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Engineering failure analysis
Elsevier Science
Engineering failure analysis

Elsevier Science

1350-6307

Engineering failure analysis/Journal Engineering failure analysisSCIEIISTP
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    Effects of spalling fault on dynamic responses of gear system considering three-dimensional line contact elasto-hydrodynamic lubrication

    Huang, WenbinYang, XiaoqingWang, LimingDeng, Chunlong...
    19页
    查看更多>>摘要：Spalling is a common fault in gear system, which directly degrades the performance of the gear system and increases the risk of downtime of the entire system. Until now, lots of efforts have been done to study the underlying mechanism of the spalling fault and its effects on dynamic characteristics for the purpose of accurate diagnosis. However, the lubrication characteristics affected by the spalling fault are usually neglected, which degrades the modelling accuracy of gear system with spalling fault. Therefore, a new dynamic modelling method with spalling fault considering three-dimensional (3D) line contact elasto-hydrodynamic lubrication (EHL) is proposed in this paper. With the established model, the contact characteristics of the lubrication film between gear teeth affected by the spalling fault and the dynamic responses of the gear system can be studied. The main differences of the proposed model are that the meshing force over the lubrication film is calculated iteratively instead of a given quasi-static meshing force and the comprehensive meshing stiffness is obtained considering the effects of both spalling fault and lubrication film. The effects of spalling fault on film pressure distribution, film thickness distribution, film stiffness, comprehensive meshing stiffness and dynamic responses are studied based on the proposed method. Finally, the proposed 3D line contact EHL model is verified by comparing to a traditional EHL model. Effects of the spalling fault size on the comprehensive meshing stiffness and the dynamic responses of the gear system are investigated and discussed. The results reveal that this work can provide a more reasonable analytical method for understanding the contact characteristics and dynamic responses of gear system with spalling fault.
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    Temporal and spatial evolution characteristics of fracture distribution of floor strata in deep coal seam mining

    Hu, YanboLi, WenpingChen, XinminXu, Hongzhong...
    14页
    查看更多>>摘要：With the increase in mining coal seam depth year by year, the high-pressure karst water hazard of coal seam floor poses a serious threat to mine safety. To solve this karst water disaster beneath the coal seam floor, it is necessary to Prevention-control the water-conducting passages developed in coal seam floor strata. Therefore, mathematical model analysis and Brillouin optical time domain reflection technology (BOTDRT) were used in this study to monitor the microstrain of floor rock in deep coal seam mining, and other methods were used to elucidate the mechanism of floor failure in deep coal seam mining. The results show that the maximum depth of floor rock breakage in coal seam mining is near the peak stress propagation line in front of the coal wall of coalface and reveals the stacking uplift of floor rock in goaf. Based on the measured data of preburied metal cable-based distributed optical fiber sensor (MCDOFS), the time-space evolution characteristics of floor breakage in coal seam mining and the law of floor breakage were revealed more finely. This study provides a basis for the prevention and control of high confined water hazard of limestone in a coal seam floor in deep seam mining.
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    • NSTL
    • Elsevier

    Using thermal annealing and salt remelting to increase tensile properties of 3D FDM prints

    Szust, AgnieszkaAdamski, Grzegorz
    13页
    查看更多>>摘要：Addtive Manufacturing techniques such as FDM (Fused Deposition Modeling) are becoming more significant in prototyping and have potential to be used in low-volume production, which generates the need of better tensile properties of FDM printed parts. The effects of process parameters (printing orientation and layer height), thermal annealing process and salt remelting process on tensile properties and anisotrophy of the FDM parts was examined. The tensile strength of PETg FDM parts measured in Z direction increases over 300% after salt remelting process and the anisotrophy of the parts becomes negligible.
      原文链接:
    • NSTL
    • Elsevier

    Tropical-cyclone-wind-induced flutter failure analysis of long-span bridges

    Fang, GenshenPang, WeichiangZhao, LinXu, Kun...
    18页
    查看更多>>摘要：Continuously growing number and span length of long-span bridges in coastal region of China require a robust aeroelastic design to against the tropical-cyclone (TC)-induced flutter instability. Instead of using the deterministic approach, this study presents a Monte-Carlo-technique-based framework to analyze the flutter reliability of a long-span suspension bridge subjected to TC winds. A limit state function formulated as the difference between the flutter capacity and the extreme gust wind, termed as the product of a random gust factor and the TC mean wind hazard is employed. The flutter fragility curve in terms of the critical wind speed is derived using 2D and 3D flutter analysis models accounting for the structural modal and damping randomness as well as experiment-induced errors of aeroelastic flutter derivatives. The TC wind hazard curves at the height of the bridge deck described as the probability of exceedance at any given years of interest versus the extreme 10-min mean wind speed are estimated through generating a large quantity of synthetic tracks around the bridge site. The probabilistic solutions of the gust factor associated with any gust duration of interest are determined utilizing the statistics of observed TCs coupled with a theoretical model. The TC-induced flutter failure probabilities of present bridge are then predicted in different combinations of gust duration, surface roughness length and flutter analysis models, which enables the assessment of flutter risk subjected to TC winds as compared to code suggested target reliability indices. The present reliability analysis provides some basic information to assist and enhance the flutter-resistant design of long-span bridges due to TC winds during the preliminary stage.
      原文链接:
    • NSTL
    • Elsevier

    Economic and financial consequences of process accidents in Brazil: Multiple case studies

    Gonzalez, Rodolfo Sapatada Silveira Rossi, Raissa AparecidaMartins Vieira, Luiz Gustavo
    24页
    查看更多>>摘要：Along with the advancement of process industries, there has been an increase in process safety accidents (as defined in the 1970s), which often cause deaths and damages to properties, communities, the environment, and the local economy. Process safety management (PSM) and legislation that can minimize dangerous incidents due to the failure of process operations are still insufficient in Brazil. Thus, this work aims to quantify the economic and financial consequences of three different process safety accidents using a case study methodology. The two first cases reflect extreme situations of accidents involving ruptures in tailings dams, which were used to store wastewater generated during ore processing (Mariana and Brumadinho). The Mariana dam disaster caused about 40 x 10(6) m(3) of mining waste to be released, covering similar to 1500 ha. The accident had a significant impact on the environment and economy throughout the Doce River Basin, resulting in a loss of US$5.28 billion. The Brumadinho disaster resulted in 270 deaths and 11 missing people, as well as severe environmental damage and property loss. Thirteen million cubic meters of tailings were released, damaging a 270-hectare region, and contaminating the Atlantic Forest natural reserves and the Paraopeba River. The total estimated cost, including production losses, fines, and damages, is US$13.48 billion. The third case is the fire at the Santos port terminal (Sao Paulo) caused by Ultracargo, which highlights the need for PSM policies and legislation because fire accidents are common in Brazil. Only the Port of Santos experienced at least one major fire case per year from 2013 to 2020. The fire spread to six storage tanks, consuming similar to 30,000 m(3) of fuel, resulting in a US$91.91 million loss for the company. The fire burned for nine days, causing delays in shipments, and a 4.3% reduction in agricultural exports during that period. Industrial process accidents, regardless of the severity of the accident or the type of product handled, have consistent economic and financial impacts on companies and the surrounding regions where they operate. This study exposes Brazil's vulnerability in terms of process safety control and product storage. Therefore, Brazil has the opportunity to explore this topic further.
      原文链接:
    • NSTL
    • Elsevier

    Fatigue optimization of rotary control head rubber core based on steady sealing

    Zeng, YijinHuang, JianWang, ZhiliangLi, Junxiong...
    16页
    查看更多>>摘要：In the process of underbalanced pressure drilling, the drill pipe body and its joint repeatedly pass though the sealing rubber core of the rotating blowout preventer (RBOP), making the rubber core susceptible to alternating cyclic load, and prone to fatigue failure. Under the premise of effective sealing realized by the rubber core, to increase its service life, first the Yeoh constitutive model and constitutive parameters describing the material of rubber core were determined by uniaxial tensile and compression tests, and the finite element governing equation of the nonlinear large deformation of the rubber core was obtained according to the principle of virtual work; then a three-dimensional finite element model of the rubber core was established by ABAQUS software to simulate the dynamic sealing process, contact pressure and Mises stress distribution and variation on the sealing surface were analyzed, and the accuracy of the finite element analysis results was verified by comparing the existing test results; subsequently, the influence of structural parameters such as inner angle, outer angle and inner diameter on the sealing surface stress was studied, and these parameters were optimized through Taguchi experiment. The optimal combination of structural parameters was obtained as inner angle 29 degrees, outer angle 69 degrees and inner diameter 84 mm. The maximum Mises stress was reduced by 2.48 MPa and the Mises stress amplitude by 42% after optimization. Finally, the suitable conditions of the optimized rubber core were selected based on the applicability analysis to conduct the field application and result shows that the rubber core has good sealing performance and significantly increased fatigue life after optimization.
      原文链接:
    • NSTL
    • Elsevier

    Interfacial failure of circular or tubular hybrid bonded joints: A theoretical description

    Biscaia, Hugo C.Martins, Ana P.Micaelo, RuiCarvalho, Marta S....
    28页
    查看更多>>摘要：In different industries, the bonding technique has gained several advances in recent years. However, due to the specificity of each industry, the bonded joints may present different configurations. For instance, in the case of metallic truss bridges, the use of Carbon Fibre Reinforced Polymers (CFRP) bonded on the steel surface members may require circular or even tubular transitions between these materials. Although the bonded transitions between a metal and a composite material have been deeply studied with flat surfaces the information on circular or tubular hybrid bonded joints is still scarce. Therefore, the present study aims to mitigate some of this lack of knowledge by proposing an analytical solution able to describe the interfacial debonding process between a circular or tubular bonded transition between two materials. The proposed model also aims to simulate the interfacial debonding of double butt (or stepped) lap joints. Under these circumstances, a bilinear local adhesive model is adopted which required the quantification of the elastic and the softened stiffnesses as well as the pure Mode II fracture energy. The Finite Element Method (FEM) is used for the validation of the proposed model. The behaviour of the adhesive joint between materials is numerically modelled through the Cohesive Zone Modelling (CZM) in which the same bilinear shape used in the analytical solutions is adopted. Different situations were analyzed thoroughly and the numerical simulations tracked very closely the analytical results obtained from the proposed closed-form solutions.
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    • NSTL
    • Elsevier

    Applying principal component analysis (PCA) to the selection of forensic analysis methodologies

    Booker, Nigel K.Knights, PeterGates, J. D.Clegg, Richard E....
    26页
    查看更多>>摘要：Booker et al. [3] stated that "in many engineering defect investigations, the choice of forensic analysis methodology is rarely questioned, and the forensic analysis methodology is chosen by the analyst without due diligence, resulting in a methodology that may not be the most accurate or expedient. This in turn has the potential to increase the risk and cost of the decision-making process." Therefore, a need was identified to identify and analyse the variables that influence practitioners' selection of an appropriate forensic analysis methodology. A review of current literature highlighted the fact that there was no definitive correlation identifying the primary variables that affect the selection of forensic analysis methodology. Noting that the determination of the correct methodology for a specific instance is not within scope of this paper, the first stage of the analysis was to apply previously collated methodology taxonomy, and then apply Principal Component Analysis (PCA) to determine which variables had the highest significance of influence on the selection of Forensic Analysis Methodology from 132 case studies selected from Case Studies in Engineering Failure Analysis [2] (Appendix A.). The analysis has determined that the methodology selected to conduct forensic analysis is primarily influenced by the geographical culture and industry of the analyst. Therefore, there is a requirement to acknowledge and understand the role of cultural and industry biases when choosing an appropriate methodology, and subsequently, when evaluating a forensic analysis case study. Although the mere recognition of the existence of cultural and industry bias does not guarantee that the right decisions will be made, it does, however, facilitate an objective rigour to the process of the selection of the forensic analysis methodology to be applied, which in turn, will mitigate subjective reasoning and potentially reduce the risk and cost of the decision-making process. Without an international standard for forensic analysis, or universally acknowledged guidelines for the selection of forensic analysis methodology, analysts will continue to be susceptible to methodology selection bias, which will increase the probability of choosing a sub-optimal methodology, which, in turn, can prolong the investigation and adversely affect the accuracy of the analysis.
      原文链接:
    • NSTL
    • Elsevier

    Detection of crankshaft faults by means of a modified Welch-Bartlett periodogram

    Carrera-Avendano, E.Urquiza-Beltran, G.Nieto-Jalil, Jose M.Carrillo-Pereyra, C....
    16页
    查看更多>>摘要：Detection, diagnostic and isolation of crankshaft failures is of vital importance to ensure reliable operation during the course of their services. However, many times the fault may be submerged in a strong background noise making the feature extraction process difficult. To solve this problem, this paper shows a new method for extracting features from the signal immersed in background noise. This method is based on linking the dyadic Wavelet transform and the Welch-Bartlett classic periodogram, obtaining a modified Welch-Bartlett periodogram; which provides a dyadic spectrum of frequencies with multiple sensitivities. The validation process was based on two scenarios. The first one did not generate a fault, while the second one presented a fault with a signal to noise ratio of 0.3269 dB. The results show that the dyadic wavelet function to be used is the Daubechies 45 as it provides an attenuation of the rejection bands close to 150 dB. Through the new modified Welch-Bartlett periodogram, an engine vibration signature detected, 29 Hz, the component 120 Hz corresponding to the deformation of the magnetic fields of the engine and the component of 177.5 Hz inherent in squirrel-cage induction motors. A final result showed that the new modified Welch-Bartlett periodogram maximizes sensitivity in frequency component analysis. In addition, the results were superior to those achieved with the procedures reported in the literature reviewed.
      原文链接:
    • NSTL
    • Elsevier

    Fatigue analysis in rotor of a prototype bulb turbine based on fluid-structure interaction

    Gao, HaiyuWang, MingmingMa, GuomingWang, Zhengwei...
    12页
    查看更多>>摘要：Bulb turbine units are widely used in run-of river or dam projects with relatively low head, and can also be used for tidal energy utilization. Some types of bulb turbines have excessive vibration and fatigue failure problems, which threats their fatigue life. The model analyzed in this paper is a prototype bulb turbine rotor which suffered cracks, probably due to erosion and welding defects. The dynamic stress characteristics are analyzed under not only the non-cracked shaft condition but also the cracked one, to find possible causes of the failure. The computational fluid dynamics (CFD) simulation is performed to obtain reliable hydraulic load on the runner for performing the FEM analysis. The CFD results are verified by comparing with the site test for the prototype one. The linear elastic fracture mechanics theory combined with the fluid-structural interaction theory is applied to developing a cracked FEM model, to obtain the dynamic stress characteristics for the runner, shaft and rotor. The results reveal that the change in dynamic stress level on the shaft flange root significantly depends on the operating conditions Based on the numerical calculations and site inspection, it could be concluded that the insufficient sealing could lead to leakage flows with specific flow rates in flange root, which resulted in the occurrence of erosion; in addition, the welding at the flange root probably generated tiny defects. These two factors are likely lead to fatigue cracks and major failure of the shaft. Suggestions for solutions for the problems of the shaft are also discussed. Results of this study helps to find the reasons of the shaft fatigue failure. Furthermore, the analysis method could be used for an accurate calculation of fatigue life and providing guidance in future designs and operations of bulb turbine units.
      原文链接:
    • NSTL
    • Elsevier