Tribology-by-Design for Bearing and Gear Steel Tribology

Advancing bearing and gear steels and their surface tribology attributes for the future requires paying attention to an enormous number of conflicting tribology mechanisms that can journey down separate performance-limiting wear, scuffing, and fatigue pathways during operation. While a rigorous technology readiness level (TRL) approach has been developed to reduce risk, the process is slow, expensive, and not conducive to the challenging high- and low-speed functional requirements for future component contact interfaces. Tribology-by-Design (T/D) is a suite of test and analysis tools, a methodology, a process, and an interface design strategy. T/D enables the engineering design of complex interface interactions to be addressed through tribology design parameters derived from physics-based first principles. The methodology is focused on the targeted interface motion, stress, and temperature (MST) and how they activate, through friction (μ), the interface tribology materials, mechanisms, and manifestations (Tm) during operation. The performance of bearing and gear components is controlled by motion-driven mechanisms that result in a wide range of oil film thicknesses (h). To capture motion-driven mechanisms, the traditional lambda ratio (h/σ) for design is expanded to capture interface fluid hydrodynamic mechanisms (hi) and surface integrity mechanisms (σi). Four T/D tools (surface integrity analysis, component design codes, simulation testing, and a single contact model) are used to design the interface for hi/σi mechanisms. The analysis tools provide a digital twin of the targeted component interface. The contact interface tribology input parameters and output manifestations, defined by MST-μ-Tm, are designed to harmonize the interface ingredients for the functional requirements of the application. T/D is implemented through a TRL 4 pseudo virtual test and analysis process. Innovative solutions, with a rapid response, are achieved through multiple and simultaneous actions within the T/D methodology. The design of a hypoid gear mesh interface for greater efficiency demonstrates how T/D is implemented.