1/2D element like membrane, plate, truss?
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- ebrahim raeyat
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1/2D element like membrane, plate, truss?
I know we have ElementGeometry1D that give a section type and typical rect, circle, pipe. ElementGeometry2D for shell element.
my question is: how can i define membrane, plate , truss and etc. I don't mean editing .ini file for calculix, i mean in general. thanks
my question is: how can i define membrane, plate , truss and etc. I don't mean editing .ini file for calculix, i mean in general. thanks
Re: 1/2D element like membrane, plate, truss?
If you mean in general by the FreeCAD FEM GUI than the answer is no it is not possible ATM. We would need some objects to define these attributes and than the ccx writer would need to be adapted in this regard.ebrahim raeyat wrote: ↑Wed Mar 18, 2020 10:51 am I know we have ElementGeometry1D that give a section type and typical rect, circle, pipe. ElementGeometry2D for shell element.
my question is: how can i define membrane, plate , truss and etc. I don't mean editing .ini file for calculix, i mean in general. thanks
bernd
- ebrahim raeyat
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Re: 1/2D element like membrane, plate, truss?
thanks. yes, and another thing:
define section? I mean another object that can assign to element. for example assign section to truss or beam element.
- ebrahim raeyat
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Re: 1/2D element like membrane, plate, truss?
opensees has complete element library for structural engineers.
OpenSees commands
can i develop some of them in FreeCAD? specially Beam-column, truss and membrane element? thanks.
for can, i mean ability?!
OpenSees commands
can i develop some of them in FreeCAD? specially Beam-column, truss and membrane element? thanks.
for can, i mean ability?!
Re: 1/2D element like membrane, plate, truss?
ccx has a lot of elements too http://web.mit.edu/calculix_v2.7/Calcul ... ode25.html
ATM in FreeCAD FEM there is no object to choose the elment type. If you mesh a mesh with 8-nodes brick, an 8-nodes brick is used in ccx. If you mesh with a prisma element a prisma element is used in ccx.
As an example. If the mesh is made with 2 node line elements in ccx a 2-node beam element is used. To use a 2-node truss element one would need to edit the input file. Same for shell elements ATM we can not distinguish between shell, plate or membrane 2D element.
For this a new object would be needed to quantify the element type. The difficaulty in an element chooser is to stay solver independent as we do with all FEM objects. The elementlibraries are quite different in different solvers. We could give it a shot and start.
I would not mix this with the OpenSees solver implementation. As said this object shuld be solver independent.
For example oofem has a wide range of elements too, but in FreeCAD only quat4, tetra4 and tetra10 are supported ATM: https://github.com/berndhahnebach/FreeC ... #L163-L184
To get started with the OpenSees you would only need one element type, your favourite one, or the one you have some examples to test with. All other element types could be added later on if the solver works.
ATM in FreeCAD FEM there is no object to choose the elment type. If you mesh a mesh with 8-nodes brick, an 8-nodes brick is used in ccx. If you mesh with a prisma element a prisma element is used in ccx.
As an example. If the mesh is made with 2 node line elements in ccx a 2-node beam element is used. To use a 2-node truss element one would need to edit the input file. Same for shell elements ATM we can not distinguish between shell, plate or membrane 2D element.
For this a new object would be needed to quantify the element type. The difficaulty in an element chooser is to stay solver independent as we do with all FEM objects. The elementlibraries are quite different in different solvers. We could give it a shot and start.
I would not mix this with the OpenSees solver implementation. As said this object shuld be solver independent.
For example oofem has a wide range of elements too, but in FreeCAD only quat4, tetra4 and tetra10 are supported ATM: https://github.com/berndhahnebach/FreeC ... #L163-L184
To get started with the OpenSees you would only need one element type, your favourite one, or the one you have some examples to test with. All other element types could be added later on if the solver works.
- ebrahim raeyat
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Re: 1/2D element like membrane, plate, truss?
it is true, but i think we can add some property to element to distinguish different element type for every solver. beside that many elements are common in all solvers like beam, truss, shell, membrane, plate and so on.bernd wrote: ↑Wed Mar 18, 2020 2:19 pm ccx has a lot of elements too http://web.mit.edu/calculix_v2.7/Calcul ... ode25.html
ATM in FreeCAD FEM there is no object to choose the elment type. If you mesh a mesh with 8-nodes brick, an 8-nodes brick is used in ccx. If you mesh with a prisma element a prisma element is used in ccx.
As an example. If the mesh is made with 2 node line elements in ccx a 2-node beam element is used. To use a 2-node truss element one would need to edit the input file. Same for shell elements ATM we can not distinguish between shell, plate or membrane 2D element.
For this a new object would be needed to quantify the element type. The difficaulty in an element chooser is to stay solver independent as we do with all FEM objects. The elementlibraries are quite different in different solvers. We could give it a shot and start.
I would not mix this with the OpenSees solver implementation. As said this object shuld be solver independent.
For example oofem has a wide range of elements too, but in FreeCAD only quat4, tetra4 and tetra10 are supported ATM: https://github.com/berndhahnebach/FreeC ... #L163-L184
To get started with the OpenSees you would only need one element type, your favourite one, or the one you have some examples to test with. All other element types could be added later on if the solver works.
- ebrahim raeyat
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Re: 1/2D element like membrane, plate, truss?
thanks @bernd. i want to analyse frame structures, like portal frame. but i don't know how can i mesh this portal frame that it would be only contain 4 nodes and 3 beam-column elements. i think it is very necessary for civil engineering.
Re: 1/2D element like membrane, plate, truss?
4 nodes means first order elements without middle node ...
- set gmsh mesh object attribute ElementOrder to 1st
- use min element size 5000 mm
- set gmsh mesh object attribute ElementOrder to 1st
- use min element size 5000 mm
- ebrahim raeyat
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Re: 1/2D element like membrane, plate, truss?
Thanks @bernd, I know it, but i mean in general. when i have 2D also element with 1D in one model.
Re: 1/2D element like membrane, plate, truss?
I do not really understand the question? Would you post an simple example?ebrahim raeyat wrote: ↑Sun Mar 29, 2020 5:28 pm Thanks @bernd, I know it, but i mean in general. when i have 2D also element with 1D in one model.