Monitoring of Fatigue Damage in Adhesively Bonded Composite-Metal Joints by Acoustic Methods

摘要

A correlation between fatigue cycles and acousto-ultrasonic (AU) parametershas been obtained from signals acquired during fatigue loading of thesingle-lap joints of a carbon-fiber reinforced plastic (CFRP) laminates andan Al6061 plate. The correlation showed an analogy to those representing thestiffness reduction (E/E_o) of polymer matrix composites by the accumulationof fatigue damage. This has been attributed to the transfer characteristicsof acoustic wave energy through bonded joints with delamination-type defectsand its influence on the change of spectral content of AU signals. Anothercorrelation between fatigue cycles and the spectral magnitude of acousticemission (AE) signals has also been found during fatigue loading. Both AUand AE can be applied almost in real-time to monitor the damage evolutionduring fatigue loading.