Gear Change Friction Mixed Finite Element Method Of Three-dimensional Contact Problem Solving And Program Design

The thesis is developed with the main thread:gear contact model-contact algorithm-contact characteristic simulation. The employment is first devoted to study of static, quasi-static and dynamic contact model of gear device, aiming at which applicable situations and calculating methods are presented based on finite element method along with contact theory. The program packages for gear contact problem are worked out by Fortran language, and are imposed to simulate gear engagement under two dimensional plane stress and three dimensional conditions respectively. The main parts and innovation points are:1. The mechanical description, applicable occasions, advantages and shortcomings for gear static contact model are illustrated. The finite element static algorithm is proposed. The deformations under given contact forces in plane stress and three dimensional conditions are computed respectively by the designed program package.2. The mechanical description, applicable occasions, advantages and shortcomings for gear quasi-static contact model are illustrated. The mixed finite element method for quasi-static contact problem is studied. The technique for three dimensional spur gear contact is put forward for the sake of increasing convergence speed on the basis of convenience to identify axial friction, where resultant friction force is treated as iterative variable to attain solution. The designed program package is employed to analyze gear contact problem with Stribeck friction model under plane stress and three dimensional conditions, where the changing rules of resultant contact forces, nodal contact components and nodal contact states with relative sliding velocity are discussed, and are compared with those gained in Coulomb friction model.3. The mechanical description, applicable occasions, advantages and shortcomings for gear dynamic contact model are illustrated. The concept of contact-impact for gear transmission is introduced in view of the impact phenomenon as a result of a sudden change in velocity during the natural meshing process. The mixed finite element method for dynamic contact problem is researched. The designed program package is used to calculate the gear impact question under plane stress condition with Stribeck friction model, where the nonal normal contact forces, nonal friction, the resultant normal contact forces and friction under different initial impact velocities are computed, and are compared with those obtained with Coulomb friction model.4. Three dimensional gear contact-impact analysis is implemented by LS-DYNA code, in which the relationship between initial impact velocity, impact position with resultant contact force, contact stress, impact time is inquired into. The achieved results are inspected by analytical solution of maximal contact force. The distribution law of maximal stress points on tooth surface during the entire impact process under diverse impact conditions is also offered.The thesis commits itself to providing corresponding processing algorithms for different gear contact model, and probing into gear contact problem with Stribeck friction model by designed program package. The validity of work in this paper is acquired by the contrastive analysis with commercial software together with experiment.