Dual-tree complex wavelet analysis and its application in defect detection of workpiece for cross wedge rolling

Aiming to miss-detection of internal tiny flaw of workpiece for cross wedge rolling, it is proposed a new ultrasonic signal testing method based on dual-tree complex wavelet transform (DT-CWT). By constructing new dual-tree complex wavelet bases, and by taking advantage of near shift-invariance of DT-CWT, it can improve common wavelet analysis methods for ultrasonic signal testing based on real orthogonal discrete wavelet transform. Experiments indicate that the method can extract weak defect feature and its results demonstrate the validity of the proposed method.