A Study Of Lamb Wave Scattering At The Corners Of A Flat Plate

Metal plate materials are widely used in industry and daily life.In order to ensure the safety and stability of the processing and use of the plate,the ultrasonic non-destructive testing of thin steel plates with Lamb waves is a feasible testing method.Lamb wave dispersion relations and wave propagation characteristics have been studied and summarized in detail in many books.However,the scattering properties of Lamb waves at various structural mutation positions are still insufficient.The mode conversion between a finite number of propagation modes and an infinite number of non-propagation modes is the main feature,resulting in the complexity of the Lamb wave scattering mechanism.This paper takes the Lamb wave scattering caused by the curved angle of the thin plate as the research object.The main contents of the paper are as follows:1.Based on the semi-analytical finite element method,the Lamb wave characteristic equations in flat and curved plates are solved,and the dispersion curves of guided waves including non-propagating modes are obtained,and their sound field distribution characteristics are analyzed.2.Based on the semi-analytical finite element mode matching method,the calculation model of the scattering matrix of the arc bending plate model is derived,and the scattering coefficient versus frequency curve is studied.3.Using finite element to simulate the excitation and propagation process of Lamb wave in the circular plate,the A0 mode and So mode are found to be more suitable single mode excitation methods.Finally,the incident signal and scattering signal are analyzed by two-dimensional Fourier transform,and the scattering characteristics of each mode of incidence are solved by signal processing.4.Using laser visualization technology and using the sound field reciprocity to conduct exploratory experiments on the arc bending plate,and analyze its scattering characteristics.