Design of hemispherical bearings using carbon fiber composite materials with nano particles

Abstract

Carbon-phenolic woven composite materials are employed in heavy-duty bearings due to their inherent self lubricating properties and thermal stability. In this thesis, a hybrid composite hemispherical bearing (CHB) composed of carbon-phenolic composite and aluminum back-up for the suspension of high mobility tracked vehicles, is developed. In order to reduce the damage generated during machining of the spherical surface of CHB, a near net-shape molding process was used. The thermal residual stresses in the composite and aluminum generated during molding process were calculated by finite element analysis with respect to the fiber types and material stacking sequences. From the calculated data and tested results for CHB, it was found that the developed CHB performed better than the conventional carbon-PEEK CHB. Since the through thickness compressive strength (TTCS) is important for the heavy-duty bearing, in this thesis, the effects of lay-up angles and specimen thickness of woven composites on TTCS were investigated for the efficient design of carbon-phenolic woven composite bearings. From the experiments and FEM analysis, it was found that the TTCS of the carbon-phenolic woven composite is much dependent on the stacking sequence rather than composite thickness because different stacking sequence produced much different interlaminar stresses. The friction and wear characteristics of carbon fiber phenolic composites are important because carbon fiber phenolic composites are increasingly employed in journal bearing materials. Since the friction and wear characteristics of phenolic composites have been mainly investigated under dry sliding conditions, in this thesis, the wear characteristics of the carbon fiber phenolic composites were experimentally investigated both under the dry sliding and oil-lubrication conditions. Nano-size particles were mixed in the surface layers of the composite specimens to improve the wear characteristics of the carbon fiber phenol...