Date of Award

2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical Engineering

First Advisor

Shivakumar, Kunigal

Abstract

This dissertation focused on the development and assessment of flexible microballoons filled elastomeric foam for shock mitigation applications. The overall goal of the research was to develop a flexible syntactic foam that has controllable bulk modulus, compressibility and shock mitigation characteristics and to validate these characteristics by experiments. Elastomer LP-2 with solid manganese dioxide and uncured BJO-093 hollow Pμb were chosen for making the syntactic foam. Hand mixing and room temperature curing was used to make foams of 0 to 30% weight of filler, which amounts to 0 to 60% of volume of the filler. Analysis using gas laws and simple elasticity equations showed that the compressibility of the foam and the resulting bulk modulus vary as a function of microballoon content. Confined compression tests confirmed these results and demonstrated that the bulk modulus can be changed from 19 MPa to 9 MPa as the filler content was increased from 0 to 30% by weight. The compressive high strain rate behavior of the foam was determined using the Split Hopkinson Pressure Bar test apparatus at strain rates ranging from 3,000/s to 4,600/s. The peak strain and strain rate values remain unaffected irrespective of the amount of filler. Both peak stress and stress rise rate decreased with increased filler content. Decrease in peak stress and stress rates were as high as 50% of the base material for filler content of 20% by weight. These characteristics show the potential of this material for shock mitigation applications.

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