correlation between bat performance and hoop frequency
Post on 09-Feb-2016
62 Views
Preview:
DESCRIPTION
TRANSCRIPT
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 1
Correlation Between Bat Performance
and Hoop Frequency
Dan RussellKettering University, Flint, MI
drussell@kettering.edu
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 2
160 Hz160 Hz
600 Hz600 Hz
Bending Modes (common to all bats)
Hoop Mode (unique to hollow bats)1500 Hz1500 Hz
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 3
What is the Trampoline Effect?Ball impacting solid bat
Ball impacting hollow bat
Movie courtesy of Movie courtesy of CE-Composites, CE-Composites,
Ottawa, CAOttawa, CA
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 4
mass-spring model of ball & bat (racket, club)
Bat modeled as a linear, damped mass-spring systeminitially at rest and fixed to rigid foundation
Ball modeled as a non-linearnon-linear, damped mass-spring system with initial velocity
Solve the coupled equations of motion numerically
Determine BBCOR = v1out / v1in for a given bat stiffness s2
Set bat stiffness s2
s2 / m2 = 2bat Hoop frequencyHoop frequency of barrel
Simple Model Trampoline Effect
hysteresishysteresis
forc
efo
rce
compressioncompression
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 5
Simple Model Trampoline Effect
Very Stiff Bat ball deforms more,
energy lost
Elastic Batbat deforms,
ball deforms less(energy lost)bat < (energy lost)ball
Optimal Bat hoop frequency
tuned for maximum trampoline effect
Soft Bat ball does not rebound
ball parameters softball
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 6
Hoop Frequency & Barrel Construction34-inch slow-pitch softball batsbending and hoop frequencies extracted from modal analysis
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 7
Hoop Frequency & PerformanceASA era study ASA era study Slow-pitch Softball BatsSlow-pitch Softball Bats ASTM F2219ASTM F2219Cannon fires ball at 110mph towards stationary (pivoted) batBatted-Ball Speed calculated from vout/vin, MOI, impact location
WoodWood
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 8
Hoop Frequency & PerformanceCrisco & Greenwald Batting Cage StudyCrisco & Greenwald Batting Cage Study19 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 9
Hoop Frequency & PerformanceCould hoop frequency be used to detect
illegally altered bats?
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 10
Portable Pendulum TestConcept: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 11
Portable Pendulum TestDirect correlation between contact time & hoop frequencyDirect correlation between contact time & hoop frequency
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 12
Portable Pendulum TestASA era study ASA era study Slow-pitch Softball BatsSlow-pitch Softball Bats ASTM F2219ASTM F2219Cannon fires ball at 110mph towards stationary (pivoted) batBatted-Ball Speed calculated from vout/vin, MOI, impact location
Dan Russell “Hoop Frequency & Bat Performance” SGMA Baseball & Softball Council Fall Meeting 2004 Page 13
Portable Pendulum TestAltered bats (barrel compression 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 14
Future WorkPortable Pendulum TesterPortable Pendulum Tester
Swing bat against stationary “ball”include mass/MOI properties of bat
Digital readout
Further correlation of data with measured performanceNeed additional bats (with performance data)Need some funding ($3,000)
Scan along barrel
top related