astm ball task force update sgma annual meeting dallas, texas, october 2, 2003 lloyd smith,...
TRANSCRIPT
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