Nonlinear viscoelastic friction reduction in the infinite length journal bearing

Abstract:

Viscoelastic fluids in shear produce normal stresses. These normal stresses have previously been included in the infinite length journal bearing through a linear viscoelastic model that predicts normal stress generation but not shear thinning. Real polymeric solutions (which are used routinely in lubrication applications) exhibit normal stress generation and shear thinning. Therefore, nonlinear viscoelastic models must be considered. Here, nonlinear viscoelasticity is included through using the Criminale-Ericksen-Filbey (CEF) model (which includes shear thinning, normal stress generation, and terminal regime viscoelasticity) in the Cauchy momentum equations in polar coordinates in the thin film limit. The resulting equations are solved using a perturbation expansion that yields a modified Reynolds equation (CEF-Reynolds equation) for the infinite length journal bearing that includes shear thinning, viscoelastic effects, and fluid inertia. The CEF-Reynolds equation matches predictions for purely viscous fluids across all eccentricity ratios, validating the model. This provides a computationally inexpensive method that can be used for designing fluid and bearing performance for decreasing friction in lubricated sliding.  This talk will focus on the mathematical structure and computations used to solve the complex system. 

Bio:

Dr. Schuh is a Teaching Associate Professor and the Associate Head for MEng Programs in the Department of Electrical and Computer Engineering at the University of Illinois Urbana-Champaign. He received his BS and MS in Mechanical Engineering in 2013 and 2015, his PhD in Theoretical and Applied Mechanics in 2018, and his MBA in 2021, all from the University of Illinois Urbana Champaign. His technical interests include electrical energy storage, tribology, rheology, and computational physics, and his teaching interests include improving learning outcomes in engineering curriculum.