Microstructure Effects on Acoustic Emission Signal Characteristics,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
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Specimens of three types of graphite-epoxy composites were fractured in bending in both the unaged and hydrothermally aged conditions. Acoustic emissions detected during the various stages in the fracture process were analyzed with a broadband system in the time and frequency domain and correlations were made between characteristics of the emissions and features of the load history, hydrothermal treatment, and topography of the fracture surfaces. Measurements were also made of the acoustic velocity, attenuation, and dispersion in a plate and in bars of one of the materials. Several attempts were also made to quantify observations made during the previous years study of the sources of acoustic emission in commercial aluminum alloys.