ASTM_F_2398_-_11_2015.pdf

Designation:F239811(Reapproved 2015)An American National StandardStandard Test Method forMeasuring Moment of Inertia and Center of Percussion of aBaseball or Softball Bat1This standard is issued under the fixed designation F2398;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 Method for determining the moment of inertia(MOI),the center of percussion(COP),and the balance point(BP)ofbaseball and softball bats.These physical properties are used inTest Method F1881,Test Method F1890,and Test MethodsF2219.1.2 The MOI,COP,and BP are measured in the laboratoryon test equipment meeting the requirements defined in this testmethod.1.3 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F1881 Test Method for Measuring Baseball Bat Perfor-mance Factor(Withdrawn 2014)3F1890 Test Method for Measuring Softball Bat PerformanceFactorF2219 Test Methods for Measuring High-Speed Bat Perfor-mance3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 balance point(BP),nthe distance to the center ofmass measured from the knob end of the bat.3.1.2 center of percussion(COP),nalso known as thecenter of oscillation.Forces and impacts at this location willnot induce reactions at the pivot point,6 in.(152 mm)from theknob end of the bat.3.1.3 cycle,none complete oscillation of a pendulumsupported at the pivot point,6 in.(152 mm)from the knob endof the bat.3.1.4 moment of inertia(MOI),nalso known as the massmoment of inertia,the measure of the bats resistance tochanges in its rotation rate about the pivot point,6 in.(152mm)from the knob end of the bat.3.1.5 period,nthe time required for a pendulum to oscil-late through one complete cycle.4.Significance and Use4.1 This test method offers a laboratory means to measurethe inertial properties of bats,specifically weight,balancepoint,center of percussion,and MOI,in support of other testmethods including the ASTM standards referenced in thisdocument.4.2 Use of this test method can provide sports governingbodies the means to establish rules regarding the physicalproperties of bats,specifically MOI.5.Apparatus5.1 Bat MOI Test Apparatus:5.1.1 Ruler,suitable for measuring lengths up to 42 in.(1067 mm)to the nearest 0.03 in.(0.8 mm).5.1.2 Weight Scales,suitable for measuring weight up to 48oz(1361 g)to the nearest 0.0035 oz(0.1 g).5.1.3 Electronic Timer,suitable device sufficiently accuratefor measuring time to the nearest 1 s(0.000001 s).5.1.4 Pendulum StandA frame with a pivoting bat collar-clamp large enough to allow a bat held in a vertical position toswing freely(see Fig.1).5.1.5 Bat Collar-ClampA lightweight clamp or collar thatcan hold the weight of a bat and provide a fixed pivot location.The clamp shall be rotationally balanced and have a maximumMOI of 4 oz-in.2(73 kg-mm2)measured about the bat pivot1This test method is under the jurisdiction of ASTM Committee F08 on SportsEquipment,Playing Surfaces,and Facilities and is the direct responsibility ofSubcommittee F08.26 on Baseball and Softball Equipment.Current edition approved Oct.1,2015.Published November 2015.Originallyapproved in 2004.Last previous edition approved in 2011 as F2398 11.DOI:10.1520/F2398-11R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 location(see Fig.1).The MOI of the clamp shall not changewith the diameter of the bat being tested.6.Calibration and Standardization6.1 Calibration RodThe calibration rod shall be 1 6 0.01in.(25.4 6 0.25 mm)in diameter by 34 6 0.1 in.(864 6 2.5mm)long,solid aluminum.6.2 Target Calibration MOIMeasure the length and theweight of the calibration rod.Compute the target calibrationrod MOI using Eq.1:IT5 WcHLc2121SLc22 dD2J1Ic(1)where:IT=target MOI of the calibration rod,oz-in.2(kg-mm2)Wc=measured weight of the calibration rod,oz(kg)Lc=measured length of the calibration rod,in.(mm)d=pivot distance(6 in.or 152 mm)Ic=MOI of the clamp about its pivot point,oz-in.2(kg-mm2)6.3 Balance