In this article a new method is presented allowing the diagnostic of bar or ring rupture of a cage of asynchronous machine. It is shown that a modelling of the asynchronous machine taking into account each bar and each portion of ring of the cage allows to consider the influence of a rupture upon the expression to the instantaneous electromagnetic torque. It has been put up an instrumentation permitting the measurement of this torque. The spectral analysis of the parameter leads to the diagnostic of a cage rupture by discriminating this fault from other faults, particularly mechanical ones. It is also observed that ruptures influence greatly the electromagnetic torque. The peak variation of the significant spectral lines is so important that it allows the detection of a first rupture without the need of a very sophisticated instrumentation.

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Abstract. Gear meshing is a complicated process, and is subjected to the simulation process in the following paper. A flexible quasi-static and dynamic finite element analysis (FEA) models were built, to calculate contact principal and shear stresses. Full sized 3D spur gears are simulated under different boundary conditions. The first model, was a quasi-static analysis, where torque was used as input; and the second model, which was transient dynamic analysis, where rotational speed was used as input. The static analysis showed high stress concentration at the tooth contact point and under the contacting surface. The dynamic analysis provided the highest stress value at the different stages of gear engagement points along the line of action. Analytical and simulation result were in agreement in general, and the use of the new simulation model was discussed.