GLTRS--Glenn
TITLE AND SUBTITLE:
3-D Surface Depression Profiling Using High Frequency Focused Air-Coupled Ultrasonic Pulses

AUTHOR(S):
Don J. Roth, Harold E. Kautz, Phillip B. Abel, Mike F. Whalen,
J. Lynne Hendricks, and James R. Bodis

REPORT DATE:
May 1999

FUNDING NUMBERS:
WU-523-22-13-00

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-11589

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-1999-209053

SUPPLEMENTARY NOTES:
Don J. Roth, Harold E. Kautz, and Phillip B. Abel, NASA Glenn Research Center; Mike F. Whalen and J. Lynne Hendricks, Sonix, Inc. Springfield, Virginia 22152 (work funded under NASA Cooperative Agreement NCC3-489); James R. Bodis, Cleveland State University, 1983 E. 24th Street, Cleveland, Ohio 44115 (work funded under NASA Cooperative Agreement NCC3-304). Responsible person, Don J. Roth, organization code 5920, (216) 433-6017.

ABSTRACT:
Surface topography is an important variable in the performance of many industrial components and is normally measured with diamond-tip profilometry over a small area or using optical scattering methods for larger area measurement. This article shows quantitative surface topography profiles as obtained using only high-frequency focused air-coupled ultrasonic pulses. The profiles were obtained using a profiling system developed by NASA Glenn Research Center and Sonix, Inc (via a formal cooperative agreement). (The air transducers are available as off-the-shelf items from several companies.) The method is simple and reproducible because it relies mainly on knowledge and constancy of the sound velocity through the air. The air transducer is scanned across the surface and sends pulses to the sample surface where they are reflected back from the surface along the same path as the incident wave. Time-of-flight images of the sample surface are acquired and converted to depth / surface profile images using the simple relation (d = V*t/2) between distance (d), time-of-flight (t), and the velocity of sound in air (V). The system has the ability to resolve surface depression variations as small as 25 µm, is useable over a 1.4 mm vertical depth range, and can profile large areas only limited by the scan limits of the particular ultrasonic system. (Best-case depth resolution is 0.25 microns which may be achievable with improved isolation from vibration and air currents.) The method using an optimized configuration is reasonably rapid and has all quantitative analysis facilities on-line including 2-D and 3-D visualization capability, extreme value filtering (for faulty data), and leveling capability. Air-coupled surface profilometry is applicable to plate-like and curved samples. In this article, results are shown for several proof-of-concept samples, plastic samples burned in microgravity on the STS-54 space shuttle mission, and a partially-coated cylindrical ceramic composite sample. Impressive results were obtained for all samples when compared with diamond-tip profiles and measurements from micrometers. The method is completely nondestructive, noninvasive, non-contact and does not require light-reflective surfaces.

SUBJECT TERMS:
Nondestructive evaluation; Surface profilometry; Ultrasonics

NUMBER OF PAGES:
38

PDF AVAILABLE FROM URL:
1999/TM-1999-209053.pdf
(2,271,892 KB)
This page contains an Adobe® Acrobat® Reader PDF file. The PDF documents have been created to show thumbnails of each page. If the thumbnails do not display properly, download the file to the hard drive and view through Acrobat® Reader. You can download Acrobat® Reader for free. click

NASA NASA GLTRS--Glenn

A service of the NASA Glenn Research Center Logistics and Technical Information Division

Suggestions or questions about this site can be directed to:

NASA official: Technical Publications Manager, Sue.E.Butts@nasa.gov

Web curator: Caroline.A.Rist@grc.nasa.gov

Privacy Policy and Important Notices