International Journal of Fatigue最新文献

英文中文

Surface fatigue in lubricated contacts: Mapping the failure modes of micropitting versus macropitting

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-04 DOI: 10.1016/j.ijfatigue.2025.108908

B. Wainwright, A. Kadiric

This paper presents a surface-fatigue failure mode map to identify contact conditions which preferentially lead to (i) micropitting, (ii) initial micropitting transitioning to surface-initiated macropitting, and (iii) surface-initiated macropitting failure modes in lubricated rolling-sliding contacts representative of rolling bearings and gears. The study used a triple disc fatigue rig to systematically investigate the effect of contact pressure, surface roughness and Λ-ratio on the type of surface fatigue damage mode. Specimens made of case-carburised 16MnCr5 steel and a custom-blended PAO + ZDDP oil were used. Results show that higher Hertz contact pressures strongly favour the occurrence of macropitting over micropitting; In present tests no macropitting was detected in any tests at Hertz pressures less than 1.5 GPa. Conversely, lower pressures favour micropitting. This is likely due to higher macro-pressure being able to drive the surface-initiated cracks deeper into the subsurface material, which was shown to be a pre-requisite for formation of macropits. Higher roughness favours micropitting due to higher asperity stresses, while the influence of Λ-ratio on the type of failure mode is relatively weak as long as contact is within mixed/boundary lubrication regime. Higher roughness and lower Λ increased the severity of micropitting. Micropitting incubation time was between 100,000 and 1 million cycles depending on contact conditions, it is shorter for higher R_q and/or lower Λ. Transition of initial micropitting to a more damaging macropitting mode is promoted by higher Hertz pressures but impeded by more severe rates of micropitting wear which occur at higher roughnesses and lower Λ-ratios. Given the different implications of micropitting versus macropitting, the presented failure mode map can be used during the design process to help improve the reliability of machines.

{"title":"Surface fatigue in lubricated contacts: Mapping the failure modes of micropitting versus macropitting","authors":"B. Wainwright, A. Kadiric","doi":"10.1016/j.ijfatigue.2025.108908","DOIUrl":"10.1016/j.ijfatigue.2025.108908","url":null,"abstract":"<div><div>This paper presents a surface-fatigue failure mode map to identify contact conditions which preferentially lead to (i) micropitting, (ii) initial micropitting transitioning to surface-initiated macropitting, and (iii) surface-initiated macropitting failure modes in lubricated rolling-sliding contacts representative of rolling bearings and gears. The study used a triple disc fatigue rig to systematically investigate the effect of contact pressure, surface roughness and Λ-ratio on the type of surface fatigue damage mode. Specimens made of case-carburised 16MnCr5 steel and a custom-blended PAO + ZDDP oil were used. Results show that higher Hertz contact pressures strongly favour the occurrence of macropitting over micropitting; In present tests no macropitting was detected in any tests at Hertz pressures less than 1.5 GPa. Conversely, lower pressures favour micropitting. This is likely due to higher macro-pressure being able to drive the surface-initiated cracks deeper into the subsurface material, which was shown to be a pre-requisite for formation of macropits. Higher roughness favours micropitting due to higher asperity stresses, while the influence of Λ-ratio on the type of failure mode is relatively weak as long as contact is within mixed/boundary lubrication regime. Higher roughness and lower Λ increased the severity of micropitting. Micropitting incubation time was between 100,000 and 1 million cycles depending on contact conditions, it is shorter for higher R<sub>q</sub> and/or lower Λ. Transition of initial micropitting to a more damaging macropitting mode is promoted by higher Hertz pressures but impeded by more severe rates of micropitting wear which occur at higher roughnesses and lower Λ-ratios. Given the different implications of micropitting versus macropitting, the presented failure mode map can be used during the design process to help improve the reliability of machines.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108908"},"PeriodicalIF":5.7,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Potentials and limitations of direct current potential drop for measuring elliptical cracks in round bars

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-03 DOI: 10.1016/j.ijfatigue.2025.108904

Luca Vecchiato , Alberto Campagnolo , Matteo Cova , Giovanni Meneghetti

This study investigates potentials and limitations of the Direct Current Potential Drop (DCPD) method for monitoring fatigue crack size in single-edge-crack round bars made of 42CrMo4 steel. Specimens with a semi-elliptical crack-starter notch were tested under axial fatigue loading, with DCPD applied in various configurations to evaluate the impact of current and potential probe positions on measurement overall accuracy. Therefore, experimental DCPD calibration data were developed by correlating the measured signals with the corresponding crack fronts identified through beach marking. Eventually, experimental data were compared with calibration curves obtained from electrical FE analyses, where semi-elliptical cracks were modelled using crack fronts best fitted to the beach-marked experimental fronts. The results confirmed the reliability and accuracy of DCPD for monitoring fatigue crack growth in single-edge-crack round bars, provided that the propagating crack shape is known a priori. Moreover, the effect of probe positioning was highlighted: current injection near the crack plane with potential probes at the crack symmetry plane improved measurability, while the highest sensitivity was achieved with probes near the crack tip. Both local and remote current injections, with current and potential probes at the crack symmetry plane, provided comparable accuracy, making these setups promising for experimental fracture mechanics testing.

{"title":"Potentials and limitations of direct current potential drop for measuring elliptical cracks in round bars","authors":"Luca Vecchiato , Alberto Campagnolo , Matteo Cova , Giovanni Meneghetti","doi":"10.1016/j.ijfatigue.2025.108904","DOIUrl":"10.1016/j.ijfatigue.2025.108904","url":null,"abstract":"<div><div>This study investigates potentials and limitations of the Direct Current Potential Drop (DCPD) method for monitoring fatigue crack size in single-edge-crack round bars made of 42CrMo4 steel. Specimens with a semi-elliptical crack-starter notch were tested under axial fatigue loading, with DCPD applied in various configurations to evaluate the impact of current and potential probe positions on measurement overall accuracy. Therefore, experimental DCPD calibration data were developed by correlating the measured signals with the corresponding crack fronts identified through beach marking. Eventually, experimental data were compared with calibration curves obtained from electrical FE analyses, where semi-elliptical cracks were modelled using crack fronts best fitted to the beach-marked experimental fronts. The results confirmed the reliability and accuracy of DCPD for monitoring fatigue crack growth in single-edge-crack round bars, provided that the propagating crack shape is known a priori. Moreover, the effect of probe positioning was highlighted: current injection near the crack plane with potential probes at the crack symmetry plane improved measurability, while the highest sensitivity was achieved with probes near the crack tip. Both local and remote current injections, with current and potential probes at the crack symmetry plane, provided comparable accuracy, making these setups promising for experimental fracture mechanics testing.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108904"},"PeriodicalIF":5.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Energy-based multi-axial fatigue prediction for tubular structures under non-proportional loading

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-03 DOI: 10.1016/j.ijfatigue.2025.108897

Jiashan Gao , Shaoping Wang , Chao Zhang , Rentong Chen , Yunhao Zhang , Yuwei Zhang , Rui Mu

The tubular structure suffers from structural complexity, and it is also subjected to multi-axial loading, which makes the prediction of its fatigue life difficult. This study proposes a multi-axial fatigue life prediction model for tubular structures based on the energy method for non-proportional loading (MFLPM-ENPL). An energy-based method, considering the impact of residual stresses in welded joints, is first proposed. This model accurately captures the complexities of fatigue behavior by calculating the elastic strain energy of the tubular structure and the plastic strain energy at the welded part. To solve the problem of equivalent loading in the context of non-proportional load paths, a novel equivalent non-proportional factor is then designed. Tailored to the stress characteristics of tubular structures, it facilitates accurate load-equivalence conversion. Finally, by combining the designed non-proportional factor with the energy-based multi-axial fatigue life prediction method for tubular structures, a multi-axial fatigue life prediction model for tubular structures based on the energy method for non-proportional loading is developed. Through validation with diverse multi-axial test datasets—including various node types, material grades (e.g., C45 steel, Al6082-T6), and loading conditions—the proposed model achieves 93.6% accuracy within a 1.5

\times

scatter band, surpassing existing methods in both predictive precision and robustness. Furthermore, its extensible design accommodates the incorporation of variable-amplitude loading scenarios and advanced damage-accumulation models, underscoring its potential to improve structural reliability across a broad spectrum of engineering domains.

{"title":"Energy-based multi-axial fatigue prediction for tubular structures under non-proportional loading","authors":"Jiashan Gao , Shaoping Wang , Chao Zhang , Rentong Chen , Yunhao Zhang , Yuwei Zhang , Rui Mu","doi":"10.1016/j.ijfatigue.2025.108897","DOIUrl":"10.1016/j.ijfatigue.2025.108897","url":null,"abstract":"<div><div>The tubular structure suffers from structural complexity, and it is also subjected to multi-axial loading, which makes the prediction of its fatigue life difficult. This study proposes a multi-axial fatigue life prediction model for tubular structures based on the energy method for non-proportional loading (MFLPM-ENPL). An energy-based method, considering the impact of residual stresses in welded joints, is first proposed. This model accurately captures the complexities of fatigue behavior by calculating the elastic strain energy of the tubular structure and the plastic strain energy at the welded part. To solve the problem of equivalent loading in the context of non-proportional load paths, a novel equivalent non-proportional factor is then designed. Tailored to the stress characteristics of tubular structures, it facilitates accurate load-equivalence conversion. Finally, by combining the designed non-proportional factor with the energy-based multi-axial fatigue life prediction method for tubular structures, a multi-axial fatigue life prediction model for tubular structures based on the energy method for non-proportional loading is developed. Through validation with diverse multi-axial test datasets—including various node types, material grades (e.g., C45 steel, Al6082-T6), and loading conditions—the proposed model achieves 93.6% accuracy within a 1.5<span><math><mo>×</mo></math></span> scatter band, surpassing existing methods in both predictive precision and robustness. Furthermore, its extensible design accommodates the incorporation of variable-amplitude loading scenarios and advanced damage-accumulation models, underscoring its potential to improve structural reliability across a broad spectrum of engineering domains.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108897"},"PeriodicalIF":5.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fatigue life prediction and optimization of two-stage stiffness leaf spring with ANN

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-03 DOI: 10.1016/j.ijfatigue.2025.108899

Weihuan Chen , Junhui Zhao

Fatigue life prediction of leaf springs is critical during the vehicle design stage. Fatigue life calculation based on linear superposition cannot guarantee accuracy, while fatigue life calculation based on direct transient analysis is extremely time-consuming. This paper aims to assess the fatigue life of two-stage stiffness leaf springs under random road loads with high accuracy and efficiency. The key to predicting the fatigue life of two-stage stiffness leaf springs is to calculate the full-field stress-time history based on artificial neural networks (ANN) and finite element analysis (FEA). Road loads were measured using a road test, and multi-body simulation (MBS) was performed to calculate the leaf spring force-time history. Statistical analysis was conducted on the force-time history to generate input for FEA to acquire ANN training data. The ANN was built and trained to calculate the leaf spring stress-time history using the leaf spring force-time history as input. Fatigue life calculations were performed using the stress-time history. The results show that the calculation efficiency of the stress-time history based on ANN is improved by orders of magnitude compared to transient dynamics analysis. Meanwhile, the calculated fatigue life correlates well with the test results, and different loads have different contributions to fatigue damage.

{"title":"Fatigue life prediction and optimization of two-stage stiffness leaf spring with ANN","authors":"Weihuan Chen , Junhui Zhao","doi":"10.1016/j.ijfatigue.2025.108899","DOIUrl":"10.1016/j.ijfatigue.2025.108899","url":null,"abstract":"<div><div>Fatigue life prediction of leaf springs is critical during the vehicle design stage. Fatigue life calculation based on linear superposition cannot guarantee accuracy, while fatigue life calculation based on direct transient analysis is extremely time-consuming. This paper aims to assess the fatigue life of two-stage stiffness leaf springs under random road loads with high accuracy and efficiency. The key to predicting the fatigue life of two-stage stiffness leaf springs is to calculate the full-field stress-time history based on artificial neural networks (ANN) and finite element analysis (FEA). Road loads were measured using a road test, and multi-body simulation (MBS) was performed to calculate the leaf spring force-time history. Statistical analysis was conducted on the force-time history to generate input for FEA to acquire ANN training data. The ANN was built and trained to calculate the leaf spring stress-time history using the leaf spring force-time history as input. Fatigue life calculations were performed using the stress-time history. The results show that the calculation efficiency of the stress-time history based on ANN is improved by orders of magnitude compared to transient dynamics analysis. Meanwhile, the calculated fatigue life correlates well with the test results, and different loads have different contributions to fatigue damage.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108899"},"PeriodicalIF":5.7,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143562003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A novel notch classification model for stress gradient-based fatigue life prediction under low and high cycle fatigue loading

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-02 DOI: 10.1016/j.ijfatigue.2025.108907

Jiayuan Gu , Rui Zhang , Xiaowei Wang , Heng Li , He Zhu , Xiancheng Zhang , Jianming Gong , Shantung Tu

In this work, a novel notch classification approach that considers the notch effects is developed. The classification of notches is implemented based on the stress gradient along the most critical path, defining the stress field diameter that quantifies the localized fatigue damage of the component. Then, a modified field intensity fatigue life prediction model using the developed notch classification is proposed. To evaluate the prediction capability of the proposed method, life predictions for various notch types of Inconel 718, Stainless steel 304 and 316H are carried out. For high temperature low cycle fatigue tests, the proposed model keeps the prediction accuracy of notched components falling within the scatter band of 2 times. Furthermore, the model also demonstrates satisfactory life prediction capabilities for high cycle fatigue. Finally, a scheme for predicting S-N curves of notched specimen is presented and validated.

引用次数: 0

Mechanism investigation of anisotropy in impact fatigue property of laser-deposited Ti-6Al-4V

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-02 DOI: 10.1016/j.ijfatigue.2025.108906

Sihan Zhao , Kangbo Yuan , Boli Li , Yushan Liu , Ruifeng Wang , Minghao Wang , Lin Jing , Weiguo Guo

For structures that are subjected to repeated impacts in service, it is critical to evaluate their impact fatigue life. When we tested the impact fatigue performance of laser metal deposited (LMD) Ti-6Al-4V (Ti64) in different orientations with our newly developed impact fatigue test device, it was found that its impact fatigue life exhibits anisotropy. Therefore, this study carried out systematic impact fatigue tests and microscopic analysis to reveal the source of anisotropy in the impact fatigue life of LMD Ti64. The SEM results show that the fatigue crack propagation process can be divided into two stages: short crack and long crack propagation stages. The impact fatigue crack propagates along the α laths and β columnar grain boundaries at the short crack stage, while directly through columnar grains at the long crack stage. Therefore, the fatigue life at the short crack stage exhibits anisotropy. Another important finding is that the impact fatigue life is significantly shorter than the non-impact fatigue life. This is due to the large localized plastic deformation caused by the impact load, which leads to the early initiation of cracks. This work contributes to revealing the fatigue failure mechanism of LMD Ti64 under repeated impact loading.

{"title":"Mechanism investigation of anisotropy in impact fatigue property of laser-deposited Ti-6Al-4V","authors":"Sihan Zhao , Kangbo Yuan , Boli Li , Yushan Liu , Ruifeng Wang , Minghao Wang , Lin Jing , Weiguo Guo","doi":"10.1016/j.ijfatigue.2025.108906","DOIUrl":"10.1016/j.ijfatigue.2025.108906","url":null,"abstract":"<div><div>For structures that are subjected to repeated impacts in service, it is critical to evaluate their impact fatigue life. When we tested the impact fatigue performance of laser metal deposited (LMD) Ti-6Al-4V (Ti64) in different orientations with our newly developed impact fatigue test device, it was found that its impact fatigue life exhibits anisotropy. Therefore, this study carried out systematic impact fatigue tests and microscopic analysis to reveal the source of anisotropy in the impact fatigue life of LMD Ti64. The SEM results show that the fatigue crack propagation process can be divided into two stages: short crack and long crack propagation stages. The impact fatigue crack propagates along the α laths and β columnar grain boundaries at the short crack stage, while directly through columnar grains at the long crack stage. Therefore, the fatigue life at the short crack stage exhibits anisotropy. Another important finding is that the impact fatigue life is significantly shorter than the non-impact fatigue life. This is due to the large localized plastic deformation caused by the impact load, which leads to the early initiation of cracks. This work contributes to revealing the fatigue failure mechanism of LMD Ti64 under repeated impact loading.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"196 ","pages":"Article 108906"},"PeriodicalIF":5.7,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143549476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Variance integral method for predicting in-plane biaxial fatigue life under asynchronous sinusoidal loading

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-02 DOI: 10.1016/j.ijfatigue.2025.108905

Youzhi Liu, Yunlong Li, Jinglong Zhao, Peifei Xu, Peiwei Zhang, Qingguo Fei

The asynchronous fatigue loading typically leads to a more complex damage mechanism and early fatigue failure. In this study, a novel Variance Integral Method (VIM) is proposed based on the framework of the integral method to determine an equivalent stress for fatigue life prediction under asynchronous loading. Firstly, the equivalent stress is obtained by performing a spherical integration of the resolved stress across all material planes, rather than focusing on a critical plane, to avoid the complexity of direction selection. Subsequently, asynchronous in-plane biaxial fatigue experiments were conducted on 8 nickel-based superalloy cruciform specimens at 420 °C, considering variations in frequency ratios and initial phase differences. Predicted fatigue lives under different loading paths were evaluated using the modified Papadopoulos model. The results show that the predicted fatigue lives are in good agreement with the experimental data, with a scatter factor within 2 about the mean life. Additionally, the effects of asynchrony including the frequency ratio and the phase difference effects are discussed. The findings suggest that the in-plane biaxial fatigue loading path does not induce non-proportional additional hardening of materials.

{"title":"Variance integral method for predicting in-plane biaxial fatigue life under asynchronous sinusoidal loading","authors":"Youzhi Liu, Yunlong Li, Jinglong Zhao, Peifei Xu, Peiwei Zhang, Qingguo Fei","doi":"10.1016/j.ijfatigue.2025.108905","DOIUrl":"10.1016/j.ijfatigue.2025.108905","url":null,"abstract":"<div><div>The asynchronous fatigue loading typically leads to a more complex damage mechanism and early fatigue failure. In this study, a novel Variance Integral Method (VIM) is proposed based on the framework of the integral method to determine an equivalent stress for fatigue life prediction under asynchronous loading. Firstly, the equivalent stress is obtained by performing a spherical integration of the resolved stress across all material planes, rather than focusing on a critical plane, to avoid the complexity of direction selection. Subsequently, asynchronous in-plane biaxial fatigue experiments were conducted on 8 nickel-based superalloy cruciform specimens at 420 °C, considering variations in frequency ratios and initial phase differences. Predicted fatigue lives under different loading paths were evaluated using the modified Papadopoulos model. The results show that the predicted fatigue lives are in good agreement with the experimental data, with a scatter factor within 2 about the mean life. Additionally, the effects of asynchrony including the frequency ratio and the phase difference effects are discussed. The findings suggest that the in-plane biaxial fatigue loading path does not induce non-proportional additional hardening of materials.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108905"},"PeriodicalIF":5.7,"publicationDate":"2025-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fatigue fracture mechanism and life prediction of nickel-based single crystal superalloy with film cooling holes considering initial manufacturing damage 带薄膜冷却孔的镍基单晶超合金的疲劳断裂机理和寿命预测（考虑初始制造损伤

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-03-01 DOI: 10.1016/j.ijfatigue.2025.108902

Fei Li , Zhixun Wen , Lei Luo , Xi Ren , Yuan Li , Haiqing Pei , Zhufeng Yue

Film cooling holes (FCHs) in nickel-based single crystal superalloy turbine blades are critical yet fracture-prone regions, where assessing initial manufacturing damage and predicting fatigue life remain significant challenges. This study employs the equivalent initial flaw size (EIFS) model to evaluate initial damage in FCH structures and introduces a probabilistic fracture mechanics framework for fatigue life prediction. A 3D helical fluid dynamics model is developed to compute temperature and stress fields at FCH edges. A multi-angle rotatable 3D XRD device measures six interplanar spacings, enabling residual stress assessment in FCH micro-regions and validating manufacturing simulations. By quantifying geometric, metallurgical, and mechanical parameters, the initial damage state of FCHs is characterized. The EIFS strategy, applied via the time to crack initiation (TTCI) method, comprehensively quantifies this damage. The study investigates fatigue fracture mechanisms, proposes a unified crack extension driving force (ΔM_eff), and develops a probabilistic fracture mechanics model. Using the “double 95″ EIFS (EIFS_95/95) within probabilistic crack propagation rates, the fatigue life of FCHs at 850 °C is predicted and experimentally validated. Results reveal that initial damage significantly influences crack initiation and propagation, with thermal damage zones exhibiting high dislocation activity and oxidation-induced γ’-free areas serving as critical crack initiation sites. The EIFS_95/95 value is calculated as 0.0429 mm, and predicted fatigue life falls within a two-fold scatter band compared to experimental data. This study successfully predicts fatigue life while accounting for initial manufacturing damage, providing a novel approach for designing FCHs with improved longevity and reliability.

{"title":"Fatigue fracture mechanism and life prediction of nickel-based single crystal superalloy with film cooling holes considering initial manufacturing damage","authors":"Fei Li , Zhixun Wen , Lei Luo , Xi Ren , Yuan Li , Haiqing Pei , Zhufeng Yue","doi":"10.1016/j.ijfatigue.2025.108902","DOIUrl":"10.1016/j.ijfatigue.2025.108902","url":null,"abstract":"<div><div>Film cooling holes (FCHs) in nickel-based single crystal superalloy turbine blades are critical yet fracture-prone regions, where assessing initial manufacturing damage and predicting fatigue life remain significant challenges. This study employs the equivalent initial flaw size (EIFS) model to evaluate initial damage in FCH structures and introduces a probabilistic fracture mechanics framework for fatigue life prediction. A 3D helical fluid dynamics model is developed to compute temperature and stress fields at FCH edges. A multi-angle rotatable 3D XRD device measures six interplanar spacings, enabling residual stress assessment in FCH micro-regions and validating manufacturing simulations. By quantifying geometric, metallurgical, and mechanical parameters, the initial damage state of FCHs is characterized. The EIFS strategy, applied via the time to crack initiation (TTCI) method, comprehensively quantifies this damage. The study investigates fatigue fracture mechanisms, proposes a unified crack extension driving force (Δ<em>M</em><sub>eff</sub>), and develops a probabilistic fracture mechanics model. Using the “double 95″ EIFS (EIFS<sub>95/95</sub>) within probabilistic crack propagation rates, the fatigue life of FCHs at 850 °C is predicted and experimentally validated. Results reveal that initial damage significantly influences crack initiation and propagation, with thermal damage zones exhibiting high dislocation activity and oxidation-induced γ’-free areas serving as critical crack initiation sites. The EIFS<sub>95/95</sub> value is calculated as 0.0429 mm, and predicted fatigue life falls within a two-fold scatter band compared to experimental data. This study successfully predicts fatigue life while accounting for initial manufacturing damage, providing a novel approach for designing FCHs with improved longevity and reliability.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"197 ","pages":"Article 108902"},"PeriodicalIF":5.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The effect of gear module on bending fatigue failure location in carburized and shot-peened spur gears 齿轮模数对渗碳和喷丸正齿轮弯曲疲劳失效位置的影响

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-02-28 DOI: 10.1016/j.ijfatigue.2025.108901

Ivan Čular, Ivica Galić, Robert Mašović, Krešimir Vučković

Shot-peening is an emerging method used to improve the bending fatigue resistance of carburized gears. However, even though this method improves the bending fatigue resistance at the surface, bending fatigue crack initiation often shifts below the surface, making it harder to detect during regular service intervals. In this paper, an experimentally validated computational model based on the finite element analysis and the multilayer method is used to investigate the effect of gear geometry, specifically its module, on the probability of subsurface bending fatigue failure. The main goal is to reduce the chance of subsurface bending fatigue failure while retaining the beneficial effects of shot-peening. Four optimal gear modules are chosen for the investigation with respect to bending fatigue while maintaining constant fatigue properties and residual stress profiles. The results demonstrate that choosing a lower module decreases the probability of subsurface bending fatigue crack initiation in carburized and shot-peened gears. Lastly, it is also suggested that optimizing carburization parameters may enhance the beneficial compressive residual stresses below the surface, lowering the probability of subsurface bending fatigue crack initiation.

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引用次数: 0

Effect of heat input on microstructural characteristics and fatigue property of heat-affected zone in a FH690 heavy-gauge marine steel

IF 5.7 2区材料科学 Q1 ENGINEERING, MECHANICAL

International Journal of Fatigue

Pub Date : 2025-02-24 DOI: 10.1016/j.ijfatigue.2025.108898

Y. Bai , X. Guo , X.J. Sun , G.Y. Liu , Z.J. Xie , X.L. Wang , C.J. Shang

We demonstrated here the effect of welding heat input on the microstructure characteristics and fatigue behavior of the multi-pass welded joint of a FH690 grade ultra-heavy steel plate. The welded joint with a heat input of ∼15 kJ/cm exhibited higher ultimate fatigue stress (407 MPa at endurance limit of 10⁷ cycles) than that of ∼50 kJ/cm. Moreover, the welded joint with a heat input of ∼15 kJ/cm fractured within weld metal (WM), while it fractured within the coarse-grained heat affected zone (CGHAZ) with ∼50 kJ/cm. Microstructure characterization revealed that uniform lath bainite was obtained in CGHAZ by ∼15 kJ/cm heat input, whereas granular bainite with martensite-austenite (MA) constituents was obtained in CGHAZ with ∼50 kJ/cm. Transmission electron microscopy (TEM) observations showed that twin martensite was observed in MA constituents. TEM observations suggested that twin martensite played a significant role in fatigue cracking by three aspects: 1) directly crack at interface between MA constituent and matrix; 2) promote the formation of micro-voids within coarse granular bainite; 3) nano grains were observed surrounding the twin martensite near to the fractured surface, suggesting plastic deformation locally occurred in bainite lath, resulting in recrystallization and soften, which promoted crack initiation.

{"title":"Effect of heat input on microstructural characteristics and fatigue property of heat-affected zone in a FH690 heavy-gauge marine steel","authors":"Y. Bai , X. Guo , X.J. Sun , G.Y. Liu , Z.J. Xie , X.L. Wang , C.J. Shang","doi":"10.1016/j.ijfatigue.2025.108898","DOIUrl":"10.1016/j.ijfatigue.2025.108898","url":null,"abstract":"<div><div>We demonstrated here the effect of welding heat input on the microstructure characteristics and fatigue behavior of the multi-pass welded joint of a FH690 grade ultra-heavy steel plate. The welded joint with a heat input of ∼15 kJ/cm exhibited higher ultimate fatigue stress (407 MPa at endurance limit of 10<sup>7</sup> cycles) than that of ∼50 kJ/cm. Moreover, the welded joint with a heat input of ∼15 kJ/cm fractured within weld metal (WM), while it fractured within the coarse-grained heat affected zone (CGHAZ) with ∼50 kJ/cm. Microstructure characterization revealed that uniform lath bainite was obtained in CGHAZ by ∼15 kJ/cm heat input, whereas granular bainite with martensite-austenite (MA) constituents was obtained in CGHAZ with ∼50 kJ/cm. Transmission electron microscopy (TEM) observations showed that twin martensite was observed in MA constituents. TEM observations suggested that twin martensite played a significant role in fatigue cracking by three aspects: 1) directly crack at interface between MA constituent and matrix; 2) promote the formation of micro-voids within coarse granular bainite; 3) nano grains were observed surrounding the twin martensite near to the fractured surface, suggesting plastic deformation locally occurred in bainite lath, resulting in recrystallization and soften, which promoted crack initiation.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"196 ","pages":"Article 108898"},"PeriodicalIF":5.7,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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