Report ascertains the effects of thermoelastic damping on the propagation of longitudinal waves in cylindrical rods. Review of results of wave propagation in unbounded elastic solids and in elastic cylinders precedes consideration of thermal modification of elastic properties

Gillis, W. M.

English

NASA Technical Reports Server

September 1969	 Brief 69-10467 
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. 
__________	 ______	
-- - - - --------------------
	
----
Damping of Thermoelastic Structures 
A report is available which ascertains the effects of 
thermoelastic damping on the propagation of - longi-
tudinal waves in cylindrical rods. A review of classical 
results of wave propagation in unbounded elastic 
solids and in elastic cylinders precedes consideration 
of thermal modification of elastic properties. Effects 
upon the purely elastic wave motion consist of a 
change in propagation velocity and addition of a 
damping effect upon the mechanical energy of the 
elastic wave due to heat conduction. 
This report shows and concludes that thermo-
elastic effects on an assigned frequency wave are small 
in terms of the propagation velocity. However, in com-
parison, the thermoelastic damping effect is large for 
very high frequency waves traveling in small diameter 
bars. There is a linkage of the behavior of the thermo-
elastic damping coefficient to the "thermoelastic bar 
number," d v, where d is a thermoelastic material
constant; v is Poisson's ratio; and x is reduced 
frequency. Developed approximations, based upon the 
value of the thermoelastic bar number, predict the 
behavior of the thermoelastic damping coefficient as 
a function of frequency. 
Notes: 
1. Research engineers may use this work as a basis 
for investigating thermoelastic effects on other 
structural elements. 
2. Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-10467 
Source: W. M. Gillis

Marshall Space Flight Center

(M FS-20002) 
Category 02 
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.
https://ntrs.nasa.gov/search.jsp?R=19690000455 2020-03-16T18:04:14+00:00Z


Damping of thermoelastic structures

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server