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- Creators: Rajan, Subramaniam
Description
Glasses have many applications such as containers, substrates of displays, high strength fibers and portable electronic display panels. Their excellent mechanical properties such as high hardness, good forming ability and scratch resistance make glasses ideal for these applications. Many factors affect the selection of one glass over another for a given purpose such as cost, ingredients, scalability of manufacturing, etc. Typically, silicate based glasses are often selected because they satisfy most of the selection criteria. However, with the recent abundant use of these glasses in touch-based applications, understanding their abilities to dissipate energy due to surface contact loads has become increasingly desirable. The most common silicate glasses worldwide are glassy silica and soda lime. Calcium aluminosilicates are also gaining popularity due to their importance as substrates for display screens in electronic devices. The surface energy dissipation and strength of these glasses are based on several factors, but predominantly rely on ingredient composition and the so-called Indentation Size Effect (ISE), where the strength depends on the maximum surface force. Both the composition and ISE alter the strength and favored energy dissipation mechanisms of the glass. Unlocking the contribution of these mechanisms and elucidating their dependence on composition and force is the underlining goal of this thesis.Prior to cracking, silicate glasses can inelastically deform by shear and densification. However, the link between the mechanical properties, strength, glass structure and maximum force and the propensity by which either of these mechanisms are favored still remains unclear. In this study, the first aim is to elucidate the causes of the ISE and
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explore the relationships between the ISE and the dissipation mechanisms, and identify what feature(s) of the glass can be used to infer their behavior. All glasses have shown a strong link between the ISE and shear flow and densification. Second, the link between composition and the dissipation mechanisms will be elucidated. This is accomplished by performing indentation tests coupled with an annealing method to independently quantify the amount of volume associated with each dissipation mechanism and elucidate relationships with ingredients and structure of the glasses. Some conclusions will then be presented that link all these behaviors together.
ContributorsKazembeyki, Maryam (Author) / Hoover, Christian G (Thesis advisor) / Rajan, Subramaniam (Committee member) / Neithalath, Narayanan (Committee member) / Chawla, Nikhilesh (Committee member) / Perreault, Francois (Committee member) / Arizona State University (Publisher)
Created2021
Description
The civil engineering curriculum includes the engineering fields of environmental, geotechnical, hydrology, structural, and transportation. A particular focus on the structural engineering curriculum outline involves courses in mathematics, engineering mechanics, structural analysis, and structural design. The core structural analysis and design course at Arizona State University (CEE 321) is a transition course to connect realistic structural design and analysis concepts to an engineering foundation created by the first and second year mathematics and mechanics courses. CEE 321 is styled after a flipped classroom model and students are assessed through quizzes, midterms, design projects, and a final exam. Student performance was evaluated for the Spring 2013 and Fall 2013 semesters through an error analysis technique designed to categorize student mistakes based on type of error and related topic. This analysis revealed that student's basic engineering mechanics skills improved throughout the course as well as identified the areas that students struggle in. The slope-deflection and direct stiffness methods of analysis and calculating cross-sectional properties are the primary areas of concern. Using appropriate technology in the engineering classroom has the potential to enhance the learning environment and address the areas of inadequacy identified by the performance analysis. A survey of CEE 321 students demonstrated that technology is a highly integrated and useful portion of student's lives. Therefore, the engineering classroom should reflect this. Through the use of analysis and design software, students are able to begin to develop design intuition and understanding while completing realistic engineering projects in their third year of undergraduate studies. Additionally, incorporating internet resources into and outside of the classroom allows students to be connected to course content from any web-enabled device of their choice. Lecture videos posted online covering the course content were requested by many CEE 321 students and are an emerging resource that supplements the flipped classroom model. The availability of such a tool allows students to revisit concepts that they do not understand or pause, rewind, and replay the lectures when necessary. An expansion of the structural analysis and design online lecture videos for CEE 321 are expected to address and improve the areas that students struggle in as identified by the error analysis.
ContributorsMika, Krista Nicole (Author) / Rajan, Subramaniam (Thesis director) / Mamlouk, Michael (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2013-12