By building a floating isolator box of cork around the test object and using a low frequency transducer, automated conventional C scan equipment is adapted to inspect the object ultrasonically. Vibrations are isolated and reflected noise is reduced

Stuckenberg, F. H.

English

NASA Technical Reports Server

.May 1970	 Brief 70-10055 
NASA TECH BRIEF 
NASA Tech Briefs announce new technology derived from the U .S. space program. They are issued to encourage commercial 
' application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
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.	 .	 . . •.	 . 
Immersed Ultrasonic Inspection of High Acoustical Attenuative Structures 
200 kHz Ultrasonic	 Standard Yoke for Immersion 
Receiver	 Through-Transmission Ultrasonics 
Cross-Section of Test Object in Floating Isolator Box 
The problem: 
To produce a low frequency, high power transducer 
which can penetrate certain types of acoustically high 
absorbing structures. Conventional ultrasonic im-
mersion inspection of this type Of structure is not 
possible because of the high reflected noise level de-
veloped within the immersion tank. A method is 
needed that will permit the use of ultrasonic equipment 
for the inspection. 
The solution: 
By building a floating isolator box of cork around 
the test object and using a low frequency transducer 
to penetrate the structure, automated conventional 
"C" scan equipment was adapted to inspect the
object ultrasonically. Vibrations were isolated and 
reflected noise from the immersion tank walls was 
reduced by employing this technique. 
How it's done: 
A typical application is through-transmission 
ultrasonic inspection of a structure consisting of 
1/4-inch cork on 1-1/2-inch foam on 1/8-inch alumi-
num to detect unbonded areas between cork and foam. 
The drawing shows a cross-section of the test object 
in a floating cork isolator box. Primary factOrs are 
the isolator box around the part; 200 kHz trans-
ducers; transmitter on attenuative side inside of the 
containment box; and transmitter and receiver close 
to the test part. Although high gain levels are used, 
(continued overienfi 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19700000051 2020-03-17T00:03:20+00:00Z
even more attenuative structures may be examined 
by preamplifying the receiver signal. 
Notes: 
1. This technique allows ultrasonic inspection of 
acoustically high absorbing structures such as 
cork or honeycomb core panels. It should be of 
interest to manufacturers and fabricators of 
plastics, rubber products, and construction 
materials. 
2. No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Manned Spacecraft Center, Code BM7 
Houston, Texas 77058 
Reference: B70-10055
Patent status: 
No patent action is contemplated by NASA. 
Source: F. H. Stuckenberg of 
North American Rockwell Corporation 
under contract to 
Manned Spacecraft Center 
(MSC- 15702)
is 
. 
Brief 70-10055	 Category 03


Immersed ultrasonic inspection of high acoustical attenuative structures

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