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CFD analysis of nano-lubricated journal bearing considering variable viscosity and elastic deformation effects

Kadhim Zainab H., Ahmed Saba Y., Abass Basim A.

Diagnostyka

2022

Vol. 23, No. 1

art. no. 2022101

The main objective of the present work is to study the behavior of Nano-lubricated journal bearing considering elasticity and variable viscosity effects. A mathematical model for a journal bearing is employed using three-dimensional computational fluid dynamics. The study is implemented for a journal bearing with laminar flow and smooth surfaces lubricated with pure oil as well as lubricants containing different concentrations of Al2O3 Nano-particles. The dependence of the oil viscosity on the temperature is considered by using the modified Krieger Dougherty model. Pressure, temperature and elastic deformation in addition to the bearing load-carrying capacity of the bearing working under different eccentricity ratios (0.1-0.6) have been studied. The mathematical model is confirmed by comparing the results of the pressure and temperature distributions obtained in the current work with those obtained by Ferron et al.(1983) for a bearing lubricated with pure oil. Also, the pressure obtained for the Nano-lubricated bearing of the present work is validated with that obtained by Solighar (2015). The results are found in good agreement with a maximum deviation not exceeding 5%. The obtained results show that the oil film pressure increases by about 17.9% with a slight decrease in oil film temperature and friction coefficient.

Experimental and numerical studies of fatigue properties of carbon/glass fiber/epoxy hybrid composites enhanced with nano TiO2 powder

Hunain Mustafa Baqir, Abass Basim A., Akhudair Jaafar Musa

Diagnostyka

2021

Vol. 22, No. 2

75--84

The present work deals with the fatigue behavior of hybrid nanocomposites consisting epoxy strengthen by unidirectional carbon fibres, and/or woven roving glass fiber and TiO2 nanofillers. For this purpose, nanocomposite material was manufactured by mixing TiO2 nanoparticles with the epoxy using an ultrasonic mixer to insure complete dispersion of such particles in the base material. Different particle concentrations (1, 3, and 5) % wt. of TiO2 nanoparticles have been added to the epoxy. Different types of hybrid nano composite materials were manufactured by adding three layers of carbon fibers and/or woven roving glass fiber to the prepared epoxy nanocomposite materials with a constant weight fraction of 30%. The laminated hybrid nanocomposite materials were then prepared using hand lay-up technique using a vacuum device. For experimental purposes tensile and fatigue test specimens have been manufactured according to ASTM-D3039 and ASTM D 3479/D 3479M-96, respectively, while ANSYS19 program was used to analyze the fatigue behavior of such materials numerically. Tensile tests were carried out at room temperature while fatigue tests has been carried out at constant stress ratio (R=-1). Scanning electron microscope (SEM) was used to identify the underlying mechanisms for fatigue failure and the progressive of damage growth. For each test, three specimens were tested and the average magnitude for each property was taken. The results obtained indicated that the hybrid nanocomposite (EP+C/C/C+3% TiO2) has the highest fatigue limit and tensile strength in comparison with the other tested material, while the SEM results showed that the composite failed by a brittle way. It has been also generally observed that the addition of (TiO2) nanoparticles has a positive effect on the fatigue behaviour of the such materials.