Computer program generates the stiffness matrix for a particular type of structure from geometrical data, and performs static and normal mode analyses. It requires the structure to be modeled as a stable framework of uniform, weightless members, and joints at which loads are applied and weights are lumped

Bamford, R.

Batchelder, R.

Schmele, L.

Wada, B. K.

English

NASA Technical Reports Server

April 1968	 Brief 68-10096 
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. 
Computer Program Performs Stiffness Matrix Structural Analysis 
A computer program has been developed to gen-
erate the stiffness matrix for a particular type of struc-
ture from geometrical data, and perform static and 
normal mode analyses. 
The program requires the structure to be modeled 
as a stable framework of uniform, weightless mem-
bers, and joints at which loads are applied and weights 
are lumped. The framework and its environment are 
described by the input quantities from which the pro-
gram generates the stiffness matrix K. 
Static and normal mode analyses are performed 
wich? generate the solution to the equations KU = F 
and w2MU = KU where F is a matrix of static loads, 
M is a matrix of inertia terms, U is a matrix of static 
deflections or a normal-mode shape, and w is the cir-
cular frequency of a normal mode. The necessary 
eigenvalues and eigenvectors are evaluated by the 
power method or by Jacobi's method. Member loads 
are computed-from a set of deflections U and geo-
metrical properties of the members. 
The thermaliöads are computed by first calculating 
member loads induced by temperature changes with 
all joints restrained. The program stores the restraint 
forces at each joint required to prevent joint motion 
caused by temperature increase. The thermal deflec-
tions of joints and thermal loads in members are ob- 
tained by superimposing the member loads evaluated
above with the member loads and joint deflections 
evaluated by applying to the structure forces equal 
and opposite to the joint-restraining forces. 
Notes: 
1. This program is written in Fortran II for use on 
the IBM 7090/7094 computer. 
2. This program has been used extensively during the 
design of spacecraft and will be extremely useful to 
many engineers engaged in structural analysis. It 
can be used by personnel who have had little train-
ing in computer utilization since input can be easily 
revised to reflect changes in a design. 
3. Inquiries concerning this program may be made to: 
COSMIC 
Computer Center 
University of Georgia 
Athens, Georgia 30601 
Reference: B68-10096 
Patent status: 
No patent action is contemplated by NASA. 
Source: B. K. Wada, R. Batchelder 
R. Bamford, and L. Schmele 
Jet Propulsion Laboratory 
(N P0-10502) 
Category 06 
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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Computer program performs stiffness matrix structural analysis

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