James A. Sherwood

1
An Experimental Investigation of Workhardening
Effect of Aluminum Bats

• James A. Sherwood
• Patrick J. Drane
• SGMA Meeting
• 04 October 2003

2
Introduction

• Effect of Use on Aluminum Baseball Bat
  Performance
• Machine testing
• Field hitting

3
Outline

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Conclusions
• Recommendations

4
Outline

• Motivation
• History
• UMLBRC
• Past Research
• Theory

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Conclusions
• Recommendations

5
Motivation for Research

• Maintaining the integrity of collegiate baseball
• Increased interest in what drives changes in
  performance

6
Effect of Use

• Aluminum bats can be used for a long period of
  time
• Aluminum bats are certified for the NCAA with a
  performance limit
• Concern An increase in performance resulting
  from use of a bat could cause certified bat to
  exceed limit

7
UMLBRC

• Established in 1998
• Research testing for MLB
• Official certification center for all bats used
  in NCAA and high school baseball

8
BRC Capabilities

• Baum Hitting Machine

9
(No Transcript)
10
UMLBRC Capabilities

• 3-Pt Bend Testing

• Modal Testing

• COR Testing

• Finite Element Modeling

• Baseball Dissection

11
Workhardening Theory

• Increase of Yield Strength
• Plastic deformation causes changes in the
  microstructure that leads to hardening

12
C405 tensile test
13
Terminology

• Bat Performance
• Sweet Spot
• Certification Cycle
• The Bat

14
Outline

• Existing Test Methods
• Effect of Use

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Conclusions
• Recommendations

15
Effect of Use Test Method

• Performance Testing in the Hitting Machine
• All-in-Machine / Field Use with Testing
• NCAA certification testing procedure
• Same 5 locations impacted each time
• Use of official NCAA baseballs
• Complete after significant cracking or denting

16
Outline

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Conclusions
• Recommendations

• BESR
• 95 confidence
• t-test
• Control Charts

17
BESR
Conservation of Momentum Coefficient of
Restitution
18
Outline

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Conclusions
• Recommendations

• Performance
• Surface Deformation
• Hardness
• Microscopy

19
Effect of Use Test Bats
All-in-Machine

• PD02
• Performance
• Surface Deformation
• Hardness

• PD03
• Performance
• Surface Deformation
• Hardness
• Microscopy

• PD01
• (Trial Test)
• Performance

Field-Use

• PD04
• Performance
• Surface Deformation

• PD05
• Performance
• Surface Deformation

20
PD01
Average Exit Velocity (AEV) Sweet Spot
21
PD01
BESR Sweet Spot
22
PD01
AEV Average All 5 Locations
23
PD01
BESR Average All 5 Locations
24
PD01 AEV Sweet Spot
3 of 20
25
Confidence Intervals

• Statistical tool for evaluating magnitude of
  confidence in test average
• Helps to predicts likelihood of samples being
  from the same population
• 95 Confidence used

26
PD01 BESR Sweet Spot
7 of 20
27
PD01 AEV All 5 Locations
9 of 20
28
PD01 BESR All 5 Locations
17 of 20
29
PD01
Lumped Analysis Sweet Spot
30
PD01
Lumped Analysis All 5 Locations
31
PD01
Performance Summary
32
PD02
BESR All 5 Locations
33
PD02
Surface Deformation Measurements
5-inch 6-inch 7-inch
34
PD03
Sweet Spot
All 5 Locations
35
PD03
Lumped Analysis Sweet Spot
36
PD03
Lumped Analysis All 5 Locations
37
PD03
Performance Summary
38
PD03
Rockwell Hardness Measurements
39
PD03
Vickers Micro-hardness Measurements
40
PD04
Sweet Spot
5.0-, 5.5-, and 6.0-inch Locations
41
PD04
Lumped Analysis Sweet Spot
42
PD04
Lumped Analysis 5.0-, 5.5-, and 6.0-inch
Locations
43
PD04
Performance Summary
44
PD05
Lumped Analysis Sweet Spot
45
PD05
Lumped Analysis All 6 Locations
46
PD05
Performance Summary
47
Effect of Use Results Summary
48
Outline

• Background
• Test Methodologies
• Analysis Methodologies
• Effect of Use Results
• Effect of Moisture Content Results
• Conclusions
• Recommendations

49
Conclusion

• The result of using an aluminum baseball bat may
  lead to a slight increase in batted-ball
  performance
• Increase is probably a result of softening of the
  aluminum due to increased contact time