Efficient methods for predicting the effects of attached masses on the vibration characteristics of ring and shell structures have been developed and substantiated with experimental data

Lee, S. Y.

English

NASA Technical Reports Server

November 1968
	 Brief 68-10532 
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. 
Mass Loading Effects on Vibrated Ring and Shell Structures 
Efficient methods for predicting the effects of at-
tached masses on the vibration characteristics of ring 
and shell structures have been developed and sub-
stantiated with experimental data. Analytically, the 
series expansion technique is used in solving the mass-
loaded shell problem, while both the finite-element 
and transfer-matrix methods are employed in the 
analysis of mass-loaded ring structures. Experi -
mentally, aluminum ring and shell structures loaded 
with discrete masses are excited by an electrical induc-
tion force, and the vibratory motion is measured by an 
automatically revolving proximity gage. The influ-
ences of the masses of the exciter and of the instru-
mentation are thus eliminated. Response data are ob-
tained with miniature accelerometers and with a 
proximity gage for comparison purposes. The studies 
show, in addition to the amplitude changes of the 
local vibration response caused by the addition of the 
discrete masses, the frequency shifts, the change of 
modal behavior, and the transmissibility characteris-
tics resulting from the increased discrete mass on 
the structure. The results show (I) that the response 
attenuation for the first mode is somewhat similar
to the procedure currently recommended by NASA/ 
MSFC for predicting the amplitude reduction of the 
local vibration response of unloaded structure to 
account for the influence of the addition of the mass; 
(2) that for higher modes, much more amplitude re-
duction progresses very rapidly; and (3) that the 
transmissibility characteristics in a function of normal 
modes, indicate some differences for beams, plates, 
honeycomb plates, rings, and shells. 
Note: 
Documentation for the innovation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: B68-10532 
Patent status: 
No patent action is contemplated by NASA. 
Source: Stuart Y. Lee 
of North American Rockwell Corporation 
under contract to 
Marshall Space Flight Center 
(MFS-14979) 
Category 03 
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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Mass loading effects on vibrated ring and shell structures

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