Tapered Roller Bearing Accelerated Life Test Rig Design and Fabrication

L10 bearing fatigue life testing is a costly and prolonged process, as the bearing is characteristically designed for durability and reliability. Within the current testing methods, faulty materials still have the potential of passing the test. However, with this life test rig, the bearing will be tested to failure, thus providing an indicator for its predicted life span. The purpose of this project is to optimize and construct a L10 life test rig for accelerated fatigue testing of the Association of American Railroad Class K, 6 ½ x 9-inch double-row tapered roller bearing to their maximum fatigue life as quickly as possible with the use of an axial load. This Senior Design team has developed and improved upon a proposed design for an accelerated life test rig capable of testing tapered roller bearings to failure. The past design allowed for 4 bearings, but due to time restrictions, financial limitations, and other factors its construction was not feasible. Therefore, the team has designed and revised a test rig for 1 bearing. The current, radially loaded testing method takes 1.57 years to test a bearing to failure, whereas with the axially loaded method will take about 73 days. Additionally, the team will construct the single bearing test rig to verify that axial loading is an effective means of reducing the applied load in addition to reducing the normal test run time while still achieving the same single roller fatigue results across all of the rollers. The development of this test rig will allow Brenco to perform more testing of roller materials in a shorter amount of time, which will result in a higher capacity of research to determine higher quality materials.https://scholarscompass.vcu.edu/capstone/1129/thumbnail.jp

Modeling ionic liquids mixture viscosity using Eyring theory combined with a SAFT-based EOS

This work aims to calculate the viscosities of ionic liquid mixtures using the Eyring theory combined with the SAFT-VR Morse EOS. The free volume theory was used to correlate the pure viscosity of ionic liquids (ILs) and solvents. Three model parameters have been adjusted using experimental viscosity data of ILs between 282 K and 413 K and 1 bar to 350 bar. The average ARD%, Bias%, and rmsd between model estimation and viscosity experimental data for pure ILs have been obtained 4.9 %, 1.015 %, and 0.67, respectively. The average error of the proposed model tends to increase at a pressure higher than 200 bar. The average ARD% for [C2mim][Tf2N] and [C6mim][Tf2N] is about 3.8 % and 3.4 % at pressures lower than 200 bar, while the average ARD% values increase sharply at higher pressures. This is due to the weak performance of the SAFT-VR Morse EOS for the calculation of IL density at high pressures. The SAFT-VR Morse EOS has been coupled with the Eyring theory, and the Redlich-Kister mixing rule to estimate the mixture viscosity of ILs-ILs and ILs-solvent systems. The thermal contribution of excess activation free energy has been calculated using the Redlich-Kister mixing rule with four adjustable parameters. The average ARD%, rmsd, and Bias% for fifteen binary mixtures have been obtained 3.9 %, 2.51, and 0.57 %, respectively. The average error values for mixture viscosity of ILs-polar solvent are higher than non-polar solvents. In the case of binary IL-IL systems, the model results are in good agreement with experimental data. The model performance has been evaluated using the viscosity deviation property. The SAFT-VR Morse EOS predicts the negative viscosity deviation. The strong attractive interaction in the mixture than a pure component is the major contribution to negative viscosity deviation. The results show that the new model can calculate the mixture viscosity and viscosity deviation of binary systems satisfactory. The obtained error values of mixture viscosity show that the Eyring theory can be coupled with a SAFT-based EOS to calculate the viscosity of ILs over a wide range of pressures and temperatures satisfactory