Article
Engineering, Geological
Miguel A. Manica, Antonio Gens, Efrain Ovando-Shelley, Eduardo Botero, Jean Vaunat
Summary: A constitutive framework for simulating the time-dependent behavior of soft structured clays has been developed by combining existing modeling approaches, including consideration of time-dependent phenomena and structure effects. This approach was demonstrated through a specific model applied to relevant laboratory tests.
Article
Engineering, Mechanical
Zhi Liu, Jian-Guo Gong, Peng Zhao, Xiao-Cheng Zhang, Fu-Zhen Xuan
Summary: This study investigated the creep fatigue behavior of 9-12%Cr steel under stress-controlled cycling at elevated temperature, considering most previous tests were conducted under strain-controlled mode. The effects of holding time and loading rate on deformation and damage behavior were particularly focused. The results showed that a significant creep ratcheting was generally observed in the creep-fatigue tests with the stress ratio of -1. Ratcheting strain and creep damage progressed faster with longer holding time or lower loading rate, leading to a decrease in the number of cycles to creep-fatigue failure.
INTERNATIONAL JOURNAL OF FATIGUE
(2022)
Article
Engineering, Geological
Wei Zhou, Jialin Cheng, Guike Zhang, Hongbi Li, Yonggang Cheng, Gang Ma, Xiang Ji
Summary: It has been found that the physical and mechanical properties of rockfill materials deteriorate with wetting-drying cycles. The breakage characteristics of rock grains, especially slate rock grains, were studied, showing that the crushing strength and fracture energy decrease with increasing wetting-drying cycles, More small fragments are produced for highly deteriorated grains. Expansion of micropores and cracks, as well as changes in mineral composition content, were also observed.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Engineering, Mechanical
Gaole Zhao, Hongyu Qi, Shaolin Li, Xiaoguang Yang, Duoqi Shi
Summary: Fatigue-creep tests were conducted on DZ125 superalloys samples at 850 degrees C, revealing that as the hold time increased, the fatigue lifetime of a corroded alloy decreased by over 80%, but the influence of hot corrosion weakened with further increase in dwell time. Additionally, hot corrosion was found to affect the alloy's lifetime by influencing crack initiation location, with cracks initiated on the corrosion layer of salt-coated samples. These findings provide insights for accurately assessing hot-corrosion-induced fracture behavior in superalloys.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Polymer Science
Jonathon Tanks, Kimiyoshi Naito, Hisai Ueda
Summary: This study investigates the mechanical properties of a prototype basalt fiber-reinforced polypropylene (BFPP) rod under quasi-static and sustained loading conditions. The static strength and modulus at elevated temperatures do not decrease significantly, but the variability in strength increases with temperature. Creep behavior is typical of unidirectional FRP, and fatigue performance is sensitive to matrix damage, especially at lower stress ratios. These findings have implications for service life and concrete structure design guidelines.
Article
Materials Science, Multidisciplinary
J. -D. Hu, F. -Z. Xuan, C. -J. Liu, B. Chen
Summary: The CH model accounts for creep deformation and assesses the combined effect of grain boundary sliding and crystal deformation on cavity nucleation in Type 316 stainless steel. It identifies load waveform characteristics that can maximize cavity nucleation, such as long pre-compressive hold time and short load reversal time. The model also highlights the importance of time-related parameters and unbalanced stress hold in favor of tension for enhancing nucleation rate.
MECHANICS OF MATERIALS
(2021)
Article
Engineering, Mechanical
Masao Sakane, Takeshi Shiratsuchi, Yutaka Tsukada
Summary: This study focuses on the creep-fatigue life prediction of eutectic Sn37Pb solder, with experiments conducted at 313 K using various waveforms. Different prediction rules were used, but a new method based on grain boundary sliding rates was proposed due to its close relationship with creep-fatigue lives.
INTERNATIONAL JOURNAL OF FATIGUE
(2021)
Article
Nanoscience & Nanotechnology
T. D. Porter, Z. Wang, E. P. Gilbert, M. J. Kaufman, R. N. Wright, K. O. Findley
Summary: In this study, experimental analysis was conducted on Alloy 709 to investigate the differences in precipitation evolution between long-term static aging and laboratory accelerated tests. The results showed that the precipitation behavior deviated from equilibrium predictions in static-aged material, and dynamic precipitation during fatigue testing resulted in finer and more uniform distribution of carbide precipitates with higher volume fraction compared to static aging.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Nanoscience & Nanotechnology
Minqing Wang, Jinhui Du, Qun Deng
Summary: Low oxygen partial pressure significantly affects the dwell fatigue crack growth rate of 718Plus alloy at high temperatures. The dominant mechanisms include oxygen-induced dynamic embrittlement and stress-accelerated grain boundary oxidation, with the type of oxide formed in the process directly related to oxygen partial pressure and oxidation time.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Civil
Gerhard Olivier, Fruzsina Csillag, Elisabeth Tromp, Marko Pavlovic
Summary: As traffic loads increase and bridge infrastructure ages, there is a growing need for new materials and connection methods in renovation and new construction projects. The use of materials like Fibre Reinforced Polymer (FRP) can improve the lifespan and durability of bridges, but challenges remain in implementing hybrid steel-FRP structures.
ENGINEERING STRUCTURES
(2021)
Article
Materials Science, Multidisciplinary
Chengqi Sun, Yanqing Li, Kuilong Xu, Baotong Xu
Summary: This study investigated the effects of intermittent loading time and stress ratio on the dwell fatigue behavior of the titanium alloy Ti-6Al-4V ELI. The results showed that the stress ratio significantly affects dwell fatigue life and mechanism, with dwell fatigue life increasing with an increase in stress ratio and specimens with negative stress ratio tending to undergo ductile failure.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2021)
Article
Nanoscience & Nanotechnology
Yuxuan Song, Yi Ma, Haofeng Chen, Zhibo He, Hu Chen, Taihua Zhang, Zengliang Gao
Summary: This study investigated the creep-fatigue interactions on the long-term service damage of P92 welded joint by conducting tensile and compressive tests under different applied strains. Using nanoindentation, the local mechanical properties of the welded joint were examined, while scanning electron microscope was used to analyze fracture morphologies and internal defects after CF tests, revealing the effects of holding type on the local creep behavior and fracture mechanism of the welds.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Engineering, Mechanical
Kai-Shang Li, Run-Zi Wang, Xian-Cheng Zhang, Shan -Tung Tu
Summary: A dual-scale numerical procedure was developed to investigate the creep-fatigue damage mechanisms and crack initiation life of notched structures made of Inconel 718 superalloy at 650 degrees C. The macro-scale simulation accounted for creep-fatigue deformation behavior, while the micro-scale simulation focused on local damage evolutions using crystal plasticity and grain boundary cavity models. Experimental tests were conducted to validate the numerical procedure, and the crack initiation behavior under different loading conditions was explained. The simulated life predicted by the developed approach showed good agreement with experimental data within an error band of +/- 2.
INTERNATIONAL JOURNAL OF PLASTICITY
(2023)
Article
Engineering, Mechanical
Cheng Luo, Huang Yuan
Summary: This study investigated the thermomechanical fatigue behavior of nickel-base single-crystal superalloy with different crystal orientations. The crack initiation modes and damage mechanisms were characterized using SEM and optical microscopy. In IP-TMF, creep damage originated from casting pores and propagated under mode I. The creep facets were influenced by activated slip systems, while fatigue damage depended on crystal orientation and developed by slipping along different crystallographic planes. In OP-TMF tests, oxidation-assisted cracking was non-crystallographic for all crystal orientations, with the crack growing within the oxidized material.
INTERNATIONAL JOURNAL OF FATIGUE
(2023)
Article
Engineering, Civil
Bhupesh Singh Katiyar, Sushanta Kumar Panda, Partha Saha
Summary: In this study, laser welded blanks of different thicknesses were fabricated and subjected to stretch forming and crushing tests. It was found that the collapse mode was affected by the thickness ratio, while the presence of weld zone and the selection of thickness combination can enhance energy absorption capacity. The numerical modeling incorporating strain rate, material anisotropy, forming histories and WZ properties improved the prediction of collapse modes and load-displacement response.
THIN-WALLED STRUCTURES
(2021)