topic Re: Correct Modal analysis? in Robot Structural Analysis Forum

(API) Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 10:39:18 GMT

Am I doing this right? I get the same Frequency even if I add loads?

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 10:16:19 GMT

In all loadcases only SW is considered so the results are the same

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 10:19:56 GMT

From API? Do you have any samples?

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 10:38:58 GMT

Important - masses are added to case -1

Private Sub CommandButton1_Click()


Dim robapp As RobotApplication
Set robapp = New RobotApplication
    
    Dim cas As RobotSimpleCase
    Dim rec As RobotLoadRecord
    
Set cas = robapp.Project.Structure.Cases.Get(-1)

Set rec = cas.Records.Create(I_LRT_MASS_ACTIVATION)
    rec.SetValue I_MARV_FACTOR, 1.3
    rec.SetValue I_MARV_CASE_NUM, 3
    rec.SetValue I_MARV_ACTIVATION_DIR, 2
    rec.SetValue I_MARV_SIGN, 1
    
 
End Sub

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 14:00:10 GMT

Shall I use -1 as loadcase? Or the actual one I would like to calculate? Also which frequenzy is the correct one?

eigval = robapp.Project.Structure.Results.Advanced.Eigenvalues.Value(icomb, ncomb)

ncomb 1 is always hig and ncomb 10 is very low. (Does not match our tested values)

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 14:35:19 GMT

Shall I use -1 as loadcase?

-1 is a loadcase number to which you convert loads onto masses

eigval = robapp.Project.Structure.Results.Advanced.Eigenvalues.Value(icomb, ncomb)

ncomb 1 is always hig and ncomb 10 is very low. (Does not match our tested values)

No idea what you are talking about.

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 14:39:08 GMT

So 4,18 is the lowest possible frequency that can occur?

And shall I add loadcase -1 to my load combination?

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 14:41:58 GMT

These results comes from the model you attached - load case 1

You can not add converted masses case to anything.

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 14:58:09 GMT

The code you sent (CommandButton1_Click()) does not seem to generate any load to mass generation.

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 15:06:26 GMT

This was example code how to deal with load to mass conversion from API.
Not related to your model

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 15:09:21 GMT

Is there any way to invoke the "Disregard density" ?

Re: Correct Modal analysis?

Rafal.Gaweda — Mon, 24 Nov 2014 15:24:01 GMT

Example:

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 15:33:33 GMT

I would realy like to have that code! It is not possible to fullscreen your video so I can not read int .,(

Re: Correct Modal analysis?

jokiller70 — Mon, 24 Nov 2014 17:33:44 GMT

So I figured it out. But now it wont calculate. When i modify the "Load to mass coversion" with the exact same values it works...

https://screencast.autodesk.com/main/details/d2cc0bad-66f5-49a6-b376-f819c69e1f2e

Re: Correct Modal analysis?

Rafal.Gaweda — Tue, 25 Nov 2014 08:29:34 GMT

Example code (model generation is required to be run (forced to be run))

Private Sub CommandButton1_Click()


Dim robapp As RobotApplication
Set robapp = New RobotApplication
    
    Dim cas As RobotSimpleCase
    Dim rec As RobotLoadRecord
    
    Dim ModalParams As RobotModalAnalysisParams
    Dim ModalCase As RobotSimpleCase
    
    Set ModalCase = robapp.Project.Structure.Cases.CreateSimple(robapp.Project.Structure.Cases.FreeNumber, "Modal", I_CN_EXPLOATATION, I_CAT_DYNAMIC_MODAL)
    Set ModalParams = ModalCase.GetAnalysisParams
    ModalParams.DisregardDensity = True
    ModalCase.SetAnalysisParams ModalParams
    
    Set cas = robapp.Project.Structure.Cases.Get(-1)

Set rec = cas.Records.Create(I_LRT_MASS_ACTIVATION)
    rec.SetValue I_MARV_FACTOR, 1.2
    rec.SetValue I_MARV_CASE_NUM, 2
    rec.SetValue I_MARV_ACTIVATION_DIR, 2
    rec.SetValue I_MARV_SIGN, -1
    rec.SetValue I_MARV_INPUT_DIR_X, 1
    rec.SetValue I_MARV_INPUT_DIR_Y, 1
    rec.SetValue I_MARV_INPUT_DIR_Z, 1
    
    robapp.Project.CalcEngine.GenerateModel
End Sub

Re: Correct Modal analysis?

Rafal.Gaweda — Tue, 25 Nov 2014 08:41:41 GMT

    robapp.Project.CalcEngine.GenerateModel
or
    robapp.Project.CalcEngine.AutoGenerateModel = True

Re: Correct Modal analysis?

jokiller70 — Tue, 25 Nov 2014 09:51:00 GMT

Tried both, still same problem as in my video...

Re: Correct Modal analysis?

Rafal.Gaweda — Tue, 25 Nov 2014 10:29:55 GMT

Send me your this file.

Re: Correct Modal analysis?

jokiller70 — Tue, 25 Nov 2014 10:41:23 GMT

When i add automaticaly generat to mass to load conversion, thoose works.

Re: Correct Modal analysis?

Rafal.Gaweda — Tue, 25 Nov 2014 11:11:46 GMT

This is what I see: