ASTM F1890-01

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An American National Standard
Designation: F 1890 – 01
Standard Test Method for
1
Measuring Softball Bat Performance Factor
This standard is issued under the fixed designation F 1890; 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 3.1.6 coeffıcient of restitution (COR), n—a measure of
impact efficiency calculated as the relative speed of the objects
1.1 This specification defines a method for determining bat
after impact divided by the relative speed of the objects before
performance by measuring the coefficient of restitution (COR)
impact.
of the bat-ball collision using a ball with a known COR then
3.1.7 moment of inertia (MOI), n—a measure of mass
deriving a bat performance factor.
distribution relative to an axis of rotation. It is the product of
1.2 The values stated in inch-pound units are to be regarded
the mass multiplied by the square of the distance to the mass,
as the standard. The values given in parentheses are for
summed over the entire bat.
information only.
3.1.8 period, n—the time required for a pendulum to oscil-
1.3 This standard does not purport to address all of the
late through one complete cycle.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Significance and Use
priate safety and health practices and determine the applica-
4.1 This test method offers a laboratory means to compare
bility of regulatory limitations prior to use.
the overall performance of a bat as it relates to batted balls
2. Referenced Documents speeds.
4.2 Use of this test method can provide sports governing
2.1 ASTM Standards:
bodies a means to compare the anticipated batted ball speed,
F 1887 Test Method for Measuring the Coefficient of Res-
2
thus batted ball distance for the purposes of controlling the
titution (COR) of Baseballs and Softballs
game and safety.
F 1888 Test Method for Compression-Displacement of
2
4.3 Batted ball speed can be related to bat performance
Baseballs and Softballs
factor (BPF) using the following formulae:
3. Terminology 4.3.1 V = bat swing speed, mph—speed measured at the
point of impact, at the sweet spot of the bat, otherwise specified
3.1 Definitions of Terms Specific to This Standard:
as the COP. Impacts as the COP offer essentially the highest
3.1.1 balance point, n—the distance to the center of mass
batted ball speeds due to the optimization of momentum
measured from the outermost edge of the knob end of the bat.
transfer. The BPF value has been measured at this point and
3.1.2 bat-ball coeffıcient of restitution (COR), n—the COR
represents the maximum performance of the bat; therefore, the
of a specific ball colliding with a stationary bat as defined in
following calculations are correct only when the bat swing
this test method. See coeffıcient of restitution (COR).
speed at the point impact are used. The swing speed at the COP
3.1.3 bat performance factor (BPF), n—the ratio of perfor-
can be as much as 20 % slower than bat speeds measured at the
mance change a bat introduces to a ball collision, compared to
end of the bat. Typical adult values are 60 mph for average
a ball colliding with a solid wall as in Test Method F 1887.
players and 70 mph for top level non-super major softball
3.1.4 ball cover, n—the leather or equivalent material used
players. It is recognized that a players swing speed varies
to cover the ball core.
depending on skill level, conditioning, and bat swing weight
3.1.5 center of percussion (COP), n—also known as the
(MOI).
center of oscillation, the length of a simple pendulum with the
4.3.2 v = pitch speed, mph—horizontal speed of the ball
same period. Forces and impacts at this location will not induce
incoming to the batter. Typical slow pitch values are 10 mph
reactions at the pivot point.
while fast pitch speeds vary significantly with the level of play.
4.3.3 W = bat weight, oz.
1
This test method is under the jurisdiction of ASTM Committee F08 on Sports
4.3.4 w = ball weight, oz.
2
Equipment and Facilities and is the direct responsibility of Subcommittee F08.26 on
4.3.5 I = MOI, oz-in. .
Baseball and Softball Equipment and Facilities.
4.3.6 e = bat-ball COR = BPF 3 (SB COR 4 TB COR).
Current edition approved May 10, 2001. Published July 2001. Originally
published as F 1890 – 98. Last previous edition F 1890 – 98.
2
Annual Book of ASTM Standards, Vol 15.07.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F1890–01
4.3.7 a = distance from
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