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THERMAL MODELS OF HD AND EHD LUBRICANT FILM
Sergey Vasiliy Fedorov
; Kaliningrad State Technical University, Russia
Sažetak
For the case of the failure of the lubricant film under hydrodynamic lubrication a common thermodynamic theory of strength is considered. According to this theory the failure occurs when the internal energy density (potential and thermal components) in the bulk of material reaches a constant value for a given material. A special case of this theory is when only the density of heat (kinetic) component of internal energy is taken into account. This is due to the kinetic peculiarities of accumulation of internal energy of liquid materials. This condition determines the limit state for liquid lubricants - mineral oils. In the case of hydrodynamic lubrication the practical solution of this power criterion is achieved by using a more convenient criterion - temperature flashes in the lubricant film.
When analyzing the regularities of friction under EHD lubrication two separate and possible effects are taken into account. The first one is regularity of plastic deformation (states and properties) at Hertzian contact of solids. The second one is the state and properties of the oil film under irregular and hydrostatic compression. The original structural model of oil film by EHD lubrication in the form of a rotary oscillating cells with elastic interactions is proposed. This is similar to the Rayleigh-Benard cells. It is possible that the size of the cells are an order about nano level (type fullerene’s form or mechanical quantum). The oil film dissipates energy in the direction of relative motion of bodies. This oil film has the highest dissipative properties. Here, the work of the external forces is almost completely dissipated in these oil film structures. The concept of temperature for a such film has almost no meaning. The load of the EHD film is very high because it is elastic and energy dissipation is reversible.
Ključne riječi
friction; energy balance; energy density; lubricant; temperature; nanostructure
Hrčak ID:
159036
URI
Datum izdavanja:
6.4.2016.
Posjeta: 732 *