This test method covers determination of the dynamic elastic
properties of advanced ceramics at ambient temperatures. Specimens
of these materials possess specific mechanical resonant frequencies
that are determined by the elastic modulus, mass, and geometry of
the test specimen. The dynamic elastic properties of a material can
therefore be computed if the geometry, mass, and mechanical
resonant frequencies of a suitable (rectangular, cylindrical, or
disc geometry) test specimen of that material can be measured.
Dynamic Young's modulus is determined using the resonant frequency
in the flexural mode of vibration. The dynamic shear modulus, or
modulus of rigidity, is found using torsional resonant vibrations.
Dynamic Young's modulus and dynamic shear modulus are used to
compute Poisson's ratio.
This test method measures the fundamental resonant frequency of
test specimens of suitable geometry by exciting them mechanically
by a singular elastic strike with an impulse tool. Specimen
supports, impulse locations, and signal pick-up points are selected
to induce and measure specific modes of the transient vibrations. A
transducer (for example, contact accelerometer or non-contacting
microphone) senses the resulting mechanical vibrations of the
specimen and transforms them into electric signals. (See Fig. 1.)
The transient signals are analyzed, and the fundamental resonant
frequency is isolated and measured by the signal analyzer, which
provides a numerical reading that is (or is proportional to) either
the frequency or the period of the specimen vibration. The
appropriate fundamental resonant frequencies, dimensions, and mass
of the specimen are used to calculate dynamic Young's modulus,
dynamic shear modulus, and Poisson's ratio.
Although not specifically described herein, this test method can
also be performed at cryogenic and high temperatures with suitable
equipment modifications and appropriate modifications to the
calculations to compensate for thermal expansion, in accordance
with sections 9.2, 9.3, and 10.4 of C1198.
Where possible, the procedures, sample specifications, and
calculations in this test method are consistent with Test Methods
C623, C747, C848, and C1198.
This test method uses test specimens in bar, rod, and disc
geometries. The rod and bar geometries are described in the main
body. The disc geometry is addressed in Annex A1.
A modification of this test method can be used for quality
control and nondestructive evaluation, using changes in resonant
frequency to detect variations in specimen geometry and mass and
internal flaws in the specimen. (See 5.5).
The values stated in SI units are to be regarded as the
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.