How to compute a FRF with MANATEE/Ansys coupling?

Introduction

Starting from v1.07.01, MANATEE includes a coupling with Ansys Mechanical APDL® FEA software. The coupling is done though APDL code generation that automate the following tasks

  • definition of geometry and meshing (optional, for "concept" stator or rotor)
  • orthotropic material application (optional, for "concept" stator or rotor)
  • boundary conditions application (optional, for "concept" stator or rotor)
  • forces load application
  • solver and post processing

This feature enables to automatically create scripts to run a Frequency Response Function (FRF) on any MANATEE generated geometry or on an existing model. The FRF are then used in MANATEE to compute vibrations according to the Electromagnetic Vibration Synthesis Method.

APDL generation script

To use this feature, you need to define a MANATEE simulation that use the FRF wave mechanical workflow:

Input.Simu.is_mechanics=1; % Run the mechanical modul
Input.Simu.type_mech_workflow = 4; % Wave FRF workflow
Input.Simu.type_FEA_model = 2; % Ansys

To further parametrize the coupling, a separated script is added with:

Input.Simu.FRF_FEA_proj = 'My_script_name';

This script mostly defines the mesh and the method to call Ansys. An example can be found in Mechanics\APDL\Projects. This script works in the same way that default_proj or default_machine does: it is a template with all the available input parameters and their description. To create a new project, you first need to copy/paste this script. As always, you have to make sure that the name of your script is unique in your Matlab path to avoid any conflict.

This script contains the following parameters:

Input.Simu.FEA.output_name = 'cylinder_SM_STA_001_APDL_wave'; % Name of the resulting file (in Mechanics/APDL/Results
Input.Simu.FEA.overwrite_results = 1; % 1 To erase the folder Mechanics/APDL/Results/<project name> if it already exist before running the simulation
Input.Simu.FEA.ansys_path = 'C:\Program Files\ANSYS Inc\v170\ansys\bin\winx64\MAPDL.exe';

Input.Simu.FEA.N_list = [2,1,1,1,8,2,6,6]; % Mesh discretization of the tooth
Input.Simu.FEA.NLay = 20; % Number of mesh layer in Z direction
Input.Simu.FEA.ND = 200; % Maximum number of mode to compute

Calling Ansys APDL from Matlab

Input.Simu.FEA.ansys_path correspond to the command to call Ansys directly. You can provide option for this call. You can find the options that you need thanks to the "ANSYS Mechanical APDL Launcher": http://www.padtinc.com/blog/the-focus/starting-ansys-products-from-the-command-line For instance, to follow the example provided in the link, you can set:

Input.Simu.FEA.ansys_path = '"C:\Program Files\ANSYS Inc\v140\ANSYS\bin\winx64\ansys140.exe"  -g -p ane3flds -np 2 -acc nvidia -dir "c:\temp" -j "grgewrt1" -s read -m 5000 -db 1000 -l en-us -lstp1 32 -t -d win32 -custom "/temp/myansys.exe"';

MANATEE will automatically set the following options for the call:

  • -b (call ANSYS in batch mode)
  • -j MANATEE (name of the job)
  • -dir Mechanics/APDL/Results/"project_name" (initial working directory)
  • -i Mechanics/APDL/Results/"project_name"/"APDL file name" (input APDL command file for the simulation)
  • -o MANATEE.out (Output file name)

Please note that in the example the ansys_path is defined with " " around the windows path with space in it to avoid errors (C:\Program Files without " " would be interpreted as use the command C:\Program with the argument Files)

If MANATEE fails to call Ansys, the generated APDL file will be available in Mechanics/APDL/Results/"project_name"/"APDL file name" to be run manually in Ansys APDL.

Mesh definition

The lamination mesh is generated starting from a single tooth that is then replicated by rotation. So the mesh is defined according the tooth geometry. The coupling enables to use any slot shape available in MANATEE. Input.Simu.FEA.N_list define the mesh of the tooth according to the following rules:

  • The value in the list correspond to the number of mesh element on the corresponding line
  • The line are sorted from the tooth tip to the yoke (cf next figure)
  • We always suppose that the mesh is symmetrical (therefore there is no need to enter twice the values for the lines 2 to 7)
  • The first value is always half the number of element on the tooth tip. We automatically double this value to ensure that the number of element of the tooth tip is even to make sure that there are nodes at the middle of the tooth to apply the forces
    Slot 10 mesh setup in Ansys
    Slot 10 mesh setup in Ansys

Input.Simu.FEA.N_list = [2,1,1,1,8,2,6,6] means:

  • 4 elements on line 1
  • 1 element on the lines 2
  • 1 element on the lines 3
  • 1 element on the lines 4
  • 8 elements on the lines 5
  • 2 elements on the lines 6
  • 6 elements on the lines 7
  • 6 element on line 8
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