Study On Lamb Waves Propagation Characteristics In Plates With Butt Welds And Inspection Of Defects

Welding plays a very important role in the manufacture and use of large oilstorage tanks. The welding defects led to many accidents in large oil storage tanks.The welding quality directly affected the product safety and reliability. In this paper,A3-dimensional finite element model was developed to reveal the Lamb wavespropagation characteristics in butt welds. Weld end excitation method and scatteringmatrix method were used in this work. Experimental results verified the conclusionsobtained from finite element analysis method. The defects around the weld aredetected using these two methods. The variation of Lamb waves propagationcharacteristics versus the weld remaining-height, weld width and Young moduluswere investigated. The results could provide a reference method for the butt weldquality evaluation and avoid accidents caused by weld defects. The specific researchwork are as follows:(1) A3-dimensional finite element model was developed to reveal Lamb wavespropagation characteristics in butt welds. Lamb waves were excited at the weld endin the in-plane direction. Weld guided wave mode was generated. The simulationresults indicated the existence of energy trapping and energy attenuation phenomenain butt welds. Experimental results verified the conclusions obtained from finiteelement analysis method. The information about the location of defects can beobtained using this method.(2) According to the dual-elements method of Lamb waves, the single S0modewas stimulated in3-dimensional finite element model. Absorbing boundary methodwas used to avoid the interference of boundary echo. Gaussian-window filtermethod was used to eliminate the high-order noise. Scattering characteristics in thebutt weld was studied by the finite element simulation method and experiment.3-dimensional finite element model of S0mode interaction with defects wasestablished and interaction of Lamb waves with hole and crack was represented.(3)3-dimensional finite element models were developed according to weld endexcitation method and scattering matrix method. The variation of Lamb wavespropagation characteristics versus the weld remaining-height, weld width and Youngmodulus were investigated. The most appropriate range values of the three factorswere obtained and they were easy to be detected by Lamb waves. The results could provide a reference method for the butt weld quality evaluation..