The investigation of numerical methods for modelling the mechanism properties ofinvolute spur gears in mesh, over the mesh cycle, forms the major part of this thesis.Gearing is perhaps one of the most critical components in power transmission systemsand the transmission error of gears in mesh is considered to be one of the main causes ofgear noise and vibration. Numerous papers have been published on gear transmissionerror measurement and many investigations have been devoted to gear vibration analysis.There still, however, remains to be developed a general Finite Element Model capable ofpredicting the effect of variations in rigid body gear tooth position, in which the criticalstage is the prediction of gear behaviour with profile modifications (including tip-relief).In this thesis, FEA results have been obtained by using various techniques including: (a)adaptive re-mesh with contacts using quad (2D) and brick (3D) elements and (b) theelement birth and death option. Tooth profile modifications can affect the behaviour ofthe gear meshing including the T.E., ratio of local deformation and load-sharing ratioresults, etc, providing an alternative method for gear design. In the high order end, theelastic strains of the gear-shaft system have also been investigated. The results in thisthesis have shown the potential for using strain-vibration relationships to monitor orcontrol the transmission system.The investigations have also included some analysis with non-metallic gears, anapplication area that is rapidly growing. The results achieved here are at a fundamentalstage, and further research would necessitate applying a coupled field analysis (structuraland thermal).

<p> </p><p>The cooling system of a DC-motor is examined in this thesis. A change of direction of the cooling air is desired to prevent the generated coal dust from entering into the windings of the machine. Ultimately this will have a negative effect on the cooling in the machine and the loss of cooling needs to be compensated through other ways. The purpose of this thesis is to work for an improved operational safety and performance of the DC-motor and to make it more competitive in the market. By modelling the interior geometry of the machine and defining the boundaries in the software programs Gambit and FLUENT respectively, the motion and the heat transfer of the airflow could be simulated. The simulation results would give us an understanding of the flow pattern which later could be used to develop design modifications on the cooling system of a DC-motor. In this thesis the main focus lies on creating a simulation model with a sufficiently fine mesh size.</p>

The cooling system of a DC-motor is examined in this thesis. A change of direction of the cooling air is desired to prevent the generated coal dust from entering into the windings of the machine. Ultimately this will have a negative effect on the cooling in the machine and the loss of cooling needs to be compensated through other ways. The purpose of this thesis is to work for an improved operational safety and performance of the DC-motor and to make it more competitive in the market. By modelling the interior geometry of the machine and defining the boundaries in the software programs Gambit and FLUENT respectively, the motion and the heat transfer of the airflow could be simulated. The simulation results would give us an understanding of the flow pattern which later could be used to develop design modifications on the cooling system of a DC-motor. In this thesis the main focus lies on creating a simulation model with a sufficiently fine mesh size.