Evaluation of effects of vibrational multiple frequency forcing functions is discussed. Computer program for developing vibrational transfer functions is described. Possible applications of computer program are enumerated

Berry, R. L.

Jones, P. A.

English

NASA Technical Reports Server

October 1972	 B72-10648 
.
	 NASA TECH BRIEF 
Marshall Space Flight Center 
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Vibrational Transfer Functions For Complex Structures 
The problem: 
The accuracy of structurally mounted instrumentation 
and experiments with precise pointing requirements is 
greatly dependent on the operational vibration levels. This 
vibration environment is due to the structural response to 
various forcing functions applied during the operation of 
the equipment experiments. 
The solution: 
By developing vibrational transfer functions between 
equipment support areas and points of applications of the 
forcing functions, the effects of the vibrational multiple 
frequency forcing functions may be evaluated. A general 
computer program has been developed for this purpose. 
How it's done: 
The generated transfer functions can be used to 
determine structural response due to a variety of forcing 
functions. These are (1) single frequency, (2) multiple 
frequency, (3) random, and (4) complex periodic. The 
program has the capability of analyzing any complex 
structure composed of up to 50 substructures with a 
maximum of 162 degrees of freedom in each substructure. 
There is also capability of providing plots of the transfer 
functions which can easily be used to determine vibra-
tional response to any given forcing function in the above 
categories. 
The basic input to the program is the coupled structure 
modal properties. It should be noted that for use of the 
response transfer function program, basic structural analy-
sis programs such as finite element and modal analysis 
programs must be available.
Possible applications of this program are: 
1. determination of instrumentation and experiment mo-
tion due to equipment generated forcing functions for 
aerospace structures, such as payloads in orbit; 
2. determination of the response of land vehicle to 
operational forcing functions, such as rough roads 
represented by steady state or random inputs; and 
3. determination of the structural response of equipment 
support structure to excitation generated by stationary 
machinery. 
Notes: 
1. This program is written in FORTRAN IV for use on 
the CDC-6500 computer. It has plotting capability on 
the CDC-280 plotter. 
2. Inquiries concerning this program should be directed 
to:
COSMIC 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30601 
Reference: MFS-20744
Source: Paul A. Jones and

Robert L. Berry of
Martin Marietta Corp.

under contract to
Marshall Space Flight Center 
(MFS-20744) 
S
Category, 09, 06 
This document was prepared under the sponsorship of the National
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Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
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Vibrational transfer functions for complex structures

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