Shaft may include bearings, couplings, extra masses, and disks for gyroscopic effect. Shaft deflection is taken into account and provision is made in program for sections of shaft that are tapered. Plotter produces drawing of shaft with superimposed deflection curves at critical speeds together with all pertinent information related to shaft

Trivisonno, R. J.

English

NASA Technical Reports Server

December 1974	 B74-10128 
NASA TECH BRIEF 
Lewis Research Center 
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 National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Computer Program for Calculating 
Critical Speeds of Rotating Shafts 
A computer program has been written to calculate the 
critical speeds of rotating shafts. The shaft may include 
bearings, couplings, extra masses (nonshaft mass), and 
disks for the gyroscopic effect. Shear deflection is also 
taken into account and provision is made in the program 
for sections of the shaft that are tapered. The boundary 
conditions at the ends of the shaft can be fixed 
(deflection and slope equal zero) or free (shear and 
moment equal zero). The fixed end condition enables the 
program to calculate the natural frequencies of cantilever 
beams. Instead of using the lumped-parameter method, 
the program uses continuous integration of the differen-
tial equations of beam flexure across different shaft 
sections. The advantages of this method over the usual 
lumped-parameter method are less data preparation and 
better approximation of the distribution of the mass of 
the shaft. 
A main feature of the program is in the nature of the 
output. A plotter is used to produce a drawing of the 
shaft with superimposed deflection curves at the critical 
speeds together with all pertinent information related to 
the shaft.
Notes: 
1. The program is written in FORTRAN IV for the IBM 
DCS 7094/7044 computer. 
2. Inquiries concerning the program should be directed 
to:
COSMIC 
Information Services 
112 Barrow Hall 
University of Georgia 
Athens, Georgia 30602 
Reference: LEW-119 10
Source: Roger J. Trivisonno
Lewis Research Center 
(LEW-ll9lO) 
Category 09 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that Such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
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Computer program for calculating critical speeds of rotating shafts

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