James Cain 12/4/14

 Model a baseball and baseball bats in Abaqus/CAE  Perform a dynamic analysis on the bat-ball interaction in Abaqus/Explicit  Modify models with different physical properties such as material, mass, and size, and compare results

 Baseball consists of four different materials ◦ Cork ◦ Rubber ◦ Wool ◦ Cowhide Material Properties of a Baseball Density (lb/in 3 ) Short-Time Shear Modulus (psi) Long-Time Shear Modulus (psi) Decay ConstantBulk Modulus (psi)

 Average baseball diameter is 2.90” FEA model of a baseball

 Bat materials chosen are ash and aluminum Material Properties of Ash Density (lb/in 3 ) Elastic Modulus (psi)Shear Modulus (psi)Poisson’s Ratio E1E1 E2E2 E3E3 G 12 G 23 G 13 ν 12 ν 23 ν x x x x x x Material Properties of Aluminum Density (lb/in 3 )Elastic Modulus (psi)Poisson’s Ratio x

 Bat length, barrel diameter, and handle diameter are same size for all three bats ◦ Length: 34” ◦ Barrel diameter: 2.5” ◦ Handle Diameter: 1.0”  Ash bat is solid, whereas aluminum bat has solid handle and hollow barrel with 0.1” thick wall  Bats are modified with different physical properties

FEA model of a baseball bat

 FEMs of baseball and bats created  Material properties assigned to models ◦ Baseball = Viscoelastic ◦ Wood bat = Orthotropic ◦ Aluminum bat = Elastic  Assembly and steps created  Interactions and constraints applied to bat and ball  Boundary conditions and predefined fields defined  Bat and ball meshed with tetrahedral elements

Bat-Ball Interaction

 Performance of wood and aluminum bats was investigated for different bat masses, bat swing speeds, and ball impact locations  Aluminum bat outperformed wood bat in all analysis when bats were similar in weight ◦ Attributed to smaller moment of inertia of hollow aluminum bat and trampoline effect