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Correlation Between Bat Performance and Hoop Frequency PowerPoint PPT Presentation


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Correlation Between Bat Performance and Hoop Frequency. Dan Russell. Kettering University, Flint, MI. [email protected] Bending Modes ( common to all bats ). 160 Hz. 600 Hz. Hoop Mode ( unique to hollow bats ). 1500 Hz. What is the Trampoline Effect?. Ball impacting solid bat.

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Correlation Between Bat Performance and Hoop Frequency

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Correlation between bat performance and hoop frequency

Correlation Between

Bat Performance

and Hoop Frequency

Dan Russell

Kettering University, Flint, MI

[email protected]

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 1


Correlation between bat performance and hoop frequency

Bending Modes(common to all bats)

160 Hz

600 Hz

Hoop Mode(unique to hollow bats)

1500 Hz

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 2


Correlation between bat performance and hoop frequency

What is the Trampoline Effect?

Ball impacting solid bat

Ball impacting hollow bat

Movie courtesy of

CE-Composites,

Ottawa, CA

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 3


Correlation between bat performance and hoop frequency

hysteresis

force

compression

Simple Model  Trampoline Effect

mass-spring model of ball & bat (racket, club)

Ball modeled as a non-linear, damped mass-spring

system with initial velocity

Bat modeled as a linear, damped mass-spring system

initially at rest and fixed to rigid foundation

Set bat stiffness s2

s2 / m2 = w2bat Hoop frequency of barrel

Solve the coupled equations of motion numerically

Determine BBCOR = v1out / v1in for a given bat stiffness s2

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 4


Correlation between bat performance and hoop frequency

Optimal Bat

hoop frequency

tuned for maximum

trampoline effect

Elastic Bat

bat deforms,

ball deforms less

(energy lost)bat < (energy lost)ball

Very Stiff Bat

ball deforms more,

energy lost

Soft Bat

ball does not rebound

Simple Model  Trampoline Effect

ball parameters  softball

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 5


Correlation between bat performance and hoop frequency

Hoop Frequency & Barrel Construction

34-inch slow-pitch softball bats

bending and hoop frequencies extracted from modal analysis

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 6


Correlation between bat performance and hoop frequency

Hoop Frequency & Performance

ASA era study Slow-pitch Softball BatsASTM F2219

Cannon fires ball at 110mph towards stationary (pivoted) bat

Batted-Ball Speed calculated from vout/vin, MOI, impact location

Wood

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 7


Correlation between bat performance and hoop frequency

Hoop Frequency & Performance

Crisco & Greenwald Batting Cage Study

19 players (HS through minor league)

pitched balls (66mph) 6 baseball bat models (several of each)

BBCOR values extracted by Alan Nathan

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 8


Correlation between bat performance and hoop frequency

Hoop Frequency & Performance

Could hoop frequency be used to detect

illegally altered bats?

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 9


Correlation between bat performance and hoop frequency

Portable Pendulum Test

Concept:

Use a very heavy, very stiff “ball” to impact bat barrel.

Measure contact time between “ball” and bat.

Contact time determined by

mass of “ball”

stiffness of bat

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 10


Correlation between bat performance and hoop frequency

Portable Pendulum Test

Direct correlation between contact time & hoop frequency

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 11


Correlation between bat performance and hoop frequency

Portable Pendulum Test

ASA era study Slow-pitch Softball BatsASTM F2219

Cannon fires ball at 110mph towards stationary (pivoted) bat

Batted-Ball Speed calculated from vout/vin, MOI, impact location

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 12


Correlation between bat performance and hoop frequency

Portable Pendulum Test

Altered bats (barrel compression test)

robot swings bat at 60mph towards stationary ball

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 13


Correlation between bat performance and hoop frequency

Future Work

Portable Pendulum Tester

Digital readout

Swing bat against stationary “ball”

include mass/MOI properties of bat

Scan along barrel

Further correlation of data with measured performance

Need additional bats (with performance data)

Need some funding ($3,000)

Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 14


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