Pub Date : 2026-04-01Epub Date: 2026-01-19DOI: 10.1016/j.engfailanal.2026.110594
Min Lou , Bin Wu , Yangyang Wang , Weixing Liang , Yu Han
This study investigates the multi-crack propagation characteristics and predicts the fatigue life of six Q355B tubular T-joint specimens subjected to in-plane bending, utilizing a combination of experimental and numerical approaches. A series of static tensile tests and fatigue tests are conducted to study the fatigue behavior of tubular T-joints under varying bending load conditions in terms of fatigue crack trajectory, failure morphology and remaining fatigue life. Thereinto, fatigue crack growth is monitored using the beach mark technique, and the fracture morphology at different stages during the crack propagation is examined using scanning electron microscopy. A numerical investigation is carried out to capture the multiple crack coalescence and to predict the remaining fatigue life during the crack propagation process. These studies reveal that two cracks initiate at the brace near crown and propagate toward its depth direction, coalesce into a long crack, continuing to grow circumferentially along the weld toe in the case of a curved morphology. Reasonably good agreements are achieved between experimental and simulated results, with the average error of the whole fatigue life less than 13%. There is generally good agreement between experimental and predicted results in fatigue crack trajectory, failure morphology, and remaining fatigue life.
{"title":"Multi-crack propagation characteristics and fatigue life prediction of tubular T-joints subjected to in-plane bending","authors":"Min Lou , Bin Wu , Yangyang Wang , Weixing Liang , Yu Han","doi":"10.1016/j.engfailanal.2026.110594","DOIUrl":"10.1016/j.engfailanal.2026.110594","url":null,"abstract":"<div><div>This study investigates the multi-crack propagation characteristics and predicts the fatigue life of six Q355B tubular T-joint specimens subjected to in-plane bending, utilizing a combination of experimental and numerical approaches. A series of static tensile tests and fatigue tests are conducted to study the fatigue behavior of tubular T-joints under varying bending load conditions in terms of fatigue crack trajectory, failure morphology and remaining fatigue life. Thereinto, fatigue crack growth is monitored using the beach mark technique, and the fracture morphology at different stages during the crack propagation is examined using scanning electron microscopy. A numerical investigation is carried out to capture the multiple crack coalescence and to predict the remaining fatigue life during the crack propagation process. These studies reveal that two cracks initiate at the brace near crown and propagate toward its depth direction, coalesce into a long crack, continuing to grow circumferentially along the weld toe in the case of a curved morphology. Reasonably good agreements are achieved between experimental and simulated results, with the average error of the whole fatigue life less than 13%. There is generally good agreement between experimental and predicted results in fatigue crack trajectory, failure morphology, and remaining fatigue life.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"187 ","pages":"Article 110594"},"PeriodicalIF":5.7,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025778","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":"2026-04-01","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}
Pub Date : 2026-04-01Epub 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":"2026-04-01","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 : 2026-03-15Epub Date: 2026-01-11DOI: 10.1016/j.engfailanal.2026.110573
Yu Shi , Peng Liao , Youwei Xu , Wuyao Xiong , Ming Zhu
This study enhances the cavitation erosion resistance in ZL101A aluminum alloy via a Stellite 6 coating fabricated via ultra-high-speed laser cladding (UHSLC). The resulting approximately 400 μm thick coating exhibited a fine-grained microstructure and sound metallurgical bonding. A significant improvement in mechanical and tribological properties was achieved: the microhardness increased dramatically to 683.2 HV (9.3 times that of the substrate), and the friction coefficient was stabilized at 0.35. The coating’s erosion resistance was markedly improved: under solid particle impingement, it showed a mass loss of 21.66 mg and a volume loss of 3.35 mm3, corresponding to reductions of 24 % and 58 %, respectively, compared to the substrate (28.50 mg, 8.02 mm3). After 5 h of cavitation erosion testing in a 3.5 wt% NaCl solution, the coating exhibited a volume loss of 13.88 mm3 and a mass loss of 118 mg, which are 80 % and 38 % lower, respectively, than those of the uncoated ZL101A substrate (70 mm3, 189 mg). This superior performance is attributed to the synergistic effect of the ductile γ-Co solid solution matrix and the interconnected network of Cr7C3/(Cr,Co)2 3C6 hard carbides, which collectively mitigate the impact of cavitation-induced shock waves and micro-jets.
{"title":"Substantial improvement in cavitation erosion resistance of ZL101A aluminum alloy via Ultra-High-Speed laser Cladded Stellite 6 coating","authors":"Yu Shi , Peng Liao , Youwei Xu , Wuyao Xiong , Ming Zhu","doi":"10.1016/j.engfailanal.2026.110573","DOIUrl":"10.1016/j.engfailanal.2026.110573","url":null,"abstract":"<div><div>This study enhances the cavitation erosion resistance in ZL101A aluminum alloy via a Stellite 6 coating fabricated via ultra-high-speed laser cladding (UHSLC). The resulting approximately 400 μm thick coating exhibited a fine-grained microstructure and sound metallurgical bonding. A significant improvement in mechanical and tribological properties was achieved: the microhardness increased dramatically to 683.2 HV (9.3 times that of the substrate), and the friction coefficient was stabilized at 0.35. The coating’s erosion resistance was markedly improved: under solid particle impingement, it showed a mass loss of 21.66 mg and a volume loss of 3.35 mm3, corresponding to reductions of 24 % and 58 %, respectively, compared to the substrate (28.50 mg, 8.02 mm3). After 5 h of cavitation erosion testing in a 3.5 wt% NaCl solution, the coating exhibited a volume loss of 13.88 mm<sup>3</sup> and a mass loss of 118 mg, which are 80 % and 38 % lower, respectively, than those of the uncoated ZL101A substrate (70 mm<sup>3</sup>, 189 mg). This superior performance is attributed to the synergistic effect of the ductile γ-Co solid solution matrix and the interconnected network of Cr<sub>7</sub>C<sub>3</sub>/(Cr,Co)<sub>2 3</sub>C<sub>6</sub> hard carbides, which collectively mitigate the impact of cavitation-induced shock waves and micro-jets.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110573"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973283","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}
This study investigates the bio electrochemical impact of varying Headspace Volumes (HSV) as a key environmental control factor in the Microbiologically Influenced Corrosion (MIC) induced failure of API 5 L X65 pipeline steel. The degradation was driven by Enterobacter cloacae SCO6, a facultative anaerobe isolated from crude oil conveying infrastructure. The results quantitatively demonstrate that HSV significantly modulates the redox environment and metabolic state, thereby drastically accelerating the material failure rate. A clear, detrimental dependence on HSV was observed: the overall corrosion rate increased sharply from 9.84 to 25.20 mils/year as the HSV was expanded from 30 mL to 180 mL, a nearly fivefold acceleration compared to the abiotic control rate of 5.91mils/year. This escalating failure was confirmed by a consistent monotonic trend (ρ = 1, p = 0.03) between increasing bacterial counts and the rate of steel depolarization. Microstructural failure analysis via scanning electron microscopy and surface profilometry confirmed that higher HSV conditions promote highly aggressive localized attack, with maximum pit depths soaring from 6.61 µm (30 mL) to a severe16.85 µm (180 mL). Mechanistically, this failure acceleration is attributed to the HSV controlling dissolved H2S concentrations which enhances microbial viability and intensifies the extracellular electron transfer mechanism at the biofilm-electrode interface. This research provides crucial quantitative and mechanistic insight into how common operational gradients lead to unforeseen pipeline failure. This understanding is essential for optimizing maintenance protocols, implementing robust risk assessment and ultimately improving the longevity and safety of oil and gas infrastructure.
{"title":"Critical role of headspace volume in Microbiologically induced failure of API 5 L X65 pipeline steel: A bio electrochemical mechanism study using facultative anaerobe Enterobacter cloacae SCO6","authors":"C.A. Shefeena , Jesmi Yousuf , C.B. Sudheer , A.A Mohamed Hatha , A. Mathiazhagan , P.K Satheesh Babu , K.P Anand","doi":"10.1016/j.engfailanal.2026.110572","DOIUrl":"10.1016/j.engfailanal.2026.110572","url":null,"abstract":"<div><div>This study investigates the bio electrochemical impact of varying Headspace Volumes (HSV) as a key environmental control factor in the Microbiologically Influenced Corrosion (MIC) induced failure of API 5 L X65 pipeline steel. The degradation was driven by <em>Enterobacter cloacae</em> SCO6, a facultative anaerobe isolated from crude oil conveying infrastructure. The results quantitatively demonstrate that HSV significantly modulates the redox environment and metabolic state, thereby drastically accelerating the material failure rate. A clear, detrimental dependence on HSV was observed: the overall corrosion rate increased sharply from 9.84 to 25.20 mils/year as the HSV was expanded from 30 mL to 180 mL, a nearly fivefold acceleration compared to the abiotic control rate of 5.91mils/year. This escalating failure was confirmed by a consistent monotonic trend (ρ = 1, p = 0.03) between increasing bacterial counts and the rate of steel depolarization. Microstructural failure analysis via scanning electron microscopy and surface profilometry confirmed that higher HSV conditions promote highly aggressive localized attack, with maximum pit depths soaring from 6.61 µm (30 mL) to a severe16.85 µm (180 mL). Mechanistically, this failure acceleration is attributed to the HSV controlling dissolved H<sub>2</sub>S concentrations which enhances microbial viability and intensifies the extracellular electron transfer mechanism at the biofilm-electrode interface. This research provides crucial quantitative and mechanistic insight into how common operational gradients lead to unforeseen pipeline failure. This understanding is essential for optimizing maintenance protocols, implementing robust risk assessment and ultimately improving the longevity and safety of oil and gas infrastructure.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110572"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973286","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 : 2026-03-15Epub Date: 2026-01-11DOI: 10.1016/j.engfailanal.2026.110574
Alaa E. Abdelmoniem, M. Megahed, Mohamad A. Hassan, Ahmed Ibrahim
This study attempts to restore the quasi-static indentation (QSI) performance of damaged woven and chopped glass-fiber/epoxy laminates by applying different repair methods which are low cost and easy to apply. Four different repair techniques were applied to the delaminated glass-fiber/epoxy Laminates. Compared to the pristine specimen, the traditional patch repair was capable of restoring 39.5 % and 48.98 % in terms of maximum load capacity for both woven and chopped laminates. Injection repair after rebounding the surface to its original geometry, by applying heat 90 °C and pressure 20 kg, has 71.13 % and 56.87 % efficiency of maximum load recovery for both W and C specimens. Two different stitching repair patterns were developed to the damaged zone in order to study to what extent this method of stitching would restore the original load capacity. Every pattern reveals a significant percentage of restoring the original indentation performance. The first stitching pattern results 87.02 % and 82.32 % for woven/epoxy and chopped/epoxy composites, respectively. The other pattern shows distinctive powerful ability in restoring maximum load capacity as 101.7 % and 98.33 % for woven/epoxy and chopped/epoxy composites, respectively. Also, the efficiency of the repair techniques in terms of the absorbed energy was investigated during this work. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy analysis are performed to indicate and quantify the subsurface delamination and to confirm the restoration at the fiber/matrix interface.
{"title":"The influence of localized repair techniques on the indentation performance of delaminated glass-fiber/epoxy laminates","authors":"Alaa E. Abdelmoniem, M. Megahed, Mohamad A. Hassan, Ahmed Ibrahim","doi":"10.1016/j.engfailanal.2026.110574","DOIUrl":"10.1016/j.engfailanal.2026.110574","url":null,"abstract":"<div><div>This study attempts to restore the quasi-static indentation (QSI) performance of damaged woven and chopped glass-fiber/epoxy laminates by applying different repair methods which are low cost and easy to apply. Four different repair techniques were applied to the delaminated glass-fiber/epoxy Laminates. Compared to the pristine specimen, the traditional patch repair was capable of restoring 39.5 % and 48.98 % in terms of maximum load capacity for both woven and chopped laminates. Injection repair after rebounding the surface to its original geometry, by applying heat 90 °C and pressure 20 kg, has 71.13 % and 56.87 % efficiency of maximum load recovery for both W and C specimens. Two different stitching repair patterns were developed to the damaged zone in order to study to what extent this method of stitching would restore the original load capacity. Every pattern reveals a significant percentage of restoring the original indentation performance. The first stitching pattern results 87.02 % and 82.32 % for woven/epoxy and chopped/epoxy composites, respectively. The other pattern shows distinctive powerful ability in restoring maximum load capacity as 101.7 % and 98.33 % for woven/epoxy and chopped/epoxy composites, respectively. Also, the efficiency of the repair techniques in terms of the absorbed energy was investigated during this work. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy analysis are performed to indicate and quantify the subsurface delamination and to confirm the restoration at the fiber/matrix interface.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110574"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145973373","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}
This paper addresses the strength issues of the metro pantograph under complex operational conditions, systematically investigating its structural mechanical properties and optimization strategies through finite element modeling and experimental validation. A finite element model of the pantograph was first developed and validated through bench tests. The maximum discrepancy between the simulation and experimental results was less than 20 %, confirming that the model accurately reflects the load-bearing characteristics of the pantograph. Subsequently, the effects of raising height, stagger, and longitudinal impact load on the strength of the pantograph were analyzed. The results show that the raising height is negatively correlated with peak stress, the stagger primarily affects the pantograph head suspension and upper arm, and longitudinal impact load significantly influences the upper arm and pantograph head suspension. A multi-variable coupling analysis identified the limiting operational conditions as a raising height of 200 mm, stagger of −300 mm, and longitudinal load of −300 N. Under these conditions, the safety factor of the front support of the lift device in the base is only 1.04, making it the weak point of the pantograph. To address this issue, an optimization approach was proposed involving local thickening of the front beam of the base and the pivot shaft of the lower arm. Finite element simulations showed that the safety factors increased to above 1.5 and 2.0, respectively, with negligible weight increase, having an almost negligible impact on the pantograph’s dynamic performance. The findings clearly identify the limiting operational conditions and vulnerable components of the metro pantograph, and propose an efficient and feasible structural optimization path, providing important references for the design improvement and engineering application of metro pantographs.
{"title":"Impact of metro pantograph raising height, stagger, and longitudinal load on component strain: experimental validation and optimization","authors":"Wenyan Qi , Haoan Yu , Chengbin Peng , Guiming Mei , Jiwang Zhang , Weihua Zhang","doi":"10.1016/j.engfailanal.2025.110494","DOIUrl":"10.1016/j.engfailanal.2025.110494","url":null,"abstract":"<div><div>This paper addresses the strength issues of the metro pantograph under complex operational conditions, systematically investigating its structural mechanical properties and optimization strategies through finite element modeling and experimental validation. A finite element model of the pantograph was first developed and validated through bench tests. The maximum discrepancy between the simulation and experimental results was less than 20 %, confirming that the model accurately reflects the load-bearing characteristics of the pantograph. Subsequently, the effects of raising height, stagger, and longitudinal impact load on the strength of the pantograph were analyzed. The results show that the raising height is negatively correlated with peak stress, the stagger primarily affects the pantograph head suspension and upper arm, and longitudinal impact load significantly influences the upper arm and pantograph head suspension. A multi-variable coupling analysis identified the limiting operational conditions as a raising height of 200 mm, stagger of −300 mm, and longitudinal load of −300 N. Under these conditions, the safety factor of the front support of the lift device in the base is only 1.04, making it the weak point of the pantograph. To address this issue, an optimization approach was proposed involving local thickening of the front beam of the base and the pivot shaft of the lower arm. Finite element simulations showed that the safety factors increased to above 1.5 and 2.0, respectively, with negligible weight increase, having an almost negligible impact on the pantograph’s dynamic performance. The findings clearly identify the limiting operational conditions and vulnerable components of the metro pantograph, and propose an efficient and feasible structural optimization path, providing important references for the design improvement and engineering application of metro pantographs.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110494"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837830","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 : 2026-03-15Epub Date: 2025-12-26DOI: 10.1016/j.engfailanal.2025.110470
Ying Li , He Li , Xiangmin Dong , Zhifeng Liu , Lide Ma , Tengfei Bai
Thread seizure is a common mechanical failure mode that challenges product assembly reliability and increases maintenance costs. However, the underlying mechanism of seizure failure in threaded fasteners and the criteria for its identification require further investigation. This study investigates the damage process on the thread engagement surfaces and establishes a seizure failure criterion for threaded connections based on damage mechanics theory. To verify the model’s accuracy and universality, experiments were conducted to analyze the influence of material, speed, and torque on the seizure failure of threaded connections. Scanning electron microscopy (SEM) observations revealed that the seizure failure process can be divided into three stages: crack initiation on the engagement surfaces, material detachment, and debris accumulation. Building upon this, simulations were performed to analyze the influence mechanisms of fastener material, thread surface friction coefficient, bearing surface friction coefficient, and hole diameter ratio on thread seizure. The results indicate that fasteners made of titanium alloy (TC4) are more susceptible to seizure, and the thread surface friction coefficient contributes 60.7%–73.4% to the failure process in both material types. By elucidating the seizure failure mechanism in threaded connections, this study provides theoretical support for research into anti-seizure methods.
{"title":"Analysis of the seizure failure mechanism in threaded fasteners and experimental investigation","authors":"Ying Li , He Li , Xiangmin Dong , Zhifeng Liu , Lide Ma , Tengfei Bai","doi":"10.1016/j.engfailanal.2025.110470","DOIUrl":"10.1016/j.engfailanal.2025.110470","url":null,"abstract":"<div><div>Thread seizure is a common mechanical failure mode that challenges product assembly reliability and increases maintenance costs. However, the underlying mechanism of seizure failure in threaded fasteners and the criteria for its identification require further investigation. This study investigates<!--> <!-->the damage process on the thread engagement surfaces and<!--> <!-->establishes<!--> <!-->a<!--> <!-->seizure<!--> <!-->failure<!--> <!-->criterion<!--> <!-->for threaded connections based on damage mechanics theory. To verify the model’s accuracy and universality, experiments were conducted to analyze the influence of material, speed, and torque on the seizure failure of threaded connections. Scanning electron microscopy (SEM) observations revealed that the seizure failure process can be divided into three stages: crack initiation on the engagement surfaces, material detachment, and debris accumulation. Building upon this, simulations were performed to analyze the influence mechanisms of fastener material, thread surface friction coefficient, bearing surface friction coefficient, and hole diameter ratio on thread seizure. The results indicate that fasteners made of titanium alloy (TC4) are more susceptible to seizure, and the thread surface friction coefficient contributes 60.7%–73.4% to the failure process in both material types. By elucidating the seizure failure mechanism in threaded connections, this study provides theoretical support for research into anti-seizure methods.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110470"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921273","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 : 2026-03-15Epub Date: 2026-01-05DOI: 10.1016/j.engfailanal.2026.110535
Hengzhen Li , Huining Xu , Yiqiu Tan , Hongliang Qian
Freeze-thaw (F-T) and vehicle load are the main external forces acting on asphalt pavement in cold regions. Their concurrent action inflicts severe pavement damage, yet existing research has largely overlooked their combined impact, hampering a comprehensive understanding of asphalt concrete’s damage characteristics under combined F-T and load (F-T-L) conditions. Therefore, this study employed a custom-designed F-T-L testing device to simulate asphalt pavement damage scenarios. Coupling the digital image correlation method (DIC) with computed tomography technology (CT), we meticulously tracked the strain evolution within cross-sectional images of asphalt concrete samples. By comparing the strain distribution and development under F-T-L and F-T cycles, the influence of load on the deterioration of asphalt concrete under F-T cycles was clarified. The strain images of the sectional image of the specimen intuitively show that the area rich in void and the mortar interface were vulnerable areas, and with the continuous application of external forces, the strain level increased and the damage progressed unevenly. The differences in strain distribution under F-T-L and F-T underscore that F-T action primarily drives expansive deformation in asphalt concrete, while load intensifies the deformation, introducing damage gradients, and augmenting damage non-uniformity, especially under high load levels. Our study not only uncovers the intricate interplay between F-T and load but also provides critical insights for enhancing pavement durability in frigid climates.
{"title":"Investigation of asphalt concrete damage under the combined action of freeze-thaw and load using DIC-CT method","authors":"Hengzhen Li , Huining Xu , Yiqiu Tan , Hongliang Qian","doi":"10.1016/j.engfailanal.2026.110535","DOIUrl":"10.1016/j.engfailanal.2026.110535","url":null,"abstract":"<div><div>Freeze-thaw (F-T) and vehicle load are the main external forces acting on asphalt pavement in cold regions. Their concurrent action inflicts severe pavement damage, yet existing research has largely overlooked their combined impact, hampering a comprehensive understanding of asphalt concrete’s damage characteristics under combined F-T and load (F-T-L) conditions. Therefore, this study employed a custom-designed F-T-L testing device to simulate asphalt pavement damage scenarios. Coupling the digital image correlation method (DIC) with computed tomography technology (CT), we meticulously tracked the strain evolution within cross-sectional images of asphalt concrete samples. By comparing the strain distribution and development under F-T-L and F-T cycles, the influence of load on the deterioration of asphalt concrete under F-T cycles was clarified. The strain images of the sectional image of the specimen intuitively show that the area rich in void and the mortar interface were vulnerable areas, and with the continuous application of external forces, the strain level increased and the damage progressed unevenly. The differences in strain distribution under F-T-L and F-T underscore that F-T action primarily drives expansive deformation in asphalt concrete, while load intensifies the deformation, introducing damage gradients, and augmenting damage non-uniformity, especially under high load levels. Our study not only uncovers the intricate interplay between F-T and load but also provides critical insights for enhancing pavement durability in frigid climates.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110535"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921285","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 : 2026-03-15Epub Date: 2026-01-02DOI: 10.1016/j.engfailanal.2026.110527
Guang Liu , Guochun Wang , Chao Wang , Youping Sun , Wangzhen Li , Chengbo Gu
For 0.8 mm thick steel sheets, conventional self-piercing riveting (C-SPR) joints are prone to failure on the weaker side of the steel sheet. The gasket-assisted self-piercing riveting (GA-SPR) process is proposed to enhance the fatigue life and mechanical performance of SPR joints composed of thin steel sheet. This study utilizes quasi-static shear, fatigue tests, and microscopic analysis to study the impact of gasket diameter and thickness on the mechanical performance, failure modes, failure mechanisms, and fatigue life. Fatigue life is predicted based on the Weibull distribution. The results indicate that GA-SPR joints exhibit a greater undercut compared to the C-SPR joint(without gasket), with an average increase of 16.4 %. As the gasket thickness increases, the undercut value decreases. The peak force and energy absorption of the G06-25 joint improved by 30.71 % and 97.04 %, respectively, compared to the C-SPR joint. The peak force and energy absorption of GA-SPR joints decrease with increasing gasket thickness, but increase with larger gasket diameter. At the same load level, GA-SPR joints show a significant advantage in fatigue performance over C-SPR joints. The load amplitudes with fatigue life of 105 and 106 cycles increase by 30.8 % and 25.2 %, respectively.
{"title":"Study on the influence of gasket thickness and diameter on mechanical and fatigue performance of gasket-assisted self-piercing riveting joints with thinner steel sheet","authors":"Guang Liu , Guochun Wang , Chao Wang , Youping Sun , Wangzhen Li , Chengbo Gu","doi":"10.1016/j.engfailanal.2026.110527","DOIUrl":"10.1016/j.engfailanal.2026.110527","url":null,"abstract":"<div><div>For 0.8 mm thick steel sheets, conventional self-piercing riveting (C-SPR) joints are prone to failure on the weaker side of the steel sheet. The gasket-assisted self-piercing riveting (GA-SPR) process is proposed to enhance the fatigue life and mechanical performance of SPR joints composed of thin steel sheet. This study utilizes quasi-static shear, fatigue tests, and microscopic analysis to study the impact of gasket diameter and thickness on the mechanical performance, failure modes, failure mechanisms, and fatigue life. Fatigue life is predicted based on the Weibull distribution. The results indicate that GA-SPR joints exhibit a greater undercut compared to the C-SPR joint(without gasket), with an average increase of 16.4 %. As the gasket thickness increases, the undercut value decreases. The peak force and energy absorption of the G06-25 joint improved by 30.71 % and 97.04 %, respectively, compared to the C-SPR joint. The peak force and energy absorption of GA-SPR joints decrease with increasing gasket thickness, but increase with larger gasket diameter. At the same load level, GA-SPR joints show a significant advantage in fatigue performance over C-SPR joints. The load amplitudes with fatigue life of 10<sup>5</sup> and 10<sup>6</sup> cycles increase by 30.8 % and 25.2 %, respectively.</div></div>","PeriodicalId":11677,"journal":{"name":"Engineering Failure Analysis","volume":"186 ","pages":"Article 110527"},"PeriodicalIF":5.7,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145921366","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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