Uniform moment in bar in local coordinate system with API

LuisCRodrigues — Mon, 09 Jan 2023 22:20:33 GMT

Hi all,
I'm trying to generate uniform loads and uniform moments in bars with API.
For uniform loads, the member "I_BURV_LOCAL" defines if the loads values refer to the global or local coordinate system.
For uniform moments, it seems we can only create load records in the global coordinate system with API.
Does anyone know how to impose the local coordinate system?

Thanks in advance.

Re: Uniform moment in bar in local coordinate system with API

Stephane.kapetanovic — Sat, 27 Sep 2025 10:00:09 GMT

hi @LuisCRodrigues

here after an example to set local loads (uniform and moment distributed moments)

Sub CreateBarsUniformAndMomentLocalLoad() Dim RobApp As IRobotApplication: Set RobApp = New RobotApplication If Not (RobApp.Visible = -1 And RobApp.Project.IsActive = -1) Then Set RobApp = Nothing: Exit Sub End If Dim CasSel As RobotSelection, CasCol As RobotCaseCollection, Cas As IRobotCase, FirstAvailableCase As RobotSimpleCase Dim Bars As RobotBarServer, Bar As RobotBar, TbForces() As Double: mtx(0 To 2, 0 To 2) As Double With RobApp.Project.Structure Set Bars = .Bars Set CasSel = .Selections.CreatePredefined(I_PS_CASE_SIMPLE_CASES) Set CasCol = .Cases.GetMany(CasSel) End With For i = 1 To CasCol.Count Set Cas = CasCol.Get(i) If Cas.AnalizeType <> I_CAT_DYNAMIC_MODAL Then Set FirstAvailableCase = Cas With FirstAvailableCase.Records.Create(I_LRT_BAR_UNIFORM) .Description = "New Uniform Load": .Objects.FromText "1 2": .SetValue IRobotBarUniformRecordValues.I_BURV_PY, -5000: .SetValue I_BURV_LOCAL, 1 End With With FirstAvailableCase.Records.Create(I_LRT_BAR_MOMENT_DISTRIBUTED) .Description = "New Distributed Moment Load": .Objects.FromText "3 4": .SetValue IRobotBarMomentDistributedRecordValues.I_BMDRV_MX, -5000 End With TbBarNos = Array(5, 6) For j = 0 To UBound(TbBarNos) BarNo = TbBarNos(j): Set Bar = Bars.Get(BarNo) Bar.GetLocalMtx mtx(0, 0), mtx(0, 1), mtx(0, 2), mtx(1, 0), mtx(1, 1), mtx(1, 2), mtx(2, 0), mtx(2, 1), mtx(2, 2) TbForces = SetForces(0, 0, 0, -5000, 0, 0): Transform TbForces, Invert(mtx) With FirstAvailableCase.Records.Create(I_LRT_BAR_MOMENT_DISTRIBUTED) .Description = "New Distributed Moment Load - Local": .Objects.FromText Str(BarNo) .SetValue I_BMDRV_MX, TbForces(3): .SetValue I_BMDRV_MY, TbForces(4): .SetValue I_BMDRV_MZ, TbForces(5) End With Next j Exit For End If Next i Set RobApp = Nothing End Sub

Function SetForces(Fx As Double, Fy As Double, Fz As Double, Mx As Double, My As Double, Mz As Double) As Double() Dim TbForces(0 To 5) As Double: Tb = Array(Fx, Fy, Fz, Mx, My, Mz) For I = 0 To 5: TbForces(I) = Tb(I): Next SetForces = TbForces End Function

Function Invert(m() As Double) As Double() Dim rm(0 To 2, 0 To 2) As Double For I = 0 To 2 For j = 0 To 2: rm(I, j) = m(j, I): Next j Next Invert = rm End Function

Sub Transform(v() As Double, m() As Double) Dim vt(0 To 5) As Double For I = 0 To 2 For j = 0 To 2 cm = m(I, j): vt(I) = vt(I) + v(j) * cm: vt(I + 3) = vt(I + 3) + v(j + 3) * cm Next j Next I For I = 0 To 5: v(I) = vt(I): Next I End Sub

Function GetLocalMtx(x_ As RobotGeoPoint3D, y_ As RobotGeoPoint3D, z_ As RobotGeoPoint3D) As Double() Dim m(0 To 2, 0 To 2) As Double m(0, 0) = x_.X: m(0, 1) = x_.Y: m(0, 2) = x_.Z: m(1, 0) = y_.X: m(1, 1) = y_.Y: m(1, 2) = y_.Z: m(2, 0) = z_.X: m(2, 1) = z_.Y: m(2, 2) = z_.Z GetLocalMtx = m End Function

Best Regards

Re: Uniform moment in bar in local coordinate system with API

LuisCRodrigues — Tue, 10 Jan 2023 10:58:41 GMT

Hi@Stephane.kapetanovic

This is a very interesting approach.
Thanks for your help.

Re: Uniform moment in bar in local coordinate system with API

Stephane.kapetanovic — Mon, 05 Jun 2023 14:28:34 GMT

msg 2 updated

Re: Uniform moment in bar in local coordinate system with API

LuisCRodrigues — Tue, 10 Jan 2023 16:14:34 GMT

I understand you corrected how the moments in the local coordinate system are translated to the global coordinate system. I was precisely working in the same direction.
Thank you for your time. This will be very helpful.

It's just a workaround, but the real question is why the API can't set the load as local as it does for others.

To be seen by Autodesk Team? Maybe @Rafal.Gaweda could comment.

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Uniform moment in bar in local coordinate system with API

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