(API) Correct Modal analysis?

[jokiller70]

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

[jokiller70]

Could it be I am using 64 bit code?

This is what happens when I issue your code;

Dim robapp As RobotApplication
        robapp = New RobotApplication
        Dim cas As RobotSimpleCase
        Dim rec As RobotLoadRecord
        Dim ModalParams As RobotModalAnalysisParams
        Dim ModalCase As RobotSimpleCase
        Dim I_CN_EXPLOATATION As Integer = 1
        Dim I_MARV_FACTOR As Integer = 3
        Dim I_MARV_CASE_NUM As Integer = 4
        Dim I_MARV_ACTIVATION_DIR As Integer = 6
        Dim I_MARV_SIGN As Integer = 7
        Dim I_MARV_INPUT_DIR_Z As Integer = 2
        Dim I_CAT_DYNAMIC_MODAL As Integer = 11
        Dim I_MARV_INPUT_DIR_X As Integer = 0
        Dim I_MARV_INPUT_DIR_Y As Integer = 1
        Dim I_LRT_MASS_ACTIVATION As Integer = 39
        ModalCase = robapp.Project.Structure.Cases.CreateSimple(robapp.Project.Structure.Cases.FreeNumber, "Modal", I_CN_EXPLOATATION _
                                                                , IRobotCaseAnalizeType.I_CAT_DYNAMIC_MODAL)
        ModalParams = ModalCase.GetAnalysisParams
        ModalParams.DisregardDensity = True
        ModalCase.SetAnalysisParams(ModalParams)
        cas = robapp.Project.Structure.Cases.Get(-1)
        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()

 video here;

https://screencast.autodesk.com/Main/Details/c3a3df37-81ba-4931-9b71-6e92c12b51e2

[jokiller70]

Soved it with 32bit code! Robot API also works a lot faster! Autocad nearly same performance. Now to the big question, what is the correct value for self resonant frequency?

[Rafal.Gaweda]

you can not convert in some of your models (at least the ones you sent us) case 2

rec.SetValue(I_MARV_CASE_NUM, 2)

because there no loads in it.

So compile your code using "Any CPU" settings

[Rafal.Gaweda]

Now to the big question, what is the correct value for self resonant frequency?

All of them are listed in the table you attached to your post.

[jokiller70]

And the Natural frequency?

[Rafal.Gaweda]

First column : Frequency (Hz) results

[jokiller70]

from this ;

http://forums.autodesk.com/t5/robot-structural-analysis/eigen-values-natural-frequencies/td-p/351684...

post;

"Just be careful with how you understand modal analysis. The term "natural" frequency is not applied to every mode. Every mode has a frequency associated with it. That may not be the "natural" one for the structure. If you only get three modes this could be OK for a simple structure, depends on a lot of things. "

[Rafal.Gaweda · Accepted solution]

"Just be careful with how you understand modal analysis. The term "natural" frequency is not applied to every mode. Every mode has a frequency associated with it. That may not be the "natural" one for the structure. If you only get three modes this could be OK for a simple structure, depends on a lot of things. "

I do not know he meant. Ask Tony Ridley.

Robot calculates natural frequencies  in Modal analysis.

http://help.autodesk.com/view/RSAPRO/2015/ENU/?guid=GUID-3400C9A4-F47F-4A7F-9B67-66BEE7B9105A

[jokiller70 · Accepted solution]

Found the problem! I had robapp.UserControl set to False