Evaluation of COMSOL Multiphyscis for rotordynamical analysis

University essay from KTH/MWL Marcus Wallenberg Laboratoriet

Author: Hessameddin Moradi Motlagh; [2012]

Keywords: ;

Abstract:

Rotary machinery systems are widely used in different industries. As they have rotational movements, the resonances will be the function of rotational speed. Nowadays, there are different CAE (Computer Aided Engineering ) softwares that use finite element method to solve complex problems by simplifying the model to a limited DOF (Degree Of Freedom) system. Some of the CAE software have built-in module for rotary machinery to solve eigenvalue problems, unbalance response, stability, etc. COMSOL multiphysics 1 is a CAE software that can deal with structural mechanics. There is not any specific module for the rotor dynamics analysis in COMSOL multiphysics version 4.2a; however, It is possible to make a model based on 1D beam elements or even structural mechanics elements and solve the problem by using equivalent gyroscopic moment and unbalance force terms. The scope of this thesis is based on 1D beam element solution. Moreover, the result of the COMSOL solution has been compared with ANSYS based on 3D element 2.

In this thesis, the main purpose is implementing rotor dynamics concepts in COMSOL multiphysics based on beam element 3 . Second chapter is focused on the theory part of the rotordynamics where the equations in the stationary cases are derived which measn the rotational speed of the rotor does not change by time; moreover, a brief overview of finite element method has been mentioned. The third chapter covers the implementation of the rotor dynamics in COMSOL where a very brief overview of different COMSOL’s sections that are used in this thesis are described; Moreover, load implementation , 3D mapping based on extrusion integration and comparison a result data with ANSYS are mentioned. In the fourth chapter rotordynamics analysis is described based on Campbell plot 4, stability analysis and harmonic response from a model that is made in COMSOL.

Final chapter is the conclusion part about this thesis based on the results that have been shown.

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