Scanning Laser Vibrometry for Lamb Wave Evaluation of Composite Tubulars

Abstract This paper is concerned with the development of a technique for long-range ultrasonic nondestructive inspection of composite tubulars. A dry-contact piezoelectric transducer is used to excite Lamb waves in the axial direction. The field scattered by a defect and/or the mode shape distortion caused by the defect is measured by the use of a laser vibrometer. The presence of the defect is indicated by anomalies in the scattered field. The technique was tested on glass/epoxy composite tubes. It is shown that the presence of a defect (for example, a delamination of I ern diameter) can be remotely detected as far away as one meter from the transmitter, and its position can be located with an accuracy of a few centimeters.