Article
Engineering, Mechanical
Qixing Sun, Qu Liu, Xiaogang Li, Zhipeng Cai, Xin Huo, Manjie Fan, Yi He, Xinzhe Yao, Jiluan Pan, Kejian Li
Summary: This study investigated the threshold value (??Kth) and fatigue crack growth behavior in the weld metal (WM) and heat-affected zone (HAZ) of an ex-service CrMoV steel joint at different temperatures and stress ratios. It was found that the ??Kth at high temperatures (500 ??C and 540 ??C) remained high due to significant oxide-induced crack closure (OICC) occurring in both WM and HAZ. The high-temperature ??Kth of HAZ was higher than that of WM, which can be attributed to the lower Si and Cr content and smaller grain size in HAZ.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Chemistry, Physical
Luka Starcevic, Nenad Gubeljak, Jozef Predan
Summary: This study aimed to simulate the fracture behavior in a multi-pass mis-matched X-weld joint by incorporating local variation in material properties. The finite element model used included five material groups in the weld and three layers in the heat-affected zone, representing the local variation. The modeling approach used showed comparable crack propagation and stiffness behavior, as well as the expected scatter and instabilities of measured fracture behavior in inhomogeneous welds.
Article
Engineering, Mechanical
R. Sunder, Devaraj Raut, Vikram Jayaram, Praveen Kumar, Vijayendra Shastri
Summary: The closure-free intrinsic threshold stress intensity Delta Kth,i is significantly influenced by near-tip residual stress, as observed in experiments using marker loads on 7075-T6 Al-alloy specimens. This effect is similar to a "micro latency" phenomenon, with variations correlating with Delta Kth,i under different gaseous environments and hold time experiment conditions. The study confirms that near-tip residual stress acts as an independent load interaction mechanism affecting fatigue crack growth rates under closure-free conditions.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Engineering, Mechanical
Qixing Sun, Xiaogang Li, Kejian Li, Zhipeng Cai, Shanlin Li, Mengjia Hu, Shao-Shi Rui, Jiluan Pan
Summary: The study revealed that phosphorus segregation at prior austenite grain boundaries can cause local intergranular fracture and high crack growth rates in the turbine part weld metal, but has little effect on near-threshold fatigue crack growth and Delta Kth in the compressor part weld metal.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Materials Science, Multidisciplinary
Ruike Zhao, Huaizhi Zhao, Lei Lu
Summary: In this study, we investigated the fatigue crack growth characteristics of bulk nanotwinned Cu with different microstructural aspects. The results show that the nanotwinned Cu has significantly improved fatigue resistance compared to conventional polycrystalline Cu, which can be attributed to the activation of specific primary slip systems.
SCIENCE CHINA-MATERIALS
(2023)
Article
Engineering, Mechanical
Huan Wang, Qinyang Zhao, Shewei Xin, Yongqing Zhao, Shixing Huang, Wei Zhou, Weidong Zeng
Summary: The fatigue crack propagation behaviors of a novel high strength Ti-5Al-3Mo-3V-2Zr-2Cr-1Nb-1Fe alloy with equiaxed and lamellar microstructures were systematically investigated. The study found that the lamellar microstructure displayed faster fatigue crack propagation rates in the near-threshold regime compared to the equiaxed microstructure, while the equiaxed microstructure showed slightly slower steady state crack growth rates in the Paris regime. In the rapid growth regime, the crack in lamellar microstructure was found to be extended along the grain boundary alpha, leading to a faster crack propagation rate.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Materials Science, Characterization & Testing
Salim Caliskan, Riza Gurbuz
Summary: The microstructure effect is crucial for fatigue crack propagation in the near-threshold region. Although numerous studies have been conducted, the mechanism behind it is not yet comprehensively understood. The fatigue crack growth occurs in the plastic zone region, which is small in size and considered as microstructural units, especially under low stress intensities. Differences in microstructure caused by heat treatment methods are often associated with changes in monotonic and yield strength, leading to differences in plastic zone size.
Article
Materials Science, Multidisciplinary
E. T. Furton, A. M. Beese
Summary: This study investigates the effects of pores on the mechanical properties of metals produced by additive manufacturing, which can limit strength and ductility. The rate of crack growth emanating from these pores in additively manufactured Ti-6Al-4 V fabricated with laser powder bed fusion was measured and modeled. The results showed that crack growth occurred after necking in samples with small pores, while samples with large pores experienced continuous crack growth with strain.
EXPERIMENTAL MECHANICS
(2023)
Article
Engineering, Mechanical
Quanyi Wang, Fei Yang, Tongfei Zou, Meng Liu, Yunqing Jiang, Yubing Pei, Hong Zhang, Yongjie Liu, Qingyuan Wang
Summary: FCG experiments were conducted on 9%Cr martensitic steel under high temperatures to investigate the effects of mean stress and microstructure. The results showed that higher stress ratios resulted in a higher fatigue crack growth rate. The FCG path exhibited a zigzag pattern for higher da/dN values and a purely horizontal pattern for lower da/dN values. The martensitic lath fracture angles near the FCG path were statistically related to the stress ratio, mainly ranging from 60 degrees to 80 degrees and 100 degrees to 130 degrees. The deflection angle of secondary cracks increased when encountering HAGBs according to the EBSD map.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Tongjiao Chu, Chendong Shao, Yaqi Wang, Ninshu Ma, Fenggui Lu
Summary: The multi-layer weld metal of NiCrMoV steels used in nuclear rotors was subjected to stress corrosion cracking (SCC) tests, revealing that various factors, such as crack branching behavior and amorphous films, played roles in influencing crack growth rates in different environments.
MATERIALS & DESIGN
(2022)
Article
Engineering, Mechanical
M. Tarik Hasib, Halsey E. Ostergaard, Xiaopeng Li, Jamie J. Kruzic
Summary: The study found that the fatigue crack growth rates of Ti-6Al-4V material are influenced by build orientation and post heat treatments, while texture and build orientation have minimal impact on slow crack growth rates and fatigue thresholds. The definition of fatigue thresholds lies in the ability to transfer slip from one α' / α laths to another, with some effect of crack closure induced by roughness. The transition away from microstructure sensitive fatigue crack growth occurred when the packet/colony size equaled the cyclic plastic zone size.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Materials Science, Multidisciplinary
Jesus Toribio, Juan-Carlos Matos, Beatriz Gonzalez
Summary: This article investigates the retardation effect in plasticity-induced fatigue crack growth rate for low-medium strength steel, finding that the retardation effect increases with an increase in the initial kinked crack tip angle and length, as well as with a decrease in the stress intensity factor (SIF) range.
Article
Chemistry, Physical
Yang Liu, Ping Jiang, Guihua Duan, Jing Wang, Lingling Zhou, Jijia Xie
Summary: This paper investigates the behavior and mechanism of fatigue crack propagation in CrCoNi medium-entropy alloys with heterogeneous microstructures. Experimental results show that specimens with partial recrystallization microstructures have higher crack propagation rates and opposite effects on fatigue crack thresholds compared to those with complete recrystallization microstructures. Fatigue cracks in recrystallization grains grow along slip planes or twin boundaries, leading to crack deflections and roughness-induced crack closure effect. The area percentage of recrystallization and grain size of recrystallization grains significantly affect the value of the fatigue crack growth threshold.
Article
Engineering, Mechanical
Sergio Blason, Tiago Werner, Julius Kruse, Mauro Madia, Petr Miarka, Stanislav Seitl, Matteo Benedetti
Summary: A complete description of the experimental procedure for characterizing the intrinsic fatigue crack propagation threshold (delta(Kth,eff)) and the fatigue crack growth rate (FCGR) in small-scale specimens is presented. The results show a good agreement between tests conducted on different specimen sizes, indicating the potential of using small-scale specimens for characterizing fatigue crack growth properties in metallic materials. Recommendations and limitations of the procedure are provided and discussed.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Mechanics
T. Riedel, U. Haehnel, H. Flederer, P. Huebner, L. Sieber
Summary: In the early 20th century, numerous steel structures, especially railway bridges, were built in Europe and are still in use. Fracture mechanics is used to assess the safety of these structures in terms of fatigue failure, along with the stress-life concept. This study aims to experimentally determine fracture mechanics parameters for old mild steel in relation to the stress ratio R, compare the results with literature values, and assess different models based on simulated crack growth calculations.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Engineering, Mechanical
Miloslav Kepka, Miloslav Kepka Jr, Radovan Minich
Summary: This paper focuses on the fatigue life evaluation of the bodywork of a new articulated electric (battery) bus. The findings resulted in recommendations to improve the operational reliability of a particular vehicle and provided challenges for future research.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
T. Dusautoir, B. Berthel, S. Fouvry, P. Matzen, K-D. Meck
Summary: This study investigates the impact of post-processing treatments on the fatigue limit of additive manufactured Ti-6Al-4V under stress gradients, with a focus on surface integrity.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Zhuofan Xia, Di Wu, Xiaochen Zhang, Jianqiu Wang, En -Hou Han
Summary: The study reveals the surface-initiated rolling contact fatigue (RCF) failure mechanism under heavy load and initial high roughness surface. The results indicate that precursor of collapsed morphology and nanocrystalline layer are the main factors causing lower RCF life with high roughness compared to low roughness surfaces. The spalling failure initiating from low roughness surface under heavy load is strongly dependent on surface plastic deformation.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Daniel Gren, Knut Andreas Meyer
Summary: Rolling contact loading can cause plastic deformation and fatigue cracks. Current rail standards do not consider the effect of plasticity on mechanical behavior. This study proposes a new method for evaluating the fatigue life of deformed material and finds that superimposed compressive axial loads can increase fatigue life.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
R. Kumar, S. Sanyal, J. Bhagyaraj, E. Hari Krishna, S. Mukherjee, K. Prasad, S. Mandal
Summary: This study investigates the thermomechanical fatigue (TMF) behavior of Timetal 834 alloy under different loading conditions. The results show that the alloy exhibits different cyclic hardening and softening responses at different strain amplitudes. The strain amplitude and phase angle have significant effects on the TMF life.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Kai Donnerbauer, Tobias Bill, Peter Starke, Ruth Acosta, Bharath Yerrapa, Christian Boller, Klaus Heckmann, Frank Walther
Summary: Given the aging of nuclear power plants, it is important to develop methods for evaluating the integrity of components and structures in nuclear engineering. Suitable nondestructive testing methods can detect material degradation and determine its fatigue life. This study utilized various NDT parameters and scanning electron microscopic methods to explore the relationship between microstructure evolution and NDT data.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Liuyong He, Jiang Zheng, Tianjiao Li, Houkun Zhou, Lihong Xia, Bin Jiang
Summary: This study quantitatively analyzed the effects of precipitates on the deformation mode, cracking mode, and mechanical behavior of WE54 magnesium alloy during low-cycle fatigue. It was found that precipitates promoted the activation of dislocation slip and suppressed the activation of twinning, affecting the cracking mode and mechanical behavior.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Xiangkang Zeng, Conghui Zhang, Wenguang Zhu, Mingliang Zhu, Tongguang Zhai, Xiaomei He, Kangkai Song, Zhuohang Xie
Summary: The cyclic deformation behaviors and damage mechanisms of pure Zr were investigated. The cyclic stress response was mainly influenced by substructure evolutions. Prismatic < a > dislocation slip was identified as the dominant deformation mechanism. Fatigue damage was not only influenced by the initial texture, but also other factors.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Jingyu Yang, Bingbing Li, Yiming Zheng, Gang Chen, Xu Chen
Summary: Heat treatment is used to improve the low-cycle fatigue performance of additive manufactured 316LN stainless steel. The heat-treated material demonstrates initially cyclic hardening followed by softening behavior, and shows a stronger resistance to crack propagation compared to the as-built material, resulting in a longer fatigue life.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Lang Zou, Dongfang Zeng, Xiong Chen, Jun Li, Hai Zhao, Liantao Lu
Summary: This study investigates the competitive relationship between fretting fatigue and plain fatigue in press-fitted railway axles. By changing the depth of the stress relief groove, the plain fatigue limit and fretting fatigue strength were tested. Detailed information was gathered, and an evaluation methodology integrating finite element simulation and the Modified Wohler Curve Method was established. The study concludes that the optimal groove depth, which balances the anti-fatigue capabilities, depends on the number of test cycles.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Davide Leonetti, Koji Kinoshita, Yukina Takai, Alain Nussbaumer
Summary: This paper investigates the fatigue behavior of non-load-carrying transverse welded steel attachments, including fatigue crack monitoring and fracture surface analysis under constant and variable amplitude loading. A procedure is proposed to obtain a Markov transition matrix based on the measured strain signal and to randomly resample the stress history for variable amplitude fatigue tests.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Zhe Zhang, Bing Yang, Yuedong Wang, Shoune Xiao
Summary: This paper presents a method for designing fatigue life prediction models with small sample sizes by handling limited sample data. The method integrates the equivalent structural stress method with the maximum likelihood estimation method and adds reliability verification, resulting in enhanced goodness of fit, stability, and optimized sample quantity.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Cooper K. Hansen, Gary F. Whelan, Jacob D. Hochhalter
Summary: This paper presents a method to address the computational demand issue of computing FIPs using CPFEM by developing an interpretable machine learning model. Genetic programming is used to evolve interpretable expressions of FIPs from microstructure features, and these models can serve as efficient substitutes for CPFEM and be easily integrated into engineering workflows.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Luca Susmel
Summary: This paper discusses the problem of estimating notch fatigue limits using machine learning. The results show that machine learning is a promising approach for designing notched components against fatigue. The accuracy in estimating the fatigue limit can be increased by increasing the size and quality of the calibration dataset, as well as including additional input features.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)
Article
Engineering, Mechanical
Kefeng Gao, Guoqi Tan, Yanyan Liu, Qiang Wang, Qian Tang, Xuegang Wang, Qiqiang Duan, Zengqian Liu, Zhe Yi, Zhefeng Zhang
Summary: Bioinspired architectures have significant effects on material enhancement. This study investigates the fatigue properties of bioinspired ceramic-polymer composites and natural nacre, revealing the close relationship between architectural types, orientations, fatigue performance, and damage mechanisms.
INTERNATIONAL JOURNAL OF FATIGUE
(2024)