2026-09-23T05:35:47Zhttps://bura.brunel.ac.uk/oai/request

oai:bura.brunel.ac.uk:2438/72842014-11-01T13:10:03Zcom_2438_58col_2438_3672

London, GJ Carlyle, John Michael 2013-03-08T14:42:38Z 2013-03-08T14:42:38Z 1982 http://bura.brunel.ac.uk/handle/2438/7284 This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. An extension of acoustic emission technology was made which permits identification of probable source mechanisms for signals emitted during the failure of metals. This was achieved through the construction of a unique instrument and the development of special computer programs. The instrument permitted wideband digital waveform recordings to be made of both acoustic emission signals generated during the failure of a specimen, as well as calibration signals derived from a helium gas jet. These recordings were then processed by the computer programs to yield power spectra insensitive to specimen geometry, thus allowing the direct comparison of acoustic emissions from different specimens. A series of experiments conducted to test the instrument and the programs resulted in the conclusion that, at the 95% confidence level, acoustic emission caused by brittle particle fracture in 7039 aluminum could be differentiated from acoustic emission caused by the discontinuous movement of a crack in 4340 steel. Detailed descriptions of acoustic emission source modeling, transducer operating principles, calibration techniques and digital signal processing provide the necessary theoretical background for the reported technology extension, while a comprehensive review of the literature of acoustic emission places the experimental work into the proper context. Submitted by Lesh Gowreesunker (lesh.gowreesunker@brunel.ac.uk) on 2013-03-08T14:42:23Z No. of bitstreams: 1 FulltextThesis.pdf: 12330700 bytes, checksum: 7f5d2ce31d20afb0028cc9ef98b45bf2 (MD5) Approved for entry into archive by Lesh Gowreesunker(lesh.gowreesunker@brunel.ac.uk) on 2013-03-08T14:42:38Z (GMT) No. of bitstreams: 1 FulltextThesis.pdf: 12330700 bytes, checksum: 7f5d2ce31d20afb0028cc9ef98b45bf2 (MD5) Made available in DSpace on 2013-03-08T14:42:38Z (GMT). No. of bitstreams: 1 FulltextThesis.pdf: 12330700 bytes, checksum: 7f5d2ce31d20afb0028cc9ef98b45bf2 (MD5) This study is funded by the Naval Air Development Center, Warminster, Pennsylvania. en Brunel University School of Engineering and Design PhD Theses http://bura.brunel.ac.uk/bitstream/2438/7284/1/FulltextThesis.pdf Acoustic emission signal analysis Thesis