Acoustic emission monitoring and finite element analysis for torsion failure of Metal/FRP cylinder-shell adhesive joints

摘要

In this work, acoustic emission (AE) testing technology was used to monitor the damage mechanisms of adhesive joints for wind turbine blade Metal/fiber-reinforced polymer (FRP) cylinder-shell with different overlapping lengths under torsion test in real time. Finite element analysis models were developed to verify the experimental results. Results showed that the load-bearing ability of Metal/FRP cylinder-shell was enhanced with the increase of the overlapping length; however, the average shear stress was found to reduce at the same time. It was found that the cohesive failure is the dominant failure mode, with the major damage initiating and propagating at the edge of the adhesive joint due to the stress concentration. Besides, AE parameters, especially the amplitude distribution, were strongly related to the damage process. For the failure of adhesive joints with longer overlapping length, more AE signals with the amplitude from 60 to 80dB increased at the evolution stage, and more AE signals with the amplitude above 80dB increased at the failure stage, which is suggested that the dynamic characteristics of AE signals could effectively provide evidences for the security evaluation of wind turbine blades composite roots.