The effect of triboelastodynamics of rings on energy efficiency with particular focus on internal combustion engines TurnbullRob 2021 High performance, fuel efficiency, and noise and vibration refinement are key customer desired attributes for vehicular powertrain systems, including engines. Energy efficiency and reduced emissions have become even more important with the drive for sustainability and environmental protection with increasingly stringent legislation. Powertrain systems, such as internal combustion engines and their sub-systems, such as bearings, are utilised in a large number of applications/systems. Therefore, improving energy efficiency in their use is particularly important. In the case of internal combustion engines, significant frictional and power losses occur from piston compression rings. These losses are disproportional to the sizes of these small components. Therefore, much attention has been devoted to the study of compression ring behaviour. Similarly, the ideal function of bearings is dictated by both thermal and elastic distortions of their raceways.This thesis presents multi-physics integrated models for thin and thick rings, representative of piston compression rings and bearing races respectively. [Continues.]