A time-of-flight revising approach to improve the image quality of Lamb wave tomography for the detection of defects in composite panels

Abstract

Lamb wave tomography can be used to evaluate structural integrity. The time-of-flight (TOF) data are usually recorded as input to the reconstruction algorithm. For composite materials, TOF estimation is complicated due to their anisotropy. To reduce the effects of anisotropy on image reconstruction, the TOF data of flawed plates are revised according to baseline data obtained from an unflawed plate. Tomographic images are reconstructed using the original and revised TOF data, respectively. Results show that images reconstructed using the revised TOF data have better visual quality and that TOF data revision can substantially reduce the artifacts resulting from anisotropy in defect detection of composite materials.

A Cross-Scanning Crack Damage Quantitative Monitoring and Imaging Method

“…In order to collect excitation and monitoring signal, lead zirconate titanate piezoelectric element (PZT) is used as sensor in the experiment. Excitation sensing methods can be divided into pulse echo and pitch catch [22][23][24]. Pulse echo method is adverse to determine the orientation of crack damage [14], so pitch catch method is used for monitoring.…”

An Inverse Approach of Damage Identification Using Lamb Wave Tomography

“…Huang et al [16] proposed a multi-mode electromagnetic ultrasonic LWT method for variable-depth defects in metal plates, and the imaging results show that the computed thickness distribution is more accurate than the ones of the traditional signal-mode LWT method. Chen et al [17] developed a time-of-flight revising LWT method for composite panels to improve the image quality. The time-of-flight data of flawed plates are revised according to baseline data obtained from an unflawed plate to reduce the effects of anisotropy on image reconstruction.…”