In-situ damage assessment of FML joints under uniaxial tension combining with acoustic emission and DIC: Geometric influence on damage formation

摘要

This work presents an in-situ assessment of damage occurring in the single-lap fiber metal laminate joints with various geometries under uniaxial tension and identify the crucial geometric role in the damage formation. The acoustic emission combined with digital image correlation is applied to record the damage events and strain field. The identification is made with the peak frequency, in which intervals of peak frequency containing 0-100 kHz, 100-200 kHz, 200-300 kHz and 300-400 kHz represent matrix/metal crack, delamination, fiber pull-out and breakage, respectively. The Hashin criterion, cohesive constitutive relation and ductile damage criterion are used to predict the damage evolution of fiber metal laminate. The combination of cumulative AE energy and simulation results reveals damage onset, evolution and severity. The incongruity of bearing capacities and stress situations caused by the distinction of geometric parameters result in the bearing damage, the brittle damage and the ductile shear damage in different structures.