Sensors Distribution Strategies in Guided Wave Sparse Arrays Based on Defects Scattering Properties

Most of imaging algorithms used in guided wave arrays share the same assumption that the signal scattered from defects will propagate uniformly in all directions. However, some recent researches on scattering properties of guided wave in defects demonstrate that the scattered signal is un-uniform even for a circular hole. Scattering properties of defects were studied and effects of sensors distribution strategies were presented in this paper. A 3D FE model was employed to study the sensor arrangement method and two basic imaging methods ellipse and hyperbola algorithm was used. Experiment was implemented in a 3mm aluminum plate with piezoelectric elements. Results show that for crack-like defects and through-hole, both ellipse and hyperbola imaging algorithms were valid. The number and position of transducers affect the accuracy of crack imaging. To detecting different kinds of defect the preferable array arrangement should be set according to the scattering characterization of defect.