ASTM Ball Task Force Update

SGMA Annual MeetingDallas, Texas, October 2, 2003

Lloyd Smith, Washington State University

1) Static vs. Dynamic Compression

• Objectives:– Do static and dynamic compression correlate for softballs?– Do COR values at 60 mph and 90 mph correlate?– Does impacting a load cell affect the measured ball COR?– Is the effect of speed on COR different for a cylindrical impact

surface?

• Materials/Instructions:– Three balls types (44/375-leather, 47/375-synthetic, 44/525-

leather)– 2 manufacturers– Test 1 dozen from each manufacturer at 60 and 90 mph (6 dozen

total)

1) Static vs. Dynamic Compression

• Test Procedure:– a) Condition balls to 50% relative humidity for 2 weeks, then

weigh balls.– b) Static compression all balls (2 sides)– c) Wait 1 day (minimum)– d) Impact all balls against load cell (dynamic compression and

COR) at 60 mph & 90 mph– e) Wait 1 day (minimum)– f) Impact 1 dozen 44/375 balls against a rigid plate (ball COR)– g) Wait 1 day (minimum)– h) Impact 1 dozen 44/375 balls against a round solid rod (mount

rod to load cell if it doesn’t affect ball COR measurement)

2) Ball Conditioning• Objectives:

– What is the effect of humidity on ball COR and compression (static and dynamic)?

– Does the ball heat up in high speed impacts?– How quickly does the ball degrade?

• Materials/Instructions:– .44/375 ball– 2 manufacturers– Test 1 dozen from each manufacturer (2 dozen total)– Use dynamic compression setup on all COR tests– Measure ball temperature with non-contact infrared thermometer

after each impact– Measure the ball diameter every ten impacts.

2) Ball Conditioning• Test Procedure:

– a) Condition balls to 30% relative humidity for 2 weeks (lab conditions).

– b) Measure static compression, COR at 60 mph, and weight of all balls.

– c) Condition balls to 50% relative humidity for 2 weeks.– d) Measure static compression, COR at 60 mph, and weight of

all balls.– e) Impact 6 balls from each manufacturer 100 times

consecutively at 90 mph.– f) Impact 6 balls from each manufacturer 10 times at 90 mph – g) Wait 1 hour (minimum) – h) Repeat f) & g) until each ball has been impacted 100 times.

3) Ball Scaling• Objectives:

– Verify that the effect of variation in ball COR and weight can be normalized when finding the BBS

• Materials/Instructions:– .44/375 ball– 2 manufacturers– Test ½ dozen balls from each manufacturer (1 dozen total)– Use previous studies to select balls that fit the following criteria:

COR Group: • Static compression of ± 5 lbs• Weight of ± 0.005 oz• COR varying ± 0.01

Weight Group: • Static compression of ± 5 lbs• COR of ± 0.002• Weight varying from 6.25 oz to 6.75 oz

3) Ball Scaling• Test Procedure:

– a) Select high performance, durable bat– b) Impact the bat at 22.0” from pivot point 6

times with each ball.– c) Normalize the results.– d) Test each ball for static compression,

dynamic compression, COR and measure the weight

Tasks• 1) Static vs. Dynamic Compression

– 90% complete

• 2) Ball Conditioning– not started

• 3) Ball Scaling (Normalizing)– not started

Testing Sequence• Study of 44/375 balls, 3 replicates

COR (60 mph), Scan, (110 mph)– Comp/COR/Comp (Mfg A)

17% compression decrease– Comp/1 hr/Comp (Mfg B)

4% compression increase– COR/Comp/COR (Mfg A )

0.2% COR increase– COR/Scan(5)/COR (Mfg B)

2% COR increase– COR/Scan(20)/COR (Mfg B)

2% COR increase – COR/Scan(40)/30 days/COR (Mfg B)

3% COR decrease

Measuring COR

0.450

0.455

0.460

0.465

1 2 3 4 5 6 7 8 9 10

Impact Number

CO

R

Mfg A, 3 dz

Mfg B, 3 dz

60 mph 90 mph

0.395

0.400

0.405

0.410

0.415

0.420

1 2 3 4 5 6 7 8 9 10

Impact Number

CO

R

Mfg A, 3 dz

Mfg B, 3 dz

60 mph COR vs. 90 mph COR

0.36

0.38

0.4

0.42

0.44

0.44 0.45 0.46 0.47 0.48

60 mph COR

90 m

ph C

OR

Mfg A, 44/375

Mfg A, 44/525

Mfg A, 47/375

Mfg B, 44/375

Mfg B, 44/525

Mfg B, 47/375

Average COR Comparison

0.36

0.38

0.4

0.42

0.44

0.46

0.48

Mfg

A, 4

4/375

Mfg

B, 4

4/375

Mfg

A, 4

4/525

Mfg

B,4

4/52

5

Mfg

A, 4

7/375

Mfg

B,4

7/37

5

Bal

l CO

R

60 mph

90 mph

Dynamic Compression

-5000

-4000

-3000

-2000

-1000

0

1000

0 1 2 3

Time (ms)

Lo

ad

(lb

s)

60 mph

90 mph

110 mph

Measuring Dynamic Compression

2800

2850

2900

2950

3000

1 2 3 4 5 6 7 8 9 10

Impact Number

Dyn

amic

Com

pres

sion

(lb

s)

Mfg A, 3 dz

Mfg B, 3 dz

4150

4200

4250

4300

4350

4400

4450

4500

4550

1 2 3 4 5 6 7 8 9 10

Impact Number

Dyn

amic

Com

pres

sion

(lb

s)Mfg A, 3 dz

Mfg B, 3 dz

60 mph 90 mph

Effect of Load Cell on COR

0.440

0.445

0.450

0.455

0.460

0.465

1 3 5 7 9 11 13 15 17 19 21

CO

R

Mfg A, 1 dz

10 days

Load Cell Rigid Wall

0.453

0.456

Load Cell COR vs. Light Gate COR

1000

1100

1200

1300

1400

1500

1600

1700

1800

1 2 3 4 5 6 7 8 9 10 11 12

Ball Number

v(in

)+V

(out

) (in

/s)

Load Cell

Light Gates

60 mph 90 mph

2000

2100

2200

2300

2400

2500

1 2 3 4 5 6 7 8 9 10 11 12

Ball Number

v(in

) +

v(o

ut)

(in/s

)Load Cell

Light Gates

Load Cell COR vs. Light Gate COR

110 mph

2200

2300

2400

2500

2600

2700

2800

2900

3000

1 2 3 4 5 6 7 8 9 10 11 12

Ball Number

v(in

)+V

(out

) (in

/s)

Load Cell

Light Gates

Static vs. Dynamic Compression60 mph 90 mph

0.35

0.37

0.39

0.41

0.43

0.45

0.47

0.49

300 350 400 450 500 550 600

Static Compression (lbs)

Nor

m.

Dyn

. C

omp.

(F

/mv)

Mfg A, 44/375

Mfg A, 44/525

Mfg A, 47/375

Mfg B, 44/375

Mfg B, 44/525

Mfg B, 47/3750.35

0.37

0.39

0.41

0.43

0.45

0.47

0.49

300 350 400 450 500 550 600

Static Compression (lbs)

Nor

m.

Dyn

. C

omp.

(F

/mv)

Mfg A, 44/375

Mfg A, 44/525

Mfg A, 47/375

Mfg B, 44/375

Mfg B, 44/525

Mfg B, 47/375

Static vs. Dynamic Compression

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Mfg

A, 4

4/375

Mfg

B, 4

4/375

Mfg

A, 4

4/525

Mfg

B,4

4/52

5

Mfg

A, 4

7/375

Mfg

B,4

7/37

5

Dyn

amic

Com

pres

sion

(F

/mv)

0

100

200

300

400

500

600

Sta

tic C

ompr

essi

on (

lbs)

Dynamic

Static

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Mfg

A, 4

4/375

Mfg

B,4

4/37

5

Mfg

A, 4

4/525

Mfg

B,4

4/52

5

Mfg

A, 4

7/375

Mfg

B,4

7/37

5D

ynam

ic C

ompr

essi

on (

F/m

v)0

100

200

300

400

500

600

Sta

tic C

ompr

essi

on (

lbs)

Dynamic

Static

60 mph 90 mph

average variation: dynamic 0.8%, static 1.5%

Effect of Humidity

• Measurable effect on compression– 20% RH change => ~ 40 lbs

• Small effect on COR

Some Ball Degradation Data

• 8 - 44/375 balls, Mfg B– Compression tested– Impacted bat 40 times– Compression tested again– Compression decreased 35 lbs– Standard deviation was 15 lbs

Summary• Compression test should precede COR test• Mandatory extra hits to measure ball COR• Effect of load cell on measured ball COR

appears small• Dynamic and static compression correlate• Some rate affects are apparent with dynamic

compression• Experimental measure of dynamic compression

is ongoing