Diamond and diamondlike carbon (DLC) films exhibit a wide range of sometimes contradictory tribological behavior. Experimentally, isolating the influences of factors such as film structure, testing conditions, and environmental effects has proven difficult. In this work, molecular dynamics simulations were used to examine the effects of film structure, passivation, adhesion, tribochemistry, and...

For two simple setups it is discussed, how dissipative grain-grain interactions give rise to unexpected properties on large scales. In the rst example, a spherical particle rolling along a rough surface experiences an eeective viscous friction on large time scales. It is due to temporal correlations among collisions with incomplete normal restitution. The second example is a sheared granular pa...

The tribological protection of carbon fiber reinforced epoxy composites (CFC) is essential for broadening their use from structural to functional applications, e.g., to linear bearings in mechanical engineering. However, their wear resistance in sliding and rolling contacts is low. This work focusses on the possibility of improving their tribological properties by the application of thin hard m...

Solids at incommensurate contact display low-friction, ’superlubric’, sliding. For graphene flakes on a graphite surface, superlubric sliding is only temporary due to rotation of the flakes from incommensurate to commensurate contact with the substrate. We examine this rotational channel of friction in a prototype geometry of mesoand macroscopic solid lubrication. By molecular dynamics simulati...

Aluminium alloy composites have been extensively investigated for use in tribo-contact applications, however little detailed literature exists on the sub-surface microstructural evolution as a result of lubricated sliding wear. In this study two un-reinforced alloys (2124 & 5056) and identical alloy composites, reinforced with 15vol.% MoSi2 intermetallic particles were produced by a powder meta...

A general approach to numerically simulating wear in rolling and sliding contacts is presented in this thesis. A simulation scheme is developed that calculates the wear at a detailed level. The removal of material follows Archard‟s wear law, which states that the reduction of volume is linearly proportional to the sliding distance, the normal load and the wear coefficient Careful attention is p...

Abstract Cellulose nanofibers (CNFs), which are plant-derived materials, have recently garnered considerable attention owing to their excellent mechanical properties, such as low weight and high Young’s modulus. Novel methods for producing 100% CNF bulk structural materials been developed. However, the tribological properties of CNFs not investigated thus far although known comparable those som...

Flagellar beating of hyperactivated golden hamster spermatozoa was analyzed in detail using digital image analysis and was compared to that of nonhyperactivated (activated) spermatozoa in order to understand the change in flagellar beating during hyperactivation and the active microtubule sliding that brought about the change in flagellar beating. Hyperactivated flagellar beating, which was cha...