Structural dynamics of electric machine stators: Modelling guidelines and identification of three-dimensional equivalent material properties for multi-layered orthotropic laminates

P Millithaler,É Sadoulet-Reboul,M Ouisse,J.-B Dupont,N Bouhaddi

doi:10.1016/j.jsv.2015.03.010

Abstract

Simulating the dynamic behaviour of heterogeneous finite-element structures such as electric motors often requires to homogenise the models in the first place. Current homogenisation methods do not always imply computing an equivalent homogeneous material׳s elasticity matrix and are often restrained to specific uses. In this document, a novel approach of equivalent material identification is developed for multi-layered orthotropic structures. A finite-element model of a 3D stratified structure is created, as well as its equivalent homogeneous medium. The dynamic behaviour of the homogeneous structure with the equivalent material identified by the new method is compared at low frequencies to the reference stack and to equivalent materials created using other existing homogenisation techniques. It is shown that this approach is more accurate than existing reference homogenisation methods. Applied to the magnetic core׳s finite-element model of a real laminated electric machine stator, the method enables simulating the experimental behaviour with good accuracy, without need of time-consuming model updating procedures.

Highlights

In order to analyse a complex structure’s dynamic behaviour, modelling its components may become difficult if they are numerous, small, or if some of the assembly properties are not known
This is one of the reasons why so-called “homogenisation” methods have been developed. They aim at recreating a given heterogeneous structure’s behaviour by reducing the multiplicity of its components’ properties, and enable to mesh the structure independently from the sizes of the heterogeneities, that could have imposed numerous degrees of freedom in the models. Such methods are much desired for modelling composite materials, and especially for laminated structures
As a necessity in order to reduce the number of degrees of freedom in the finiteelement models of heterogeneous structures such as electric motor stators, the identification method enabled modelling them with equivalent representative homogeneous material properties

Summary

Introduction

In order to analyse a complex structure’s dynamic behaviour, modelling its components may become difficult if they are numerous, small, or if some of the assembly properties are not known This is one of the reasons why so-called “homogenisation” methods have been developed. They aim at recreating a given heterogeneous structure’s behaviour by reducing the multiplicity of its components’ properties, and enable to mesh the structure independently from the sizes of the heterogeneities, that could have imposed numerous degrees of freedom in the models. Such methods are much desired for modelling composite materials, and especially for laminated structures. Kalamkarov et al [1] have thoroughly listed and compared over 200 studies about homogenisation and have assessed the pros and cons of various analytical methods and specific applications.

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