SUMMARYThe use of contacting components such as gear teeth in mesh and shrink-fitted shafts is very common in engineering practice. This paper deals with the development of a theoretical method which gives a solution for non-linear contact problems with irreversibility resulting from stick-slip phenomenon.The method is based on the finite element method and load incremental theory. The geometrical and the statical boundary conditions on contact surfaces are treated as additional conditions being independent of stiffness equations. As a result, the algorithm of calculation is simplified and only a part of the simultaneous equations related to the contact surfaces is required t o be solved instead of the overall stiffness equations at each step. Furthermore, the magnitude of load causing a change in a contact condition of one contact nodepair is taken as a load increment, in analogy with the incremental iterative procedure for elastic-plastic problems. Therefore, the method provides a general and efficient method for analysis and design of such problems.As illustrative examples, the stick-slip behaviour of turbo-alternator end-bells and other problems are discussed. The calculated results show a reasonable agreement with experimental data and other solutions.

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This study demonstrates the application of a precise and variable impedance control to the homogeneous electrorheological (ER) clutch. The viscous coefficient of a homogeneous ER fluid can be changed by the application of an electric field. However, the ER effect of the fluid is easily changed by shear rate variation or temperature variation. Therefore, some feedback compensations are necessary for these systems to maintain a more precise viscosity.In this paper, we apply a force-based impedance control to the homogeneous ER clutch in order to use ER fluid more effectively. First, we study the fundamental characteristics of the homogeneous ER clutch. Next, we apply the viscous control based on the force control in order to maintain a more precise viscosity. The results of our experiment clearly show that the viscosity of the clutch has been accurately and stably controlled by the proposed control method.