Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

Displaying 1 - 2 of 2
Filtering by

Clear all filters

161746-Thumbnail Image.png

Predicting Flow Function of Bulk Solids Based on Particle Size and Moisture Content

Description
The way a granular material is transported and handled plays a huge part in the quality of final product and the overall efficiency of the manufacturing process. Currently, there is a gap in the understanding of the basic relationship between the fundamental variables of granular materials such as moisture content,…

The way a granular material is transported and handled plays a huge part in the quality of final product and the overall efficiency of the manufacturing process. Currently, there is a gap in the understanding of the basic relationship between the fundamental variables of granular materials such as moisture content, particle shape and size. This can lead to flowability issues like arching and ratholing, which can lead to unexpected downtimes in the whole manufacturing process and considerable wastage of time, energy, and resources. This study specifically focuses on the development of a model based on the surface mean diameter and the moisture content to predict the flow metric flow function coefficient (FFC) to describe the nature of flow of the material. The investigation involved three parts. The first entailed the characterization of the test materials with respect to their physical properties - density, size, and shape distributions. In the second, flowability tests were conducted with the FT4 Powder Rheometer. Shear cell tests were utilized to calculate each test specimen's flow function parameters. Finally, the physical properties were correlated with the results from the flowability tests to develop a reliable model to predict the nature of flow of the test specimens. The model displayed an average error of -6.5%. Predicted values showed great correlation with values obtained from further shear cell tests on the FT4 Rheometer. Additionally, particle shape factors and other flowability descriptors like Carr Index and Hausner Ratio were also evaluated for the sample materials. All size ranges displayed a decreasing trend in the values of Carr Index, Hausner Ratio, and FFC with increasing moisture percentages except the 5-11 micron glass beads, which showed an increasing trend in FFC. The results from this investigation could be helpful in designing equipment for powder handling and avoiding potential flowability issues.
ContributorsDeb, Anindya (Author) / Emady, Heather (Thesis advisor) / Marvi, Hamidreza (Committee member) / Jiao, Yang (Committee member) / Arizona State University (Publisher)
Created2021
161763-Thumbnail Image.png

Effects of Particle and Environmental Variables on Rheology and Interaction of Granular Materials

Description
Granular materials demonstrate complexity in many physical attributes with various shapes and sizes, varying from several centimeters down to less than a few microns. Some materials are highly cohesive, while others are free-flowing. Despite such complexity in their physical properties, they are extremely important in industries dealing with bulk materials.…

Granular materials demonstrate complexity in many physical attributes with various shapes and sizes, varying from several centimeters down to less than a few microns. Some materials are highly cohesive, while others are free-flowing. Despite such complexity in their physical properties, they are extremely important in industries dealing with bulk materials. Through this research, the factors affecting flowability of particulate solids and their interaction with projectiles were explored. In Part I, a novel set of characterization tools to relate various granular material properties to their flow behavior in confined and unconfined environments was investigated. Through this work, a thorough characterization study to examine the effects of particle size, particle size distribution, and moisture on bulk powder flowability were proposed. Additionally, a mathematical model to predict the flow function coefficient (FFC) was developed, based on the surface mean diameter and moisture level, which can serve as a flowability descriptor. Part II of this research focuses on the impact dynamics of low velocity projectiles on granular media. Interaction of granular media with external foreign bodies occurs in everyday events like a human footprint on the beach. Several studies involving numerical and experimental methods have focused on the study of impact dynamics in both dry and wet granular media. However, most of the studies involving impact dynamics considered spherical projectiles under different conditions, while practical models should involve more complex, realistic shapes. Different impacting geometries with conserved density, volume, and velocity on a granular bed may experience contrasting drag forces upon penetration. This is due to the difference in the surface areas coming into contact with the granular media. In this study, a set of non-spherical geometries comprising cuboids, cylinders, hexagonal prisms and triangular prisms with constant density, volume, and impact velocities, were released onto a loosely packed, non-cohesive, dry granular bed. From these experimental results, a model to determine the penetration depth of projectiles upon impact was developed and how it is influenced by the release height and surface area of the projectiles in contact with the granular media was studied.
ContributorsVajrala, Spandana (Author) / Emady, Heather N (Thesis advisor) / Marvi, Hamidreza (Committee member) / Jiao, Yang (Committee member) / Arizona State University (Publisher)
Created2021