ASTM F2845-11
(Test Method)Standard Test Method for Measuring the Dynamic Stiffness (DS) and Cylindrical Coefficient of Restitution (CCOR) of Baseballs and Softballs
Standard Test Method for Measuring the Dynamic Stiffness (DS) and Cylindrical Coefficient of Restitution (CCOR) of Baseballs and Softballs
SIGNIFICANCE AND USE
1 The ball dynamic stiffness is a measure of a ball’s hardness. Its measurement is conducted to represent bat-ball impact forces. It is normalized by the ball weight and speed to minimize the influence of manufacturing and test variations from the measure.
The cylindrical coefficient of restitution is a ball property of relative velocity change caused by impact with a cylindrical surface.
This test method compares the performance of baseballs and softballs after impact with a cylindrical test surface.
Sports associations can use DS and CCOR measurements in specifications for official baseballs and softballs.
SCOPE
1.1 This procedure describes a method of measuring the dynamic stiffness (DS) and cylindrical coefficient of restitution (CCOR) of baseballs and softballs providing similar impact forces and ball deformation as are observed in a bat-ball collision.
1.2 This procedure is for a ball that is intended for the game of baseball or softball.
1.3 The test method is based on ball speed measurements before and after impact with a cylindrical test surface and the impact force between the ball and impacted surface.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.5 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.
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Designation: F2845 − 11 AnAmerican National Standard
Standard Test Method for
Measuring the Dynamic Stiffness (DS) and Cylindrical
Coefficient of Restitution (CCOR) of Baseballs and
1
Softballs
This standard is issued under the fixed designation F2845; 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 3.1.1 baseball or softball, n—any ball defined by the rules
for the game of baseball or softball, respectively.
1.1 This procedure describes a method of measuring the
3.1.2 cylindrical coeffıcient of restitution (CCOR), n—the
dynamic stiffness (DS) and cylindrical coefficient of restitution
ratio of the rebound to incoming speed of a ball impacting a
(CCOR) of baseballs and softballs providing similar impact
solid rigid cylinder.
forces and ball deformation as are observed in a bat-ball
collision.
3.1.3 dynamic stiffness (DS), n—a normalized measure of
the ball impact force having units of stiffness (lb/in. or kN/m).
1.2 This procedure is for a ball that is intended for the game
It is obtained by dividing the square of the peak force between
of baseball or softball.
the ball and impact surface by the ball mass and the square of
1.3 The test method is based on ball speed measurements
the incoming ball speed.
before and after impact with a cylindrical test surface and the
impact force between the ball and impacted surface.
4. Summary of Test Method
1.4 The values stated in inch-pound units are to be regarded
4.1 A load cell or array of load cells is mounted between a
as standard. The values given in parentheses are mathematical
cylindrical solid steel impact surface and a rigid wall. The ball
conversions to SI units that are provided for information only
speed is measured before and after impact with the impact
and are not considered standard.
surface and the force is measured throughout the impact event.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 1 The ball dynamic stiffness is a measure of a ball’s
priate safety and health practices and determine the applica-
hardness. Its measurement is conducted to represent bat-ball
bility of regulatory limitations prior to use.
impact forces. It is normalized by the ball weight and speed to
minimize the influence of manufacturing and test variations
2. Referenced Documents
from the measure.
2
2.1 ASTM Standards:
5.2 The cylindrical coefficient of restitution is a ball prop-
E177 Practice for Use of the Terms Precision and Bias in
erty of relative velocity change caused by impact with a
ASTM Test Methods
cylindrical surface.
E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
5.3 This test method compares the performance of baseballs
and softballs after impact with a cylindrical test surface.
3. Terminology
5.4 Sports associations can use DS and CCOR measure-
3.1 Definitions of Terms Specific to This Standard:
ments in specifications for official baseballs and softballs.
6. Apparatus
1
This test method is under the jurisdiction of ASTM Committee F08 on Sports
Equipment, Playing Surfaces, and Facilities and is the direct responsibility of
6.1 Strike Plate:
Subcommittee F08.26 on Baseball and Softball Equipment.
6.1.1 Load Cell—Adevice capable of measuring force up to
Current edition approved April 1, 2011. Published May 2011. Originally
10 kip (45 kN) within 61 %. The peak load-cell reading after
approved in 2010. Last previous edition approved in 2010 as F2845 – 10. DOI:
10.1520/F2845-11.
ball impact due to oscillation shall not exceed 5 % of the
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
measured peak impact force.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1.2 Impact Surface—A4 6 0.1-in. (102 6 2-mm) long
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. solid steel half cylinder. For softballs, the diameter of the half
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F2845 − 11
FIG. 1 Test Apparatus
cylinder is 2.25 6 0.01 in. (57.2 6 0.3 mm). For baseballs the 8.2 Load Cells—The load cells used to measure the impact
diameter of the half cylinder is 2.62 6 0.01 in. (66.7 6 0.3 force should be calibrated on at least a yearly basis.
mm).
9. Conditioning
6.1.3 Mounting—The load cell and impact surface shall be
9.1 Ball Co
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F2845–10 Designation:F2845–11
Standard Test Method for
Measuring the Dynamic Stiffness (DS) and Cylindrical
Coefficient of Restitution (CCOR) of Baseballs and
1
Softballs
This standard is issued under the fixed designation F2845; 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
1.1 Thisproceduredescribesamethodofmeasuringthedynamicstiffness(DS)andcylindricalcoefficientofrestitution(CCOR)
of baseballs and softballs providing similar impact forces and ball deformation as are observed in a bat-ball collision.
1.2 This procedure is for a ball that is intended for the game of baseball or softball.
1.3 The test method is based on ball speed measurements before and after impact with a cylindrical test surface and the impact
force between the ball and impacted surface.
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.5 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.
2. Referenced Documents
2
2.1 ASTM Standards:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 baseball or softball, n—any ball defined by the rules for the game of baseball or softball, respectively.
3.1.2 cylindrical coeffıcient of restitution (CCOR), n—the ratio of the rebound to incoming speed of a ball impacting a solid
rigid cylinder.
3.1.3 dynamic stiffness (DS), n—a normalized measure of the ball impact force having units of stiffness (lb/in. or kN/m). It is
obtained by dividing the square of the peak force between the ball and impact surface by the ball mass and the square of the
incoming ball speed.
4. Summary of Test Method
4.1A load cell or array of cells is mounted between a cylindrical solid steel impact surface and a rigid wall. The ball speed is
measured before and after impact with the impact surface and the force is measured throughout the impact event.
4.2Method A—The cylindrical impact surface for softballs is 2.25 6 0.01 in. (57.2 6 0.3 mm) in diameter. The ball inbound
speed is 95 mph (42.5 m/s).
4.3Method B—The cylindrical impact surface for baseballs is 2.62 6 0.01 in. (66.7 6 0.3 mm) in diameter. The ball inbound
speed is 115 mph (51.4 m/s).
4.1 Aload cell or array of load cells is mounted between a cylindrical solid steel impact surface and a rigid wall.The ball speed
is measured before and after impact with the impact surface and the force is measured throughout the impact event.
1
This test method is under the jurisdiction of ASTM Committee F08 on Sports Equipment and Facilities and is the direct responsibility of Subcommittee F08.26 on
Baseball and Softball Equipment.
Current edition approved May 1, 2010. Published June 2010. DOI: 10.1520/F2845-10.
CurrenteditionapprovedApril1,2011.PublishedMay2011.Originallyapprovedin2010.Lastpreviouseditionapprovedin2010asF2845 – 10.DOI:10.1520/F2845-11.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
F2845–11
5. Significance and Use
5.1 1 The ball dynamic stiffness is a measure of a ball’s hardness. Its measurement is conducted to represent bat-ball impact
forces. It is normalized by the ball weight and speed to minimize the influence of manufacturing and test variations from the
measure.
5.2 The cylindrical coefficient of restitution is a ball property of relative velocity change caused by impact with a cylindrical
surface.
5.3 This test method compares the performance of baseballs and softballs after impact with a cylindrical test su
...
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