Identification of Damages in Unidirectional Carbon Fiber-Epoxy Composites with Artificial Flaws via Acoustic Emission Techniques

摘要

An experimental investigation is made on mechanical, electrical and acoustic emission behavior of unidirectional carbon fiber epoxy composites with or without pre-cut plies that were tested in tension. Fiber and matrix fracture, delamination, splitting (or cracking along fibers) and friction of delaminated faces contributed to characteristic acoustic emission behavior. These can be discriminated on the basis of peak amplitude and event duration of observed acoustic emission signals. Advanced digital signal processing techniques were also employed. Auto-regression coefficients were used as feature vectors in pattern recognition analysis, which can distinguish signal types without resorting to the signal amplitude or duration. The pattern classification scheme successfully identified five distinct types of signals without relying on the peak amplitude information. By combining the conventional acoustic emission parameters and auto-regression analysis, it is expected that in-service damage assessment procedures can be developed using acoustic emission.