Experimental and Numerical Analysis on the Seizure of a Carbon-Filled PTFE Central Groove Journal Bearing during Start-Up Period

Abstract

During the start-up period, if the journals bearing bushing and shaft materials have different heat conductivities, the thermal expansion of the shaft might be more rapid than that of the bushing. This reduces the radial clearance between the bearing components and generates higher shear stresses in the lubricating fluid, which can lead to bearing seizure, resulting in the deterioration of the journal bearing.(1) First, we present an experimental case study of the seizure of a central groove journal bearing with a carbon-filled polytetrafluoroethylene (PTFE) bushing and a steel shaft; (2) Then, a static thermoelastohydrodynamic (TEHD) simulation is compared to Cristea's experiments (Cristea, A.-F., 2012); (3) Then, a pseudo-transient TEHD simulation is performed in order to numerically predict the observed phenomena on the test rig; (4) Finally, the evolution of the oil flow rate and the bushing temperatures during the start-up period determined with the pseudo-transient TEHD modelling are compared to the experimental data of the test rig. The pressure field is determined with the thermohydrodynamic (THD) Elrod's modelling, with Vijayaraghvan's robust solver algorithm. The pseudo-transient temperature field in the bearing components as well as the thermal and mechanical deformations are calculated with a commercial software.

Experimental Research on Insufficient Water Lubrication of Marine Stern Tube Journal Bearing with Elastic Polymer Bush

“…The causes of thermal bush seizures are the subject of analyses conducted by some research centres [18,43,44]. They assess, among others, the impact of the polymer bush's thermal expansion on the bearing's diameter clearance.…”

“…Takabi et al [39] indicates that the faster the revolution speed of the shaft, the higher the probability of bush seizure due to overheating. Pap B. et al [18] point out that, as a result of decreasing the bearing diameter clearance, a drop occurs in the flow of lubricating agent through the bearing, in consequence leading to a rise of temperature inside the bearing.…”

“…The steel shaft has higher thermal conductivity than the polymer bush. Therefore, the shaft conducts more heat than the bushing, and the shaft expands toward the bush [18].…”

Thermal–Hydrodynamic Behaviour of Coated Pivoted Pad Thrust Bearings: Comparison between Babbitt, PTFE and DLC

“…As a result of the higher elasticity of the sliding layer in the case of softer materials such as PTFE, the load distribution can become greater even among individual pads of the bearing. For example, the elasticity of the bearing faces can entrap oil in the loaded area, helping in such way the cases of lubricant misfeeding or offering excellent anti-seizure properties [22]. TEHD (thermo-elasto-hydrodynamic) bearing models were used by Glavatskih and Fillon [20].…”

“…A method of allowing for creep in numerical modelling was also discussed. Bálint et al [22] presented an experimental study as well as a THD and pseudo-transient TEHD simulation in order to examine the seizure of the PTFE in grooved journal bearings during start up.…”