Pub Date : 2026-01-29DOI: 10.1016/j.engfailanal.2026.110628
Santhosh K G , Imran M. Jamadar , Prasanta Kumar Samal
This study investigates the rotating bending fatigue behaviour of specimens fabricated using the Fused Deposition Modeling (FDM) technique, including pure Polylactic acid (PLA) and its composites reinforced with short glass fibres (PLA-GF) and short carbon fibres (PLA-CF). Test specimens were fabricated with three infill densities (50%, 75%, and 100%) and raster orientations (0°, 45°, and 90°). Rotating bending fatigue tests were performed under completely reversed cyclic loading conditions, both in the as-printed state and after the application of an epoxy surface coating. The fatigue performance of the specimens was evaluated in three-fold method: in the first method, the number of experiments to be carried out was optimized using Taguchi’s design of experiments. In the second method, analysis of variance (ANOVA) was used to study the impact of input parameters and in the final method, the failure mechanisms were analysed using scanning electron microscopy (SEM).The results showed that the fatigue life of the specimens is significantly affected by the epoxy coating. The epoxy coating has increased the fatigue life of PLA by 26% followed by 19% and 18% for PLA-CF and PLA-GF respectively. The increase in fatigue life is primarily attributed to reduction of surface defects, roughness and delayed crack initiation under repeated Out of the process variable parameters investigated; the infill density percentage has the major influence, followed by raster angle. The maximum fatigue life was recorded for the specimens with infill density percentage of 100% and raster angle of 00.The SEM analysis of the fracture surfaces of the tested specimens revealed that the epoxy coating effectively reduced interlayer delamination, fibre pull-out, and void formation, resulting in mixed-mode failure. Overall, the fatigue performance of the additively manufactured PLA polymer specimens improved considerably with the incorporation of short fibres and the application of an epoxy surface coating. This research provides valuable insights for enhancing the durability and reliability of 3D-printed components subjected to light, repeated loading applications.
{"title":"Rotating bending fatigue analysis of 3D-printed PLA polymer composites: Effect of short fiber reinforcement and epoxy coating","authors":"Santhosh K G , Imran M. Jamadar , Prasanta Kumar Samal","doi":"10.1016/j.engfailanal.2026.110628","DOIUrl":"10.1016/j.engfailanal.2026.110628","url":null,"abstract":"<div><div>This study investigates the rotating bending fatigue behaviour of specimens fabricated using the Fused Deposition Modeling (FDM) technique, including pure Polylactic acid (PLA) and its composites reinforced with short glass fibres (PLA-GF) and short carbon fibres (PLA-CF). Test specimens were fabricated with three infill densities (50%, 75%, and 100%) and raster orientations (0°, 45°, and 90°). Rotating bending fatigue tests were performed under completely reversed cyclic loading conditions, both in the as-printed state and after the application of an epoxy surface coating. The fatigue performance of the specimens was evaluated in three-fold method: in the first method, the number of experiments to be carried out was optimized using Taguchi’s design of experiments. In the second method, analysis of variance (ANOVA) was used to study the impact of input parameters and in the final method, the failure mechanisms were analysed using scanning electron microscopy (SEM).The results showed that the fatigue life of the specimens is significantly affected by the epoxy coating. The epoxy coating has increased the fatigue life of PLA by 26% followed by 19% and 18% for PLA-CF and PLA-GF respectively. The increase in fatigue life is primarily attributed to reduction of surface defects, roughness and delayed crack initiation under repeated Out of the process variable parameters investigated; the infill density percentage has the major influence, followed by raster angle. The maximum fatigue life was recorded for the specimens with infill density percentage of 100% and raster angle of 0<sup>0</sup>.The SEM analysis of the fracture surfaces of the tested specimens revealed that the epoxy coating effectively reduced interlayer delamination, fibre pull-out, and void formation, resulting in mixed-mode failure. Overall, the fatigue performance of the additively manufactured PLA polymer specimens improved considerably with the incorporation of short fibres and the application of an epoxy surface coating. This research provides valuable insights for enhancing the durability and reliability of 3D-printed components subjected to light, repeated loading applications.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"188 ","pages":"Article 110628"},"PeriodicalIF":5.7,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-28DOI: 10.1016/j.engfailanal.2026.110625
Kesong Fan , Mengyin Feng , Shaowei Liu , Dengpan Zhang , Hui Liu , Yi Kang , Deyin He , Guohao Liang
<div><div>Threaded steel resin bolts are extensively utilized for supporting mine roadways. However, various factors such as underground humidity, high stress, and significant disturbances increase the susceptibility of these support components to corrosion, particularly in environments characterized by roof water seepage. This corrosion poses serious risks to the safety and efficiency of mining production. Focusing on the Dangjiahe Coal Mine in Shaanxi Province, China, this study elucidates the corrosion mechanisms affecting bolts in the presence of prolonged stress and water exposure. It further explains the propagation characteristics of ultrasonic guided waves within corroded anchorage structures, investigates guided wave propagation properties across varying corrosion scales, and explores guided wave non-destructive testing (NDT) methodologies for anchorage bodies exhibiting corrosion defects. The findings indicate that: (i) Mine water quality assessments, coupled with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses of corroded samples, reveal that Cl<sup>−</sup> plays a crucial catalytic role in the corrosion process. Following corrosion, the bolt’s surface becomes rough and loose, resulting in a decrease in Fe content and an increase in oxide formation, thereby undermining the bonding performance at the “bolt-resin” interface and consequently reducing the overall anchorage capacity; (ii) Dispersion curve analyses suggest that employing a detection frequency below 100 kHz in the L (0,1) mode effectively mitigates multimodal interference and minimizes dispersion effects. Upon encountering an interface or corrosion defect, the guided wave experiences significant reflection and transmission due to abrupt changes in wave impedance, along with reductions in wave velocity and energy attenuation; and (iii) Through finite element numerical simulations, the guided wave propagation characteristics across various corrosion scales are analyzed. The study reveals minor discrepancies in wave propagation at various corrosion locations, with the error associated with estimating the corrosion location based on echo characteristics being less than 6.66 %. As the defect depth increases, the amplitude of the defect echo markedly rises, whereas the amplitude of the bottom echo diminishes correspondingly. Notably, when the length of the corrosion defect exceeds 200 mm, the echo signals from the defect’s front and rear ends diverge, allowing for the calculation of the corrosion defect’s initiation point; (iv) A non-destructive testing platform based on the inverse piezoelectric effect is developed, and non-destructive testing experiments are carried out on threaded steel resin bolts with corrosion defects; (v) To address challenges posed by chaotic and noise-interfered original ultrasonic guided wave echo signals collected in the laboratory, this paper introduces an optimized SVMD-OMP signal processing technique that employs s
{"title":"Guided wave characteristics and nondestructive testing of corrosion defects in threaded steel resin bolts","authors":"Kesong Fan , Mengyin Feng , Shaowei Liu , Dengpan Zhang , Hui Liu , Yi Kang , Deyin He , Guohao Liang","doi":"10.1016/j.engfailanal.2026.110625","DOIUrl":"10.1016/j.engfailanal.2026.110625","url":null,"abstract":"<div><div>Threaded steel resin bolts are extensively utilized for supporting mine roadways. However, various factors such as underground humidity, high stress, and significant disturbances increase the susceptibility of these support components to corrosion, particularly in environments characterized by roof water seepage. This corrosion poses serious risks to the safety and efficiency of mining production. Focusing on the Dangjiahe Coal Mine in Shaanxi Province, China, this study elucidates the corrosion mechanisms affecting bolts in the presence of prolonged stress and water exposure. It further explains the propagation characteristics of ultrasonic guided waves within corroded anchorage structures, investigates guided wave propagation properties across varying corrosion scales, and explores guided wave non-destructive testing (NDT) methodologies for anchorage bodies exhibiting corrosion defects. The findings indicate that: (i) Mine water quality assessments, coupled with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses of corroded samples, reveal that Cl<sup>−</sup> plays a crucial catalytic role in the corrosion process. Following corrosion, the bolt’s surface becomes rough and loose, resulting in a decrease in Fe content and an increase in oxide formation, thereby undermining the bonding performance at the “bolt-resin” interface and consequently reducing the overall anchorage capacity; (ii) Dispersion curve analyses suggest that employing a detection frequency below 100 kHz in the L (0,1) mode effectively mitigates multimodal interference and minimizes dispersion effects. Upon encountering an interface or corrosion defect, the guided wave experiences significant reflection and transmission due to abrupt changes in wave impedance, along with reductions in wave velocity and energy attenuation; and (iii) Through finite element numerical simulations, the guided wave propagation characteristics across various corrosion scales are analyzed. The study reveals minor discrepancies in wave propagation at various corrosion locations, with the error associated with estimating the corrosion location based on echo characteristics being less than 6.66 %. As the defect depth increases, the amplitude of the defect echo markedly rises, whereas the amplitude of the bottom echo diminishes correspondingly. Notably, when the length of the corrosion defect exceeds 200 mm, the echo signals from the defect’s front and rear ends diverge, allowing for the calculation of the corrosion defect’s initiation point; (iv) A non-destructive testing platform based on the inverse piezoelectric effect is developed, and non-destructive testing experiments are carried out on threaded steel resin bolts with corrosion defects; (v) To address challenges posed by chaotic and noise-interfered original ultrasonic guided wave echo signals collected in the laboratory, this paper introduces an optimized SVMD-OMP signal processing technique that employs s","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"188 ","pages":"Article 110625"},"PeriodicalIF":5.7,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146098548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the cause of failure of a bearing used in a gas turbine of a thermal power plant was investigated. Bearings are critical mechanical components whose proper function directly affects the safety and stability of mechanical systems. The failure of this bearing led to reduced system performance and sudden unit shutdown. The objective was to identify the root cause of failure and assess the manufacturing quality of the bearing. To this end, the damaged sample was compared with a standard bearing, and multiple microstructural evaluations including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and optical microscopy were performed on both samples. The results revealed that the damaged bearing exhibited a non-uniform microstructure, concentration gradients, and undesirable phases due to improper manufacturing processes. In the standard bearing, a distinct layer of FeSn2 was identified, which was not present in the damaged bearing. This intermetallic layer plays a crucial role in promoting adhesion between the babbitt layer and the steel substrate. These factors contributed to reduced mechanical strength and premature failure of the bearing. Based on the findings, stricter control over the manufacturing process and raw material inspection are recommended to ensure proper performance under power plant operating conditions.
{"title":"Characterization and evaluation of a failed journal bearing: A microstructural study and comparative approach","authors":"Hananeh Mostafavi , Mahmoud Sarkari Khorrami , Saeed Khani Moghanaki","doi":"10.1016/j.engfailanal.2026.110621","DOIUrl":"10.1016/j.engfailanal.2026.110621","url":null,"abstract":"<div><div>In this study, the cause of failure of a bearing used in a gas turbine of a thermal power plant was investigated. Bearings are critical mechanical components whose proper function directly affects the safety and stability of mechanical systems. The failure of this bearing led to reduced system performance and sudden unit shutdown. The objective was to identify the root cause of failure and assess the manufacturing quality of the bearing. To this end, the damaged sample was compared with a standard bearing, and multiple microstructural evaluations including Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and optical microscopy were performed on both samples. The results revealed that the damaged bearing exhibited a non-uniform microstructure, concentration gradients, and undesirable phases due to improper manufacturing processes. In the standard bearing, a distinct layer of FeSn<sub>2</sub> was identified, which was not present in the damaged bearing. This intermetallic layer plays a crucial role in promoting adhesion between the babbitt layer and the steel substrate. These factors contributed to reduced mechanical strength and premature failure of the bearing. Based on the findings, stricter control over the manufacturing process and raw material inspection are recommended to ensure proper performance under power plant operating conditions.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110621"},"PeriodicalIF":5.7,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-27DOI: 10.1016/j.engfailanal.2026.110624
Zhibin Zhao , Nian Wang , Jianwu Zhou , Haijun Jiang , Heyang Miao , Wei Zhang , Zhengwei Yang
With the expanding application of thermoplastic composites in aerospace engineering, there is an urgent need for non-destructive testing of impact damage in CF/PEEK composites. This study aims to address two major challenges in ultrasonic infrared thermography (UIT) testing of CF/PEEK composites: unclear excitation parameter settings and low damage segmentation accuracy. To this end, a two-stage method combining excitation parameter optimization and unsupervised thermal image segmentation is proposed. First, a quantitative mapping model between excitation parameters and thermal response characteristics was systematically established through single-factor experiments and response surface methodology, thereby determining the optimal excitation parameter combination. On this basis, a novel multi-order graph clustering segmentation model named Fast Multi-order Graph Fusion Clustering (FMGFC) was developed. Its core innovations lie in the introduction of an adaptive multi-order graph selection mechanism and a graph fusion strategy based on low-rank tensor approximation. The model generates anchors through superpixel learning, reducing computational complexity to linear level; it then adaptively selects specific orders of sample-anchor graphs and learns their consistent and accurate similarity representations via low-rank tensor approximation. Experimental results show that the optimized excitation scheme significantly enhances the signal-to-noise ratio of damage thermal images; the proposed FMGFC model achieved over 95% segmentation accuracy on three specimens while reducing runtime by approximately 50–70% compared to other algorithms, effectively unifying high precision and high efficiency. This research provides critical technical support and methodological references for UIT testing of thermoplastic composites.
{"title":"CF/PEEK composites ultrasonic infrared thermography testing: Excitation parameter optimization and fast multi-order graph fusion clustering segmentation","authors":"Zhibin Zhao , Nian Wang , Jianwu Zhou , Haijun Jiang , Heyang Miao , Wei Zhang , Zhengwei Yang","doi":"10.1016/j.engfailanal.2026.110624","DOIUrl":"10.1016/j.engfailanal.2026.110624","url":null,"abstract":"<div><div>With the expanding application of thermoplastic composites in aerospace engineering, there is an urgent need for non-destructive testing of impact damage in CF/PEEK composites. This study aims to address two major challenges in ultrasonic infrared thermography (UIT) testing of CF/PEEK composites: unclear excitation parameter settings and low damage segmentation accuracy. To this end, a two-stage method combining excitation parameter optimization and unsupervised thermal image segmentation is proposed. First, a quantitative mapping model between excitation parameters and thermal response characteristics was systematically established through single-factor experiments and response surface methodology, thereby determining the optimal excitation parameter combination. On this basis, a novel multi-order graph clustering segmentation model named Fast Multi-order Graph Fusion Clustering (FMGFC) was developed. Its core innovations lie in the introduction of an adaptive multi-order graph selection mechanism and a graph fusion strategy based on low-rank tensor approximation. The model generates anchors through superpixel learning, reducing computational complexity to linear level; it then adaptively selects specific orders of sample-anchor graphs and learns their consistent and accurate similarity representations via low-rank tensor approximation. Experimental results show that the optimized excitation scheme significantly enhances the signal-to-noise ratio of damage thermal images; the proposed FMGFC model achieved over 95% segmentation accuracy on three specimens while reducing runtime by approximately 50–70% compared to other algorithms, effectively unifying high precision and high efficiency. This research provides critical technical support and methodological references for UIT testing of thermoplastic composites.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110624"},"PeriodicalIF":5.7,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075751","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}
Electrical discharge machining (EDM) is widely used in the manufacturing of H13 die steel due to its capability for processing complex geometries and high-hardness materials. Despite its advantages, EDM introduces surface defects—such as recast layers, microcracks, and residual tensile stresses—that significantly promote early-stage crack initiation and accelerate crack propagation under thermal cycling. This study investigates the damage accumulation behavior of H13 hot-work die steel subjected to EDM and evaluates the crack suppression potential of shot peening (SP) at different Almen intensities (0.11–0.28 mmA). Thermal cycling tests were performed over 450 to 1500 cycles (with a step size of 150 cycles) using a self-constrained thermal cycling system. Based on the Uddeholm standard, each thermal cycle involved heating from room temperature to 700 °C within 5.5 s, followed by a 17 s cooling phase. Compared to ground specimens, EDM-processed samples exhibited earlier crack initiation, more complex branched crack networks, and deeper main cracks, with a maximum depth of 684.2 μm. SP was subsequently applied to induce stress and hardness gradients in surface-near regions, effectively reshaping the mechanical conditions that control crack evolution. The results reveal a nonlinear correlation between SP intensity and mitigation of cracking under thermal cycling. While moderate intensities may induce stress reversals or sub-surface microstructural instabilities, the optimal SP intensity (0.28 mmA) generated a compressive residual stress field (∼–700 MPa, 150 μm depth) and a gradual hardness gradient (∼180 μm), forming an effective barrier to crack extension. These surface integrity gradients significantly delayed crack coalescence and reduced overall damage accumulation. This study highlights that intensity-optimized SP is an effective strategy for altering the crack driving force distribution in EDM-affected regions and for improving the structural endurance of hot-work tooling under cyclic thermal loading.
{"title":"Enhancement of resistance to cracking under thermal cycling of EDM-treated H13 steel by shot peening with optimized intensity","authors":"Pengpeng Zuo , Zhiyang Dou , Huikai Yang , Haoyan Hou , Yafeng Zheng","doi":"10.1016/j.engfailanal.2026.110622","DOIUrl":"10.1016/j.engfailanal.2026.110622","url":null,"abstract":"<div><div>Electrical discharge machining (EDM) is widely used in the manufacturing of H13 die steel due to its capability for processing complex geometries and high-hardness materials. Despite its advantages, EDM introduces surface defects—such as recast layers, microcracks, and residual tensile stresses—that significantly promote early-stage crack initiation and accelerate crack propagation under thermal cycling. This study investigates the damage accumulation behavior of H13 hot-work die steel subjected to EDM and evaluates the crack suppression potential of shot peening (SP) at different Almen intensities (0.11–0.28 mmA). Thermal cycling tests were performed over 450 to 1500 cycles (with a step size of 150 cycles) using a self-constrained thermal cycling system. Based on the Uddeholm standard, each thermal cycle involved heating from room temperature to 700 °C within 5.5 s, followed by a 17 s cooling phase. Compared to ground specimens, EDM-processed samples exhibited earlier crack initiation, more complex branched crack networks, and deeper main cracks, with a maximum depth of 684.2 μm. SP was subsequently applied to induce stress and hardness gradients in surface-near regions, effectively reshaping the mechanical conditions that control crack evolution. The results reveal a nonlinear correlation between SP intensity and mitigation of cracking under thermal cycling. While moderate intensities may induce stress reversals or sub-surface microstructural instabilities, the optimal SP intensity (0.28 mmA) generated a compressive residual stress field (∼–700 MPa, 150 μm depth) and a gradual hardness gradient (∼180 μm), forming an effective barrier to crack extension. These surface integrity gradients significantly delayed crack coalescence and reduced overall damage accumulation. This study highlights that intensity-optimized SP is an effective strategy for altering the crack driving force distribution in EDM-affected regions and for improving the structural endurance of hot-work tooling under cyclic thermal loading.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110622"},"PeriodicalIF":5.7,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075745","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 : 2026-01-27DOI: 10.1016/j.engfailanal.2026.110623
Gao Zhang, Chang He, LiZhong Jiang, Wei Guo
This study systematically investigates the dynamic response and traffic safety performance of simply supported beam bridges on mountainous high-speed railways under rockfall hazards. By coupling rockfall trajectory simulation with refined finite element analysis, the study elucidates the damage evolution mechanism of bridge structures under rockfall impacts and the correlations among key parameters. The findings indicate that the dynamic response of superstructure components (including the track system, mortar layer, and sliding layer) is a strong correlation with pier displacement and exhibits higher damage sensitivity. Furthermore, an innovative bridge fragility model accounting for rockfall mass ranges is established, enabling quantitative assessment of the damage probabilities for piers, mortar layers, and sliding layers. Building upon this foundation, a method for evaluating train safety based on track geometric deformation after rockfall impact is proposed, identifying critical impact conditions at different operational speeds. This research provides theoretical support and technical references for the anti-impact design, safety protection, and operational decision-making of high-speed railway bridges in rockfall hazard environments.
{"title":"Dynamic response and safety assessment of high-speed railway simply-supported beam bridge under rockfall impact","authors":"Gao Zhang, Chang He, LiZhong Jiang, Wei Guo","doi":"10.1016/j.engfailanal.2026.110623","DOIUrl":"10.1016/j.engfailanal.2026.110623","url":null,"abstract":"<div><div>This study systematically investigates the dynamic response and traffic safety performance of simply supported beam bridges on mountainous high-speed railways under rockfall hazards. By coupling rockfall trajectory simulation with refined finite element analysis, the study elucidates the damage evolution mechanism of bridge structures under rockfall impacts and the correlations among key parameters. The findings indicate that the dynamic response of superstructure components (including the track system, mortar layer, and sliding layer) is a strong correlation with pier displacement and exhibits higher damage sensitivity. Furthermore, an innovative bridge fragility model accounting for rockfall mass ranges is established, enabling quantitative assessment of the damage probabilities for piers, mortar layers, and sliding layers. Building upon this foundation, a method for evaluating train safety based on track geometric deformation after rockfall impact is proposed, identifying critical impact conditions at different operational speeds. This research provides theoretical support and technical references for the anti-impact design, safety protection, and operational decision-making of high-speed railway bridges in rockfall hazard environments.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110623"},"PeriodicalIF":5.7,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075750","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 : 2026-01-26DOI: 10.1016/j.engfailanal.2026.110619
Yu Huang , Zhian Chen , Musa Sheikh MD Abu , Derek O. Northwood , Cheng Liu
A comprehensive failure analysis is conducted on the first roller, made of 18CrNiMo7-6 steel, in cold roll-forming automotive single-piece flywheels. The results show that the thickness of the carburized layer on the roll groove (the working part of the roller) is about 2 mm, which is below the design requirement of 3 mm. Macro-hardness testing reveals that the surface hardness of the roll groove is below the design requirement. The results from over 1,000 microhardness measurement points within entire carburized layer across the roll groove show that some low-hardness micro-zones with a microhardness below 550 HV are present, indicating an overall inhomogeneous hardness distribution. Fractographic examination reveals the presence of material loss and cracks within the groove. Once initiated, cracks propagate along adjacent regions with high microhardness differences within the carburized layer, and extend into the interior of the roller. The uneven hardness distribution is associated with the non-uniform dispersion of retained austenite and tempered martensite. Electron backscatter diffraction (EBSD) analysis indicates that the microstructure at the groove surface is finer than that in the core region, accompanied by higher Kernel Average Misorientation (KAM) values. Compared to the crack arrest region, the crack propagation area contains fewer high-angle grain boundaries and higher KAM values. Finite element simulation demonstrates that the high stress concentration at the feeding slot of the roller groove is the main driving force for crack propagation. The roller failure is linked to a combination of its specific geometry, heat treatment process, and operating conditions. This research forms the basis for developing new roller types in the future.
{"title":"Failure mechanism of the roller for roll-forming of single-piece flywheels in automobiles","authors":"Yu Huang , Zhian Chen , Musa Sheikh MD Abu , Derek O. Northwood , Cheng Liu","doi":"10.1016/j.engfailanal.2026.110619","DOIUrl":"10.1016/j.engfailanal.2026.110619","url":null,"abstract":"<div><div>A comprehensive failure analysis is conducted on the first roller, made of 18CrNiMo7-6 steel, in cold roll-forming automotive single-piece flywheels. The results show that the thickness of the carburized layer on the roll groove (the working part of the roller) is about 2 mm, which is below the design requirement of 3 mm. Macro-hardness testing reveals that the surface hardness of the roll groove is below the design requirement. The results from over 1,000 microhardness measurement points within entire carburized layer across the roll groove show that some low-hardness micro-zones with a microhardness below 550 HV are present, indicating an overall inhomogeneous hardness distribution. Fractographic examination reveals the presence of material loss and cracks within the groove. Once initiated, cracks propagate along adjacent regions with high microhardness differences within the carburized layer, and extend into the interior of the roller. The uneven hardness distribution is associated with the non-uniform dispersion of retained austenite and tempered martensite. Electron backscatter diffraction (EBSD) analysis indicates that the microstructure at the groove surface is finer than that in the core region, accompanied by higher Kernel Average Misorientation (KAM) values. Compared to the crack arrest region, the crack propagation area contains fewer high-angle grain boundaries and higher KAM values. Finite element simulation demonstrates that the high stress concentration at the feeding slot of the roller groove is the main driving force for crack propagation. The roller failure is linked to a combination of its specific geometry, heat treatment process, and operating conditions. This research forms the basis for developing new roller types in the future.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110619"},"PeriodicalIF":5.7,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075746","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 : 2026-01-26DOI: 10.1016/j.engfailanal.2026.110618
Xu Wang , Jingyu He , Guohui Li , Liqian Zhao , Shuo Li , Yan Li , Huawei Zhang , Xiang Chen
This study investigates the hydrogen embrittlement (HE) sensitivity of L245NS steel (a low-strength carbon-manganese steel) after 8 years of service under a pure hydrogen atmosphere. The steel was welded using a combination of Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW). Results show that despite the weld metal having a finer average grain size (10.9 μm) than the base metal (17.6 μm), its hydrogen embrittlement sensitivity index (HEI) (59.2%) is significantly higher than the base metal’s (17.5%). Thermal desorption spectroscopy (TDS) tests identify a characteristic desorption peak at 105 °C (shallow-trapped hydrogen, with the weld metal accumulating more hydrogen (1.81 ppm) than the base metal (1.50 ppm). EBSD analysis reveals the weld metal has a longer grain boundary length (5610 μm) and a higher density of high-Σ grain boundaries, which collectively provide abundant shallow hydrogen trapping sites, promoting long-term hydrogen accumulation and higher HE sensitivity.
{"title":"Base metal vs. weld metal hydrogen embrittlement sensitivity in L245NS pipeline steel after eight years of pure hydrogen exposure: a slow strain rate tensile test analysis","authors":"Xu Wang , Jingyu He , Guohui Li , Liqian Zhao , Shuo Li , Yan Li , Huawei Zhang , Xiang Chen","doi":"10.1016/j.engfailanal.2026.110618","DOIUrl":"10.1016/j.engfailanal.2026.110618","url":null,"abstract":"<div><div>This study investigates the hydrogen embrittlement (HE) sensitivity of L245NS steel (a low-strength carbon-manganese steel) after 8 years of service under a pure hydrogen atmosphere. The steel was welded using a combination of Gas Tungsten Arc Welding (GTAW) and Shielded Metal Arc Welding (SMAW). Results show that despite the weld metal having a finer average grain size (10.9 μm) than the base metal (17.6 μm), its hydrogen embrittlement sensitivity index (HEI) (59.2%) is significantly higher than the base metal’s (17.5%). Thermal desorption spectroscopy (TDS) tests identify a characteristic desorption peak at 105 °C (shallow-trapped hydrogen, with the weld metal accumulating more hydrogen (1.81 ppm) than the base metal (1.50 ppm). EBSD analysis reveals the weld metal has a longer grain boundary length (5610 μm) and a higher density of high-Σ grain boundaries, which collectively provide abundant shallow hydrogen trapping sites, promoting long-term hydrogen accumulation and higher HE sensitivity.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110618"},"PeriodicalIF":5.7,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075747","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 : 2026-01-26DOI: 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}
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