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Wheel rail rolling contact fatigue is a very common form of damage, which can lead to uneven rail treads, railhead nuclear damage, etc. Therefore, ANSYS software was used to establish a three-dimensional wheel-rail contact model and analyze the effects of several main characteristics, such as the rail crack length and crack propagation angle, on the fatigue crack intensity factor during crack propagation. The main findings were as follows: (1) With the rail crack length increasing, the position where the crack propagated by mode I moved from the inner edge of the wheel-rail contact spot to the outer edge. When the crack propagated to 0.3-0.5 mm, it propagated to the rail surface, causing the rail material to peel or fall off and other damage. (2) When the crack propagation angle was less than 30°, the cracks were mainly mode II cracks. When the angle was between 30 and 70°, the cracks were mode I-II cracks. When the angle was more than 70°, the cracks were mainly mode I cracks. When the crack propagation angle was 60°, the equivalent stress intensity factor reached the maximum, and the rail cracks propagated the fastest.
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http://dx.doi.org/10.3390/ma14195720 | DOI Listing |
ACS Omega
September 2025
School of Civil Engineering, Liaoning Technical University, Fuxin, Liaoning Province 123000, China.
The presence of internal cracks in rocks within underground engineering environments has significantly compromised their stability, and groundwater has substantially influenced the mechanical properties and fracture evolution of rock masses. In this study, sandstone specimens containing three parallel cracks under saturated water conditions were investigated. Using uniaxial compression tests and digital image correlation (DIC) technology, the influence of the inclination angles of the three parallel cracks on the mechanical properties and fracture evolution of rocks under saturated water conditions was examined.
View Article and Find Full Text PDFBone Rep
September 2025
Department of Orthopaedic Surgery, Vanderbilt University Medical Center, 1215 21st Ave. S., Suite 4200, Nashville, TN 37232, USA.
This study applied Raman spectroscopy (RS) to ex vivo human cadaveric femoral mid-diaphysis cortical bone specimens ( = 118 donors; age range 21-101 years) to predict fracture toughness properties via machine learning (ML) models. Spectral features, together with demographic variables (age, sex) and structural parameters (cortical porosity, volumetric bone mineral density), were fed into support vector regression (SVR), extreme tree regression (ETR), extreme gradient boosting (XGB), and ensemble models to predict fracture-toughness metrics such as crack-initiation toughness (K) and energy-to-fracture (J-integral). Feature selection was based on Raman-derived mineral and organic matrix parameters, such as νPhosphate (PO)/CH-wag, νPO/Amide I, and others, to capture the complex composition of bone.
View Article and Find Full Text PDFJ Mater Sci
August 2025
Faculty of Science and Health, School of Medicine, Pharmacy and Biomedical Sciences, University of Portsmouth, St Michael's Building, White Swan Road, Portsmouth, PO1 2DT UK.
Unlabelled: Biodegradable magnesium (Mg) alloys are promising for various biomedical applications but their susceptibility to corrosion poses significant challenges. This study systematically examines the microstructural integrity and failure mechanisms of electrochemically deposited phosphate- and fluorine-rich coatings on AZ31 Mg alloy subjected to three-point bending (3 PB) in both non-corrosive and physiological (HBSS) environments. High-resolution digital image correlation (HR-DIC) combined with scanning electron microscopy (SEM) enables in situ visualization and quantitative analysis of crack initiation, evolution, and propagation within the coatings.
View Article and Find Full Text PDFACS Omega
August 2025
Department of Materials Science and Engineering, Federal University of São Carlos, Rod. Washington Luís, São Carlos, SP CEP 13565-905, Brazil.
Supermartensitic stainless steels (SMSS) reinforced with a percolated boride network offer exceptional corrosion and wear resistance, making them well-suited for oil and gas applications. However, hydrogen embrittlement (HE) poses significant challenges in offshore environments. This study examines HE in SMSS with boron additions ranging from 0.
View Article and Find Full Text PDFACS Omega
August 2025
Key Laboratory of Safe and Effective Coal Mining, Ministry of Education of China, Anhui University of Science and Technology, Huainan 232001, China.
To investigate the failure behavior and cracking mechanisms in surrounding rock, a true triaxial experimental system and digital imaging were employed to perform compression tests on sandstone specimens containing preexisting flaws. Experimental results revealed the propagation characteristics of microfractures under stress concentration conditions and their correlation with failure patterns. Furthermore, a fracture propagation model was implemented to evaluate the susceptibility of surrounding rock to failure.
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