Ultrasonic inspection of defects in welded plates and tubes

The characterization of defects, their size and orientation is of primary interest in quantitative NDE. A model for wave propagation through a weld between two plates is presented. An analytic method based on orthogonality relationship for Lamb modes is used to determine the reflected and transmitted fields for two welded plates. Some interesting experimental results have been obtained using guided waves inspection of hollow cylinders. Some frequencies are more sensitive to specific shapes and positions of defects.