OPTIMIZATION OF THE LUBRICATION LAYER’S STRUCTURAL PARAMETERS WHEN THEY ARE MODELLED BY MEANS OF MOLECULAR DYNAMICS
The paper assesses the current state of the issue of computer molecular modeling methods application in the construction of virtual tribosystems with boundary lubrication layer. The role of optimization procedures in these calculations is shown. A method for describing the lubrication process by molecular dynamics using step-by-step relative shear displacement of the friction surfaces is proposed. The optimization procedure used by the authors in relation to the energy of a limited cluster of lubricants is characterized. An approach to calculating the order parameter of the lubricant layer - the molecular orientation coefficient - is formulated, a calculation formula for its estimation is selected, and a calculation algorithm is constructed. According to the proposed algorithm, a selected direction (Director) is constructed for all the molecules of the selected cluster of lubricant molecules, and then the data array containing the angular components is processed to get the instantaneous value of the order parameter. In the step-by-step shift process, this calculation cycle is performed after each shift, thereby reflecting the evolution of the orientation state of the lubricant layer. Calculation procedures can serve as an explanation of the nature of the lubricating action (including taking into account the tribological activity of additives), as well as contribute to the faster and more efficient creation of new-generation lubricants. More extensive experimental studies of mesogenic lubricants and triboactive additives for the correlation of layer mesomorphism and its antifriction characteristics are considered promising.