A More Efficient Direct Iterative Algorithm And Its Research For Point Contact EHL Problems

This thesis is on the study of the fast algorithm for point contact elastohydrodynamic lubrication (EHL) problems and it is composed of six chapters.Chapter 1 reviews the development history of EHL, mainly analyses and comments several major algorithms in the development of point contact EHL. Also, the meaning and importance of this research topic are proposed.Chapter 2 introduces the equations of isothermal point contact EHL and the composite direct iterative method.In chapter 3, a more efficient direct iterative algorithm called band algorithm for point contact EHL problems is proposed. A large number of examples are calculated and they prove that the new algorithm is feasible, correct and accurate.Chapter 4 researches the computing efficiency of the new algorithm and factors related to the computing efficiency. Many examples demonstrate that the new algorithm is faster dozens of times than composite direct iterative method and with the increase of the encryption of the calculation regional grid, the advantage of the new algorithm gets more and more obvious. Besides, it is found that the new algorithm has the best convergence rate and the largest load range when the half-bandwidth of the iteration matrix is 22% to 25% of its full elements.In chapter 5, the new algorithm is applied to solve heavy-load point contact EHL problems. Seven heavy-load cases are calculated and the typical features of point contact EHL are obtained, which proves the new algorithm could be applied to the heavy load conditions and the traditional views that direct iterative algorithm can not be applied to solve heavy-load EHL problems is broken up.Chapter 6 summarizes all works of the thesis and some worthwhile tasks in the future are proposed.