Damage Identification Using Acoustic Emission Data Obtained from Large Composite Structures

Acoustic emission was implemented to monitor damage initiation and its progression in a full-scale Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) carbon/epoxy fuselage panel subjected to combined loading of internal pressure and axial load. Prior to panel fracture, emission was generated at a very high rate, with a significant amount of emission apparently generated by fretting among the nearly infinite newly formed fracture surfaces. The separation of burst type waveforms (i.e., which are caused by actual new damage) and emission caused from extraneous sources is demonstrated. The effect of high rate of emission on the corresponding AE signal features is demonstrated. It is shown that the high rate of failure in composites is an added difficulty for damage source identification, which the current AE methodology needs to address.