freecad: some considerations on the fem

[DoctorBomber90]

Good afternoon to all.
I would like to put some considerations regarding the freecad fem.
for the realization of a simulation on a certain model (which is static, thermal, electrical or vibrational) I have to:

1. impose constraints;
2. impose forces;
3. meshare(create a grid on the model, which I will go to thread or not depending on what I want);
4. choose the material;
5. go to the command window, click on ccx_results, choose the type of simulation (if mechanical, thermal, etc.).

Now I have the following questions:

• What kind of bond does it impose? to see from the image put by me it seems of the incastri. I wondered if it was possible to impose different constraints such as hinge, support, skate (as happens in solidworks, ansys and other programs).

• Could you explain the difference between these two meshatura options (or grid)?ie:the distinction between netgen and gmsh in what is it?
• When I follow the iter from me described in the first lines of the discussion, I happen that, first choosing the material and then meshando the model (or the contrary), my model disappears (and the femmesh becomes stiff). Where am I wrong? that is due to the yellow-orange writing in the window "report"(low left)? firstafterin the command window

 

[DoctorBomber90]

of course I thank you in advance whoever will have force to answer me and solve all my doubts.

 

[meccanicamg]

the ink win is the standard button lock. the icon that is there with the neighbor allows you to make custom constraints by indicating what is free and what is bound.
on the official website there are all the explanations and the dedicated forum. explanations about the mesh type are qui.
In reality first you create the type of simulation, then the material, then constraints and mesh and launches the solutor.
when it doesn't make you mesh....or it's empty because the model has strange geometries that can't meshare.

 

[meccanicamg]

each feautures can be turned on and off, for viewing. just press on the processing and select the corresponding item. It is usually combined with the "space bar" command that you press after selecting what you want to show or not.

even if you draw a cube, then make the rays and then a hole. If you've done in sequence, you'll see everything. if you go to the cube function and press space bar you will see only the model until that point... I mean the cube.

 

[meccanicamg]

Good afternoon to all.
I would like to put some considerations regarding the freecad fem.
for the realization of a simulation on a certain model (which is static, thermal, electrical or vibrational) I have to:

1. impose constraints;
2. impose forces;
3. meshare(create a grid on the model, which I will go to thread or not depending on what I want);
4. choose the material;
5. go to the command window, click on ccx_results, choose the type of simulation (if mechanical, thermal, etc.).

Now I have the following questions:

• What kind of bond does it impose? to see from the image put by me it seems of the incastri. I wondered if it was possible to impose different constraints such as hinge, support, skate (as happens in solidworks, ansys and other programs).

View attachment 67573

• Could you explain the difference between these two meshatura options (or grid)?View attachment 67574ie:the distinction between netgen and gmsh in what is it?
• When I follow the iter from me described in the first lines of the discussion, I happen that, first choosing the material and then meshando the model (or the contrary), my model disappears (and the femmesh becomes stiff). Where am I wrong? that is due to the yellow-orange writing in the window "report"(low left)? firstView attachment 67576afterView attachment 67577in the command windowView attachment 67578

always read and interpret the log messages that are given to us. That yellow writing means something....maybe try to change mesher.
Moreover there is written that the material has no thermal propitiage.

I see you are using version 0.19....if it's not a problem I suggest you update to 0.20.2

 

[DoctorBomber90]

always read and interpret the log messages that are given to us. That yellow writing means something....maybe try to change mesher.
Moreover there is written that the material has no thermal propitiage.

I see you are using version 0.19....if it's not a problem I suggest you update to 0.20.2

Okay.
I update the latest version.

 

[meccanicamg]

these days I am trying on virtual machine linux mint and installed freecad. I discovered that for windows there is available both netgen and gmesh. for linux instead it has been suspended from a few years netgen that I use often and willingly. Now I'm trying gmesh but apart from mesh parameters can be set after making mesh as with the other method I don't see big differences. from the panel you can choose whether to use elements 2d or 3d.... But then you can decide if first or second order, finishing etc.
the program that gives you error is because you have meshato without having the active analysis. tried yesterday.

 

[DoctorBomber90]

these days I am trying on virtual machine linux mint and installed freecad. I discovered that for windows there is available both netgen and gmesh. for linux instead it has been suspended from a few years netgen that I use often and willingly. Now I'm trying gmesh but apart from mesh parameters can be set after making mesh as with the other method I don't see big differences. from the panel you can choose whether to use elements 2d or 3d.... But then you can decide if first or second order, finishing etc.
the program that gives you error is because you have meshato without having the active analysis. tried yesterday.

Thanks for the tip.
I got another question. When I apply force, I choose the surface on which to apply it (then I apply a force of 1000 n on all face, for example). if, instead, you want a punctual force applied at a very precise point of that surface and not on the whole face. is it possible to realize it or not?

 

[meccanicamg]

the dot application exists only on the vertices or on the surfaces created specifically on the main faces. I remember that a dot force exists only in theoretical simplification and not in practice.