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Title: Study of acoustic emissions from polymers
Author: Lilley, T.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1981
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Acoustic emissions have been detected from polymers under tensile loading. A purposely designed frictionless stressor incorporating air bearings, has been constructed for these experiments. The rate of production of acoustic energy was monitored by measuring the R.M.S. voltage of the acoustic signal detected by a resonant piezoelectric transducer. A data acquisition system for recording individual emission transients, with a wideband transducer, is described. Several methods of analysing the acoustic data are proposed, namely: autocorrelation, frequency analysis, median frequency measurements and cepstrum analysis which is a novel method of detecting echoes in a signal. In parallel experiments free radicals have been detected from bulk polymer under load by electron spin resonance. Acoustic emissions have also been monitored from a number of chemical reactions. A pattern recognition program has been developed to investigate correlations between chemical, mechanical and acoustic parameters by cluster analysis. The preliminary results from this are presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available