97th Annual Meeting Short Course

Instructor: Lilian Hsiao (NCSU) | Co-instructors: James Eickoff (Anton Paar), Keith Coasey (TA)

The movement of non-Newtonian fluids across solid interfaces to produce frictional forces is found in the design of consumer products for tactile pleasantness, lubricants that enable automation and robotics, as well as new technologies such as triboelectric energy harvesting. These applications involve the lubrication flows of non-Newtonian fluids in narrow, fluctuating gaps with fixed normal loads, where the presence of particles and macromolecules produce complex feedback with the varying shear rates and the fluid properties, and where the dynamics of interfacial confinement may lead to a breakdown of the continuum approximation. In short, predicting the friction coefficient when fluids are present between compressed sliding surfaces remains a challenging task and where predictive capability has great socioeconomic importance.

This 2-day short course:

• combines the fundamental principles of engineering tribo-rheology with experimental demonstration of the characterization tools that will provide meaningful and interpretable data
• is valuable for scientists and engineers who wish to better understand the experimental data from tribo-rheology and to learn how to design the friction coefficient of dry and wet systems in practical conditions
• is directly linked to a Special Invited Session at the SOR Annual Meeting where a group of invited speakers will discuss the principles of tribo-rheology as well as the needs and advances of the field.

Topics of interest include:

Fundamentals of tribo-rheology | Saturday
• Different friction laws for dry and wet systems
• Considerations of material properties for the solids and the lubricants at the interface
• Deviations of Amonton’s and Hertzian mechanics for soft/adhesive surfaces
• Introduction to the Stribeck curve for boundary, mixed, and elastohydrodynamic lubrication
• Material properties important for tribology (e.g.: viscoelasticity, shear strength, viscosity)
• Using rheological models for non-Newtonian lubricants
• Effect of surface interactions and textures on the macroscopic friction
• Effect of modulus of the bulk substrate
• How to account for the varying contact gap in tribo-rheology
• Validity of the continuum approximation (i.e. textbook correlations) in confined gaps
• Connecting rheology and tribology flow curves

Hands-on tribo-rheology | Sunday
• Principles of tribo-rheometry and experimental methods
• Instrument accessories
• Food and starch applications case studies
• Industrially relevant formulations including but not limited to skin care products, viscosity modified lubricants, connection to the human sense of touch
• Demonstration of Stribeck behavior for hard and soft (skin-like) substrates
• Opportunity to provide samples for measurement and analysis

Course Fees