Application of zero-group-velocity feature guided waves in welded joints damage assessment
The application of zero-group-velocity feature guided waves(ZGV-FGWs)in welded joints damage detection is investigated by numerical simulation.The two-dimensional(2D)frequency-domain finite element(FE)model of a welded joint is established with different levels of damage represented by varying its Young's modulus.The resonance phenomenon in the welded joint is verified and the resonance frequency is identified when the energy is concentrated near the feature region of the welded joint.The existence of ZGV-FGWs resonance is determined by three-dimensional(3D)time domain FE method,and the propagation characteristics of ZGV-FGWs in the welded joint with different Young's modulus are analyzed.The results show that the amplitude of the ZGV-FGWs spectrum signals significantly decreases monotonically with the decrease of Young's modulus,and the variation trend of spectrum amplitude at the ZGV-FGWs'frequencies with different Young's modulus coincides with the spectral curve of the excitation signal.Based on this characteristic,suitable excitation signals can be set to obtain ZGV-FGWs spectrum signals with more significant amplitude changes,thereby accurately evaluating the damage levels of welded joints.
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