Published Online: 4 March 2013
Page Count: 14
Qamhia, Issam I.
Gradaute Research Assistant, Dept. of Civil Engineering and Mechanics, College of Engineering & Applied Science, Univ. of Wisconsin, Milwaukee, WI
Lauer-Hunt, Eric M.
Undergraduate Research Assistant, Dept. of Civil Engineering and Mechanics, College of Engineering & Applied Science, Univ. of Wisconsin, Milwaukee, WI
El-Hajjar, Rani F.
Assistant Professor, Dept. of Civil Engineering and Mechanics, College of Engineering & Applied Science, Univ. of Wisconsin, Milwaukee, WI
(Received 15 September 2012; accepted 27 December 2012)
The manufacturing of composite structures can result in manufacturing defects such as fiber waviness and porosity. These can have a significant and usually adverse impact on the mechanical and non-mechanical properties. In this study, we propose the use of an acoustic emission methodology to study the acoustic signature when porosity and fiber waviness are present in a composite structure. The methodology shows the possibility of identifying the signals near regions of high stress concentration in specimens subject to quasi-static loading. The analysis of the acoustic waveforms is performed through temporal characterization of the acoustic emissions and individual waveform analysis. The study reveals that the presence of fiber waviness and local porosity can be detected by the time at which major events start to occur and from the recorded magnitudes of cumulative energy and counts against time. However, the combined presence of porosity and waviness results in increased difficulties in the interpretation of the acoustic emission signals. A fast Fourier transform analysis of the captured waveform is examined in order to decouple the acoustic emissions and understand the defect modes present.
Paper ID: ACEM20120033