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ASTM Ball Task Force Update

ASTM Ball Task Force Update. SGMA Annual Meeting Dallas, 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?

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ASTM Ball Task Force Update

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  1. ASTM Ball Task Force Update SGMA Annual Meeting Dallas, Texas, October 2, 2003 Lloyd Smith, Washington State University

  2. 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)

  3. 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)

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Tasks • 1) Static vs. Dynamic Compression • 90% complete • 2) Ball Conditioning • not started • 3) Ball Scaling (Normalizing) • not started

  9. 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

  10. Measuring COR 60 mph 90 mph

  11. 60 mph COR vs. 90 mph COR

  12. Average COR Comparison

  13. Dynamic Compression

  14. Measuring Dynamic Compression 60 mph 90 mph

  15. Effect of Load Cell on COR

  16. Load Cell COR vs. Light Gate COR 60 mph 90 mph

  17. Load Cell COR vs. Light Gate COR 110 mph

  18. Static vs. Dynamic Compression 60 mph 90 mph

  19. Static vs. Dynamic Compression 60 mph 90 mph average variation: dynamic 0.8%, static 1.5%

  20. Effect of Humidity • Measurable effect on compression • 20% RH change => ~ 40 lbs • Small effect on COR

  21. 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

  22. 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

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