NASA 1996 SBIR Phase I

PROJECT TITLE : Three-Dimensional Ultrasonic Shear Wave Imaging

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

This project proposes to develop a three-dimensional nondestructive imaging technique for thick samples that uses focused ultrasonic shear waves. Using shear waves provides for better resolution and deeper sample interrogation than using longitudinal or mixed-mode imaging. Digital Signal Processing optimizes the point spread function to improve sensitivity and resolution throughout the depth of the sample. Additional novel processing removes reflections from sample boundaries, increasing sensitivity to nearby defects. The proposed technique is useful for characterizing material properties, and detecting defects such as cracks, voids, corrosion, and poor bonds. It is designed for use on isotropic and layered material systems such as metals, polymers, glasses, ceramics, light metallic alloys, metal laminates. It should also work on weakly anisotropic composites and it may be possible to refine the technique to work on more anisotropic composites. Phase I will build a prototype to test the approach on planar samples made of aluminum and several composite materials. Phase II will build a more advanced prototype that is easily tailored to different materials and samples with curved geometry. Phase III will incorporate this technique into commercial NDE systems.

The proposed technique would provide an improved capability for NDE of thick samples. The techniques combination of 3D imaging, improved resolution, increased working distance, and sensitivity to vertical cracks will provide a cost effective means of testing thick samples that is not currently available.

Dr. Paul Reinholdtsen
Metrium
3767 Bay Road
Menlo Park, CA 94025

Metrium
3767 Bay Road
Menlo Park, CA 94025