particle fragmentation
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2021 ◽  
pp. 117073
Author(s):  
Dazhao Gou ◽  
Yaoyu Li ◽  
Xizhong An ◽  
Runyu Yang

2021 ◽  
Author(s):  
Giuseppe Pintaude

Abrasive wear is highly dependent on the characteristics and properties of abrasive particles. Their hardness and size can define the severity of abrasion in terms of wear rates. Typically, critical values have been empirically determined to define the transition between mild and severe wear. This review aims to update some of the issues related to these critical values and their relations to abrasive wear. After presenting the current state-of-art, the following items are discussed: a) the scratchability of materials; b) the particle fragmentation associated with size effects; and c) description of abrasion severity.


Author(s):  
Mengmeng Wu ◽  
Jianfeng Wang ◽  
Budi Zhao

This paper presents a novel framework of modeling crushable granular materials under mechanical loadings based on the discrete element method (DEM). The framework is featured with the construction of the one-to-one model in which every particle in a physical experiment has its own numerical twin and allows the modeling of irregular shaped fragments during the continuous breakage process. First, image processing techniques and spherical harmonic (SH) analysis were adopted, respectively, to segment and label particles and to construct a one-to-one model mathematically in DEM. Then, a particle crushing criterion based on the maximum inter-particle contact force was used to predict the crushing events, showing fitting results that agreed very well with a large number of single particle crushing tests. Next, a statistical approach for the generation of particle fragmentation modes of a given type of sand particles based on the principal component analysis (PCA) was proposed. The aim of the PCA was to analyze the statistical trends of the coefficient matrix, which was composed of the SH coefficients of all the particles involved in the analysis. Finally, a successful modeling of a particle crushing event was achieved by replacing the particle, which was judged by the crushing criterion to undergo crushing, with a few sub-particles chosen randomly from a specific fragment template constructed using the micro-computed tomography (micro-CT) data.


Author(s):  
Vítor Lumertz ◽  
Fernando Pereira ◽  
Juliana Pohlmann ◽  
Amanda Tavares de Oliveira ◽  
Roberto Coelho Andriotti ◽  
...  

Author(s):  
Silvia Zanoni ◽  
Nikolaos Nikolopoulos ◽  
Alexander Welle ◽  
Aurelien Vantomme ◽  
Bert Weckhuysen

Efficient fragmentation of catalyst particles during the polymerization of olefins is a necessary process to maintain catalyst activity and obtain discrete polymer particles with ideal density and morphology. Collecting experimental...


BioEssays ◽  
2020 ◽  
Vol 42 (12) ◽  
pp. 2000149
Author(s):  
Daniel J. Mayor ◽  
Wendy C. Gentleman ◽  
Thomas R. Anderson

2020 ◽  
Vol 5 (11) ◽  
pp. 94
Author(s):  
Daniel Bassey ◽  
Ben Ngene ◽  
Isaac Akinwumi ◽  
Victor Akpan ◽  
Gideon Bamigboye

Across the world, ballasted railway tracks are utilised extensively due to their cost efficiency, ease of drainage, and capacity to withstand cyclic imposed loadings from heavy trains. In spite of these benefits, the ballast is often considered as a flexible medium; as such, its continuous deterioration is largely disregarded. Geotechnical challenges such as ballast contamination in the form of particle fragmentation, deposition of weathered materials, upward pumping of clay and fines from underlayers, and coal intrusion have led to differential settlements and reduced drainability of tracks, thereby exacerbating track maintenance costs. This study reviews existing works of literature to expound on the mechanisms for ballast contamination and to highlight the fundamental parameters that guide the characterisation and performance evaluation of railway ballasts. The study shows that ballast fragmentation accounts for about 76% of commonly recorded contaminations, while it is also observed as the most critical to track stability. As such, a variety of indices and specifications for ballast gradation have been established worldwide to guide practice in ballast characterisation and performance evaluation. However, the mechanisms of ballast fragmentation and deterioration require further research to guide the improvement of contemporary guidelines, and mitigate the risk of abrupt track failures, especially in developing countries.


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