There are different types of electric motors; one of them is the induction motor. Such a motor consists of a winded stator and an induction rotor. The rotor squirrel cage is made with aluminium high-pressure die casting technology. Besides relatively low motor-producing costs and good repeatability, the motor efficiency and torque/speed characteristics are also important. One of the loss factors for the rotor is the loss of conductance of die cast material. This study researches how different casting conditions influence the material's electrical resistivity of Al 99.7. With melting of the alloy in an induction vacuum furnace and testing various casting conditions during the solidification (such as the vacuum, air and filtering), the temperature and electrical resistivity of the castings were measured using the four-point measuring method. The porosity proportions of the samples were examined with X-ray, as well as with optical microscopy. The presence of Fe-eutectic (alpha-Al + Al13Fe4) was confirmed in the investigated samples' microstructures. as was predicted by a calculation of the equilibrium phase diagram. The electrical resistivity values were additionally measured with an eddy-current measuring method. The results show a good correlation with the four-point measuring method and are in a range 29-33 n Omega m at 20 degrees C. Based on the obtained results, the influence of impurities and porosity on the electrical properties of aluminium was evaluated.

Cores for electrical motors are typically produced by blanking of laminations and then stacking them together, with, for instance, interlocking ribs or welding. Strict geometrical tolerances, both on the lamination and on the stack, combined with complex part geometry and harder steel strip material, call for use of predictive methods to optimize the process before actual blanking to reduce the costs and speed up the process. One of the major influences on the final stack geometry is the quality of the interlocking ribs. A rib is formed in one step and joined with the rib of the preceding lamination in the next. The quality of the joint determines the firmness of the stack and also influences its. The geometrical and positional accuracy is thus crucial in rib formation process. In this study, a complex experimental and numerical analysis of interlocking rib formation has been performed. The aim of the analysis is to numerically predict the shape of the rib in order to perform a numerical simulation of the stack formation in the next step of the process. A detailed experimental research has been performed in order to characterize influential parameters on the rib formation and the geometry of the ribs itself, using classical and 3D laser microscopy. The formation of the interlocking rib is then simulated using Abaqus Explicit. The Hill 48 constitutive material model is based on extensive and novel material characterization process, combining data from in-plane and out-of-plane material tests to perform a 3D analysis of both, rib formation and rib joining. The study shows good correlation between the experimental and numerical results.

This paper deals with determination of stress, strain and displacement state of a circular annulus which is made of material with Cartesian orthotropic rheological behaviour. There is a continuous and constant load on the inner and/or outer edge. Stress and strain state in the circular annulus is in the elastic domain. Stress state is determined on the basis of an Airy stress function, where all boundary conditions have to be fulfilled. The Ritz's method was applied to determine unknown parameters of the Airy function. References F. Kosel. The stress and deflection state in the circular annulus with Cartesian orthotropy. Proceedings 14th Canadian Congress of Applied Mechanics, volume 2, pages 493--494. CANCAM, 1993. Pistonesi, C. and Laura, P. A. A., Forced vibrations of a clamped, circular plate of rectangular orthotropy, J. Sound Vibr., 228, 1999, 712--716. Tahan, N., PavloviÊ, M. N. and Kotsovos, M. D., Orthotropic rectangular plates under in-plane loading part 1: closed-form solutions for stresses, Compos. Struct., 33, 1995, 35--48. Wu, Z. J. and Wardenier, J., Further investigation on the exact elasticity solution for anisotropic thick rectangular plates, Int. J. Solids Struct., 35, 1998, 747--758. Adewale, A. O., Application of the singularity function method to semi-infinite orthotropic rectangular plates on an elastic foundation, Int. J. Mech. Sci., 43, 2001, 2261--2279. Bhaskar, K. and Kaushik, B., Simple and exact series solutions for flexure of orthotropic rectangular plates with any combination of clamped and simply supported edges, Compos. Struct., 63, 2004, 63--68. S. G. Lekhnitskii. Theory of elasticity of an anisotropic body. Mir Publishers, Moscow, 1981.

Today engineers involved in the stamping process used for high-volume production of rotor and stator laminations are faced with a great challenge to achieve extremely narrow dimensional and geometrical tolerance on their products. Because materials are produced by different suppliers, adjustments of technological parameters to the emerging differences are required to maintain the high quality of products. An upgraded engineering method was developed in which electrical steel sheet of semi-finish grade was not treated traditionally, but as a 3D body with orthotropic material behaviour. The round profile of the cutting edge was studied from the experimental and numerical point of view. If the completely round punch was used, the profile of the cutting edge appeared as a non-round shape. With additional FEM analyses a new profile of punch was designed as a non-round shape to be able to provide much better circularity. FEM simulation showed that 10 times lower profile deviations were found on the workpiece shaped by the new cutting element profile.