Tham khảo tài liệu 'mechanical engineering-tribology in machine design episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Basic principles of tribology 37 Thus eqn becomes Am Âi a bA l and finally Am lPb Pa-Pb AT. Thus the fractional film defect of the compounded lubricant is given by ô Am Aĩ Ịỉb Ịỉli-Ịỉb . Following the same argument as in the case of the simple lubricant it is possible to relate the fractional film defect for both a and b to the heat of adsorption Ec for additive a . A 1-expn 2 74 for the base fluid b . f J Ec b 1 h exprL jexfv O 2-75 . Load sharing in lubricated contacts The adhesive wear of lubricated contacts and in particular lubricated concentrated contacts is now considered. The solution of the problem is based on partial elastohydrodynamic lubrication theory. In this theory both the contacting asperities and the lubricating film contribute to supporting the load. Thus WC WS W where Wc is the total load IVS is the load supported by the lubricating film and w is the load supported by the contacting asperities. Only part of the total load namely w can contribute to the adhesive wear. In view of the experimental results this assumption seems to be justified. Load w supported by the contacting asperities results in the asperity pressure p given by p 2 3E Nrơ ơ rýFị de ơẠ The total pressure resulting from the load Wc is given by pc 3 yiRe- Thus the ratio p pc is given by p pc i i Nra. ơ. r iFị ư. ữ. where Fị deơA is a statistical function in the Greenwood-Williamson 38 Tribology in machine design model of contact between two real surfaces Re is the relative radius of curvature of the contacting surfaces E is the effective elastic modulus N is the asperity density r is the average radius of curvature at the peak of asperities Ơ is the standard deviation of the peaks and de is the equivalent separation between the mean height of the peaks and the flat smooth surface. The ratio of lubricant pressure to total pressure is given by Ps Pc 7 R Â h J where Ẳ is the specific film thickness defined .
