Viscoelastic behavior of extended interval lubricator cartrid ges made from nylon and glassylon composites

摘要

Recent efforts to characterize time-dependent behavior of polymer and polymer composite lubricant cartridges in a new extended itnerval continuous lubricator are summarized. The lubricator consists of a tubular, lubricant-filled polymer or polymer composite cartridge which is activated by a pre-stressed composite force sleeve-the cartridge then gradually flattens out with tiem, forcing the lubricant out under pressure. Prediction of time-dependent behavior of the cartridge over the desired two years design life was the goal. A finite element analysis including viscoelastic materials behavior, geometric nonlinearity due to large deflections, and special gap elements to model variable contact surfaces was used to predict the time dependent behavior of the cartridge. The analytical predictions were compared with measured creep of a nylon cartridege under constant compressive loaidng between two flat steel plates, and agreement was found to be good. The model was also used to predict the time-dependent forces required to produce the ideal linear dispensation curve for the cartridge. It was shown that the use of glass fiber reinforcement significantly reduces the influence of environmental conditions on the response of the cartridge, and that the use of motched cartridge greatly reduces the forces needed to flatten the cartridge near the end of the two year design life.