Article
Engineering, Mechanical
J. Telesman, T. P. Gabb, P. T. Kantzos, P. J. Bonacuse, R. L. Barrie, C. A. Kantzos
Summary: In this study, crack initiation, crack coalescence, and small crack growth behavior of over 400 seeded inclusions in P/M Udimet 720 nickel disk alloy were monitored during interrupted low cycle fatigue testing at 650 degrees C. Two types of seeded alumina inclusions were used with average sizes of 54 μm and 122 μm, with fatigue behavior sub-categorized into four groups and detailed visual maps developed for inclusion size/cycle history. The effect of surface residual stresses on fatigue life was also investigated.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Materials Science, Multidisciplinary
C. H. Wu, R. Jiang, L. C. Zhang, Y. C. Wang, Y. Chen, Y. D. Song
Summary: This study investigates the fatigue crack growth (FCG) mechanisms of Ni-based superalloy FGH4098 at temperatures ranging from 650 to 800 degrees Celsius. The results show that the FCG rate increases by 2-3 orders of magnitude with increased temperature and prolonged dwell time, which is attributed to grain boundary oxidation. Characterization of the crack tips reveals that deformation, such as dislocations and stacking faults, mainly occurs within the gamma channel, accompanied by a change in grain orientation due to severe deformation. Pre-formed oxides at uncracked grain boundaries facilitate the FCG process. A mechanism map of the interaction between deformation-assisted grain boundary oxidation and FCG is proposed.
Article
Engineering, Mechanical
Rohan Acharya, Alexander N. N. Caputo, Richard W. W. Neu
Summary: This paper explores the use of a neural network with a probabilistic physics-guided architecture to learn the relationships between parameters and fatigue life in various creep-fatigue and thermomechanical fatigue histories and predict cycles to failure. The model is evaluated to determine its success in learning the relationship between applied TMF histories and cycles to failure.
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
(2023)
Article
Nanoscience & Nanotechnology
Alice Cervellon, Chris J. Torbet, Tresa M. Pollock
Summary: The anisotropic fatigue properties of three Ni-based SX superalloys were investigated in the very high cycle fatigue regime. The [111] orientation showed higher fatigue lives at high stresses but lower fatigue lives at very low stresses. The resolved shear stress on the octahedral slip systems and the pseudo-cube slip in the matrix were identified as the main reasons for the anisotropy effect.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Shiyu Suzuki, Motoki Sakaguchi, Masaya Domen, Takanori Karato, Kenta Suzuki
Summary: The effects of grain boundaries on fatigue crack propagation in a cast Ni-base superalloy were investigated. The study found that grain boundaries can retard the propagation of shear cracks and accelerate the propagation of cracks along high angle boundaries. Secondary cracks can also be nucleated along high angle boundaries.
Article
Engineering, Mechanical
Diego Erena, Jesus Vazquez, Carlos Navarro, Jaime Dominguez
Summary: In this article, a new fretting fatigue life prediction model is proposed, which automatically determines the crack direction based on the crack initiation length, and obtains excellent correlation between experimental and predicted results.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Engineering, Mechanical
Yucheng Zhang, Xiaolong Li, Shihua Yuan, Rui Sun, Tatsuo Sakai, Muhammad Imran Lashari, Usama Hamid, Wei Li
Summary: This study investigated the influence of building directions on the high cycle fatigue property of selective laser melted AlSi10Mg through two-dimensional microscope observation and three-dimensional ultra-depth imaging. The results showed that the fatigue strength decreases with the increase of building angle due to larger defects and sparser melting pool boundaries. Based on the observations, a microstructure-based fatigue life prediction model considering the stress concentration effect of defects was proposed.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Engineering, Mechanical
Sarah A. Paluskiewicz, Santosh B. Narasimhachary, Sachin R. Shinde, Chris Kain, Zachary B. Towner, Christopher L. Muhlstein
Summary: This study investigates the fatigue crack growth mechanisms in nickel-based superalloys under high, negative stress ratios, challenging the classical crack tip shielding and closure concepts. The fatigue crack growth rates and closure levels were evaluated for nickel-based superalloy 718 specimens with single edge notches at 100 degrees C under different stress ratios. Multiple methods were used to calculate the effective driving force for crack growth rates, and the relationships between the effective driving forces, experimentally-measured crack closure levels, and fractographic evidence of damage mechanisms are discussed.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Mechanical
Ganfang Luo, Jialin Guo, Chi Zhang, Xiaoniu Yang
Summary: In this paper, the fatigue performance of cord/rubber laminates is investigated under multiaxial loadings provided by pulley/bending fatigue tests. Life predictions are performed based on the crack growth approach and the crack nucleation approach. The results show that using the prediction models based on interfacial fatigue performance improves the life prediction of cord/rubber laminates, and the most satisfying prediction in terms of crack initiation plane and fatigue life is obtained by using cracking energy density as the predictor.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Materials Science, Multidisciplinary
Donghyuk Kim, Rong Jiang, Ian Sinclair, Philippa Reed
Summary: The effects of unimodal secondary gamma' size and grain orientation on fatigue crack initiation and early crack propagation at room temperature were investigated in RR1000 alloy. The results showed that cracks mainly initiated at slip bands and/or pores followed by crystallographic facet formation. More diffuse strain localisation around the pores was observed by SEM-DIC analysis. Fatigue lifetime was found to be linked to the number of crack initiations and consequent crack coalescence, which accelerated crack propagation. Slip trace analysis with EBSD mapping indicated that cracks are likely to propagate along the primary active slip system with a relatively high Schmid Factor. In the conducted tests, the stochasticity of crack initiation events had a greater impact on overall lifetime than variations in secondary gamma' size.
MATERIALS SCIENCE AND TECHNOLOGY
(2022)
Article
Chemistry, Physical
Jianxing Mao, Zhixing Xiao, Dianyin Hu, Xiaojun Guo, Rongqiao Wang
Summary: This paper systematically investigates the creep-fatigue crack growth behavior of the nickel-based superalloy GH4720Li under different temperature, stress ratio, and dwell time conditions. A concise binomial crack growth model is proposed and validated, which accurately predicts the experimental data.
Article
Engineering, Mechanical
Mengzhen Cao, Yang Liu, Fionn P. E. Dunne
Summary: A comparative study using crystal plasticity finite element modeling reveals that fatigue crack nucleation is highly sensitive to both lack of fusion and gas/keyhole pores in AlSi10Mg material. Lack of fusion pores, in particular, significantly reduces fatigue life at high stress levels.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Mechanics
L. Tan, X. G. Yang, D. Q. Shi, W. Q. Hao, Y. S. Fan
Summary: This paper presents an efficient supervised machine learning model based on support vector regression for predicting the fatigue life of Ni-based superalloys. The model is effective in predicting the fatigue life under various loading conditions and regimes compared to classical fatigue life models. Additionally, a model fusion approach is employed to estimate the uncertainty and data dependency of the model. The coefficient of uncertainty is found to be optimal when the training percentage is 70% of the samples. The results of this study are significant for fatigue investigation under complex loading conditions.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Metallurgy & Metallurgical Engineering
Keli Liu, Junsheng Wang, Bing Wang, Pengcheng Mao, Yanhong Yang, Yizhou Zhou
Summary: The study revealed that porosity is more detrimental than carbides in crack initiation and propagation during fatigue tests of nickel-based single-crystal superalloys. Among all controlling pore characteristics, pore spacing was found to be the most significant factor in the crack initiation stage, while sphericity was the most critical pore characteristic in the crack propagation stage.
ACTA METALLURGICA SINICA-ENGLISH LETTERS
(2022)
Article
Materials Science, Multidisciplinary
D. F. Shi, Z. J. Zhang, Y. H. Yang, Y. Z. Zhou, R. Liu, P. Zhang, Z. F. Zhang
Summary: Nickel-based single-crystal superalloys are widely used in manufacturing aeroengine turbine vanes due to their excellent high-temperature performance. However, the presence of low-angle grain boundaries (LAGBs) during their manufacture can weaken the mechanical properties of the superalloys. In this study, the relationship between grain boundary misorientation (GBM) and fatigue properties of superalloys at elevated temperatures was systematically investigated using six different bicrystals with varying tilt LAGBs. The study found that an increase in GBM led to an increase in GB precipitates and cast micropores, resulting in a decrease in fatigue life and fatigue strength. The study also established a quantitative fatigue strength prediction model and evaluated the coupling effect of cast micropores and GBM on the fatigue damage mechanisms of the bicrystals.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)