To prevent fatigue due to flow-induced vibrations in metal bellows connected to ducts carrying liquid hydrogen, a study was made which shows that the flexure lines are in general a function of the vibration coupling between the fluid and bellows structure, and the nature of the external environment

Daniels, C. M.

Fargo, C. G.

English

NASA Technical Reports Server

March 1969	 Brief 69-10071 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information-, Springfield, Virginia 22151. 
Fatigue Failure in Metal Bellows Due to Flow-Induced Vibrations 
A study has been made in an effort to prevent fa-
tigue failure due to flow-induced vibrations in metal 
bellows connected to ducts carrying liquid hydrogen. 
The study, based on an analysis of bellows structure, 
fluid dynamics, and the environment (that is, air or 
vacuum) surrounding the bellows, showed that the 
flexure lines are in general a function of the vibra-
tion coupling between the fluid and bellows structure 
and the nature of the external environment. Each de-
sign must be proved by flow testing over its operating 
range in both vacuum and atmospheric surroundings. 
The results of this study are applicable to all metal 
flexure lines in which a flow-structural frequency 
coupling can occur and cause eventual fatigue failure 
of the metal. The information is important for lines 
carrying cryogenic liquids which condense air on their 
outer surfaces when tested in an air environment but 
whose actual service environment is a vacuum.
Note: 
Documentation i available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-1007 I 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C., 20546. 
Source: C. M. Daniels and C. G. Fargo

of North American Rockwell Corporation

under contract to

Marshall Space Flight Center 
(M FS- 18383) 
Category 05 
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.
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Fatigue failure in metal bellows due to flow-induced vibrations

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