Paper Number
RS31                         My Program 

Session
Real-World Rheology & Sustainability

Title
Multiscale rheo-tribological origins of baseball mud gripping mechanics

Presentation Date and Time
October 15, 2024 (Tuesday) 4:25

Track / Room
Track 7 / Room 502

Authors (Click on name to view author profile)

  1. Pradeep, Shravan (University of Pennsylvania, Earth and Environmental Science)
  2. Chen, Xiangyu (University of Pennsylvania, Mechanical Engineering and Applied Mechanics)
  3. Arratia, Paulo E. (University of Pennsylvania, Mechanical Engineering and Applied Mechanics)
  4. Jerolmack, Douglas J. (University of Pennsylvania, Department of Earth and Environmental Science)

Author and Affiliation Lines (in printed abstract book)
Shravan Pradeep1, Xiangyu Chen2, Paulo E. Arratia2 and Douglas J. Jerolmack1
1Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA 19104; 2Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA 19104

Speaker / Presenter 
Arratia, Paulo E.

Keywords
experimental methods; colloids; gels; non-Newtonian fluids; particles; particualte systems; real-world rheology; suspensions; sustainability; techniques

Text of Abstract
Mud harvested from the Delaware river basin in New Jersey, dubbed as “Magic Mud” in the popular sports media, is the primary material used to tune baseball gripping for the Major League Baseball. Despite their extensive usage for the past 90 years, the fundamental mechanics underpinning their flow and frictional properties remains elusive. The mechanical properties of soil-based materials have optimized interparticle interactions from a mixture of cohesive agents, natural stabilizers, geo/biopolymers, frictional particles, and adequately distributed moisture. Here we decouple the rheological and tribological dissipation modes on the gripping mechanics in three length scales: using macroscale rheology, microscale soft tribology, and nanoscale atomic force characterizations, to determine the grain-scale composition and its control on flow, frictional, and adhesive properties. Our results show that the “Magic Mud” material is an elastic-shear thinning complex fluid, that enhances frictional and adhesive properties of the baseball, at mesoscale and nanoscale, respectively. Our results suggest that the rheo-tribological properties of baseball mud are controlled by two main components: (1) the micron-sized sand particles, that contribute to the frictional gripping; and (2) the clay particles that aid in mud material processing and nanoscale adhesive properties. The rheo-tribological framework developed here aids in developing bottom-up design rules for engineering sustainable earth-based lubricants and gripping agents.