1、Designation: F 1887 02An American National StandardStandard Test Method forMeasuring the Coefficient of Restitution (COR) of Baseballsand Softballs1This standard is issued under the fixed designation F 1887; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This procedure is intended to standardize a method ofmeasuring the coefficient o
3、f restitution (COR) of baseballs andsoftballs.1.2 This procedure is established to provide a single, repeat-able, 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 aft
4、er impact with either of two test surfaces: woodor metal.1.5 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-bili
5、ty of regulatory limitations prior to use.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 baseball and softball, nany ball defined by the rulesfor the game of baseball or softball.2.1.2 coeffcient of restitution (COR), na numerical valuedetermined by the exit speed of the ball
6、 after contact divided bythe incoming speed of the ball before contact with a massive,rigid, flat wall of either wood or metal.3. Summary of Test Method3.1 Method AThe strike plate is a rigid metal surface, andball speed is measured before and after impact with the strikeplate.3.2 Method BThe strike
7、 plate is a rigid wood surface, andball speed is measured before and after impact with the strikeplate.4. Significance and Use4.1 The ball coefficient of restitution is a ball dynamicproperty of relative velocity change caused by impact with arigid wall.4.2 This test method is suitable for obtaining
8、 data inresearch and development, quality control, and classifyingballs by liveliness.4.3 Sports associations can use coefficient of restitutionstandards in specifications for official baseballs and softballs.4.4 This same test procedure can be utilized at impactspeeds other then that prescribed in
9、this procedure and so notedin any reported test results.5. Apparatus5.1 Strike Plate, Method A:5.1.1 Material, 5.08-cm (2-in.) thick steel.5.1.2 Size, 61 by 61 cm (24 by 24 in.).5.1.3 Mounting, secured flush to a massive rigid wall ofcinder block or concrete, minimally 20.3-cm (8-in.) thick, andbolt
10、ed at all four corners sufficiently secure to prevent move-ment during ball impact.5.2 Strike Plate, Method B:5.2.1 Material, 10.2-cm (4-in.) thick northern white ashwood with moisture content between 10 and 15 % with a flatsmooth surface.5.2.2 Same as 5.1.2.5.2.3 Same as 5.1.3.5.3 Ball Throwing Dev
11、ice2A ball throwing device capableof delivering the ball through the electronic speed monitor at26.82 m/s (60 mph) with a maximum tolerance of 60.30 m/s.The machine should be calibrated using the electronic speedmonitor.5.4 Electronic Speed Monitors3An electronic ball speedmeasuring system consistin
12、g 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 triggersa timing device on ball passage to measure the time for the ballto traverse the distance between the two vertical planes beforeand after impact w
13、ith the strike plate. Resolution shall be60.03 m/s.5.5 Ball Trajectory TargetA lightweight target with a30.48-cm (12-in.) diameter circular opening positioned at the1These test methods are under the jurisdiction of ASTM Committee F08 onSports Equipment and Facilities and is the direct responsibility
14、 of SubcommitteeF08.26 on Baseball and Softball Equipment and Facilities.Current edition approved Dec. 10, 2002. Published January 2003. Originallyapproved in 1998. Last previous edition approved in 1998 as F 1887 98.2ATEC, Model “Casey” or equivalent, or a suitable air cannon device, availablefrom
15、Athletic Training Equipment Co., Sparks, NV.3Oehler Research Chronograph, Model 35x2, or equivalent; Oehler ResearchSkyscreens, Model 55, or equivalent; available from Oehler Research Inc., Austin,TX.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
16、 United States.second light screen and centered on the ball line of travelbetween the throwing device and the center of the strike plate.6. Preparation of Apparatus6.1 Mount the strike plate on a rigid wall such that thecenter is approximately 1.22 cm (4 ft) from the floor. Tightenall mounting bolts
17、 before each test. Torque to 81.35 N-m (60ft-lbs) min.6.2 Position the first speed monitor (light screen) 30.48 60.32 cm (12 6 0.125 in.) from the strike plate (see Fig. 1).6.3 Position the second speed monitor (light screen) 30.486 0.079 cm (12 6 0.312 in.) from the first speed monitor.6.4 Position
18、 the ball throwing device such that the ballimpacts the strike plate within 15.24 cm (6 in.) of the centerand on rebound, passes through the 30.48 cm (12 in.) targetmounted at the second light screen.7. Conditioning7.1 Ball Conditioning:7.1.1 Test balls shall be placed in an environmentallycontrolle
19、d space for at least 24 h immediately before testing.7.1.2 Temperature is to be maintained at 22 6 2C (72 64F).7.1.3 Relative humidity is to be maintained at 50 6 10 %.7.1.4 Balls are to be tested within 20 min after removal fromcontrolled storage area.7.2 Test Room Conditioning:7.2.1 The test room
20、is to be environmentally controlled.7.2.2 Temperature will be 22 6 2C (72 6 4F).7.2.3 Relative humidity will be between 20 and 60 %.8. Procedure8.1 The ball throwing device is set to deliver the ball at26.82 6 0.305 m/s (60 mph). All shots above or below thistolerance range will not be used.8.2 Each
21、 ball is shot at the strike plate a minimum of sixtimes to a maximum of 12 times. A minimum 30-s rest periodis required between each shot.8.3 Only those speed readings for impacts falling within the6-in. target at the strike plate, within the 12-in. target at thesecond speed monitor, and thrown with
22、in the prescribed speedrange will be used in the calculation of COR.8.4 The average of the six acceptable COR values for eachball is used to determine the ball COR.8.4.1 Formulae:COR 5 Vb/Va 516FVb1Va11Vb2Va21Vb3Va31Vb4Va41Vb5Va51Vb6Va6G(1)where:Va = incoming speed, andVb = exit speed.9. Precision a
23、nd Bias9.1 Precision and bias evaluations have not been conductedfor these test methods. When such data are available, aprecision and bias section will be added.9.2 Report COR values to three digits (that is, x.xxx).10. Keywords10.1 ball liveliness; ball resilience; baseball; coefficient ofrestituti
24、on; softballFIG. 1 Test ApparatusF1887022ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and th
25、e riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision o
26、f this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
27、make your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).F1887023
