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In order to get to know the sound field in the surroundings of the alternator, the sound field was evaluated for just a few selected cases of the operation.
![catt acoustic price catt acoustic price](https://i.ytimg.com/vi/6fe7wLyGMtk/mqdefault.jpg)
For the description of the acoustic medium, the air properties under regular conditions were adopted. In our case of an acoustic BEM model, the maximum length of the boundary element was smaller than 9 mm, so an accurate solving in the region of 6.4 kHz was ensured. This enables an easy transfer of the boundary conditions from the structural FEM model to the acoustic BEM model. The mesh of the boundary elements was formed in such a way that its nodes coincided with the nodes of the structural FEM model. The entire external surface of the alternator, which had been formed in the structural FEM model from the DEB and REB meshes, was covered with a less dense mesh consisting of triangular boundary elements. The basis for the acoustic BEM model was the structural FEM model. Knowing the sound field for each harmonic component makes it possible to reconstruct the entire sound field as a consequence of the structural response of the alternator due to the magnetic force excitations. Thus, each operational shape, or the structural response at a particular harmonic component, contributes a belonging component to the sound field. Suppose that the mechanical structure of the alternator and the phenomenon of the sound field in its surrounding can be described using a linear model, the solving of the discussed combined problem can then be transformed to a forced vibration problem or to solve a particular harmonic component. The structural response during such an operation on the external surfaces of the alternator causes a sound radiation or the so-called magnetic noise.
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The demand to have a stationary operation of the alternator is essential.
#Catt acoustic price verification
During the verification of the sound field the same restriction as at the verification of the structural response was used.
#Catt acoustic price upgrade
The numerical verification of the sound field is basically just an upgrade in the solving of the structural problem, where, on the basis of known structural response and by means of the boundary- element method (BEM), the sound field is calculated. This was obtained from the known structural response of the alternator FEM model. 4 ACOUSTIC RESPONSE OF THE ALTERNATOR In the final step of the vibro- acoustic modelling of the alternator, a sound field in its surroundings was determined.