Pub Date : 2026-01-26DOI: 10.1016/j.engfailanal.2026.110596
Chengpu Li , Hai Tang , Sunyang Qiu , Chao Yang , Jing Rao , Zhengli Hua , Baihui Xing , Juan Shang
With the widespread application of hydrogen-blended natural gas pipelines, evaluating the hydrogen compatibility and residual life of compressor impeller has become essential for ensuring the safe and reliable operation of hydrogen pipeline systems. In this study, fatigue crack growth rate (FCGR) and fracture toughness tests were carried out on FV520B, a representative impeller blade material, under various simulated hydrogen-blended natural gas environments. Results show that under 12 MPa 20 vol% H2-blended environment, the FCGR increases to about 24 times that of the nitrogen environment, and the fracture toughness (KIH) decreases to only 25% of that in nitrogen. Moreover, higher stress ratios and total pressures further increase the crack growth rate. Based on these experimental data, finite element analyses based on adaptive grid technique were conducted to assess the effects of hydrogen-blended ratio and stress ratio on impeller residual life through a damage tolerance evaluation method. The results show that under the 20 vol% H2-blended environment, the residual life of the blade with an initial crack depth of 0.1 mm at stress ratio (R) of 0.1 was 12,874 cycles − only half of that under the 10 vol% H2-blended environment. Additionally, when R = 0.5 and 0.7, the life of blades were 22,603 and 19,902 cycles, respectively, due to complex influence of stress ratio on FCGR. These findings highlight the need for rigorous hydrogen-compatibility evaluations and careful control of blending ratios and stress conditions to ensure the safe and reliable operation of impellers in hydrogen-blended environments.
{"title":"Mechanical properties and residual life assessment of FV520B centrifugal compressor blades under hydrogen-blended environment","authors":"Chengpu Li , Hai Tang , Sunyang Qiu , Chao Yang , Jing Rao , Zhengli Hua , Baihui Xing , Juan Shang","doi":"10.1016/j.engfailanal.2026.110596","DOIUrl":"10.1016/j.engfailanal.2026.110596","url":null,"abstract":"<div><div>With the widespread application of hydrogen-blended natural gas pipelines, evaluating the hydrogen compatibility and residual life of compressor impeller has become essential for ensuring the safe and reliable operation of hydrogen pipeline systems. In this study, fatigue crack growth rate (FCGR) and fracture toughness tests were carried out on FV520B, a representative impeller blade material, under various simulated hydrogen-blended natural gas environments. Results show that under 12 MPa 20 vol% H<sub>2</sub>-blended environment, the FCGR increases to about 24 times that of the nitrogen environment, and the fracture toughness (<em>K<sub>IH</sub></em>) decreases to only 25% of that in nitrogen. Moreover, higher stress ratios and total pressures further increase the crack growth rate. Based on these experimental data, finite element analyses based on adaptive grid technique were conducted to assess the effects of hydrogen-blended ratio and stress ratio on impeller residual life through a damage tolerance evaluation method. The results show that under the 20 vol% H<sub>2</sub>-blended environment, the residual life of the blade with an initial crack depth of 0.1 mm at stress ratio (<em>R</em>) of 0.1 was 12,874 cycles − only half of that under the 10 vol% H<sub>2</sub>-blended environment. Additionally, when <em>R</em> = 0.5 and 0.7, the life of blades were 22,603 and 19,902 cycles, respectively, due to complex influence of stress ratio on FCGR. These findings highlight the need for rigorous hydrogen-compatibility evaluations and careful control of blending ratios and stress conditions to ensure the safe and reliable operation of impellers in hydrogen-blended environments.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110596"},"PeriodicalIF":5.7,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075743","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 : 2026-01-25DOI: 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":"2026-01-25","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 : 2026-01-24DOI: 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 : 2026-01-23DOI: 10.1016/j.engfailanal.2026.110607
Jinghua Li , Guichen Li , Haoyu Rong , Yaoqi Liu , Zeyu Shao , Bo Zhang
Most studies on progressive failure in rocks have mainly focused on brittle materials, with limited attention given to mudstone, particularly regarding the effects of water. To address this gap, this study conducted mechanical tests on mudstone with varying water saturation, together with AE monitoring and SEM characterisation. The influence of water on physical state in mudstone was analyzed. The mechanisms by which water affects failure was revealed. The influence of water on progressive failure was discussed. Results indicate that, after water intruding mudstone develops tensile microcracks. Elastic modulus decreases linearly with saturation increasing. In mechanical tests, the proportion of AE tensile events and tensile cracking energy decrease linearly with water saturation, while plastic energy is the opposite. Macroscopic failure shifts from compressive shear to tensile rupture occurs with water saturation increasing. During the progressive failure process, crack initiation stress, crack damage stress, and peak stress all decreases exponentially with saturation increasing. While the uniformity of water distribution within the mudstone exerts a limited influence on both elastic modulus and P-wave velocity, it does effect on both stress threshold and progressive failure behaviour. After water intruding, the proportion of microcracking in elasto-plastic deformation stage (stage Ⅱ&Ⅲ) increases 20% average. Failure to account for the increased cracking behaviour into the elasto-plastic stage, may lead to overestimation of the long-term bearing capacity of mudstone in engineering application where potential leakage is a concern. This study provided a new insight into the long-term stability of mudstone under water intruding and stress loading.
{"title":"Experimental study on the influence of water saturation state on the progressive failure characteristics in mudstone subjected stress loading","authors":"Jinghua Li , Guichen Li , Haoyu Rong , Yaoqi Liu , Zeyu Shao , Bo Zhang","doi":"10.1016/j.engfailanal.2026.110607","DOIUrl":"10.1016/j.engfailanal.2026.110607","url":null,"abstract":"<div><div>Most studies on progressive failure in rocks have mainly focused on brittle materials, with limited attention given to mudstone, particularly regarding the effects of water. To address this gap, this study conducted mechanical tests on mudstone with varying water saturation, together with AE monitoring and SEM characterisation. The influence of water on physical state in mudstone was analyzed. The mechanisms by which water affects failure was revealed. The influence of water on progressive failure was discussed. Results indicate that, after water intruding mudstone develops tensile microcracks. Elastic modulus decreases linearly with saturation increasing. In mechanical tests, the proportion of AE tensile events and tensile cracking energy decrease linearly with water saturation, while plastic energy is the opposite. Macroscopic failure shifts from compressive shear to tensile rupture occurs with water saturation increasing. During the progressive failure process, crack initiation stress, crack damage stress, and peak stress all decreases exponentially with saturation increasing. While the uniformity of water distribution within the mudstone exerts a limited influence on both elastic modulus and <em>P</em>-wave velocity, it does effect on both stress threshold and progressive failure behaviour. After water intruding, the proportion of microcracking in elasto-plastic deformation stage (stage Ⅱ&Ⅲ) increases 20% average. Failure to account for the increased cracking behaviour into the elasto-plastic stage, may lead to overestimation of the long-term bearing capacity of mudstone in engineering application where potential leakage is a concern. This study provided a new insight into the long-term stability of mudstone under water intruding and stress loading.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110607"},"PeriodicalIF":5.7,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170686","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号