Mechanical properties of single glass bead at different loading speeds

Abstract

Glass beads are originally used for decorative purposes. However, their superior qualities of hardness, heat resistance and chemical inertness bring about great application in the field of engineering. The usages of glass beads include metal blasting, dental bur sterilization, reflective paint fillers and as reinforcement filler. Glass often offers high strength to weight ratio, but is very brittle.

In this project, we aim to investigate the mechanical properties of single glass bead under constant loading speed, and further understand the behaviors and mechanical properties of glass beads under different constant strain rates.

The glass beads tested in this project are silica glass beads that ranges from a diameter of 169μm to 232μm provided by Abrasive Engineering Pte Ltd. A Micro-compression setup is build by a fellow student, to provide loading test for subject of micron-scale. The setup is capable of running compressive test at different loading speed, providing loading force of up to 40N, data acquisition and image capturing. As understanding of stress components in a spherical bead structure is critical to the analysis, thus the report made reference to a stress component analysis by Y.Hiramatsu and Y.Oka. Young’s Modulus is found to be the critical component to determine the stress analysis and determining the mechanical properties. As glass beads are of irregular cross-sectional area, Hertz Theory is applied to determine the Young’s Modulus of the beads.

In the experiment, it was found that glass bead do offer high strength to weight ratio, but failing catastrophically without giving any warning (i.e. cracks) prior to the failure. The limitation of the experiment setup resulted in the failure to acquire the required unknowns of the Hertz Theory thus being unable to analyze the Young’s Modulus effectively. The relationship of strain rate to the stress-strain curves of the glass bead was unable to be clear shown too.

The failure to achieve required objectives are likely caused by system limitations, which could be resolved given sufficient time and budget. Future team could follow up with the report’s analysis and improve on the experimental setup and acquire a clearer and more accurate analysis.