Acoustic emission response and progressive failure behaviors of composite adhesively bonded joints loaded by Mode i and II

Abstract

The analysis of progressive failure process is one of the critical issues in the research of composite adhesive joints. In view of this point, acoustic emission (AE) is applied to real-time monitoring of the dynamic damage process of composite adhesive joints in some loading modes such as Mode I (double cantilever beam (DCB)) and Mode II (end notch flexures (ENF)). Furthermore, the high speed camera and scanning electron microscopy are carried to analyses the damage mechanisms of composite bonded joints. Results show that there are significant differences in the load- deflection curves of the specimens under the loads of Mode I and II. The main failure mode of the two types of loading modes is adhesion failure, and the accumulation of damage observed at the edge of the adhesively bonded layer cause defeat of the composite bonded joints. In addition, AE parameters including amplitude, hits, energy, and duration are connected with the fail mechanism. Furthermore, the dynamic characteristics of the AE signal, especially amplitude spectrum distribution, can provide evidences for studying progressive failure behaviors of composite adhesive joints.