The George W. Woodruff School of Mechanical Engineering and School of Materials Science and Engineering Georgia Institute of Technology Atlanta, Georgia
Failure of in-service components due to fatigue and fracture processes occurring at points of contact and attachments is a heavy annual cost burden on consumers and corporations. Microstructure-property-performance relations for friction are poorly understood at present, lacking substantial input from computational materials science tools particularly at the mesoscopic microstructural length scale. This research revisits friction energy dissipation in tractive rolling and sliding contacts in light of explicitly capturing the microstructural length scale in crystalline metals and alloys. Crystal structure alone cannot explain differences in friction and one must look at the details of the deformation in a crystal plasticity framework. To explore the merits of the approach, fundamental studies of elastic-plastic deformation of the surface layer will be reexamined using an elastic - crystal viscoplasticity material model. The models will be calibrated and validated using new experimental approaches that capture the microstructural length scale. State-of-the-art orientation imaging microscopy based on electron backscatter diffraction (EBSD) will be use to map out the spatial microstructural changes in the surface layers to establish the evolution of microtexture, grain and dislocation substructure formation, and microcracks occurring during tractive rolling and sliding contacts. This research serves as a step in developing fundamental materials models that can serve as building blocks for applications of materials design applied to tribological-relevant coatings and thin films. This research will help to establish next generation computational materials design approaches for wear resistance coatings, palliatives for fretting fatigue and wear, materials interfaces at structural attachments, and tribological interfaces in micro-machines.
