1、Designation: F 1881 09An American National StandardStandard Test Method forMeasuring Baseball Bat Performance Factor1This standard is issued under the fixed designation F 1881; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 test method defines a method for determining batperformance by measuring the bat-ball coefficient of restit
3、ution(BBCOR), deriving the bat performance factor (BPF), andcalculating batted-ball speed (BBS). It is applicable to baseballbats of any construction or material. The test method providesa quantitative measure of bat dynamic performance that may beused for comparison purposes.1.2 The BBCOR, BPF, and
4、 BBS are each calculated frommeasurements taken in the laboratory on test equipmentmeeting the requirements defined in this test method.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 f
5、or information onlyand are not considered standard.1.4 This standard does not purport to address all the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and to determine the applicability of reg
6、ula-tory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2F 1887 Test Method for Measuring the Coefficient of Res-titution (COR) of Baseballs and SoftballsF 1888 Test Method for Compression-Displacement ofBaseballs and SoftballsF 2398 Test Method for Measuring Moment of Inertia an
7、dCenter of Percussion of a Baseball or Softball Bat3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 balance point, ndistance to the center of mass of abat when measured from the distal end of the bat knob.3.1.2 bat-ball coeffcient of restitution (BBCOR), nCORof a specific ball
8、colliding with a bat as defined in this testmethod. See coeffcient of restitution (COR).3.1.3 bat performance factor (BPF), nratio of BBCOR toball COR in accordance with this test method.3.1.4 center of percussion (COP), nalso known as thecenter of oscillation, length of a simple pendulum with thesa
9、me period as a physical pendulum, as in a bat oscillating ona pivot. Forces and impacts at this location will not induceaxial reactions at the pivot point.3.1.5 coeffcient of restitution (COR), nmeasure of impactefficiency calculated as the relative speed of the objects afterimpact divided by the re
10、lative speed of the objects beforeimpact.3.1.6 moment of inertia (MOI), nmeasure of mass distri-bution relative to an axis of rotation. It is the product of themass multiplied by the square of the distance to the mass,summed over the entire bat.4. Significance and Use4.1 This test method offers a la
11、boratory means to comparethe relative performances of baseball bats.4.2 Use of this test method can provide sports governingbodies a means to compare calculated batted-ball speed andother physical properties of the bats.5. Apparatus and Equipment5.1 Test BallsOfficial balls approved for play and tes
12、ted inaccordance with the following procedures. Perform ball com-pression test of Test Method F 1888 prior to ball COR test ofTest Method F 1887.5.1.1 Compression300 to 375 lb at 0.25-in. deflection(1135 to 1668 N at 6.4 mm deflection). Compression valuesdetermined in accordance with Test Method F 1
13、888. Balls to belabeled with compression value.5.1.2 Weight5.00 to 5.25 oz (142 to 149 g), balls to belabeled with weight value.5.1.3 Size9.00 to 9.50-in. circumference (228.6 to 241.3mm), balls to be labeled with size value.1This test method is under the jurisdiction of ASTM Committee F08 on Sports
14、Equipment and Facilities and is the direct responsibility of Subcommittee F08.26 onBaseball and Softball Equipment.Current edition approved June 1, 2009. Published June 2009. Originallyapproved in 1998. Last previous edition approved in 2005 as F 1881 05.2For referenced ASTM standards, visit the AST
15、M 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unite
16、d States.5.1.4 COR0.525 to 0.555, balls to be labeled with CORand test speed in ft/s.5.2 Bat-Ball COR Test Apparatus:5.2.1 Ball CannonA device capable of shooting a ball ata speed of 88 ft/s (26.8 m/s). The ball shall not have a spin ratein excess of 10 rpm. Typical pitching machines cannot yield th
17、eaiming accuracy required by this test method. Cannon exhaustair must not cause motion of the bat in the absence of animpact. The cannon shall not blow out a match located in theimpact location when it is dry-fired (fired without a ball). Theball cannon can be any distance from impact location, as l
18、ongas it can meet the ball aim requirements and provide six validimpacts in twelve shots or less.5.2.2 Bat Speed GateA light trap, device, or an equiva-lent, capable of measuring an edge traveling at speeds in excessof 88 ft/s (26.8 m/s) with an accuracy of 0.5 ft/s or better (0.2m/s). The first sen
19、sor shall trigger when the bat rotates no lessthan 15 and no more than 20 from its start position. It issuggested the second trigger be 3 in. (76.2 mm) away from thefirst and must not be any further than 3.6 in. (91.4 mm) awayon a 6-in. (15.24-cm) radius.5.2.3 Ball Speed GateA light trap, device, or
20、 an equiva-lent, capable of measuring a sphere traveling at speeds inexcess of 88 ft/s (26.8 m/s) with an accuracy of 0.5 ft/s or better(0.2 m/s). The device shall measure across a length of no lessthan half the ball diameter to avoid centering error. Forexample, when testing baseballs, the device s
21、hall sense anobject across a 2.0-in. (50.8-mm) line. The first sensor shalltrigger when the ball is no more than 12 in. (30.5 cm) from thebat surface. The second sensor shall trigger between 3.6 in.(91.4 mm) and 8 in. (203.2 mm) from the first sensor.5.2.4 Bat Pivot SupportA turntable, rotating in t
22、he hori-zontal plane, with clamps to support and align the bat in thepath of the ball. The clamp surfaces shall be a 45 Vee clampwith a radius no greater than 2.0 in. (50.8 mm). The rotatingclamp and shaft assembly shall not weigh more than 6 lb (2.7kg) and shall spin freely via ball bearings (see F
23、ig. 1). Thepolar MOI for the clamp turntable assembly shall not exceed192 oz-in.2(35 117 g-cm2). The actual MOI of the clampturntable assembly shall be determined and used in theperformance calculations.6. Calibration and Standardization6.1 Ball Speed GateThe distances between the sensors ofthe spee
24、d gates must be known and recorded to the statedtolerances. The accuracy of the timers used in the velocitysensors must be adequate to provide the stated velocityaccuracy at the maximum stated speeds. The timers used shallbe calibrated on a yearly basis.6.2 Reference Standards and BlanksA standard b
25、at andball shall be used for reference purposes to verify propermachine operation.7. Conditioning7.1 Ball and Bat Conditioning and Test Room Conditions:7.1.1 Test balls shall be stored in an environmentallycontrolled space for at least 14 days immediately beforetesting. Wood bats shall be stored at
26、these environmentalconditions for at least 24 h prior to testing. Non-wood batsshall be stored at these environmental conditions for at least 2h prior to testing.7.1.2 Temperature is to be maintained at 72 6 4F (22 62C).7.1.3 Relative humidity is to be maintained between 40 and60 %.7.1.4 Temperature
27、 and relative humidity are to be measuredand recorded hourly within 60.5F (60.3C) and 2 % RH overconditioning and test duration.8. Procedure8.1 Determination of Bat Features and Test LocationDetermine bat balance point (BP), bat MOI, and bat COP inaccordance with Test Method F 2398.8.2 Bat Test Proc
28、edure:8.2.1 Ready and calibrate ball and bat speed gates inaccordance with the manufacturers instructions.8.2.2 Select a test ball in accordance with 5.1, and record theweight to the nearest 0.0035 oz (0.1 g) along with the size,compression, and COR of the ball in accordance with 5.1.8.2.3 Set ball
29、cannon to fire the ball at the desired impactspeed of 88 ft/s (26.8 m/s). Valid test speeds are considered tobe those done within 61 % of the targeted test speed.FIG. 1 Bat Testing MachineF18810928.2.4 Mount the bat in the clamps on the bat pivot support.The distal end of the bat knob must be 6 in.
30、(152.4 mm) fromthe axis of rotation of the turntable assembly.8.2.5 The ball impact must be centered vertically andhorizontally on the bat diameter at the previously measuredCOP.8.2.6 Position the bat against the start position reference,which must place the bat axis perpendicular to the ball line o
31、ftravel.8.2.7 Verify that all speed traps are reset and ready to takedata.8.2.8 Load selected test ball in ball cannon. Attempt to loadtest ball so that its impact with the bat will occur between thestitches of the ball.8.2.9 Shoot the ball at the bat, observing the necessarysafety precautions.8.2.1
32、0 Record ball inbound speed and bat rebound speed.Do not use data where the ball inbound speed deviates by morethan the tolerances stated in 8.2.3 from the targeted test speed.8.2.11 Continue testing for six valid impact readings or fortwelve total impacts. For a given test ball, rotate the ball in
33、thecannon between impacts so that the impact area of the ball isdifferent for each impact. A single test ball may be tested onceon each impact area of the ball, with no rest period betweenimpacts. Following this series of up to four impacts on a singleball, a rest period of at least 10 min following
34、 the last impactis required prior to retesting, using the same ball. If six validimpacts are not achieved prior to twelve total impacts, fix thesetup to alleviate cause of invalid impacts. Verify supportsystem for ball cannon, ball speed gate, and bat pivot supportare rigid.9. Calculation of Results
35、9.1 Calculate the bat-ball coefficient of restitution (BBCOR)for each valid impact using Eq 1:BBCOR 5S1 1IwR2DSDRtdrTD 1 (1)where:D = distance between bat-speed sensors, in. (cm),d = distance between ball-speed sensors, in. (cm),I = moment of inertia (MOI), of bat, oz-in.2(g-cm2),R = center of percu
36、ssion distance (COP), in. (cm),r = radius to bat speed sensors, in. (cm),T = time for bat to travel through bat speed sensors, s,t = time for ball to travel through ball speed sensors, s, andw = weight of the ball used in each event, oz (g).9.2 CalibrationDetermine the value of the combinations(D/dr
37、) using Eq 2. Place a large calibration mass (MOI 30 000oz-in.2) in the bat position on the pivoting stage. Measure itsMOI and COR as described above. Shoot a ball of known CORand weight (w). Measure t and T. Determine (D/dr) from ballCOR as follows:D/dr 51 1 ball CORS1 1IwR2DSRtTD(2)9.3 Calculate t
38、he bat performance factor (BPF) for eachvalid impact using Eq 3:BPF 5BBCORball COR(3)5SS1 1IwR2DSDdrDSRtTD1Dball COR9.4 Calculate the average BPF for the test bat from the sixvalid impacts using Eq 4. When different balls are used to testthe same bat, always be sure to calculate the BBCOR and BPFusi
39、ng the actual size, weight, compression, and COR of the ballused in each of the six valid impacts.BPFavg5BPF!11 BPF!21 .1 BPF!6!6(4)9.5 Calculate batted-ball speed (BBS) value of the test batusing Eq 5 and Eq 6.k 5SwWD1Sw R a!2I Wa2 D(5)BBS 5V1 1 e! 1 ve k!1 1 k!(6)where:V = bat swing speed (mph) at
40、 the COP,v = pitch speed (mph), the horizontal speed of the ballincoming to the batter,W = bat weight, oz,w = weight of ball used in each event, oz,e = BPF 3 ball COR,a = distance from pivot to center of mass (balance point),R = COP, in., andk = bat-ball inertia ratio.9.6 Calculate the average batte
41、d-ball speed (BBS) value ofthe test bat from the six valid impacts using Eq 7.BBSavgBBS!11 BBS!21 .1 BBS!66(7)10. Report10.1 Report the following information:10.1.1 Name of the test facility and test operator,10.1.2 Test date,10.1.3 Hourly measurements of test conditions, including:10.1.3.1 Relative
42、 humidity and temperature of the ball andbat conditioning and test-room environments, and10.1.3.2 Number of hours ball and bat were in conditioningenvironment.10.1.4 Test equipment used for this test method,10.1.5 Test ball information in accordance with 5.1, includ-ing the compression, weight, size
43、, and COR of the test ball andnormalization values m0and COR0,10.1.6 Bat model, length, weight tested, and any otherpertinent data such as condition of the bat or modification tothe bat,10.1.7 Bat MOI and COP, and MOI of bat pivot support,10.1.8 For each event impact (including invalid impacts)ball
44、inbound speed, bat rebound speed, impact location fromthe rotation point, BBCOR, and BPF,10.1.9 Any and all unique observations, including but notexclusively, any damage to the bat or test ball, misdirected ballimpacts, and any odd noises or vibrations, andF188109310.1.10 Calibration certificate num
45、bers for measurementdevices and velocity timers.11. Precision and Bias11.1 Precision and bias evaluations have not been conductedfor this test method. When such data are available, a precisionand bias section will be added.12. Keywords12.1 baseball bats; baseballs; bat performance; BBCOR;BPF; CORAST
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