Research On Lamb Wave Structure Damage Identification Technology

Composite materials play a very important role in the development of modern industry due to their better strength-weight ratio,which make them apply more and more widely.However,their forms of damage are diversified and complicated.The different kinds of damage make the repair methods become different.It is need to identify the kinds of damage in order to take more effective repair measures.Structural Health Monitoring(SHM)is an emerging technology that can evaluate the healthy state of the structure without damaging its own characteristics.This paper studies the influence mechanism of Lamb wave propagating to different damage of structure that extract several statistical characteristic parameters of response signal to characterize the feature of different types of damage,and establishes Gaussian mixture model(GMM)identification system with different damage of structure to realize the classification and evaluation for unknown damage.This paper mainly studies the following aspects:(1)The basic theory of SHM and Lamb wave propagation are discussed,including the dispersion characteristics of Lamb wave and the choice of excited Lamb wave,and the main methods of damage identification based on Lamb wave are expounded.(2)Based on the analysis of the propagation characteristics of Lamb wave with different damage,several statistical characteristic parameters are extracted to characterize the different damage.The GMM model is introduced into the identification of damage types.By establishing GMM identification system with different damage,the type of unknown damage is identified.(3)A Lamb wave damage identification experiment system based on GMM model is designed.Three different types of damage such as corrosion,impact hole and crack are classified and identified in the glass fiber-reinforced epoxy composite laminate plate.The optimization of parameters and optimization process of building the identification model to realize the purpose of identifying the unknown damage type were put forward.Compared with the SOM identification method,the optimized GMM model has higher accuracy and it also has a simple process to build model.The experiment data show that the Lamb wave damage identification technology based on GMM model proposed in this paper can accurately classify defects and improve the diagnostic value of the Lamb wave defect,which has a good application prospect.