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Author: search.filters.author.Mongkol, Mongkolwongrojn

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    Effect of micro-particles on rough surface spur gears under TEHL with non-Newtonian lubricant
    (2016-01-01)
    Mongkol, Mongkolwongrojn
    ;
    Jesda, Panichakorn
    This paper presents the performance characteristics of rough surface spur gears under thermo-elastohydrodynamic lubrication (TEHL) with non-Newtonian solid-liquid lubricant based on a Power law viscosity model. The bi-phase lubricant contains oil with Molybdenum disulfide particles. The time dependent modified Reynolds equation, elasticity equation, powder load carrying capacity, and energy equation with initial conditions were formulated and solved numerically using a multigrid multilevel with full approximation technique for an involute spur gear. In this analysis, the normal load and overloads are applied on either two pairs or one pair of gear teeth respectively. The transitions from two pairs to one pair and vice versa are modeled as a step variation of load. The effects of solid particle concentration, diameter of solid particle and surface roughness were examined in the region along the line of action of the meshing gear. The results show that both solid particle concentration and surface roughness affect significantly the film thickness, film temperature and friction coefficient, but the diameters of solid particle are relatively insignificant for rough TEHL.
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    TEHL analysis of rough surface spur gears with non-newtonian lubricants under sudden overloads
    (2012-10-15)
    Mongkol, Mongkolwongrojn
    ;
    Jesda, Panichakorn
    The time-dependent modified Reynolds equation, elasticity equation, and energy equation with initial conditions were formulated and solved numerically using a multi-grid multilevel with full approximation technique for an involute spur gear. In this analysis, the normal load and sudden overload are applied on either two pairs or one pair of gear teeth. The transition from two pairs to one pair and vice versa are modeled as a step variation of load. The effects of overload, surface roughness, non-Newtonian lubricant properties of the meshing gear in the region along the line of action are examined. The results show that lubricant properties and surface roughness have significant effects on film thickness, film temperature and friction coefficient for spur gears with rough surfaces. The minimum film thickness is decreased rapidly with the decrease of lubricant power law index. For gears operated at a sudden overload condition, the film temperature and friction coefficient are severely increased. Copyright © 2012 by JSME.
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    Analysis of two surfaces in line contact under TEHL with non-Newtonian lubricants
    (2012-01-18)
    Sountaree, Rattapasakorn
    ;
    Mongkol, Mongkolwongrojn
    This paper presents the static characteristics of two surfaces in line contact under TEHL with non-Newtonian lubricant. Modified Reynolds equation, elastic equation and energy equation were formulated to obtain the model. The model was simulated based on numerical method by using Newton-Raphson and multigrid multilevel techniques. The static characteristics of the two surfaces in line contact under TEHL such as film pressure, film thickness and film temperature profiles in the contact region were examined at various loads, speeds, roller radius and elastic modulus respectively. The results showed the significant effect of load, elastic modulus and surface velocity on the TEHL for machine element operated at severe conditions. © (2012) Trans Tech Publications, Switzerland.
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    Effect of liquid-solid lubricant on mixed lubrication in line contact
    (2012-01-18)
    Sountaree, Rattapasakorn
    ;
    Jesda, Panichakorn
    ;
    Mongkol, Mongkolwongrojn
    This paper presents the performance characteristics of two surfaces in line contact under isothermal mixed lubrication with non-Newtonian liquid-solid lubricant base on Power law viscosity model. The time dependent Reynolds equation, elastic equation and viscosity equation were formulated for compressible fluid. Newton-Raphson method and multigrid technique were implemented to obtain film thickness profiles, friction coefficient and load carrying in the contact region at various roughness amplitudes, applied loads, speeds and the concentration of solid lubricant. The simulation results showed that roughness amplitude has a significant effect on the film pressure, film thickness and surface contact pressure in the contact region. The film thickness decrease but friction coefficient and asperities load rapidly increases when surface roughness amplitude increases or surface speed decreases. When the concentration of solid lubricant increased, friction coefficient and asperities load decrease but traction and film thickness increase. © (2012) Trans Tech Publications, Switzerland.