Three-Dimensional Imaging of Impact Damage in Composite Laminates

Abstract

Conventional ultrasonic C-scanning for detection and characterization of mate- rial defects has limitations because it provides only an overall planar view of the damage without accurate definition of the size and location of flaws. Hence, a three-dimensional reconstruction from the digitized ultrasonic fulse-echo waveform database was developed for full volume evaluation of damage [1 . Since the A-scans contain a great deal of information of wave interactions with flaws at a point through the thickness of the material in the pulse-echo mode, record- ing of the entire waveform at every location is very useful in subsequent analyses. The database approach has the advantage that all A, B, or C-scans as well as the perspective 3-D view of the flaw map can be constructed from the database. For instance, if the peak values of the back face reflection in each A-scan is mapped on a 2-D plane, a gray-scale C-scan image can be obtained. If there is a region of par- ticular interest in the C-scan, the corresponding A-scan can be presented promptly from the database. The ultrasonic response to anomalies was studied in an effort to determine the existence of flaws and the location of these flaws from time-of-flight measurements. ECHO