ASTM C769-98(2005)

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An American National Standard
Designation:C769–98 (Reapproved 2005)
Standard Test Method for
Sonic Velocity in Manufactured Carbon and Graphite
Materials for Use in Obtaining an Approximate Young’s
Modulus
This standard is issued under the fixed designation C 769; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.3 zero time, (T )—the travel time (correction factor),
o
measured in seconds, associated with the electronic circuits in
1.1 This test method covers a procedure for measuring the
the pulse-propagation system.
sonic velocity in manufactured carbon and graphite materials
having a grain size less than 0.80 mm ( ⁄32 in.). The sonic
4. Summary of Test Method
velocity can be used to obtain an approximate value for
4.1 The velocity of sound waves passing through the test
Young’s modulus.
specimen is determined by measuring the distance through the
1.2 The values stated in SI units are to be regarded as the
specimen and dividing by the time lapse, between the trans-
standard.
,
3 4
mitted pulse and the received pulse. An approximate value
1.3 This standard does not purport to address all of the
for Young’s modulus can then be obtained as follows:
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
E5rv (1)
priate safety and health practices and determine the applica-
where:
bility of regulatory limitations prior to use.
E = Young’s modulus of elasticity, Pa,
2. Referenced Documents r = density, kg/m , and
v = signal velocity, m/s.
2.1 ASTM Standards:
Strictly speaking, the elastic constant given by this measure-
C 559 Test Method for Bulk Density by Physical Measure-
ment is not E but C , provided the sonic pulse is longitudinal
ment of Manufactured Carbon and Graphite Articles
and the direction of propagation is along the axis of symme-
C 747 Test Method for Moduli of Elasticity and Fundamen-
,
3 4
try.
tal Frequencies of Carbon and Graphite Materials by Sonic
Resonance
5. Significance and Use
IEEE/ASTM SI 10 Standard for Use of the International
5.1 Sonic velocity measurements are useful for comparing
System of Units (SI) (the Modern Metric System)
materials.
5.2 Avalue for Young’s modulus can be obtained for many
3. Terminology
applications, which will generally be within 10 % of the value
3.1 Definitions of Terms Specific to This Standard:
obtained by other methods, such as in Test Method C 747.
3.1.1 longitudinal sonic pulse—a sonic pulse in which the
displacements are in the direction of propagation of the pulse.
6. Apparatus
3.1.2 pulse travel time, (T)—the total time, measured in
t
6.1 Driving Circuit, which consists of an ultrasonic pulse
seconds, required for the sonic pulse to traverse the specimen
generator capable of producing pulses in a frequency range
being tested, and for the associated electronic signals to
from 0. 5 to 2.6 MHz.
traverse the circuits of the pulse-propagation circuitry.
6.2 Transducer, input.
6.3 Transducer, output.
This test method is under the jurisdiction of ASTM Committee D02 on
6.4 Oscilloscope, dual trace with a preamplifier and time-
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
delay circuitry.
D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved May 1, 2005. Published May 2005. Originally
approved in 1980. Last previous edition approved in 1998 as C 769 – 98.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Schreiber, Anderson, and Soga, Elastic Constants and Their Measurement,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM McGraw-HillBookCo.,1221AvenueoftheAmericas,NewYork,NY10020,1973.
Standards volume information, refer to the standard’s Document Summary page on American Institute of Physics Handbook,3rded.,McGraw-HillBookCo.,1221
the ASTM website. Avenue of the Americas, New York 10020, 1972, pp. 3–98ff.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C769–98 (2005)
6.5 See Fig. 1 for a typical setup. 8.4 Determine T ,thetraveltime(zerocorrection)measured
o
in seconds, associated with the electronic circuits in the
7. Test Specimen
pulse-propagation instrument and coupling.
8.5 Measure and weigh the test specimen as in 7.2.
7.1 Selection and Preparation of Specimens—Take special
8.6 Calculate the density of the test specimen in accordance
care to assure obtaining representative specimens that are
with Test Method C 559.
straight, uniform in cross section, and free of extraneous
8.7 Lightly grease the faces of the test specimens that will
liquids. The specimen end faces shall be perpendicular to the
contact the transducers or provide another suitable medium for
specimen cylindrical surface to within 0.125 mm (0.005 in.)
this purpose. Place the transducers against the test specimen
total indicator reading.
end faces.
7.2 Measurement of Weight and Dimensions—Determine
8.8 Tune the signal generator to transducer frequency, and
the weight and the average specimen dimensions to within
adjust the electronic components to give good visual amplitude
60.5 %.
resolution on the oscilloscope.
7.3 Limitations on Dimensions—The specimen shall have a
8.9 Determine T, the total
...