1、Designation:F188714An American National StandardStandard Test Method forMeasuring the Coefficient of Restitution(COR)of Baseballsand Softballs1This standard is issued under the fixed designation F1887;the number immediately following the designation indicates the year oforiginal adoption or,in the c
2、ase 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 This procedure is intended to standardize a method ofmeasuring the coefficient of restitution(C
3、OR)of baseballs andsoftballs.1.2 This procedure is established to provide a single,repeatable,and uniform test method.1.3 This procedure is for a ball that is intended for use in thegame of baseball or softball.1.4 The test method is based on ball speed measurementsbefore and after impact with eithe
4、r of two test surfaces:woodor metal.1.5 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user o
5、f 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:E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaborat
6、ory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 baseball and softball,nany ball defined by the rulesfor the game of baseball or softball.3.1.2 coeffcient of restitution(COR),n a numerical valuedetermined by the exit speed of t
7、he ball after contact divided bythe incoming speed of the ball before contact with a massive,rigid,flat wall of either wood or metal.4.Summary of Test Method4.1 Method AThe strike plate is a rigid metal surface,andball speed is measured before and after impact with the strikeplate.4.2 Method BThe st
8、rike plate is a rigid wood surface,andball speed is measured before and after impact with the strikeplate.5.Significance and Use5.1 The ball coefficient of restitution is a ball dynamicproperty of relative velocity change caused by impact with arigid wall.5.2 This test method is suitable for obtaini
9、ng data inresearch and development,quality control,and classifyingballs by liveliness.5.3 Sports associations can use coefficient of restitutionstandards in specifications for official baseballs and softballs.5.4 This same test procedure can be utilized at impactspeeds other then that prescribed in
10、this procedure and so notedin any reported test results.6.Apparatus6.1 Strike Plate,Method A:6.1.1 Material,5.08-cm(2-in.)thick steel.6.1.2 Size,61 by 61 cm(24 by 24 in.).6.1.3 Mounting,secured flush to a massive rigid wall ofcinder block or concrete,minimally 20.3-cm(8-in.)thick,andbolted at all fo
11、ur corners sufficiently secure to prevent move-ment during ball impact.6.2 Strike Plate,Method B:6.2.1 Material,10.2-cm(4-in.)thick northern white ashwood with moisture content between 10 and 15%with a flatsmooth surface.6.2.2 Same as 6.1.2.6.2.3 Same as 6.1.3.6.3 Ball Throwing DeviceA ball throwing
12、 device capableof delivering the ball through the electronic speed monitor at1This 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
13、approved May 1,2014.Published June 2014.Originallyapproved in 1998.Last previous edition approved in 2009 as F1887 09.DOI:10.1520/F1887-14.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 26.82 m/s(60 mph)with a maximum tolerance of 60.30
14、m/s.The machine should be calibrated using the electronic speedmonitor.6.4 Electronic Speed MonitorsAn electronic ball speedmeasuring system consisting of two vertical light screensmounted 30.48 cm(12 in.)apart with a tolerance of 60.32 cm,and a photoelectric sensor located at each screen that trigg
15、ersa timing device on ball passage to measure the time for the ballto traverse the distance between the two vertical planes beforeand after impact with the strike plate.Resolution shall be60.03 m/s.6.5 Ball Trajectory TargetA lightweight target with a30.48-cm(12-in.)diameter circular opening positio
16、ned at thesecond light screen and centered on the ball line of travelbetween the throwing device and the center of the strike plate.7.Preparation of Apparatus7.1 Mount the strike plate on a rigid wall such that thecenter is approximately 1.22 cm(4 ft)from the floor.Tightenall mounting bolts before each test.Torque to 81.35 N-m(60ft-lb)min.7.2 Position the first speed monitor(light screen)30.48 60.32 cm(12 6 0.125 in.)from the strike plate(see Fig.1).7.3 Position the second speed monitor(light sc
