ASTM F2398-11

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Designation: F2398 − 11 AnAmerican National Standard
Standard Test Method for
Measuring Moment of Inertia and Center of Percussion of a
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Baseball or Softball Bat
This standard is issued under the fixed designation F2398; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 center of percussion (COP), n—also known as the
center of oscillation. Forces and impacts at this location will
1.1 Method for determining the moment of inertia (MOI),
not induce reactions at the pivot point, 6 in. (152 mm) from the
the center of percussion (COP), and the balance point (BP) of
knob end of the bat.
baseball and softball bats.These physical properties are used in
3.1.3 cycle, n—one complete oscillation of a pendulum
Test Method F1881, Test Method F1890, and Test Methods
supported at the pivot point, 6 in. (152 mm) from the knob end
F2219.
of the bat.
1.2 The MOI, COP, and BP are measured in the laboratory
3.1.4 moment of inertia (MOI), n—also known as the mass
on test equipment meeting the requirements defined in this test
moment of inertia, the measure of the bat’s resistance to
method.
changes in its rotation rate about the pivot point, 6 in. (152
1.3 The values stated in inch-pound units are to be regarded
mm) from the knob end of the bat.
as standard. The values given in parentheses are mathematical
3.1.5 period, n—the time required for a pendulum to oscil-
conversions to SI units that are provided for information only
late through one complete cycle.
and are not considered standard.
1.4 This standard does not purport to address all of the
4. Significance and Use
safety concerns, if any, associated with its use. It is the
4.1 This test method offers a laboratory means to measure
responsibility of the user of this standard to establish appro-
the inertial properties of bats, specifically weight, balance
priate safety and health practices and determine the applica-
point, center of percussion, and MOI, in support of other test
bility of regulatory limitations prior to use.
methods including the ASTM standards referenced in this
2. Referenced Documents
document.
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2.1 ASTM Standards:
4.2 Use of this test method can provide sports governing
F1881 Test Method for Measuring Baseball Bat Perfor-
bodies the means to establish rules regarding the physical
mance Factor
properties of bats, specifically MOI.
F1890 Test Method for Measuring Softball Bat Performance
Factor
5. Apparatus
F2219 Test Methods for Measuring High-Speed Bat Perfor-
5.1 Bat MOI Test Apparatus:
mance
5.1.1 Ruler, suitable for measuring lengths up to 42 in.
(1067 mm) to the nearest 0.03 in. (0.8 mm).
3. Terminology
5.1.2 Weight Scales, suitable for measuring weight up to 48
3.1 Definitions of Terms Specific to This Standard:
oz (1361 g) to the nearest 0.0035 oz (0.1 g).
3.1.1 balance point (BP), n—the distance to the center of
5.1.3 Electronic Timer, suitable device sufficiently accurate
mass measured from the knob end of the bat.
for measuring time to the nearest 1 µs (0.000001 s).
5.1.4 Pendulum Stand—A frame with a pivoting bat collar-
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This test method is under the jurisdiction of ASTM Committee F08 on Sports
clamp large enough to allow a bat held in a vertical position to
Equipment, Playing Surfaces, and Facilities and is the direct responsibility of
swing freely (see Fig. 1).
Subcommittee F08.26 on Baseball and Softball Equipment.
5.1.5 Bat Collar-Clamp—Alightweight clamp or collar that
Current edition approved April 1, 2011. Published May 2011. Originally
can hold the weight of a bat and provide a fixed pivot location.
approved in 2004. Last previous edition approved in 2010 as F2398 – 10. DOI:
10.1520/F2398-11.
The clamp shall be rotationally balanced and have a maximum
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or 2 2
MOI of 4 oz-in. (73 kg-mm ) measured about the bat pivot
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
location (see Fig. 1). The MOI of the clamp shall not change
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. with the diameter of the bat being tested.
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F2398 − 11
FIG. 1 MOI Fixture
6. Calibration and Standardization 7. Procedure
6.1 Calibration Rod—The calibration rod shall be 1 6 0.01
7.1 Determination of BP:
in. (25.4 6 0.25 mm) in diameter by 34 6 0.1 in. (864 6 2.5
7.1.1 Measure and record the overall bat length to the
mm) long, solid aluminu
...