Frédéric Palleschi

Influence of temperature on the vibro-acoustic behavior of claw-pole alternators

Audible noise of automotive alternators is a key point for future cars. Its reduction requires a multiphysic approach including electromagnetic, vibro-acoustic and thermal aspects. In this perspective, this paper investigates the influence of stator temperature on the acoustic noise of a claw-pole alternator. Experimental results show a clear reduction of sound power level and change in noise peak frequencies with an increased temperature. An experimental modal analysis of the stator is carried out to explain this effect. Based on these measurements, a model is developed to predict the resonant frequencies of the wound stator at different temperatures.

Vibro-Acoustic Simulation and Optimization of a Claw-Pole Alternator

This study aims at minimizing the acoustic noise from a magnetic origin of a claw-pole alternator. This optimization is carried out through a multiphysics simulation, which includes the computation of magnetic forces, vibrations, and the resulting noise. Therefore, a mechanical model of the alternator has to be developed to determine its main modes. Predicted modal parameters are checked against experimental results. Based on this model, the sound power level is simulated and compared with measurements. Finally, the rotor shape is optimized and a significant reduction of the noise level is found by simulation.

Vibro-acoustic simulation and optimization of a claw-pole alternator

This study aims at minimizing the acoustic noise from a magnetic origin of a claw-pole alternator. This optimization is carried out through a multiphysic simulation which includes the computation of magnetic forces, vibrations and the resulting noise. Therefore, a mechanical model of the alternator has to be developed to determine its main modes. Predicted modal parameters are checked against experimental results. Based on this model, the sound power level is simulated and compared with measurements. Finally, the rotor shape is optimized and a significant reduction of the noise level is found by simulation.

Influence of the manufacturing process of a claw-pole alternator on its stator shape and acoustic noise

This paper shows the influence of the manufacturing process of a claw-pole alternator on its acoustic noise. First, the stator welds and the assembly of the stator in the brackets are linked to deformations of the inner diameter of the stator. Then, the influences of these deformations on the magnetic forces and the subsequent acoustic noise are investigated. Results show that the deformations caused by the manufacturing process significantly increase the sound power level of particular orders.

Estimation of local cyclic plasticity based on a coupled EBSD and TEM analysis

Abstract In the present work, a novel approach is adopted to evaluate the low cycle fatigue (LCF) damage at a mesoscopic scale. The fatigue behavior of a ferritic steel has been studied and damage criteria were assessed by a metallurgical approach that combines two analysis techniques: transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). After characterizing the cyclic behavior of the material for different loading parameters at a total strain range varying from 0.3 % to 0.7 %, the microstructure evolution induced by the cyclic plasticity was studied in a multi-scale investigation. Here, TEM and SEM-EBSD give complementary information about the link between macroscopic fatigue behavior and microstructure changes. TEM shows a clear indication of the dislocations structures related to fatigue damage. SEM-EBSD completes the investigation by giving quantitative data associated to local deformation. This relation enables to determine plastic strain assessment, for example, of industrial components.