Device measures the coefficient of static friction of magnetic tape over a range of temperatures and relative humidities. It uses a strain gage to measure the force of friction between a reference surface and the tape drawn at a constant velocity of approximately 0.0001 inch per second relative to the reference surface

Cole, P. T.

English

NASA Technical Reports Server

Strain Gage Leads 
id Reverse 
December 1967
	 Brief 67-10586 
NASA TECH BRIEF	
J7^ 
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. 
Device Measures Static Friction of Magnetic Tape 
The problem: 
To design a device that will accurately measure the 
coefficient of static friction of magnetic tape over a 
range of temperatures and relative humidities. 
The solution: 
A device using a strain gage to measure the force of 
friction between a reference surface and the tape 
drawn at a constant velocity of approximately 0.0001 
inch per second relative to the reference surface. At 
a constant velocity of this small magnitude, the 
difference in value between static and kinetic friction 
is negligible for practical purposes.
How it's done: 
The device is mounted so that the test surfaces are 
enclosed in an environmental chamber. A sample of 
tape to be tested is clamped at its upper end to a 
cantilever spring containing a strain gage. The base of 
the cantilever spring is mounted on the drive block of 
a motor-driven lead screw mechanism. The tape, with 
a precision weight secured to the lower end, is sus-
pended over a rounded face block made of any desired 
metal. For testing the tape against other materials, a 
film of the desired material can be wrapped around 
the metal block and held in tension by a weight. A 
thermocouple is embedded in the metal block close 
(continued overleaf) 
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=19670000585 2020-03-11T21:31:44+00:00Z
to the test surfaces. which .are enclosed in the test 
chamber. The environment in this chamber can be 
controlled at temperatures ranging from 00 to 120°C 
and relative humidities from 
.
1 to 90 percent. 
When the drive block is moved upward at the 
0.0001 ips rate, the strain gage output will rise to a 
steady maximum value. This output is amplified and 
converted (by calibration) to the value of the friction 
load plus the suspended precision weight in ounces. 
By the use of a simple equation the coefficient of fric-
tion can then be determined for any frictional load. 
Notes: 
1. This device can also be adapted to measuring 
kinetic friction.
2. An inductance tranducer may be used in place of a 
strain gage. 
3. Inquiries concerning this device may be directed 
to:
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: B67-10586 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: Pleasant T. Cole 
(GSC- 10360) 
Brief 67-10586	 Category 03


Device measures static friction of magnetic tape

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server