Development of hybrid composite journal bearings

Abstract

In this thesis, a hybrid composite journal bearing (HCJB) composed of carbon/phenolic laminated composite bush and steel housing was designed to reduce the possibility of the seizure problem between the journal and bearing. To estimate the wear resistance of carbon/phenolic composite, wear tests were performed with respect to pressure and velocity. The thermal residual stresses in the composite were calculated to evaluate the reliability of the composite journal bearing with the assumption that the interface of two components of bearing was perfectly bonded. The two components of bearing were assembled by interference fit joining method and a series of durability tests were conducted with the laboratory bench using the lubricants of SAE 30 oil, water, and sea water. The HCJB was also assembled by adhesive joining method. The thermal deformation of composite liner after fabrication was analyzed with respect to stacking sequences using FEM and compared with the experimental results. The effect of thermal residual stress on the adhesive strength of the hybrid composite journal bearing was investigated by performing Chalmers test. In order to improve the tribological behavior of carbon epoxy composites, many small surface grooves of $100 \mu m$ width was created on the surface of the composite, and its characteristics were experimentally investigated with respect to the sliding direction against groove orientation, surface pressure and velocity. The wear mechanism of the composites was observed using a scanning electron microscopic (SEM), from which the relationship between the wear volume and friction coefficient was derived. The tribological behavior of carbon epoxy composites with many small surface grooves were also compared with respect to coating materials such as epoxy and polyethylene mixed with self-lubricating MoS2 and PTFE powders under dry sliding and water lubricating conditions.