation system, and enhances further CBM decision making.
Originality/value
This paper highlights the necessity and benefits of updating a PHM using emerging new training resources, which has not received enough attention in existing research/practice of a PHM.
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Keywords
Fang Liu, Guang Meng and Junfeng Zhao
The purpose of this paper is to propose an alternative test board design with only one loading condition and sufficiently large sample size, which is more suitable for the…
Abstract
Purpose
The purpose of this paper is to propose an alternative test board design with only one loading condition and sufficiently large sample size, which is more suitable for the statistical package qualification. With the exception of the board shape and size and package component layout, all other aspects of the design strictly follow the JEDEC standard so that the board design can be easily implemented.
Design/methodology/approach
A test board in a round shape was introduced. First, drop tests were carried out. Then, the dye stain test and metallurgical analysis were performed in order to study the failure mechanism of lead‐free solder joint under drop impact.
Findings
The test results indicate that the combined effect of mechanical shock and PCB bending vibration is the root cause of solder joint failure under drop impact, and that the maximum peeling stress of the critical solder joint could be considered to be the dominant failure factor. On the other hand, the fracture of BGA lead‐free solder joints occurs at intermetallic compound (IMC) interface near the package side, and failure mode is brittle fracture.
Originality/value
These results are the same as those of JEDEC standard test board. Furthermore, the solder joint loading conditions in this design are simplified from six to one. The round test board can take the place of JEDEC standard test board to carry out drop test and to enable good solder joint life prediction and statistical analysis.
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Fang Liu, Guang Meng and Mei Zhao
The purpose of this paper is to investigate the mechanism of ball grid array (BGA) lead‐free solder joint failure under board‐level drop impact.
Abstract
Purpose
The purpose of this paper is to investigate the mechanism of ball grid array (BGA) lead‐free solder joint failure under board‐level drop impact.
Design/methodology/approach
A round shaped test board was used. First, drop tests at three different heights were carried out. Then, dye stain testing and metallurgical analysis were performed in order to study the failure mechanism of lead‐free solder joints under drop impact.
Findings
The test results indicate that the combined effect of mechanical shock and printed circuit board bending vibration is the root cause of solder joint failure under drop impact. On the other hand, the fracture of BGA lead‐free solder joints occurs at the intermetallic compound interface near the package side, and the failure mode is brittle fracture.
Originality/value
These results are the same as those for JEDEC standard test boards. The round test board could take the place of the JEDEC standard test board when conducting drop testing.
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Keywords
Jun-peng Shao, Guang-dong Liu, Xiao-dong Yu, Yan-qin Zhang, Xiu-li Meng and Hui Jiang
The purpose of this paper is to describe a simulation and experimental research concerning the effect of recess depth on the lubrication performance of a hydrostatic thrust…
Abstract
Purpose
The purpose of this paper is to describe a simulation and experimental research concerning the effect of recess depth on the lubrication performance of a hydrostatic thrust bearing by constant rate flow.
Design/methodology/approach
The computational fluid dynamics and finite volume method have been used to compute the lubrication characteristics of an annular recess hydrostatic thrust bearing with different recess depths. The performances are oil recess pressure, oil recess temperature and oil film velocity. The recess depth has been optimized. A test rig is established for testing the pressure field of the structure of hydrostatic thrust bearing after recess depth optimization, and experimental results show that experimental data are basically identical with the simulation results, which demonstrates the validity of the proposed numerical simulation method.
Findings
The results demonstrate that the oil film temperature decreases and the oil film pressure first increases and then decreases with an increase in the recess depth, but oil film velocity is constant. To sum up comprehensive lubrication performance, the recess depth of 3.5 mm is its optimal value for the annular recess hydrostatic thrust bearing.
Originality/value
The computed results indicate that to get an improved performance from a constant flow hydrostatic thrust bearing, a proper selection of the recess depth is essential.
Details
Keywords
Hong Zhang, Lu-Kai Song, Guang-Chen Bai and Xue-Qin Li
The purpose of this study is to improve the computational efficiency and accuracy of fatigue reliability analysis.
Abstract
Purpose
The purpose of this study is to improve the computational efficiency and accuracy of fatigue reliability analysis.
Design/methodology/approach
By absorbing the advantages of Markov chain and active Kriging model into the hierarchical collaborative strategy, an enhanced active Kriging-based hierarchical collaborative model (DCEAK) is proposed.
Findings
The analysis results show that the proposed DCEAK method holds high accuracy and efficiency in dealing with fatigue reliability analysis with high nonlinearity and small failure probability.
Research limitations/implications
The effectiveness of the presented method in more complex reliability analysis problems (i.e. noisy problems, high-dimensional issues etc.) should be further validated.
Practical implications
The current efforts can provide a feasible way to analyze the reliability performance and identify the sensitive variables in aeroengine mechanisms.
Originality/value
To improve the computational efficiency and accuracy of fatigue reliability analysis, an enhanced active DCEAK is proposed and the corresponding fatigue reliability framework is established for the first time.
Details
Keywords
Jun-peng Shao, Guang-dong Liu and Xiaodong Yu
This paper aims to improve the bearing capacity of hydrostatic thrust bearing under working conditions of high speed and heavy load; a new wedge-shaped structure opened on an edge…
Abstract
Purpose
This paper aims to improve the bearing capacity of hydrostatic thrust bearing under working conditions of high speed and heavy load; a new wedge-shaped structure opened on an edge of oil seal is put forward, the loss and insufficiency for hydrostatic bearing capacity are made up by using dynamic pressure, and then, hydrostatic hydrodynamic lubrication is realized.
Design/methodology/approach
Oil film three-dimensional models of unidirectional and bi-directional hydrostatic hydrodynamic oil pad are established by using UG. The oil film pressure fields of two kinds of oil pad are simulated by using ANSYS ICEM CFD and ANSYS CFX; the pressure fields distribution characteristics are obtained, and the effects of workbench rotary speed and bearing weight on pressure field are analyzed. Also, the experimental verification is made.
Findings
The results demonstrate that with an increase in workbench rotary speed, the oil film pressure of two kinds of hybrid oil pad increases gradually, and the maximum pressure of the bi-directional one accounts for 95 per cent of the unidirectional one when the load is constant. With an increase in load, the oil film pressure of two kinds of hybrid oil pad increases gradually, the difference between them is 9.4 per cent under the condition of load of 25 t when the rotary speed is constant.
Originality/value
The paper can provide theoretical basis for a structure design of hybrid thrust bearing under different rotary speed and load conditions, and compensate the shortage of static pressure-bearing capacity by using dynamic pressure, improve the stability of vertical CNC machining equipment.
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This study aims to explore the intricate relationship between financial literacy, digital transformation, Fintech adoption, competitiveness and sustainable firm performance…
Abstract
Purpose
This study aims to explore the intricate relationship between financial literacy, digital transformation, Fintech adoption, competitiveness and sustainable firm performance, particularly focusing on how financial literacy empowers firms in the evolving digital landscape. Leveraging technological innovation systems (TIS) and resource-based view (RBV), this research suggests a model that incorporates these concepts, focusing on the moderating role of financial literacy in essential interactions.
Design/methodology/approach
This study employed a survey-based methodology, collecting data from employees across five major Pakistani banks. The survey yielded 426 responses, from which 387 valid ones were selected for analysis. The analysis utilized partial least squares-structural equation modeling (PLS-SEM), complemented by the Hayes Process Model for moderated mediation analysis. This approach ensured robust examination of the relationships between the constructs of the proposed model.
Findings
The study's findings validate that digital transformation significantly enhances sustainable performance, with Fintech adoption and competitiveness acting as crucial mediators. Financial literacy is highlighted as a key moderator, influencing the effects of digital transformation on Fintech adoption and competitiveness, although its direct impact on sustainable performance is less pronounced. This comprehensive analysis underscores the complex interplay among these factors in driving sustainable performance in the banking sector.
Originality/value
This research enriches the theoretical and practical comprehension of how digital transformation and Fintech integration, underpinned by financial literacy, bolster sustainable business outcomes. It sheds light on the synergy between technology, strategy and organizational success, offering key insights for the banking industry's navigation through the digital era's challenges.
Details
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Yuqing Xu, Guang-Ling Song and Dajiang Zheng
This study aims to provide a model to predict the service life of a thick organic coating.
Abstract
Purpose
This study aims to provide a model to predict the service life of a thick organic coating.
Design/methodology/approach
A series of thin coating films are rapidly tested under the same exposure condition as the thick coating in its service condition by means of electrochemical impedance spectroscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction.
Findings
The validity of the model is successfully verified. The long-term protectiveness or service life of a thick organic coating can be rapidly predicted.
Originality/value
The prediction model does not require long-term experiments or any test that may alter the degradation mechanism of the thick coating.
Details
Keywords
Xue-Qin Li, Lu-Kai Song and Guang-Chen Bai
To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.
Abstract
Purpose
To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.
Design/methodology/approach
In this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.
Findings
The recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.
Originality/value
For the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.