Document Type

Theses, Ph.D

Rights

This item is available under a Creative Commons License for non-commercial use only

Disciplines

Other engineering and technologies

Publication Details

Successfully submitted for the award of Doctor of Philosophy to the Dublin Institute of Technology, September, 2009.

Abstract

his work opens with a broad overview of several factors influencing the behaviour of elastomeric materials under constant deformation. Following this, an evaluation of the common difficulties surrounding industry-standard lifetime prediction methods is presented. Subsequently, a novel method for the lifetime prediction of stress relaxation in elastomeric materials under constant deformation is introduced. Experimental testing to determine the influence of filler type and content was conducted on several natural rubber materials. The effect of altering the vulcanising agent, crosslink density and mixing time was also examined. Chemiluminescence was used to determine the influence that oxidation has on the overall life of elastomers. A critical assessment of current industry-standard lifetime estimation methods are presented through practical examples. This work evaluates some of the common problems surrounding these life time prediction methods and discusses their limitations. Comprehensive investigations were initiated to develop the time and temperature dependent fitting of relaxation data using spectral analysis. A novel concept is introduced to accurately predict the long-term behaviour of elastomers under constant deformation. The concept of analysing relaxation spectra and Arrhenius extrapolation offers a promising route to more accurate lifetime predictions.