Potential NASA Commercial Applications: There is enormous commercial potential for design software that fills the gaps in current understanding of gearbox life. Traditionally, due to a lack of fundamental understanding and methods to incorporate gear teeth interaction, gearboxes are simply "overdesigned" by incorporating large safety factors. However, this approach becomes problematic in applications where constrained weight and space are desirable (e.g. aerospace, wind turbines, etc.). The proposed software provides a more rigorous analysis of gear tooth life based on a fundamental understanding of the tribological phenomena at the gear mesh. This software will provide a means of optimizing gearbox designs for weight and size, as well as improved estimations of gearbox life under variable loading. This latter factor is a proving to be of significant interest in both commercial and military applications, as it is an enabling technology for condition-based maintenance strategies.