How to enforce user-defined modal properties?

Objectives

This article shows how to apply a user-defined modal property in MANATEE software specialized in noise mitigation of electrical machines.

Principle

A specific natural frequency and damping of a particular modal shape can be enforced when using MANATEE semi analytic structural models. In this case, damping and natural frequencies of a specific cylindrical mode (m,n) can be enforced by the user.

GUI implementation

TBC

Scripting implementation

By default, the damping of all structural modes used by MANATEE is frozen to 2% by the following input value: Input.Simu.ksi_damp = 2/100;

To perform a modal parameter enforcement, one must set

Input.Simu.is_force_natfreq = 1;

The following script lines change the ovalization mode (2,0) natural frequency to 500 Hz and the associated damping to 1%, change the breathing mode (order 0) damping of the stator stack to 2.78% without changing the corresponding natural frequency, and change the mode (5,0) natural frequency to 4000 Hz without changing the damping:

Input.Simu.ExpModes=[[2 0];[0 0];[5 0]];
Input.Simu.ExpDamp=[1/100 2.78/100 NaN];
Input.Simu.ExpFreq=[500 NaN 4000];

This feature of MANATEE allows you to check the influence of a structural redesign, or enforce your own modal parameters which can be based on FEA simulations or experimental modal analysis.

Plot commands

NA

Validation cases

NA

See also

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