Pub Date : 2026-05-01Epub Date: 2026-01-28DOI: 10.1016/j.engfailanal.2026.110625
Kesong Fan , Mengyin Feng , Shaowei Liu , Dengpan Zhang , Hui Liu , Yi Kang , Deyin He , Guohao Liang
<div><div>Threaded steel resin bolts are extensively utilized for supporting mine roadways. However, various factors such as underground humidity, high stress, and significant disturbances increase the susceptibility of these support components to corrosion, particularly in environments characterized by roof water seepage. This corrosion poses serious risks to the safety and efficiency of mining production. Focusing on the Dangjiahe Coal Mine in Shaanxi Province, China, this study elucidates the corrosion mechanisms affecting bolts in the presence of prolonged stress and water exposure. It further explains the propagation characteristics of ultrasonic guided waves within corroded anchorage structures, investigates guided wave propagation properties across varying corrosion scales, and explores guided wave non-destructive testing (NDT) methodologies for anchorage bodies exhibiting corrosion defects. The findings indicate that: (i) Mine water quality assessments, coupled with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses of corroded samples, reveal that Cl<sup>−</sup> plays a crucial catalytic role in the corrosion process. Following corrosion, the bolt’s surface becomes rough and loose, resulting in a decrease in Fe content and an increase in oxide formation, thereby undermining the bonding performance at the “bolt-resin” interface and consequently reducing the overall anchorage capacity; (ii) Dispersion curve analyses suggest that employing a detection frequency below 100 kHz in the L (0,1) mode effectively mitigates multimodal interference and minimizes dispersion effects. Upon encountering an interface or corrosion defect, the guided wave experiences significant reflection and transmission due to abrupt changes in wave impedance, along with reductions in wave velocity and energy attenuation; and (iii) Through finite element numerical simulations, the guided wave propagation characteristics across various corrosion scales are analyzed. The study reveals minor discrepancies in wave propagation at various corrosion locations, with the error associated with estimating the corrosion location based on echo characteristics being less than 6.66 %. As the defect depth increases, the amplitude of the defect echo markedly rises, whereas the amplitude of the bottom echo diminishes correspondingly. Notably, when the length of the corrosion defect exceeds 200 mm, the echo signals from the defect’s front and rear ends diverge, allowing for the calculation of the corrosion defect’s initiation point; (iv) A non-destructive testing platform based on the inverse piezoelectric effect is developed, and non-destructive testing experiments are carried out on threaded steel resin bolts with corrosion defects; (v) To address challenges posed by chaotic and noise-interfered original ultrasonic guided wave echo signals collected in the laboratory, this paper introduces an optimized SVMD-OMP signal processing technique that employs s
{"title":"Guided wave characteristics and nondestructive testing of corrosion defects in threaded steel resin bolts","authors":"Kesong Fan , Mengyin Feng , Shaowei Liu , Dengpan Zhang , Hui Liu , Yi Kang , Deyin He , Guohao Liang","doi":"10.1016/j.engfailanal.2026.110625","DOIUrl":"10.1016/j.engfailanal.2026.110625","url":null,"abstract":"<div><div>Threaded steel resin bolts are extensively utilized for supporting mine roadways. However, various factors such as underground humidity, high stress, and significant disturbances increase the susceptibility of these support components to corrosion, particularly in environments characterized by roof water seepage. This corrosion poses serious risks to the safety and efficiency of mining production. Focusing on the Dangjiahe Coal Mine in Shaanxi Province, China, this study elucidates the corrosion mechanisms affecting bolts in the presence of prolonged stress and water exposure. It further explains the propagation characteristics of ultrasonic guided waves within corroded anchorage structures, investigates guided wave propagation properties across varying corrosion scales, and explores guided wave non-destructive testing (NDT) methodologies for anchorage bodies exhibiting corrosion defects. The findings indicate that: (i) Mine water quality assessments, coupled with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses of corroded samples, reveal that Cl<sup>−</sup> plays a crucial catalytic role in the corrosion process. Following corrosion, the bolt’s surface becomes rough and loose, resulting in a decrease in Fe content and an increase in oxide formation, thereby undermining the bonding performance at the “bolt-resin” interface and consequently reducing the overall anchorage capacity; (ii) Dispersion curve analyses suggest that employing a detection frequency below 100 kHz in the L (0,1) mode effectively mitigates multimodal interference and minimizes dispersion effects. Upon encountering an interface or corrosion defect, the guided wave experiences significant reflection and transmission due to abrupt changes in wave impedance, along with reductions in wave velocity and energy attenuation; and (iii) Through finite element numerical simulations, the guided wave propagation characteristics across various corrosion scales are analyzed. The study reveals minor discrepancies in wave propagation at various corrosion locations, with the error associated with estimating the corrosion location based on echo characteristics being less than 6.66 %. As the defect depth increases, the amplitude of the defect echo markedly rises, whereas the amplitude of the bottom echo diminishes correspondingly. Notably, when the length of the corrosion defect exceeds 200 mm, the echo signals from the defect’s front and rear ends diverge, allowing for the calculation of the corrosion defect’s initiation point; (iv) A non-destructive testing platform based on the inverse piezoelectric effect is developed, and non-destructive testing experiments are carried out on threaded steel resin bolts with corrosion defects; (v) To address challenges posed by chaotic and noise-interfered original ultrasonic guided wave echo signals collected in the laboratory, this paper introduces an optimized SVMD-OMP signal processing technique that employs s","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"188 ","pages":"Article 110625"},"PeriodicalIF":5.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-29DOI: 10.1016/j.engfailanal.2026.110628
Santhosh K G , Imran M. Jamadar , Prasanta Kumar Samal
This study investigates the rotating bending fatigue behaviour of specimens fabricated using the Fused Deposition Modeling (FDM) technique, including pure Polylactic acid (PLA) and its composites reinforced with short glass fibres (PLA-GF) and short carbon fibres (PLA-CF). Test specimens were fabricated with three infill densities (50%, 75%, and 100%) and raster orientations (0°, 45°, and 90°). Rotating bending fatigue tests were performed under completely reversed cyclic loading conditions, both in the as-printed state and after the application of an epoxy surface coating. The fatigue performance of the specimens was evaluated in three-fold method: in the first method, the number of experiments to be carried out was optimized using Taguchi’s design of experiments. In the second method, analysis of variance (ANOVA) was used to study the impact of input parameters and in the final method, the failure mechanisms were analysed using scanning electron microscopy (SEM).The results showed that the fatigue life of the specimens is significantly affected by the epoxy coating. The epoxy coating has increased the fatigue life of PLA by 26% followed by 19% and 18% for PLA-CF and PLA-GF respectively. The increase in fatigue life is primarily attributed to reduction of surface defects, roughness and delayed crack initiation under repeated Out of the process variable parameters investigated; the infill density percentage has the major influence, followed by raster angle. The maximum fatigue life was recorded for the specimens with infill density percentage of 100% and raster angle of 00.The SEM analysis of the fracture surfaces of the tested specimens revealed that the epoxy coating effectively reduced interlayer delamination, fibre pull-out, and void formation, resulting in mixed-mode failure. Overall, the fatigue performance of the additively manufactured PLA polymer specimens improved considerably with the incorporation of short fibres and the application of an epoxy surface coating. This research provides valuable insights for enhancing the durability and reliability of 3D-printed components subjected to light, repeated loading applications.
{"title":"Rotating bending fatigue analysis of 3D-printed PLA polymer composites: Effect of short fiber reinforcement and epoxy coating","authors":"Santhosh K G , Imran M. Jamadar , Prasanta Kumar Samal","doi":"10.1016/j.engfailanal.2026.110628","DOIUrl":"10.1016/j.engfailanal.2026.110628","url":null,"abstract":"<div><div>This study investigates the rotating bending fatigue behaviour of specimens fabricated using the Fused Deposition Modeling (FDM) technique, including pure Polylactic acid (PLA) and its composites reinforced with short glass fibres (PLA-GF) and short carbon fibres (PLA-CF). Test specimens were fabricated with three infill densities (50%, 75%, and 100%) and raster orientations (0°, 45°, and 90°). Rotating bending fatigue tests were performed under completely reversed cyclic loading conditions, both in the as-printed state and after the application of an epoxy surface coating. The fatigue performance of the specimens was evaluated in three-fold method: in the first method, the number of experiments to be carried out was optimized using Taguchi’s design of experiments. In the second method, analysis of variance (ANOVA) was used to study the impact of input parameters and in the final method, the failure mechanisms were analysed using scanning electron microscopy (SEM).The results showed that the fatigue life of the specimens is significantly affected by the epoxy coating. The epoxy coating has increased the fatigue life of PLA by 26% followed by 19% and 18% for PLA-CF and PLA-GF respectively. The increase in fatigue life is primarily attributed to reduction of surface defects, roughness and delayed crack initiation under repeated Out of the process variable parameters investigated; the infill density percentage has the major influence, followed by raster angle. The maximum fatigue life was recorded for the specimens with infill density percentage of 100% and raster angle of 0<sup>0</sup>.The SEM analysis of the fracture surfaces of the tested specimens revealed that the epoxy coating effectively reduced interlayer delamination, fibre pull-out, and void formation, resulting in mixed-mode failure. Overall, the fatigue performance of the additively manufactured PLA polymer specimens improved considerably with the incorporation of short fibres and the application of an epoxy surface coating. This research provides valuable insights for enhancing the durability and reliability of 3D-printed components subjected to light, repeated loading applications.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"188 ","pages":"Article 110628"},"PeriodicalIF":5.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-05-01Epub Date: 2026-01-24DOI: 10.1016/j.engfailanal.2026.110614
Jingqiang Yuan , Xiaolei Yang , Donghui Xiao , Benhua Liu , Yubiao Liu , Weizhong Chen
<div><div>Insufficient vault lining thickness and back cavities in the cast-in-place secondary linings of drill-and-blast tunnels cause cracking, spalling, threatening safety. To resolve these issues, the waffle-slab ultra-high performance concrete (UHPC) prefabricated lining was developed; four-point bending tests were conducted to investigate segments bearing characteristics with varied web and rib reinforcement ratios, focusing on bearing capacity, deformation, failure mechanisms and crack propagation. The results indicate that: (1) UHPC prefabricated lining reinforced segments undergo four failure stages through the slope change of the load–deflection curve: the elastic stage, the strain-hardening stage, the ultimate bearing stage, and the strain-softening stage; (2) The load-bearing performance of the web and rib in the UHPC waffle-slab prefabricated lining structure varies significantly. An increase in the reinforcement ratio of the rib directly enhances the load-bearing capacity of the segments. The cracking load for samples S6-S9 increases by more than 260%, while the peak load rises by over 80%. Additionally, an increase in the web reinforcement ratio leads to the formation of more micro-cracks in the concrete, which helps dissipate load and improves the energy absorption capacity of the segments, thereby influencing the peak load. However, this increase has a minimal effect on the cracking load. For samples S2-S7, the cracking load increases by only 0.37%, whereas the peak load rises between 5.48% and 24.20%.; (3) Based on the load–deflection curve, the deformation behavior of concrete and steel bars under load, and the failure characteristics of concrete segments, the following reinforcement scheme for UHPC prefabricated linings is recommended: For rib plates, the total reinforcement ratio must exceed 1.75% and the tensile zone reinforcement ratio must be over 1.3%, with double-layer reinforcement allowed. For web plates, the reinforcement ratio should exceed 1%; (4) Analysis of crack propagation characteristics in the specimens, conducted using Digital Image Correlation (DIC) equipment, reveals that the crack propagation in unreinforced specimens occurs in two distinct stages: microcrack initiation and crack development. At loads ranging from 25.67 kN to 45.92 kN, microcracks initiate and develop, eventually evolving into macroscopic through cracks, which leads to a loss of bearing capacity in the specimens. In contrast, the crack propagation in reinforced specimens is categorized into three stages: microcrack initiation, microcrack development, and macroscopic crack development. During this process, the localization of the strain field gradually intensifies, deformation damage becomes increasingly concentrated, and crack propagation stabilizes as it approaches the post-peak stage. These findings are provided as reference for the design and bearing performance analysis of UHPC prefabricated linings for drill-and-blast tunnels.</div></
{"title":"Experimental study on the bearing characteristics of UHPC prefabricated lining structures for drill-and-blast tunnel","authors":"Jingqiang Yuan , Xiaolei Yang , Donghui Xiao , Benhua Liu , Yubiao Liu , Weizhong Chen","doi":"10.1016/j.engfailanal.2026.110614","DOIUrl":"10.1016/j.engfailanal.2026.110614","url":null,"abstract":"<div><div>Insufficient vault lining thickness and back cavities in the cast-in-place secondary linings of drill-and-blast tunnels cause cracking, spalling, threatening safety. To resolve these issues, the waffle-slab ultra-high performance concrete (UHPC) prefabricated lining was developed; four-point bending tests were conducted to investigate segments bearing characteristics with varied web and rib reinforcement ratios, focusing on bearing capacity, deformation, failure mechanisms and crack propagation. The results indicate that: (1) UHPC prefabricated lining reinforced segments undergo four failure stages through the slope change of the load–deflection curve: the elastic stage, the strain-hardening stage, the ultimate bearing stage, and the strain-softening stage; (2) The load-bearing performance of the web and rib in the UHPC waffle-slab prefabricated lining structure varies significantly. An increase in the reinforcement ratio of the rib directly enhances the load-bearing capacity of the segments. The cracking load for samples S6-S9 increases by more than 260%, while the peak load rises by over 80%. Additionally, an increase in the web reinforcement ratio leads to the formation of more micro-cracks in the concrete, which helps dissipate load and improves the energy absorption capacity of the segments, thereby influencing the peak load. However, this increase has a minimal effect on the cracking load. For samples S2-S7, the cracking load increases by only 0.37%, whereas the peak load rises between 5.48% and 24.20%.; (3) Based on the load–deflection curve, the deformation behavior of concrete and steel bars under load, and the failure characteristics of concrete segments, the following reinforcement scheme for UHPC prefabricated linings is recommended: For rib plates, the total reinforcement ratio must exceed 1.75% and the tensile zone reinforcement ratio must be over 1.3%, with double-layer reinforcement allowed. For web plates, the reinforcement ratio should exceed 1%; (4) Analysis of crack propagation characteristics in the specimens, conducted using Digital Image Correlation (DIC) equipment, reveals that the crack propagation in unreinforced specimens occurs in two distinct stages: microcrack initiation and crack development. At loads ranging from 25.67 kN to 45.92 kN, microcracks initiate and develop, eventually evolving into macroscopic through cracks, which leads to a loss of bearing capacity in the specimens. In contrast, the crack propagation in reinforced specimens is categorized into three stages: microcrack initiation, microcrack development, and macroscopic crack development. During this process, the localization of the strain field gradually intensifies, deformation damage becomes increasingly concentrated, and crack propagation stabilizes as it approaches the post-peak stage. These findings are provided as reference for the design and bearing performance analysis of UHPC prefabricated linings for drill-and-blast tunnels.</div></","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"188 ","pages":"Article 110614"},"PeriodicalIF":5.7,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the cause of failure of a bearing used in a gas turbine of a thermal power plant was investigated. Bearings are critical mechanical components whose proper function directly affects the safety and stability of mechanical systems. The failure of this bearing led to reduced system performance and sudden unit shutdown. The objective was to identify the root cause of failure and assess the manufacturing quality of the bearing. To this end, the damaged sample was compared with a standard bearing, and multiple microstructural evaluations including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and optical microscopy were performed on both samples. The results revealed that the damaged bearing exhibited a non-uniform microstructure, concentration gradients, and undesirable phases due to improper manufacturing processes. In the standard bearing, a distinct layer of FeSn2 was identified, which was not present in the damaged bearing. This intermetallic layer plays a crucial role in promoting adhesion between the babbitt layer and the steel substrate. These factors contributed to reduced mechanical strength and premature failure of the bearing. Based on the findings, stricter control over the manufacturing process and raw material inspection are recommended to ensure proper performance under power plant operating conditions.
{"title":"Characterization and evaluation of a failed journal bearing: A microstructural study and comparative approach","authors":"Hananeh Mostafavi , Mahmoud Sarkari Khorrami , Saeed Khani Moghanaki","doi":"10.1016/j.engfailanal.2026.110621","DOIUrl":"10.1016/j.engfailanal.2026.110621","url":null,"abstract":"<div><div>In this study, the cause of failure of a bearing used in a gas turbine of a thermal power plant was investigated. Bearings are critical mechanical components whose proper function directly affects the safety and stability of mechanical systems. The failure of this bearing led to reduced system performance and sudden unit shutdown. The objective was to identify the root cause of failure and assess the manufacturing quality of the bearing. To this end, the damaged sample was compared with a standard bearing, and multiple microstructural evaluations including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and optical microscopy were performed on both samples. The results revealed that the damaged bearing exhibited a non-uniform microstructure, concentration gradients, and undesirable phases due to improper manufacturing processes. In the standard bearing, a distinct layer of FeSn<sub>2</sub> was identified, which was not present in the damaged bearing. This intermetallic layer plays a crucial role in promoting adhesion between the babbitt layer and the steel substrate. These factors contributed to reduced mechanical strength and premature failure of the bearing. Based on the findings, stricter control over the manufacturing process and raw material inspection are recommended to ensure proper performance under power plant operating conditions.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110621"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-18DOI: 10.1016/j.engfailanal.2026.110586
Feili Yang , Wei Zhang , Dongsheng Zhang , Yuezhang Zhu , Jingcheng Wang , Beihai Huang , Yanpeng Wang , Mingzhao Dong , Jinfeng Mao
To address severe deformation and control difficulties of underlying roadway groups under fully mechanized top-coal caving (FMTCC)–induced dynamic pressure, this study investigates the 885 FMTCC face and the underlying roadway group of the 88 panel at Zhuxianzhuang Coal Mine through field measurements, numerical simulations, and engineering practice. In situ borehole stress monitoring combined with quantitative borehole peering analysis was used to clarify the stress distribution and fracture development characteristics of the floor under mining. Using a coupled FLAC3D–PFC3D approach, a numerical model was developed to analyze the differentiated failure characteristics of the floor under FMTCC-induced disturbance. Moreover, the failure mechanisms of underlying roadway groups were elucidated. The results revealed that the floor surrounding rock first underwent stress concentration and then stress unloading as the working face advanced. The stress response of different strata varies markedly with burial depth and lithology. All the underlying roadways underwent four evolutionary stages—undisturbed, mining induced failure, disturbance stability transition, and final stabilization—and the intensity of disturbance-induced failure decreases markedly with increasing vertical distance. Building on these findings, a differentiated surrounding rock control technology centered on the “Unloading–Grouting–Anchoring” concept was proposed for underlying roadways at different vertical distances. Field applications show that roadway deformation is effectively controlled across all distances, with an average cross-sectional area retention exceeding 92.6% in major production roadways, confirming the effectiveness of the proposed technology under FMTCC-induced dynamic pressure.
{"title":"Failure mechanism and differential stability control of surrounding rock in an underlying roadway group under fully mechanized top-coal caving: A case study","authors":"Feili Yang , Wei Zhang , Dongsheng Zhang , Yuezhang Zhu , Jingcheng Wang , Beihai Huang , Yanpeng Wang , Mingzhao Dong , Jinfeng Mao","doi":"10.1016/j.engfailanal.2026.110586","DOIUrl":"10.1016/j.engfailanal.2026.110586","url":null,"abstract":"<div><div>To address severe deformation and control difficulties of underlying roadway groups under fully mechanized top-coal caving (FMTCC)–induced dynamic pressure, this study investigates the 885 FMTCC face and the underlying roadway group of the 88 panel at Zhuxianzhuang Coal Mine through field measurements, numerical simulations, and engineering practice. In situ borehole stress monitoring combined with quantitative borehole peering analysis was used to clarify the stress distribution and fracture development characteristics of the floor under mining. Using a coupled FLAC3D–PFC3D approach, a numerical model was developed to analyze the differentiated failure characteristics of the floor under FMTCC-induced disturbance. Moreover, the failure mechanisms of underlying roadway groups were elucidated. The results revealed that the floor surrounding rock first underwent stress concentration and then stress unloading as the working face advanced. The stress response of different strata varies markedly with burial depth and lithology. All the underlying roadways underwent four evolutionary stages—undisturbed, mining induced failure, disturbance stability transition, and final stabilization—and the intensity of disturbance-induced failure decreases markedly with increasing vertical distance. Building on these findings, a differentiated surrounding rock control technology centered on the “Unloading–Grouting–Anchoring” concept was proposed for underlying roadways at different vertical distances. Field applications show that roadway deformation is effectively controlled across all distances, with an average cross-sectional area retention exceeding 92.6% in major production roadways, confirming the effectiveness of the proposed technology under FMTCC-induced dynamic pressure.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110586"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-22DOI: 10.1016/j.engfailanal.2026.110613
Wenliang Li , Xiangdong Zhang , Lijuan Su , Jiashun Liu , Yao Dong , Guanjun Cai , Qiong Wu
The existence of internal cracks in rock significantly changes its pore structure, which leads to the failure of rock mass and engineering. In this study, sandstone-like materials were prepared using a similarity model test, and a novel crystal dissolution method was proposed to prefabricate internal fractures. Through uniaxial compression, triaxial compression, and creep tests, the mechanical properties and creep behavior of prefabricated internal fractured sandstone-like materials (PIFSLM) under different porosity conditions were systematically investigated. A creep model for fissure damage was established, identified, and validated. Additionally, nuclear magnetic resonance (NMR) tests were conducted to explore the effects of stress aging on the T2 spectrum curve, porosity, pore size, and NMR imaging of PIFSLM. The results indicate that with the increase of prefabricated internal fissures, the uniaxial compressive strength (UCS), triaxial compressive strength (TCS), and elastic modulus of PIFSLM significantly decrease, while the creep deformation and creep rate markedly increase. The nonlinear viscoelastic-plastic creep model considering fissure damage accurately describes the creep damage characteristics of PIFSLM at various stages. NMR tests further reveal the instability of the pore structure caused by long-term creep loading, indicating that the increase in prefabricated fissures leads to higher porosity, larger pore sizes, and enhanced pore connectivity. A multimodal approach combining NMR/MRI with creep tests was employed to achieve non-destructive, quantitative, and visual characterization of internal material damage and pore structure evolution during the creep process. This study elucidates the damage characteristics and pore structure evolution mechanisms of fractured rock masses under long-term loading conditions, providing crucial theoretical foundations and parameter support for the long-term stability analysis and time-dependent deformation prediction in underground engineering, tunneling projects, and other similar applications.
{"title":"Study on creep damage characteristics and pore structure evolution of prefabricated internal fractured sandstone-like materials","authors":"Wenliang Li , Xiangdong Zhang , Lijuan Su , Jiashun Liu , Yao Dong , Guanjun Cai , Qiong Wu","doi":"10.1016/j.engfailanal.2026.110613","DOIUrl":"10.1016/j.engfailanal.2026.110613","url":null,"abstract":"<div><div>The existence of internal cracks in rock significantly changes its pore structure, which leads to the failure of rock mass and engineering. In this study, sandstone-like materials were prepared using a similarity model test, and a novel crystal dissolution method was proposed to prefabricate internal fractures. Through uniaxial compression, triaxial compression, and creep tests, the mechanical properties and creep behavior of prefabricated internal fractured sandstone-like materials (PIFSLM) under different porosity conditions were systematically investigated. A creep model for fissure damage was established, identified, and validated. Additionally, nuclear magnetic resonance (NMR) tests were conducted to explore the effects of stress aging on the <em>T</em><sub>2</sub> spectrum curve, porosity, pore size, and NMR imaging of PIFSLM. The results indicate that with the increase of prefabricated internal fissures, the uniaxial compressive strength (UCS), triaxial compressive strength (TCS), and elastic modulus of PIFSLM significantly decrease, while the creep deformation and creep rate markedly increase. The nonlinear viscoelastic-plastic creep model considering fissure damage accurately describes the creep damage characteristics of PIFSLM at various stages. NMR tests further reveal the instability of the pore structure caused by long-term creep loading, indicating that the increase in prefabricated fissures leads to higher porosity, larger pore sizes, and enhanced pore connectivity. A multimodal approach combining NMR/MRI with creep tests was employed to achieve non-destructive, quantitative, and visual characterization of internal material damage and pore structure evolution during the creep process. This study elucidates the damage characteristics and pore structure evolution mechanisms of fractured rock masses under long-term loading conditions, providing crucial theoretical foundations and parameter support for the long-term stability analysis and time-dependent deformation prediction in underground engineering, tunneling projects, and other similar applications.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110613"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-29DOI: 10.1016/j.engfailanal.2026.110620
Fanyu Meng, Yuan Yao, Qun Ma, Haohao Wei
Aiming at the problem of low-frequency carbody swaying caused by the hunting stability failure of a certain high-speed locomotive when using new reprofiling wheel in some lines at the initial stage. According to the line test, the reason is that the wheel profile has poor adaptability to the rail profile under complex conditions, resulting in a lower equivalent conicity, which leads to the carbody hunting. To solve this, the wheel profile was optimized. The nominal equivalent conicity dispersion corresponding to the matching of wheel profile with CN60 and CN60N rails under different rail cants and wheel diameter differences was taken as the optimization objective. The wheel profile is characterized by the combination of arc and straight line. The NSGA-II genetic algorithm was used to optimize the geometric parameters of the key arc to enhance the adaptability of the wheel profile to different wheel-rail conditions, and the radial basis function neural network was used to train the surrogate model to improve the optimization efficiency. Finally, the wheel-rail contact characteristics and locomotive dynamic of the wheel profile before and after optimization were compared. The results show that the optimized wheel profile significantly improves the concentration of the equivalent conicity and enhances the adaptability of the wheel profile to different line conditions. At the same time, the hunting stability, lateral ride comfort and curve passing performance index of the optimized wheel profile are improved compared with the original wheel profile. The problem of locomotives’ hunting stability failure on specific lines was solved.
{"title":"Wheel profile optimization for high-speed locomotives to suppress carbody hunting stability failure under complex wheel-rail conditions","authors":"Fanyu Meng, Yuan Yao, Qun Ma, Haohao Wei","doi":"10.1016/j.engfailanal.2026.110620","DOIUrl":"10.1016/j.engfailanal.2026.110620","url":null,"abstract":"<div><div>Aiming at the problem of low-frequency carbody swaying caused by the hunting stability failure of a certain high-speed locomotive when using new reprofiling wheel in some lines at the initial stage. According to the line test, the reason is that the wheel profile has poor adaptability to the rail profile under complex conditions, resulting in a lower equivalent conicity, which leads to the carbody hunting. To solve this, the wheel profile was optimized. The nominal equivalent conicity dispersion corresponding to the matching of wheel profile with CN60 and CN60N rails under different rail cants and wheel diameter differences was taken as the optimization objective. The wheel profile is characterized by the combination of arc and straight line. The NSGA-II genetic algorithm was used to optimize the geometric parameters of the key arc to enhance the adaptability of the wheel profile to different wheel-rail conditions, and the radial basis function neural network was used to train the surrogate model to improve the optimization efficiency. Finally, the wheel-rail contact characteristics and locomotive dynamic of the wheel profile before and after optimization were compared. The results show that the optimized wheel profile significantly improves the concentration of the equivalent conicity and enhances the adaptability of the wheel profile to different line conditions. At the same time, the hunting stability, lateral ride comfort and curve passing performance index of the optimized wheel profile are improved compared with the original wheel profile. The problem of locomotives’ hunting stability failure on specific lines was solved.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110620"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-23DOI: 10.1016/j.engfailanal.2026.110585
Dong-Bok Lee, Jeong-Won Yoon
Recently, numerous studies have been conducted to apply transient liquid-phase (TLP) bonding technology to power conversion modules, which are critical components of eco-friendly mobility systems. Although intermetallic compound (IMC) joints formed via TLP bonding offer excellent thermal properties, the prolonged duration required for IMC formation and reactions remains a significant limitation, and the inherently high brittleness of the resulting IMCs is also a major drawback. To address this issue, in this study, a Sn/Ni/Sn laminated metal preform was fabricated by inserting a Ni foil between the Sn foils to reduce the joint formation time. Using this preform, the chip and substrate were bonded. Cross-sectional analysis showed that the Sn layers were completely converted to Ni3Sn4 IMC within 25 min, and the initial shear strength was 55.1 MPa. The results demonstrated that using a Sn/Ni/Sn laminated metal preform enabled rapid IMC formation when a chip was bonded to a substrate. This finding confirmed the feasibility of a time-reduced TLP bonding process compared to conventional methods. In addition, long-term high-temperature reliability testing was conducted at 230 °C for up to 1260 h to assess reliability and observe microstructural changes. From 756 h onward, as Ni3Sn began to grow, the phase transformation rate slowed, and the shear strength stabilized at 38 MPa. The high-temperature long-term reliability test further confirmed that the joint maintained this shear strength even after 1260 h, demonstrating its excellent long-term thermal stability.
{"title":"High-Temperature Long-Term reliability of transient liquid phase bonding using Sn/Ni/Sn laminated metal preform","authors":"Dong-Bok Lee, Jeong-Won Yoon","doi":"10.1016/j.engfailanal.2026.110585","DOIUrl":"10.1016/j.engfailanal.2026.110585","url":null,"abstract":"<div><div>Recently, numerous studies have been conducted to apply transient liquid-phase (TLP) bonding technology to power conversion modules, which are critical components of eco-friendly mobility systems. Although intermetallic compound (IMC) joints formed via TLP bonding offer excellent thermal properties, the prolonged duration required for IMC formation and reactions remains a significant limitation, and the inherently high brittleness of the resulting IMCs is also a major drawback. To address this issue, in this study, a Sn/Ni/Sn laminated metal preform was fabricated by inserting a Ni foil between the Sn foils to reduce the joint formation time. Using this preform, the chip and substrate were bonded. Cross-sectional analysis showed that the Sn layers were completely converted to Ni<sub>3</sub>Sn<sub>4</sub> IMC within 25 min, and the initial shear strength was 55.1 MPa. The results demonstrated that using a Sn/Ni/Sn laminated metal preform enabled rapid IMC formation when a chip was bonded to a substrate. This finding confirmed the feasibility of a time-reduced TLP bonding process compared to conventional methods. In addition, long-term high-temperature reliability testing was conducted at 230 °C for up to 1260 h to assess reliability and observe microstructural changes. From 756 h onward, as Ni<sub>3</sub>Sn began to grow, the phase transformation rate slowed, and the shear strength stabilized at 38 MPa. The high-temperature long-term reliability test further confirmed that the joint maintained this shear strength even after 1260 h, demonstrating its excellent long-term thermal stability.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110585"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-25DOI: 10.1016/j.engfailanal.2026.110617
Levy Bertoletti, Marcello Gelfi, Luca Girelli, Annalisa Pola
CuZn40Pb2 brass is a Cu-Zn-Pb alloy widely used in hydraulic applications due to its high formability, good machinability and suitable resistance to aqueous corrosion. This study investigated the failure of a CuZn40Pb2 brass hydraulic component due to water leakage when it was put in service. This failure analysis was performed using X-Ray Fluorescence spectroscopy to verify the chemical composition of the component, optical microscopy to analyze the microstructure and scanning electron microscopy to identify the fracture mechanism. The results, combined with the detailed examination of production process, showed that post-manufacturing steps must be carefully conducted to avoid damaging the components. Therefore, the root cause of the examined failure was detected, leading to recommendation for process improvements to prevent future occurrences.
{"title":"Failure analysis of a hot stamped CuZn40Pb2 brass hydraulic component","authors":"Levy Bertoletti, Marcello Gelfi, Luca Girelli, Annalisa Pola","doi":"10.1016/j.engfailanal.2026.110617","DOIUrl":"10.1016/j.engfailanal.2026.110617","url":null,"abstract":"<div><div>CuZn40Pb2 brass is a Cu-Zn-Pb alloy widely used in hydraulic applications due to its high formability, good machinability and suitable resistance to aqueous corrosion. This study investigated the failure of a CuZn40Pb2 brass hydraulic component due to water leakage when it was put in service. This failure analysis was performed using X-Ray Fluorescence spectroscopy to verify the chemical composition of the component, optical microscopy to analyze the microstructure and scanning electron microscopy to identify the fracture mechanism. The results, combined with the detailed examination of production process, showed that post-manufacturing steps must be carefully conducted to avoid damaging the components. Therefore, the root cause of the examined failure was detected, leading to recommendation for process improvements to prevent future occurrences.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110617"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-04-01Epub Date: 2026-01-20DOI: 10.1016/j.engfailanal.2026.110597
Zenghai Wang , Zhihao Yao , Yisheng Meng , Lang Ju , Shengming Chen , Bingyin Ji , Jiaoqi Shi
Low-pressure thread leakage can still occur in small-diameter API EU tubing connections (Φ48.26 mm × 3.68 mm, N80Q) even when the connection geometry satisfies API 5CT tolerances and the make-up torque reaches the specified target. This study investigates why a nominally compliant connection can lose sealing integrity by experimentally examining the coupled effects of thread-compound friction and make-up position (J-value) on sealing performance. Full-scale hydrostatic and coupled axial tension–pressure tests were conducted to reproduce the leakage behavior. The results show that a friction-induced assembly displacement of ∼ 1 mm (≈0.3 turns) can trigger sealing failure by reducing thread contact pressure, with a critical leakage threshold identified at J ≈ 12.3 mm. Torque-based control alone is therefore insufficient to prevent leakage under adverse tolerance–friction conditions, and coupled loading further compresses the positional safety margin. From a scientific perspective, this work establishes a quantitative positional failure criterion by linking friction-controlled make-up position to sealing-interface degradation. From an engineering perspective, the results support a position-based quality-control strategy using J-value as the primary assembly metric with torque as an auxiliary indicator for improving sealing reliability in small-diameter EU connections.
即使在接头几何形状满足API 5CT公差且补紧扭矩达到指定目标的情况下，小直径API EU管接头（Φ48.26 mm × 3.68 mm, N80Q）仍可能发生低压螺纹泄漏。本研究通过实验研究螺纹复合摩擦和上扣位置（j值）对密封性能的耦合影响，探讨了为什么一个名义上符合要求的连接会失去密封完整性。进行了全尺寸静水试验和轴向耦合拉压试验来重现泄漏行为。结果表明，摩擦引起的组件位移约1 mm（≈0.3转）会通过降低螺纹接触压力引发密封失效，并在J≈12.3 mm处确定临界泄漏阈值。因此，在不利的容差摩擦条件下，仅基于扭矩的控制不足以防止泄漏，耦合载荷进一步压缩了位置安全裕度。从科学的角度来看，本研究通过将摩擦控制的修复位置与密封界面退化联系起来，建立了定量的位置失效准则。从工程角度来看，研究结果支持基于位置的质量控制策略，使用j值作为主要装配度量，扭矩作为辅助指标，以提高小直径EU连接的密封可靠性。
{"title":"Failure mechanism of low-pressure leakage in small-diameter API EU tubing induced by friction-controlled make-up position","authors":"Zenghai Wang , Zhihao Yao , Yisheng Meng , Lang Ju , Shengming Chen , Bingyin Ji , Jiaoqi Shi","doi":"10.1016/j.engfailanal.2026.110597","DOIUrl":"10.1016/j.engfailanal.2026.110597","url":null,"abstract":"<div><div>Low-pressure thread leakage can still occur in small-diameter API EU tubing connections (Φ48.26 mm × 3.68 mm, N80Q) even when the connection geometry satisfies API 5CT tolerances and the make-up torque reaches the specified target. This study investigates why a nominally compliant connection can lose sealing integrity by experimentally examining the coupled effects of thread-compound friction and make-up position (J-value) on sealing performance. Full-scale hydrostatic and coupled axial tension–pressure tests were conducted to reproduce the leakage behavior. The results show that a friction-induced assembly displacement of ∼ 1 mm (≈0.3 turns) can trigger sealing failure by reducing thread contact pressure, with a critical leakage threshold identified at J ≈ 12.3 mm. Torque-based control alone is therefore insufficient to prevent leakage under adverse tolerance–friction conditions, and coupled loading further compresses the positional safety margin. From a scientific perspective, this work establishes a quantitative positional failure criterion by linking friction-controlled make-up position to sealing-interface degradation. From an engineering perspective, the results support a position-based quality-control strategy using J-value as the primary assembly metric with torque as an auxiliary indicator for improving sealing reliability in small-diameter EU connections.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110597"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：