Research On Array Guided Waves Nondestructive Testing Method For Plates

Plateparts are widely used in industry,especially irregular irregular plates,such as curved plates,variable-thickness plates,playing an important role in aerospace,automotive equipment and ship chemicals.However,due to the multiple processes such as heating,perforation and high-speed extrusion,it is difficult to avoid cracks,grooves and other defects.These defects brings great security risks to the industrial production.Therefore,it is of great significance to research on the non-destructive testing methods of plateparts.In this paper,the array guided-wave transducer is used to study methods of the defection for plateparts.The phase-delay mode focus method and the directivity characteristics of the array are studied.Non-destructive testing method of non-uniform thickness plates are explored.Beam directivity is an important indicator of array structure characteristics.A general formulas of the array structure directivity is deduced through constructing a general model satisfying both near and far fields.By systematically analyzing the influences of the beam directivity,methods of improving the beam directivity are summarized.Guided wave signal is a one-dimensional time signal with information of time and amplitude.Through the two-dimensional Fourier transform,several important parameters of the guided wave are obtained,and the modes in the guided-wave packet are distinguished.For non-equal thickness plates,it is difficult to be defected due to its internal guided wave propagation velocity.By theoretically studying the feasibility of A0 mode guided wave to detect the non-equal thickness plates,experiments are designed and the effectiveness is verified.The effectiveness of guided wave focusing for non-equal thickness using A0 mode guided wave provides a new direction for the detection of non-uniform thickness plates.