From NDT Technician , Vol. 11, No. 4, pp: 1 –5. Copyright © 2012 The American Society for Nondestructive Testing, Inc.

The American Society for Nondestructive Testing www.asnt.org

FOCUS Nondestructive Testing Detects Altered

Baseball Bats Daniel A. Russell*

Corked Bats The prevalence of corked bats in X-rays and CT scans. is not known was frequently accused of using The history of the game of baseball because players are caught only corked bats during his 1985 chase is peppered with interesting stories when the doctored bat breaks, of the all-time hits record, but no of attempts to break the rules. revealing the interior. For broken bats ever exposed cork. Managers have been example, in 1974, Several of Rose’s bats from 1985 signs; groundskeepers have altered Yankees’ shattered his are now in private collections. Cthe playing conditions of the field bat, sending several superballs Recent X-ray scans of two of these to the advantage of the home team; bouncing around home plate. In bats show that they were indeed have used petroleum jelly, 1987, corked. 3 mud, emery boards, or thumbtacks ’s bat broke and one of Following the Sosa to alter the surface of the baseball; the pieces ended up in the hands of incident in 2003, the Major League and Major League Baseball players third baseman Keith Baseball commissioner’s office like , , Graig Moreland, who promptly showed ordered that X-ray scans be taken Nettles, and , have used the exposed cork filling to the of the rest of Sosa’s bats, including 1,4 corked bats. nearby umpire. The most recent several that had been sent to the Major League example occurred on June 3, 2003 Baseball Hall of Fame after the dictate that a bat must be made when the bat swung by Chicago 1998 home record breaking from a solid piece of wood. A Cubs centerfielder Sammy Sosa season. The X-rays of all 76 of corked bat has a hole drilled into shattered and the umpire who Sosa’s other bats came back the barrel that is about 1 in. picked up the barrel fragment saw negative; the bat that broke during (25 mm) in diameter and about the exposed cork filling. the 2003 game was the only one 8-10 in. (0.20-0.25 m) deep. The A physics analysis of the bat- found to have been corked. hole is filled with tightly packed collision concludes that corking a Sosa’s 2003 corked bat fragment cork or rubber superballs and bat does not provide any was eventually purchased by Grant capped with a wooden plug sanded performance advantage to a hitter, 2 DePorter, CEO of the and painted to disguise its presence. but cannot determine whether or Restaurant Group, and a doctor not a wood bat has been corked. friend used computed tomography * Graduate Program in Acoustics, 4 The Pennsylvania State University; There are, however, several (CT) to scan the bat. The CT scan 201-D Applied Science Building; University Park, PA 16802; nondestructive methods for images in Fig. 1, clearly show the (814) 865-6365; [email protected]. detecting corked bats. FOCUS continued on page 2.

Vol. 11, No. 4 TNT · October 2012 · 1 FOCUS continued from page 1.

hole filled with cork as well as the mismatch in the grain between the barrel and the wood plug used to fill the hole. In August of 1987, just weeks before the Billy Hatcher incident, Major League Baseball commissioner had asked experts at the National Institute of Standards and Technology to perform a quick study of several nondestructive methods for detecting the presence of illegal cork in a hollowed wood bat. 5 The study found that CT scans provided the clearest image quality and were the best at detecting corking. However, the study concluded that standard medical X-ray scans were the quickest and most practical, especially since many professional ball parks have in-house X-ray machines for diagnosing player injuries. Ultrasonic Scanning. The 1987 NIST study also explored ultrasonic tests, but found that it was difficult to conclude

(a)

(b)

Figure 1. Computed tomography (CT) images of corked bat used in 2003 by Sammy Sosa: (a) side view of bat fragment and (b) end view of bat showing wooden plug. Reprinted with permission of Dr. Richard Heller and Harry Caray Restaurant Group.

2 · Vol. 11, No. 4 with certainty whether a specific are possible with a solid wood bat. bats, and X-ray scans would not easily reflected signal was due to the Governing bodies, such as the detect evidence of shaving in a presence of cork or the imperfections Amateur Association or the thin-walled hollow composite bat. in the wood grain. However, a recently Specialty Sports Ultrasonic measurement techniques published study used a pair of Association have implemented would seem to be the preferred 100 kHz narrow-band contact performance standards to regulate bat method for detecting alterations in transducers (receiver and source) to performance either by placing an hollow softball bats since ultrasonic measure the signal strength upper limit on the batted-ball speed or sensors are frequently used to measure transmitted through three 4 in. by limiting the coefficient of the thickness of hollow metal, plastic (102 mm) thick blocks of sample restitution between bat and ball. Bat and composite pipes. However, wood: with and without cork filled performance is measured following an knowing the barrel wall thickness holes. 6 The signal transmitted through ASTM test protocol 9 which fires balls would detect modification only if one the hollow block suffered an at approximately 150 mph (240 km/h) knew the original wall thickness and attenuation of 15.2 dB compared to toward a stationary bat and uses manufacturers are unwilling to make the solid block. The corked block measurements of the bat and ball this information publically available. resulted in 9.6 dB of attenuation. speeds before and after the collision Reflections from the air gaps between Clean signals require a layer of liquid to determine the coefficient of the thin layers of a -walled between the transducer and the bat restitution of the bat. Knowledge of aluminum bat, or from the different barrel surface, something prohibited the inertial properties of the bat layers of composite and resin in by Major League Baseball rules. The allows for calculation of the batted multi-walled composite bats could lead device has not yet been brought to ball speed. Measurement of bat to errors in thickness measurements. market, but the technique shows performance in the laboratory is time The difficulty in detecting illegally promise. intensive and expensive, and requires altered softball bats is exacerbated by Doctored Metal And Composite specialized ball cannons, light gates, the fact that it is possible to improve Softball Bats bat pivot devices, and computer the performance of a composite bat hardware for data collection and without actually changing the The problem of illegally altering wood processing. 10 thickness of the barrel walls. A bats in Major League Baseball is Almost as soon as bat performance currently popular technique for certainly newsworthy when it happens, standards for softball were adopted, improving the performance of a but it does not occur with great players discovered that they could composite bat is to use one of several regularity. The opposite is true in significantly improve the performance accelerated break-in methods. 12 It is amateur slow- softball, where the of a bat by modifying it to increase well known that the performance of illegal modification of bats is much the trampoline effect. So-called bat composite bats improves with use as more prevalent but does not often doctors sprang up around the country, the layers of composite materials make the news. 7 The bats used for offering to cleverly repaint banned gradually delaminate with use and the men’s amateur slow-pitch softball are high-performance bats, add or remove bat wall softens, increasing the manufactured almost exclusively from mass in the barrel or handle of the bat trampoline effect. A quick search of aluminum or composite materials, and to change the swing weight the web will reveal a small industry for the barrels of these bats are hollow. (moment-of-inertia), or the more rolling and pressing bats to accelerate The collision between a softball and a drastic modification of removing the the break-in process. Awareness of hollow bat barrel gives rise to the end-cap and using a lathe to shave the this phenomenon led the Amateur so-called trampoline effect in which the inner wall of the barrel. 11 Governing Softball Association to begin rolling hollow barrel compresses as a spring, bodies have imposed heavy penalties bats prior to certification testing for temporarily storing the energy from and fines against players caught using compliance with their performance the collision and then returning almost illegally altered bats, but the detection standard, and also caused the National all of that energy to the ball as the of altered bats in the field of play has College Athletics Association in 2009 barrel elastically recoils to its original presented a challenge. to ban composite bats from use in shape. 8 Careful design of the barrel While X-ray machines may exist in college baseball after a large number wall thickness and material properties most Major League Baseball stadiums, of certified composite bats were allows the trampoline effect to be they certainly do not exist in a found to exceed performance tuned, maximizing the efficiency of portable form at the thousands of standards when tested following the the bat-ball collision to the extent that amateur softball parks across the College World that year. hollow aluminum and composite bats country. Even if they were available, However, approximate estimates of can be designed to produce batted-ball X-ray scans could not be used to performance may be obtained speeds that are significantly faster than detect the modification of aluminum FOCUS continued on page 4.

TNT · October 2012 · 3 FOCUS continued from page 3. Amateur Softball Association requires frequencies, and damping rates by that the laboratory measured curve fitting the data with modal indirectly from vibration frequencies batted-ball speed fall below 98-mph, analysis software. A typical setup for and stiffness values. suggesting that a bat with a hoop measuring the vibrational response of Hoop Frequency. A hollow softball frequency lower than 1300 Hz would a softball bat includes power supplies or exhibits a number of exceed this performance limit. for hammer and accelerometer as well vibrational modes involving radial The hoop mode frequencies in as a two-channel analyzer to capture oscillations of the cylindrical barrel. Fig. 2 were obtained through the frequency response function. The fundamental mode shape with the experimental modal analysis, a test While suitable for laboratory testing, lowest frequency is termed the procedure in which a hammer with an this experimental setup is not hoop-mode of the bat. Modeling this instrumented force gage provides an conducive to field tests. vibrational hoop mode using a simple impulse to the barrel of the bat and An ongoing project hopes to mass-spring approach captures the the resulting vibration response is develop a hand-held device to essential physics of the bat-ball measured with an accelerometer. The measure the frequency of the hoop 8 collision. Experimental results for frequency response function (the ratio mode using a microphone and a softball and baseball bats have shown of acceleration to force as a function programmable dedicated microchip to that the frequency of this hoop mode of frequency) for a combination of sample, filter and process the signal, may be used as a fairly accurate impact and measurement locations and compare the measured frequency predictor of the performance of a along the length of the bat may be to a reference value. Such a device 13,14 bat. Figure 2 shows the measured used to obtain the vibrational mode would not be able to detect whether a batted-ball speeds for a variety of shapes, corresponding natural bat had been illegally modified, but it aluminum -walled and double-walled, titanium, and (a) composite softball bats plotted as a function of the hoop mode frequency. The data shows that bats with lower hoop frequencies tend to produce higher batted-ball speeds. The

107 106 105 104 103 102 ) h p 101 m (

d

e 100 e p s

l 99 l a b 98 d (b) e t t

a 97 B 96 95 94 93 92 91 90 1000 1200 1400 1600 1800 2000 Hoop frequency (Hz)

Figure 2. Batted-ball speeds for collection of softball bats showing increases in performance Figure 3. Barrel compression testers measure barrel stiffness of hollow composite as hoop frequency decreases. or aluminum softball bats: (a) setup for laboratory testing and (b) portable device.

4 · Vol. 11, No. 4 could predict whether or not the bat Conclusion Edge.” might exceed the required Online, New York, NY: Dow performance limits. Nondestructive test methods may be Jones (20 May 2005) used to detect baseball and softball Barrel Stiffness. Another approach to 8. Nathan, A.M., D.A. Russell, and bats that have been illegally altered. measuring the elastic springiness of a L.V. Smith. “The Physics of the X-ray scans and ultrasonic testing can hollow bat barrel involves the static Trampoline Effect in Baseball and easily detect corking in a wood bat. stiffness of the barrel. Experimental Softball Bats.” Engineering of Measurements of the hoop frequency data relating performance to barrel Sport 5, Vol. 2. Sheffield, United of barrel vibrations and/or the static stiffness, as measured using a Kingdom: International Sports stiffness of the barrel can identify compression tester in the laboratory, Engineering Association (2004): hollow aluminum and composite follows a trend similar to that shown p 38-44. softball bats that may exceed in Fig. 2; lower values of barrel 9. ASTM F2219-05, Test Methods for stiffness result in higher batted-ball performance limits due to illegal Measuring High-Speed Bat modification. speeds. In 2004, the Sporting Goods Performance. West Conshohocken, and Manufacturing Association References PA: American Society for Testing commissioned the portable barrel and Materials (2005). compression tester for field use 1. “Biggest Cheaters in Baseball.” 10. Smith, L.V. “Progress in (Fig. 3a). The force in pounds required Web page. Bristol, CT: ESPN Measuring the Performance of to compress the barrel by 0.05 in. (2007; accessed June 2012). Baseball and Softball Bats.” Sports (1.27 mm) is used to calculate the 2. Nathan, A.M., L.V. Smith, Warren Technology. Vol. 1, No. 6. barrel stiffness. This device was used L. Faber and D.A. Russell. Hoboken, NJ: John Wiley (2008): to police bats at a 2004 national “Corked Bats, Juiced Balls, and p 291-299. slow-pitch softball tournament Humidors: The Physics of 11. Russell, D.A. “Why is Doctoring sponsored by the United States American in Baseball.” (Painting, End-Loading, or Specialty Sports Association. Five Journal of Physics. Vol. 79, No. 6. Shaving) a Bat Illegal?” Web page. hundred bats were tested and 75 bats Melville, NY: American Institute State College, PA: Pennsylvania were removed from play due to of Physics (June, 2011): State University (2008; accessed excessively low stiffness values. p 575-580. June 2012). A more portable (requiring no 3. Petchesky, B. “This is Pete Rose’s electricity) and simpler to use barrel 12. Russell, D.A. “Do ABI Corked Bat” web page. New York, compression tester was recently Techniques Really Work?” Web NY: Gawker Media (June 2010; developed by the Sports Science Lab page. State College, PA: accessed June 2012) at Washington State University Pennsylvania State University (Fig. 3b). Bats for which the pressure 4. Telander, R. “The Inside Story of (2009). (accessed June 25, 2012). gage reading falls in the red zone are Sammy Sosa’s Corked Bat.” Web 13. Russell, D.A. “Hoop Frequency as Chicago Sun-Times not stiff enough to be legal. The page. . Chicago, a Predictor of Performance for stiffness values from this portable IL: Sun-Times Media Group Softball Bats.” Engineering of tester do not completely correlate to (16 February 2011; accessed June Sport 5, Vol. 2. Sheffield, United values measured in the laboratory with 2012). Kingdom: International Sports a compression tester, but a portable 5. Schramm, R. “NIST and the Engineering Association (2004): tester like this could indicate whether American Pastime: A Real p 641-647. a bat might be suspect of having been Corker.” Web page. Gaithersburg, 14. Sutton, A.D. and J. A. Sherwood. tampered with, or at least whether it MD: National Institute of “Using Vibrational Analysis to might exceed performance limits. Standards and Technology (May Investigate the Batted-Ball Further research in these areas is 2001; accessed June 2012). Performance of Baseball Bats.” ongoing. Available data suggests the 6. Gamache, P., A. Galante, G. Procedia Engineering. Vol. 2, No. 2. correlation between performance and Seben, and A.J. Elbirt. “Validating New York, NY: Elsevier (2010): laboratory measurements of hoop Baseball Bat Compliance.” Sports p 2687-2692. Engineering. frequency or barrel stiffness for Vol. 10. London, 15. Smith, L.V. and C.M. Cruz. specific softball bats that are known to United Kingdom: Springer (2007): “Identifying Altered Softball Bats have been altered is not yet close p 57-164. and Their Effect on enough for reliable field detection of 7. Dougherty, C. “Softball, Hard Performance.” Sports Technology. illegally altered bats using portable Questions: On America’s Other Vol. 1, No. 4-6. Hoboken, NJ: devices in the field, but results are Diamonds, Players Try Doctored John Wiley and Sons (2008): encouraging. 15 Bats; How Bobby Buggs Got an p 196-201.

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