ABSTRACT
The purpose of this chapter is to provide an opportunity of a new prospective on classic EHL problems. We propose and analyze a new formulation of EHL problems that explains and predicts the abnormal phenomena observed in experiments with hard and soft lubricated solids by M. Kaneta and associates [1, 2]. For the first time, they have described the formation of a dimple in a heavily loaded lubricated contact of a relatively soft elastic solid with a hard one. The occurrence of a dimple cannot be predicted by the classic EHL theory. Kaneta et al. [1, 2] believe that the abnormal behavior of lubricated elastic surfaces can be explained by invoking solidification of oil in contact. Another interpretation of the abnormal phenomena based on a non-steady approach to the EHL problem is offered by Cermk [3]. However, the results of this approach contradict the steady nature of the experimental data presented by Kaneta et al. [1, 2]. Recently a number of numerical studies on this subject were published by Kaneta and Young [4, 5]. The main idea of the latter studies is that the dimple phenomenon is caused by the heat generation in the lubrication layer and its dissipation in the solids. However, the formulation of the problem in which it is studied in [4, 5] has a serious defect. Namely, for sufficiently high slide-to-roll ratios, the lubricant flows in opposite directions near two contact surfaces. Therefore, at the separatrix between the two oppositely directed flows, a condition for continuity of heat flux must be imposed. That condition was not used by Kaneta and Young in their studies. In spite of the fact that heat generation is important under high sliding conditions the lack of the above-mentioned boundary condition invalidates their analysis. Moreover, in spite of the importance of lubricant heat generation and its dissipation in solids the Kaneta and Young [4, 5] solution does not and cannot predict all the features (a)-(d) of such a lubricated contact observed in experiments (see Section 18.6). The new formulation of the problem [6] is based on the traditional for
the EHL theory approach to steady lubricated contacts as contacts of two elastic solids separated by a fluid film without oil solidification phenomenon. A new formulation of a steady problem for lubricated rollers made of elastic materials with low Young’s modulus is considered. The distinct feature of
for Line and Point
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FIGURE 18.1
The general view of a lubricated contact.
