Pub 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":"2026-01-24","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}
Pub 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":"2026-01-23","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 : 2026-01-23DOI: 10.1016/j.engfailanal.2026.110608
V.M. Sreedevi , A. Anisha , Robin Davis , Sujith Mangalathu , Prateek Negi
Accurate prediction of failure is essential for maintaining structural integrity and achieving design efficiency, as it helps prevent catastrophic failures. With the increasing adoption of cold-formed steel (CFS) members in construction, precise estimation of their failure load is necessary, especially as it undergoes various failure modes like local, distortional, global buckling or a combination of these. Existing design standards originally developed for conventional CFS members are not intended for the high strength cold formed steel (HSCFS) members. Present study proposes a hybrid data driven methodology to develop a Machine Learning based High-Fidelity Model (MLHFM) for failure load prediction. The proposed approach is found to be performing well for the failure prediction of high strength cold formed steel square hollow section (HSCFS-SHS) columns. In this hybrid method, twelve experimental data regarding HSCFS-SHS columns are collected, numerical models are generated for the same and machine learning models are developed using data generated from the numerical models. Twelve machine learning (ML) techniques with their tuned hyper-parameters are utilized in present study for developing MLHFM. CatBoost is identified as the best performing MLHFM with the R2, RMSE, MAE and MAPE values of 0.974, 0.033, 0.008 and 0.024 respectively. Additionally, a SHAP (SHapley Additive exPlanations) analysis is performed to interpret the model’s predictions. The adequacy of the developed MLHFM is established by comparing their predictions with experimental results and international design codes. Further, a reliability analysis conducted as per AISI S100 shows that MLHFM prediction is able to achieve a target reliability index of 2.5 (2.85 and 2.61 for resistance factors of 0.8 and 0.85 respectively). Finally, a graphical user interface is established for the failure prediction of HSCFS-SHS column.
{"title":"Innovative hybrid data-driven approach for failure prediction of cold-formed steel columns using high-fidelity models – performance comparison with international design codes","authors":"V.M. Sreedevi , A. Anisha , Robin Davis , Sujith Mangalathu , Prateek Negi","doi":"10.1016/j.engfailanal.2026.110608","DOIUrl":"10.1016/j.engfailanal.2026.110608","url":null,"abstract":"<div><div>Accurate prediction of failure is essential for maintaining structural integrity and achieving design efficiency, as it helps prevent catastrophic failures. With the increasing adoption of cold-formed steel (CFS) members in construction, precise estimation of their failure load is necessary, especially as it undergoes various failure modes like local, distortional, global buckling or a combination of these. Existing design standards originally developed for conventional CFS members are not intended for the high strength cold formed steel (HSCFS) members. Present study proposes a hybrid data driven methodology to develop a Machine Learning based High-Fidelity Model (MLHFM) for failure load prediction. The proposed approach is found to be performing well for the failure prediction of high strength cold formed steel square hollow section (HSCFS-SHS) columns. In this hybrid method, twelve experimental data regarding HSCFS-SHS columns are collected, numerical models are generated for the same and machine learning models are developed using data generated from the numerical models. Twelve machine learning (ML) techniques with their tuned hyper-parameters are utilized in present study for developing MLHFM. CatBoost is identified as the best performing MLHFM with the <em>R</em><sup>2</sup>, RMSE, MAE and MAPE values of 0.974, 0.033, 0.008 and 0.024 respectively. Additionally, a SHAP (SHapley Additive exPlanations) analysis is performed to interpret the model’s predictions. The adequacy of the developed MLHFM is established by comparing their predictions with experimental results and international design codes. Further, a reliability analysis conducted as per AISI S100 shows that MLHFM prediction is able to achieve a target reliability index of 2.5 (2.85 and 2.61 for resistance factors of 0.8 and 0.85 respectively). Finally, a graphical user interface is established for the failure prediction of HSCFS-SHS column.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110608"},"PeriodicalIF":5.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075744","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 : 2026-01-23DOI: 10.1016/j.engfailanal.2026.110606
Wei Lan , Chang Cong , Qingjun Gong , Bin Wang , Wuxi Bi , Daoqing Liu , Chengwei Xu , Zhe Wang
The accompanying optical cable, a critical conduit for communication and data transmission in oil and gas pipelines, plays a vital role in pipeline integrity management. However, extreme weather conditions, particularly lightning strikes, pose significant threats to the safe operation of both pipelines and their accompanying optical cables. In this work, the failure of accompanying optical cables caused by a lightning strike in Inner Mongolia, China, on April 13, 2024, is analyzed through laboratory tests on the lightning breakdown of accompanying optical cables and numerical simulations of pipeline lightning strikes, and specific protective strategies are proposed. According to the tested and simulated results, the direct cause of the event is identified as the location of the accompanying optical cable being within the soil ionization radius. The leading cause is high soil resistivity, and the impulse voltage of the lightning on the accompanying optical cable exceeding its breakdown voltage threshold. Based on the causes and characteristics of the actual lightning strike failure accident involving the accompanying optical cables, protective measures are proposed, prioritizing inner inspection of the pipelines, investigation of the trees near the pipelines, and the pipelines in high lightning strike areas. This work provides essential methods and preventive measures for ensuring pipeline integrity management and safe operation throughout the practical design and production management process of pipelines.
{"title":"Lightning-induced failure mechanisms of co-located pipeline optical cables: a soil ionization modeling approach","authors":"Wei Lan , Chang Cong , Qingjun Gong , Bin Wang , Wuxi Bi , Daoqing Liu , Chengwei Xu , Zhe Wang","doi":"10.1016/j.engfailanal.2026.110606","DOIUrl":"10.1016/j.engfailanal.2026.110606","url":null,"abstract":"<div><div>The accompanying optical cable, a critical conduit for communication and data transmission in oil and gas pipelines, plays a vital role in pipeline integrity management. However, extreme weather conditions, particularly lightning strikes, pose significant threats to the safe operation of both pipelines and their accompanying optical cables. In this work, the failure of accompanying optical cables caused by a lightning strike in Inner Mongolia, China, on April 13, 2024, is analyzed through laboratory tests on the lightning breakdown of accompanying optical cables and numerical simulations of pipeline lightning strikes, and specific protective strategies are proposed. According to the tested and simulated results, the direct cause of the event is identified as the location of the accompanying optical cable being within the soil ionization radius. The leading cause is high soil resistivity, and the impulse voltage of the lightning on the accompanying optical cable exceeding its breakdown voltage threshold. Based on the causes and characteristics of the actual lightning strike failure accident involving the accompanying optical cables, protective measures are proposed, prioritizing inner inspection of the pipelines, investigation of the trees near the pipelines, and the pipelines in high lightning strike areas. This work provides essential methods and preventive measures for ensuring pipeline integrity management and safe operation throughout the practical design and production management process of pipelines.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110606"},"PeriodicalIF":5.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075803","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 : 2026-01-23DOI: 10.1016/j.engfailanal.2026.110615
Anand A , Kumar S , Tiwari G , Venkitanarayanan Parameswaran
Rocks are often subjected to acidic environments due to both natural (e.g., acid rain) and anthropogenic factors (e.g., nuclear waste repositories), in addition to dynamic loading conditions. To investigate their response under such conditions, an extensive experimental program comprising 160 tests was conducted to study the dynamic tensile behavior of acid-treated rocks. Five representative rock types were selected based on their distinct origins, outcrop locations, mineralogical characteristics, and frequent use in construction projects: Makrana marble, Kota limestone, and three granite varieties, i.e., Colonial White, Rajasthani Black, and Jhansi Red. Circular disc specimens were prepared and exposed to sulphuric acid solutions of varying pH (1–5) for durations ranging from 30 to 120 days, simulating long-term in-situ conditions, an aspect relatively less explored in rock mechanics. The acid-treated specimens were then tested under dynamic loading using the Brazilian Disc (BD) method in a Split Hopkinson Pressure Bar (SHPB) setup. Fracture propagation was continuously monitored through high-speed camera-assisted Digital Image Correlation (DIC). The underlying micro-mechanisms governing the macroscopic response were further examined using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and petrographic thin-section analysis. Results revealed a progressive reduction in dynamic tensile strength with decreasing pH and increasing exposure duration, with limestone showing the greatest strength loss due to its higher susceptibility to chemical disintegration. Acid exposure also significantly influenced fragmentation behavior, with Fragment Size Distributions (FSDs) shifting toward well-graded types and the Average Fragment Size (AFS) reducing, attributed to grain and grain-boundary degradation. These findings highlight the coupled chemical–mechanical degradation processes in rocks subjected to acid environments under dynamic loading.
{"title":"Dynamic split tensile behaviour of different rocks pre-treated with sulphuric acid: Effect of long exposure durations and pH of acid","authors":"Anand A , Kumar S , Tiwari G , Venkitanarayanan Parameswaran","doi":"10.1016/j.engfailanal.2026.110615","DOIUrl":"10.1016/j.engfailanal.2026.110615","url":null,"abstract":"<div><div>Rocks are often subjected to acidic environments due to both natural (e.g., acid rain) and anthropogenic factors (e.g., nuclear waste repositories), in addition to dynamic loading conditions. To investigate their response under such conditions, an extensive experimental program comprising 160 tests was conducted to study the dynamic tensile behavior of acid-treated rocks. Five representative rock types were selected based on their distinct origins, outcrop locations, mineralogical characteristics, and frequent use in construction projects: Makrana marble, Kota limestone, and three granite varieties, i.e., Colonial White, Rajasthani Black, and Jhansi Red. Circular disc specimens were prepared and exposed to sulphuric acid solutions of varying pH (1–5) for durations ranging from 30 to 120 days, simulating long-term in-situ conditions, an aspect relatively less explored in rock mechanics. The acid-treated specimens were then tested under dynamic loading using the Brazilian Disc (BD) method in a Split Hopkinson Pressure Bar (SHPB) setup. Fracture propagation was continuously monitored through high-speed camera-assisted Digital Image Correlation (DIC). The underlying micro-mechanisms governing the macroscopic response were further examined using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and petrographic thin-section analysis. Results revealed a progressive reduction in dynamic tensile strength with decreasing pH and increasing exposure duration, with limestone showing the greatest strength loss due to its higher susceptibility to chemical disintegration. Acid exposure also significantly influenced fragmentation behavior, with Fragment Size Distributions (FSDs) shifting toward well-graded types and the Average Fragment Size (AFS) reducing, attributed to grain and grain-boundary degradation. These findings highlight the coupled chemical–mechanical degradation processes in rocks subjected to acid environments under dynamic loading.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110615"},"PeriodicalIF":5.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075810","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 : 2026-01-22DOI: 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":"2026-01-22","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 : 2026-01-20DOI: 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":"2026-01-20","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}
Pub Date : 2026-01-19DOI: 10.1016/j.engfailanal.2026.110595
Masoud Behzad , Mehdi Behzad , Somaye Mohammadi , Mohammad Erfan Yadegari , Mohammad Haghighi
Electro-pumps are critical assets in water distribution networks, yet their performance is compromised by scaling phenomena. Given the interdependence of pump maintenance and associated components such as the motor, coupling, and structure, an integrated framework encompassing all equipment components is needed. This paper presents a maintenance framework for electro-pumping systems that supports maintenance planning by converting vibration and thermographic condition monitoring results into prioritized maintenance actions. Faults are identified and ranked based on their severity and frequency of occurrence, providing practical input for maintenance scheduling and resource allocation. For vibration measurements, sensors were mounted on the drive and non-drive ends of both the motors and pumps. These measurements cover low (10–1,000 Hz) and high (1,000–8,000 Hz) frequency ranges to ensure adequate fault detection resolution. Thermographic images of the pumps were captured in the final round following vibration measurements. The thermographic findings were in strong agreement with the vibration analysis, confirming coupling-related anomalies. The maintenance actions with the highest priority scores were inspecting bearing lubrication and replacement (1.35), resolving coupling issues (1.13), and performing alignment (0.91). In the ranking of maintenance priorities derived from the prioritized maintenance actions, at least two pumps were classified at the highest priority level. The proposed framework not only prioritizes maintenance actions but also employs the derived maintenance priority index to identify critical pumps distributed across different water infrastructure systems on a regional scale. This approach supports failure prevention by enabling timely maintenance scheduling.
{"title":"A framework to prevent failure by mapping faults to maintenance actions in electro-pumps of water distribution networks","authors":"Masoud Behzad , Mehdi Behzad , Somaye Mohammadi , Mohammad Erfan Yadegari , Mohammad Haghighi","doi":"10.1016/j.engfailanal.2026.110595","DOIUrl":"10.1016/j.engfailanal.2026.110595","url":null,"abstract":"<div><div>Electro-pumps are critical assets in water distribution networks, yet their performance is compromised by scaling phenomena. Given the interdependence of pump maintenance and associated components such as the motor, coupling, and structure, an integrated framework encompassing all equipment components is needed. This paper presents a maintenance framework for electro-pumping systems that supports maintenance planning by converting vibration and thermographic condition monitoring results into prioritized maintenance actions. Faults are identified and ranked based on their severity and frequency of occurrence, providing practical input for maintenance scheduling and resource allocation. For vibration measurements, sensors were mounted on the drive and non-drive ends of both the motors and pumps. These measurements cover low (10–1,000 Hz) and high (1,000–8,000 Hz) frequency ranges to ensure adequate fault detection resolution. Thermographic images of the pumps were captured in the final round following vibration measurements. The thermographic findings were in strong agreement with the vibration analysis, confirming coupling-related anomalies. The maintenance actions with the highest priority scores were inspecting bearing lubrication and replacement (1.35), resolving coupling issues (1.13), and performing alignment (0.91). In the ranking of maintenance priorities derived from the prioritized maintenance actions, at least two pumps were classified at the highest priority level. The proposed framework not only prioritizes maintenance actions but also employs the derived maintenance priority index to identify critical pumps distributed across different water infrastructure systems on a regional scale. This approach supports failure prevention by enabling timely maintenance scheduling.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110595"},"PeriodicalIF":5.7,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075805","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 : 2026-01-19DOI: 10.1016/j.engfailanal.2026.110593
MN James , D Bernard , C Louis , L. Matthews , DG Hattingh
This failure investigation deals with an apparently straightforward case of gear failure that was undertaken to see whether it contained any cracking that pre-existed the final fracture of a tooth. Some interesting features were observed in this case, as there were several cracks in the gear besides the primary one that led to fracture, showing evidence of at least two different crack initiation mechanisms. These mechanisms were intergranular quench cracking, occasionally involving large inclusions where chevron markings were seen on the ductile fracture surface that pointed back to the local fracture origin, and the observation of very localised intergranular oxidation in the carburised case of the gear that occurred during heat treatment. Both mechanisms of crack initiation then led to fatigue cracking. The final conclusion was that the gears failed prematurely from fatigue cracking initiated by intergranular oxidation combined with an impact load.
{"title":"Failure investigation of gears on a tyre manufacturing machine","authors":"MN James , D Bernard , C Louis , L. Matthews , DG Hattingh","doi":"10.1016/j.engfailanal.2026.110593","DOIUrl":"10.1016/j.engfailanal.2026.110593","url":null,"abstract":"<div><div>This failure investigation deals with an apparently straightforward case of gear failure that was undertaken to see whether it contained any cracking that pre-existed the final fracture of a tooth. Some interesting features were observed in this case, as there were several cracks in the gear besides the primary one that led to fracture, showing evidence of at least two different crack initiation mechanisms. These mechanisms were intergranular quench cracking, occasionally involving large inclusions where chevron markings were seen on the ductile fracture surface that pointed back to the local fracture origin, and the observation of very localised intergranular oxidation in the carburised case of the gear that occurred during heat treatment. Both mechanisms of crack initiation then led to fatigue cracking. The final conclusion was that the gears failed prematurely from fatigue cracking initiated by intergranular oxidation combined with an impact load.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110593"},"PeriodicalIF":5.7,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025777","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}
The appropriateness of any welding process depends upon the performance of essential components satisfactorily during the operation. In friction stir welding (FSW) of high-temperature softening materials, the life of the non-consumable rotating tool plays a crucial role. During the cladding operation performed by FSW, maintaining the tool geometry intact during subsequent repetitive passes is essential to obtain defect-free cladding. Rapid tool degradation can pose challenges in joining the clad material with the substrate.
In this work, failure analysis of nickel–cobalt-bonded tungsten carbide tool materials has been evaluated while carrying out friction stir cladding of copper on a steel substrate. Two different tool materials with total cobalt-nickel binder content = 10% (designated as tool A) and another tool material designated as tool B (having total binder content = 5%) have been used to carry out the cladding operation. Tool pin abrasion, adhesion, mushrooming, oxide formation, and the appearance of radial grooves in the shoulder region were prominently visible in tool A, containing a higher cobalt-nickel percentage. On the other hand, the tool with lower cobalt content showed no signs of plastic deformation. However, this tool B was susceptible to shear failure. Tool wear characteristics were found to increase with higher clad distance travelled and with higher tool RPM. SEM EDS analysis confirmed adhesion of clad/substrate material to the tool face, while XRD analysis confirmed oxidation of the tool pin surface.
{"title":"Failure analysis of refractory tungsten carbide tool containing different cobalt percentages during friction stir cladding of copper on steel","authors":"Mithlesh Kumar Mahto , Adarsh Kumar , Sanjay Kumar Gupta , Pradeep Kumar , Meghanshu Vashista , Mohd Zaheer Khan Yusufzai","doi":"10.1016/j.engfailanal.2026.110592","DOIUrl":"10.1016/j.engfailanal.2026.110592","url":null,"abstract":"<div><div>The appropriateness of any welding process depends upon the performance of essential components satisfactorily during the operation. In friction stir welding (FSW) of high-temperature softening materials, the life of the non-consumable rotating tool plays a crucial role. During the cladding operation performed by FSW, maintaining the tool geometry intact during subsequent repetitive passes is essential to obtain defect-free cladding. Rapid tool degradation can pose challenges in joining the clad material with the substrate.</div><div>In this work, failure analysis of nickel–cobalt-bonded tungsten carbide tool materials has been evaluated while carrying out friction stir cladding of copper on a steel substrate. Two different tool materials with total cobalt-nickel binder content = 10% (designated as tool A) and another tool material designated as tool B (having total binder content = 5%) have been used to carry out the cladding operation. Tool pin abrasion, adhesion, mushrooming, oxide formation, and the appearance of radial grooves in the shoulder region were prominently visible in tool A, containing a higher cobalt-nickel percentage. On the other hand, the tool with lower cobalt content showed no signs of plastic deformation. However, this tool B was susceptible to shear failure. Tool wear characteristics were found to increase with higher clad distance travelled and with higher tool RPM. SEM EDS analysis confirmed adhesion of clad/substrate material to the tool face, while XRD analysis confirmed oxidation of the tool pin surface.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110592"},"PeriodicalIF":5.7,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025774","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}
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