Pub Date : 2024-11-28DOI: 10.1016/j.ijfatigue.2024.108735
Ateeb Ahmad Khan, Indra Vir Singh, Bhanu Kumar Mishra, Ramadas Chennamsetti
This study presents an experimental investigation of the fatigue performance and damage distribution mechanism of bi-directional GFRP composites. Uniaxial fatigue tests have been conducted under load-control, at stress ratios, R = 0.1, 0.5 and critical stress ratio (χ=-0.9). The influence of gauge length and surface roughness on fatigue life has been examined for R = 0.1. An infrared (IR) camera is employed to monitor temperature evolution and capture thermal images during the fatigue experiments. Fatigue stiffness degradation, energy dissipated per cycle, and severity of damage progression have been analyzed to elucidate the effects of stress levels and mean stress on fatigue performance. At higher stress levels, the damage is intense and localized, resulting in relatively shorter life due to fiber-breakage accompanied by rapid fatigue stiffness degradation. At lower stress levels, the damage is uniformly distributed and less severe, primarily involves stress concentration, resulting in longer fatigue lives. The study highlights the contrasting damage progression mechanisms for tension–tension and tension–compression fatigue. Under tension–tension fatigue, an oval-shaped damage zone forms perpendicular to the loading direction indicating transverse crack propagation, while under tension–compression fatigue, the damage zone aligns parallel to the loading direction indicating longitudinal crack propagation due to compressive loading.
{"title":"An experimental investigation of fatigue performance and damage distribution mechanism in Bi-Directional GFRP composites","authors":"Ateeb Ahmad Khan, Indra Vir Singh, Bhanu Kumar Mishra, Ramadas Chennamsetti","doi":"10.1016/j.ijfatigue.2024.108735","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108735","url":null,"abstract":"This study presents an experimental investigation of the fatigue performance and damage distribution mechanism of bi-directional GFRP composites. Uniaxial fatigue tests have been conducted under load-control, at stress ratios, R = 0.1, 0.5 and critical stress ratio <mml:math altimg=\"si26.svg\"><mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mi>χ</mml:mi><mml:mo linebreak=\"goodbreak\" linebreakstyle=\"after\">=</mml:mo><mml:mo linebreak=\"badbreak\" linebreakstyle=\"after\">-</mml:mo><mml:mn>0.9</mml:mn><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow></mml:math>. The influence of gauge length and surface roughness on fatigue life has been examined for R = 0.1. An infrared (IR) camera is employed to monitor temperature evolution and capture thermal images during the fatigue experiments. Fatigue stiffness degradation, energy dissipated per cycle, and severity of damage progression have been analyzed to elucidate the effects of stress levels and mean stress on fatigue performance. At higher stress levels, the damage is intense and localized, resulting in relatively shorter life due to fiber-breakage accompanied by rapid fatigue stiffness degradation. At lower stress levels, the damage is uniformly distributed and less severe, primarily involves stress concentration, resulting in longer fatigue lives. The study highlights the contrasting damage progression mechanisms for tension–tension and tension–compression fatigue. Under tension–tension fatigue, an oval-shaped damage zone forms perpendicular to the loading direction indicating transverse crack propagation, while under tension–compression fatigue, the damage zone aligns parallel to the loading direction indicating longitudinal crack propagation due to compressive loading.","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"18 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793444","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}
Pub Date : 2024-11-27DOI: 10.1016/j.ijfatigue.2024.108722
A. Koko, P. Earp, T. Wigger, J. Tong, T.J. Marrow
{"title":"Corrigendum to “J-integral analysis: An EDXD and DIC comparative study for a fatigue crack” [Int. J. Fatigue 134 (2020) 105474]","authors":"A. Koko, P. Earp, T. Wigger, J. Tong, T.J. Marrow","doi":"10.1016/j.ijfatigue.2024.108722","DOIUrl":"https://doi.org/10.1016/j.ijfatigue.2024.108722","url":null,"abstract":"","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"20 1","pages":""},"PeriodicalIF":6.0,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793447","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}
Pub Date : 2024-11-27DOI: 10.1016/j.ijfatigue.2024.108732
Wen-Rui Nie , Hang-Hang Gu , Xian-Cheng Zhang , Shan-Tung Tu , Run-Zi Wang
This paper presents a hybrid-driven probabilistic damage assessment approach by considering creep-fatigue-oxidation damage interaction (CFO-DI). Based on generalized strain energy density exhaustion (GSEDE) framework, the hybrid-driven concept integrates the strengths of both physics-based models and machine learning, exploring the frontier from deterministic evaluation to probabilistic assessment. Experimental investigations involving generalized creep-fatigue loading tests are conducted to establish a comprehensive dataset in Inconel 718 at 650 °C. Deterministic models for fatigue, creep, and oxidation damages are developed, and their interactions are analyzed using the GSEDE framework. To tackle limited experimental data, a divide-and-conquer strategy employing machine learning models is implemented for data augmentation. Probabilistic assessments are performed incorporating uncertainties from material properties, loading conditions, and model parameters using Monte Carlo simulations and Latin Hypercube Sampling. The results demonstrate accurate life prediction accuracy and reliable probability distributions in the presence of oxidation damage. Finally, a novel three-dimensional probabilistic CFO-DI assessment diagram quantified by the confidence level is developed, providing a technical pathway for safe-life design in high-temperature structural applications.
{"title":"Hybrid-driven probabilistic damage assessment of creep-fatigue-oxidation interaction","authors":"Wen-Rui Nie , Hang-Hang Gu , Xian-Cheng Zhang , Shan-Tung Tu , Run-Zi Wang","doi":"10.1016/j.ijfatigue.2024.108732","DOIUrl":"10.1016/j.ijfatigue.2024.108732","url":null,"abstract":"<div><div>This paper presents a hybrid-driven probabilistic damage assessment approach by considering creep-fatigue-oxidation damage interaction (CFO-DI). Based on generalized strain energy density exhaustion (GSEDE) framework, the hybrid-driven concept integrates the strengths of both physics-based models and machine learning, exploring the frontier from deterministic evaluation to probabilistic assessment. Experimental investigations involving generalized creep-fatigue loading tests are conducted to establish a comprehensive dataset in Inconel 718 at 650 °C. Deterministic models for fatigue, creep, and oxidation damages are developed, and their interactions are analyzed using the GSEDE framework. To tackle limited experimental data, a divide-and-conquer strategy employing machine learning models is implemented for data augmentation. Probabilistic assessments are performed incorporating uncertainties from material properties, loading conditions, and model parameters using Monte Carlo simulations and Latin Hypercube Sampling. The results demonstrate accurate life prediction accuracy and reliable probability distributions in the presence of oxidation damage. Finally, a novel three-dimensional probabilistic CFO-DI assessment diagram quantified by the confidence level is developed, providing a technical pathway for safe-life design in high-temperature structural applications.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108732"},"PeriodicalIF":5.7,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747487","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}
Accurate fatigue life prediction of additive manufactured parts is critical for the reliability and safety assessment of the designs made for aerospace applications. The fatigue life depends on the cyclic stress experienced due to loads in operation, surface roughness, internal microstructure, and defects in the parts. The microstructure of a material contains signatures of the manufacturing process and post-processing experienced by the part. Incorporating microstructure information in fatigue life prediction is difficult using analytical and empirical relations. A data–driven machine learning framework can be used to model complex phenomena without solving the detailed underlying physics. Manual selection of important features from microstructure may not capture all the properties that affect fatigue. In this work, the fatigue data of Ti-6Al-4V alloy is collected from several sources and machine learning models are trained using surface roughness, stress cycles and microstructure images. The effect of utilizing microstructure images and their 2-point statistics data with convolutional neural networks and Gaussian process regression for prediction of fatigue life are demonstrated. Various methods of image processing, data preparation, and modeling techniques are studied and outcomes are discussed.
{"title":"A microstructure sensitive machine learning-based approach for predicting fatigue life of additively manufactured parts","authors":"Prateek Kishore , Aratrick Mondal , Aayush Trivedi , Punit Singh , Alankar Alankar","doi":"10.1016/j.ijfatigue.2024.108724","DOIUrl":"10.1016/j.ijfatigue.2024.108724","url":null,"abstract":"<div><div>Accurate fatigue life prediction of additive manufactured parts is critical for the reliability and safety assessment of the designs made for aerospace applications. The fatigue life depends on the cyclic stress experienced due to loads in operation, surface roughness, internal microstructure, and defects in the parts. The microstructure of a material contains signatures of the manufacturing process and post-processing experienced by the part. Incorporating microstructure information in fatigue life prediction is difficult using analytical and empirical relations. A data–driven machine learning framework can be used to model complex phenomena without solving the detailed underlying physics. Manual selection of important features from microstructure may not capture all the properties that affect fatigue. In this work, the fatigue data of Ti-6Al-4V alloy is collected from several sources and machine learning models are trained using surface roughness, stress cycles and microstructure images. The effect of utilizing microstructure images and their 2-point statistics data with convolutional neural networks and Gaussian process regression for prediction of fatigue life are demonstrated. Various methods of image processing, data preparation, and modeling techniques are studied and outcomes are discussed.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108724"},"PeriodicalIF":5.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719972","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}
Pub Date : 2024-11-26DOI: 10.1016/j.ijfatigue.2024.108719
Jinyu Wang, Xiaofan He
Fatigue crack growth (FCG) tests were conducted on superelastic NiTi alloys, demonstrating that the da/dN-ΔK curve in the stable crack growth stage exhibits two transition points in the double-logarithmic coordinate system, presenting a tri-linear form. Fracture surface SEM analysis indicated that the FCG mechanisms differ across the three stages on either side of the two transition points. This phenomenon is first discovered and studied in NiTi alloys. The study investigated the size and position relationships between the characteristic zones at the crack tip (phase transformation zone and cyclic plasticity zone) and the microstructure during crack growth. Based on this, a critical prediction method for the transition points was established and found to be in close agreement with the experimental results. Finally, the formation mechanism of the double transition points was explained by combining the SEM results of the fracture surfaces with every stage of FCG.
{"title":"Study on the behavior and mechanism of double transition points in stable fatigue crack growth of superelastic NiTi shape memory alloy","authors":"Jinyu Wang, Xiaofan He","doi":"10.1016/j.ijfatigue.2024.108719","DOIUrl":"10.1016/j.ijfatigue.2024.108719","url":null,"abstract":"<div><div>Fatigue crack growth (FCG) tests were conducted on superelastic NiTi alloys, demonstrating that the d<em>a</em>/d<em>N</em>-Δ<em>K</em> curve in the stable crack growth stage exhibits two transition points in the double-logarithmic coordinate system, presenting a tri-linear form. Fracture surface SEM analysis indicated that the FCG mechanisms differ across the three stages on either side of the two transition points. This phenomenon is first discovered and studied in NiTi alloys. The study investigated the size and position relationships between the characteristic zones at the crack tip (phase transformation zone and cyclic plasticity zone) and the microstructure during crack growth. Based on this, a critical prediction method for the transition points was established and found to be in close agreement with the experimental results. Finally, the formation mechanism of the double transition points was explained by combining the SEM results of the fracture surfaces with every stage of FCG.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108719"},"PeriodicalIF":5.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747483","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}
Pub Date : 2024-11-26DOI: 10.1016/j.ijfatigue.2024.108731
Masahiro Goto , Takaei Yamamoto , Sangshik Kim , Eun-Ae Choi , Seung Zeon Han
High-strength cast Cu alloys often contain substantial quantities of alloying elements that promote the nucleation of heterogeneous particles, particularly at grain boundaries (GBs). In the Cu-6Ni-1.3Si alloy, intermetallic compounds such as Ni2Si form within the matrix and along the GBs following homogenization. Ni2Si particles within the matrix are homogeneously nucleated with diameters of a few tens of nanometers, which enhances matrix strength. However, heterogeneously nucleated Ni2Si particles at GBs, which can be several micrometers in size, negatively impact overall strength. To improve the strength of Cu-6Ni-1.3Si alloy, 2.1 wt% Mn was added. This Mn addition led to the formation of plate- or film-shaped intermetallic compounds, specifically Ni16Si7Mn6 (G-phase), at GBs after homogenization. Despite the Mn addition, Ni2Si precipitates with diameters of a few tens of nanometers still formed within the grains, but these were more densely distributed in the Mn-added alloy compared to the Mn-free alloy. Fatigue tests conducted on round bar specimens of both alloys showed that Mn addition enhanced fatigue strength. This enhancement is attributed to the suppression of both crack initiation and propagation along the GBs and within the matrix.
{"title":"Effect of grain boundary phase formed by Mn addition on initiation and propagation of fatigue cracks in homogenized Cu-6Ni-1.3Si alloy","authors":"Masahiro Goto , Takaei Yamamoto , Sangshik Kim , Eun-Ae Choi , Seung Zeon Han","doi":"10.1016/j.ijfatigue.2024.108731","DOIUrl":"10.1016/j.ijfatigue.2024.108731","url":null,"abstract":"<div><div>High-strength cast Cu alloys often contain substantial quantities of alloying elements that promote the nucleation of heterogeneous particles, particularly at grain boundaries (GBs). In the Cu-6Ni-1.3Si alloy, intermetallic compounds such as Ni<sub>2</sub>Si form within the matrix and along the GBs following homogenization. Ni<sub>2</sub>Si particles within the matrix are homogeneously nucleated with diameters of a few tens of nanometers, which enhances matrix strength. However, heterogeneously nucleated Ni<sub>2</sub>Si particles at GBs, which can be several micrometers in size, negatively impact overall strength. To improve the strength of Cu-6Ni-1.3Si alloy, 2.1 wt% Mn was added. This Mn addition led to the formation of plate- or film-shaped intermetallic compounds, specifically Ni<sub>16</sub>Si<sub>7</sub>Mn<sub>6</sub> (G-phase), at GBs after homogenization. Despite the Mn addition, Ni<sub>2</sub>Si precipitates with diameters of a few tens of nanometers still formed within the grains, but these were more densely distributed in the Mn-added alloy compared to the Mn-free alloy. Fatigue tests conducted on round bar specimens of both alloys showed that Mn addition enhanced fatigue strength. This enhancement is attributed to the suppression of both crack initiation and propagation along the GBs and within the matrix.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108731"},"PeriodicalIF":5.7,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747485","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}
Pub Date : 2024-11-24DOI: 10.1016/j.ijfatigue.2024.108728
Yuan-Ze Tang , Xian-Cheng Zhang , Hang-Hang Gu , Kai-Shang Li , Chang-Qi Hong , Shan-Tung Tu , Yutaka S. Sato , Run-Zi Wang
Creep-fatigue reliability assessment for high-temperature equipment is crucial but challenging due to the extensive data requirements and cumbersome methods. To enhance the implementation of creep-fatigue reliability assessment within engineering practice, this study employs multidimensional computational techniques grounded in the hybrid-driven paradigm. In detail, it presents a hybrid-driven creep-fatigue reliability assessment method integrating principles from mechanics, physics, and informatics and develops an integrated plug-in embedded in Abaqus software. The plug-in automates the implementation of parametric finite element analysis rooted in engineering damage mechanics, accommodating multiple uncertainty sources such as material properties, model parameters, geometry features, and applied loads. In particular, creep-fatigue reliability assessment utilizes a time-efficient alternative, facilitated by the adoption of surrogate modeling and Monte Carlo simulation. Furthermore, two typical examples from specimen-level (hole structure simulation specimen) to component-level (low-pressure turbine disk) are employed to demonstrate the availability and efficiency of the method and the plug-in. The plug-in with a hybrid-driven paradigm is poised to emerge as a powerful simulation-based engineering tool, facilitating the process of reliability assessment with enhanced convenience.
{"title":"Structural reliability assessment under creep-fatigue considering multiple uncertainty sources based on surrogate modeling approach","authors":"Yuan-Ze Tang , Xian-Cheng Zhang , Hang-Hang Gu , Kai-Shang Li , Chang-Qi Hong , Shan-Tung Tu , Yutaka S. Sato , Run-Zi Wang","doi":"10.1016/j.ijfatigue.2024.108728","DOIUrl":"10.1016/j.ijfatigue.2024.108728","url":null,"abstract":"<div><div>Creep-fatigue reliability assessment for high-temperature equipment is crucial but challenging due to the extensive data requirements and cumbersome methods. To enhance the implementation of creep-fatigue reliability assessment within engineering practice, this study employs multidimensional computational techniques grounded in the hybrid-driven paradigm. In detail, it presents a hybrid-driven creep-fatigue reliability assessment method integrating principles from mechanics, physics, and informatics and develops an integrated plug-in embedded in Abaqus software. The plug-in automates the implementation of parametric finite element analysis rooted in engineering damage mechanics, accommodating multiple uncertainty sources such as material properties, model parameters, geometry features, and applied loads. In particular, creep-fatigue reliability assessment utilizes a time-efficient alternative, facilitated by the adoption of surrogate modeling and Monte Carlo simulation. Furthermore, two typical examples from specimen-level (hole structure simulation specimen) to component-level (low-pressure turbine disk) are employed to demonstrate the availability and efficiency of the method and the plug-in. The plug-in with a hybrid-driven paradigm is poised to emerge as a powerful simulation-based engineering tool, facilitating the process of reliability assessment with enhanced convenience.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108728"},"PeriodicalIF":5.7,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702187","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}
Pub Date : 2024-11-23DOI: 10.1016/j.ijfatigue.2024.108730
Gabriel Riedl , Francesco Baldi , Gernot M. Wallner
A fatigue fracture mechanics methodology was developed and established, employing a slope-based J-integral approach combined with advanced image processing techniques. Adhesively bonded double cantilever beam (DCB) specimens were tested under constant displacement amplitude loading. The beam rotation was tracked by affixing a repetitive pattern on the DCB specimens and capturing images at the maximum displacement amplitude. Using a custom-developed image processing procedure, the beam rotation was deduced. To validate the methodology, DCB fatigue experiments were conducted at 23, 60 and 75 °C on aluminum adherends bonded with a structural 2-K epoxy adhesive. The J-based approach was compared with a conventional, compliance-based linear elastic fracture mechanics (LEFM) method. The epoxy was a rather brittle, high-modulus adhesive with a bond line thickness of 0.25 mm, resulting in predominantly linear elastic material behavior. By analyzing the images taken during fatigue testing, a stiffening effect of the steel load blocks was observed. Excluding pattern elements directly below the load block yielded the best agreement between J-integral and LEFM data. Both approaches were in excellent agreement within the investigated temperature range. The investigated adhesive exhibited a highly temperature-dependent behavior, which was associated with higher crack propagation rates and a lower fatigue threshold at 60 and 75 °C.
{"title":"A slope-based J-integral approach and advanced image processing for assessment of the cyclic fatigue delamination behavior of adhesive joints","authors":"Gabriel Riedl , Francesco Baldi , Gernot M. Wallner","doi":"10.1016/j.ijfatigue.2024.108730","DOIUrl":"10.1016/j.ijfatigue.2024.108730","url":null,"abstract":"<div><div>A fatigue fracture mechanics methodology was developed and established, employing a slope-based J-integral approach combined with advanced image processing techniques. Adhesively bonded double cantilever beam (DCB) specimens were tested under constant displacement amplitude loading. The beam rotation was tracked by affixing a repetitive pattern on the DCB specimens and capturing images at the maximum displacement amplitude. Using a custom-developed image processing procedure, the beam rotation was deduced. To validate the methodology, DCB fatigue experiments were conducted at 23, 60 and 75 °C on aluminum adherends bonded with a structural 2-K epoxy adhesive. The J-based approach was compared with a conventional, compliance-based linear elastic fracture mechanics (LEFM) method. The epoxy was a rather brittle, high-modulus adhesive with a bond line thickness of 0.25 mm, resulting in predominantly linear elastic material behavior. By analyzing the images taken during fatigue testing, a stiffening effect of the steel load blocks was observed. Excluding pattern elements directly below the load block yielded the best agreement between J-integral and LEFM data. Both approaches were in excellent agreement within the investigated temperature range. The investigated adhesive exhibited a highly temperature-dependent behavior, which was associated with higher crack propagation rates and a lower fatigue threshold at 60 and 75 °C.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108730"},"PeriodicalIF":5.7,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719973","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}
Pub Date : 2024-11-22DOI: 10.1016/j.ijfatigue.2024.108716
A. Chiocca , M. Pedranz , F. Zanini , S. Carmignato , V. Fontanari , M. Benedetti , F. Frendo
The fatigue assessment of structural components, especially made of ductile cast iron subjected to complex loading conditions, heavily relies on analyzing fatigue damage resulting from stress concentrations induced by geometric irregularities like notches and shrinkage pores. Standard methodologies, encompassing the Theory of Critical Distances (TCD), Strain Energy Density (SED), and Critical Plane (CP), have played pivotal roles in predicting fatigue strength for components featuring such irregularities. In this work, the authors explore the applicability of the Effective Critical Plane (ECP) approach on ductile cast iron notched specimens subjected to multiaxial and non-proportional loading conditions. The method focuses on evaluating the critical plane factor, after averaging the stress and strain field within a given control volume or area (i.e. defined by a control radius), centered on the critical node. The study aims to enhance the accuracy of fatigue life prediction for structural components made of ductile cast iron, thereby contributing to the improvement and practical applicability of fatigue assessment under complex loading conditions. The methodology, integrating the Smith-Watson-Topper and Fatemi-Socie CP factor, was applied to several experimental fatigue data obtained from ductile cast iron notched specimens, tested under multiaxial non-proportional loading conditions. After establishing the control radius associated with the investigated material, the method was utilized to perform a fatigue life forecast analysis on a specimen with porous defects.
{"title":"Application of the Effective critical plane approach for the fatigue assessment of ductile cast iron under multiaxial and non-proportional loading conditions","authors":"A. Chiocca , M. Pedranz , F. Zanini , S. Carmignato , V. Fontanari , M. Benedetti , F. Frendo","doi":"10.1016/j.ijfatigue.2024.108716","DOIUrl":"10.1016/j.ijfatigue.2024.108716","url":null,"abstract":"<div><div>The fatigue assessment of structural components, especially made of ductile cast iron subjected to complex loading conditions, heavily relies on analyzing fatigue damage resulting from stress concentrations induced by geometric irregularities like notches and shrinkage pores. Standard methodologies, encompassing the Theory of Critical Distances (TCD), Strain Energy Density (SED), and Critical Plane (CP), have played pivotal roles in predicting fatigue strength for components featuring such irregularities. In this work, the authors explore the applicability of the Effective Critical Plane (ECP) approach on ductile cast iron notched specimens subjected to multiaxial and non-proportional loading conditions. The method focuses on evaluating the critical plane factor, after averaging the stress and strain field within a given control volume or area (i.e. defined by a control radius), centered on the critical node. The study aims to enhance the accuracy of fatigue life prediction for structural components made of ductile cast iron, thereby contributing to the improvement and practical applicability of fatigue assessment under complex loading conditions. The methodology, integrating the <em>Smith-Watson-Topper</em> and <em>Fatemi-Socie</em> CP factor, was applied to several experimental fatigue data obtained from ductile cast iron notched specimens, tested under multiaxial non-proportional loading conditions. After establishing the control radius associated with the investigated material, the method was utilized to perform a fatigue life forecast analysis on a specimen with porous defects.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108716"},"PeriodicalIF":5.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142702188","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}
Pub Date : 2024-11-22DOI: 10.1016/j.ijfatigue.2024.108725
Lei He , Yang Tian , Hiroyuki Akebono , Atsushi Sugeta
This study investigated the fatigue crack propagation behavior from small defect in the elastic–plastic region under block loading conditions and clarified the influence of cycle ratio on the crack growth rate. Fatigue tests were conducted under constant and repeated two-step strain amplitude loading conditions using various cycle ratios. The results of the constant amplitude loading test indicated that the J integral can be employed to predict fatigue crack propagation rate in one master curve by considering the material constant, l0. The results of the repeated two-step test showed that the fatigue life evaluated via the J integral had a larger scatter for test conditions at strain amplitudes of 1.0%/0.2% and 0.8%/0.2% with various cycle ratios. A highly accurate model was established to predict fatigue crack propagation behavior and investigate the effect of algorithms on the precision of models. To achieve this, three deep learning algorithms feed forward neural network (FFNN), cascade-forward neural network (CFNN) and function fitting neural network (FNN), were employed. It was observed that the precision of the constructed models was dependent on the algorithms and dataset split. The model constructed using the CFNN exhibited the highest prediction accuracy.
{"title":"Prediction of fatigue crack propagation behavior in elastic plastic region under block loading for type 316 steel via artificial neural network approach","authors":"Lei He , Yang Tian , Hiroyuki Akebono , Atsushi Sugeta","doi":"10.1016/j.ijfatigue.2024.108725","DOIUrl":"10.1016/j.ijfatigue.2024.108725","url":null,"abstract":"<div><div>This study investigated the fatigue crack propagation behavior from small defect in the elastic–plastic region under block loading conditions and clarified the influence of cycle ratio on the crack growth rate. Fatigue tests were conducted under constant and repeated two-step strain amplitude loading conditions using various cycle ratios. The results of the constant amplitude loading test indicated that the <em>J</em> integral can be employed to predict fatigue crack propagation rate in one master curve by considering the material constant, <em>l<sub>0</sub></em>. The results of the repeated two-step test showed that the fatigue life evaluated via the <em>J</em> integral had a larger scatter for test conditions at strain amplitudes of 1.0%/0.2% and 0.8%/0.2% with various cycle ratios. A highly accurate model was established to predict fatigue crack propagation behavior and investigate the effect of algorithms on the precision of models. To achieve this, three deep learning algorithms feed forward neural network (FFNN), cascade-forward neural network (CFNN) and function fitting neural network (FNN), were employed. It was observed that the precision of the constructed models was dependent on the algorithms and dataset split. The model constructed using the CFNN exhibited the highest prediction accuracy.</div></div>","PeriodicalId":14112,"journal":{"name":"International Journal of Fatigue","volume":"192 ","pages":"Article 108725"},"PeriodicalIF":5.7,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719970","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}
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