GuiCommand:Container| {{GuiCommand Name: FEM ConstraintSelfWeight MenuLocation: Model , Mechanical boundary conditions and loads , Gravity load Workbenches: FEM_Workbench SeeAlso: FEM_tutorial }} {{GuiCommandFemInfo Solvers: CalculiX, Elmer }}
FEM ConstraintSelfWeight
Description
Defines a gravity acceleration acting on the whole model in the prescribed direction.
{{VersionMinus|0.21}}
: The acceleration has a fixed value of 9.81 m/s\^2.
Usage
-
There are several ways to invoke the command:
- Press the
Gravity load button. - Select the Model → Mechanical boundary conditions and loads → Gravity load option from the menu.
- Press the
-
A ConstraintSelfWeight object is created.
-
(v1.0) : Optionally change its Gravity Acceleration property.
-
Optionally change its Gravity Direction property.
Scripting
New object:
import ObjectsFem
ObjectsFem.makeConstraintSelfWeight(name)Add object to the analysis named Analysis:
App.ActiveDocument.Analysis.Member = App.ActiveDocument.Analysis.Member + [(object)]Example:
import ObjectsFem
selfweight_obj = ObjectsFem.makeConstraintSelfWeight("MySelfWeightObject")
App.ActiveDocument.Analysis.Member = App.ActiveDocument.Analysis.Member + [selfweight_obj]Solver CalculiX
Limitations
-
{{VersionMinus|0.21}}: You need to modify the .inp file to edit gravity acceleration.
-
Self-weight is applied to the element set Eall which includes the whole model.
Editing CalculiX input file
The acceleration constant can be manually edited after generating the CalculiX input file.
Example of lines in the .inp file:
*DLOAD
Eall,GRAV,9810,0.0,0.0,-1.0where 9810 is a gravity acceleration magnitude in [mm/s\^2], and 0,0,-1 is the direction vector. The value can be set as a multiple of standard gravity acceleration to simulate loading of e.g. 4g.
Solver Z88
- Currently, not implemented in the Z88 solver.
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This page is retrieved from https://github.com/FreeCAD/FreeCAD-documentation/blob/main/wiki/FEM_ConstraintSelfWeight.md