Classification and Reconstruction of Defects by Combined Acoustical Holography and Line-Saft

Summary

For the purpose of defect location, sizing and characterization a couple of analyzing nondestructive testing methods have been developed. Here a data acquisition system is presented which is based upon data collection within a synthesized aperture. US-Holography with digital reconstruction algorithm is used to describe the extension of flaws parallel to the surface (C-scan) whereas the Line Synthetic Aperture Focusing Technique (LSAFT) is applied to get the information of depth location, depth extension and flaw inclination. Specially in the case of weld defects, an exact position determination is of great importance. It is shown that in the case of shear wave insonification the LSAFT-processing is essentially to get the exact depth location, a parameter which has to be known exactly as input value for the holographic evaluation to avoid a wrong location in x- or y-direction.