## General Mechanical

#### Circular shell

• MJol
Subscriber

Hello,

I would like to design a circular shell like a cynlindrical tank shape with a thickness.

How can I do that?

Thank you

Regards

• MJol
Subscriber

In spaceclaim i meant

• peteroznewman
Subscriber

Learn how to create shapes by watching the SpaceClaim tutorials in the Tutorial category in the right.

• MJol
Subscriber

Hello Peter,

I checked and there is nothing about a cylindrical shell. I start to know SpaceClaim but I'm stuck with cylindrical shell.. Please help me.

Thank you.

• peteroznewman
Subscriber

Do you want spherical end caps to the cylindrical tank?  Or do you want flat end caps?

There are many ways to create the shape.

If you want to analyze the stresses in the tank, you should use a surface model, not a solid model. Please confirm that the FE model would use shell elements on a surface with an assigned thickness and that you don't need solid elements on a solid body.

• MJol
Subscriber

it is a surface model using shell elements with an assigned thickness.No solid boday.

Actually, th both would be interesting spherical and flat end caps.

Best regards

• peteroznewman
Subscriber

In a Static Structural analysis system, start SpaceClaim. In SC, on the Design tab, click the Sketch Mode button, select a plane for the sketch, click the Circle tool. Draw a circle. Click the 3D mode button. There will be a circular surface. Click the Pull tool, pull on the surface and turn it into a cylindrical solid.

Optional: To convert this flat end to a spherical end, click on the Pull tool, click on the circular edge of the solid and pull it all the way inward. You will have a spherical end.

Click the Select tool. Click on the end face, keyboard Ctrl-C and Ctrl-V.  That copies the face and pastes it as a surface. Repeat for the other two surface. In the Structure, you now have a solid and three surfaces.  Click on the Solid and hit the Delete key.

Click on the Workbench tab. Click on the Share button. Click on the green check mark.  Close SpaceClaim.

When you open Mechanical, you can type the thickness for the surfaces and assign a material.

• MJol
Subscriber

Hello Peter,

Thank you very much it works ! But I will keep the Solid for modeling fluid-structure-interaction.

For the water boday, I add elasticity properties in material with orthotropic elasticity with Ex=Ey=Ez=2200MPa, poisson module 0,49 and shear module as 2,2MPa.

Is the water body will be fluid80 ? Or should I add a command? If yes how do you do ?

Best regards

• MJol
Subscriber

Hello Peter

I use body inside the tank as fluid. Material water fluid.
I have a problem when i do the static structural analysis, it says :

• peteroznewman
Subscriber

Click on Mesh, and in the Details, set the Element Order to Linear.

How you model water depends on what analysis you want to perform. What is the goal of the simulation?  Is there a free surface of water in the tank with air above, or is the tank completely filled with water?

• MJol
Subscriber

Hello,

When I set the element order to linear the fluid seems to be attach to the structure.

The goal is to use the fluid body to model hydrostatic pressure and use the mass of the fluid in transient and spectral analysis with a modal analysis.

I have error when I do modal with the element order linear.

There is a free surface water. Should I model the air volume?

Best regards

• peteroznewman
Subscriber

You don't need any water in the model to do the hydrostatic pressure on the walls of the tank in a Static Structural analysis. Apply a Hydrostatic Pressure load to the inside of the tank.

No, you won't need to model the air volume.

More on modal with water in a later post.

• MJol
Subscriber

Thank you very much. I know for the hydrostatic pressure, but I want to do dynamics after static so I keep the body and wanted to know if with the body there is hydrostatic?

I have an other point on the design. I want to add beams for the roof of the structure. When I do modal I observe that the beams are not connected to the walls. I share the topology and it's marked but in static and modal analysis it's not connected...

Here my model.

Best regards

MJol

• peteroznewman
Subscriber

You have to split the edge of the tank at each vertex of the beams that you want to connect so there are coincident vertices that can be merged.

• MJol
Subscriber

Hello,

I try to do that method but doesn't work.

First I split the edges

• peteroznewman
Subscriber

In Mechanical, right click on Mesh and insert Mesh Merge.  Under Mesh Merge, insert a Node Merge Group. Right click on the Node Merge Group and Generate.

• MJol
Subscriber

Hello,

Thank you very much Peter, it works, I merged the nodes !

I would like to take into account the fluid body now for modal to do transient & spectral analysis.

I added the water body in the model. I meshed it. I did modal.Do you think that the main structure modes are in high frequences?

How do you manage the damping? Structure damping (concrete 7%) and water 0,5%. Is it in modal analysis or in transient & spectral analysis?

I have an other question, how do you create residual mode when i can't get the 90% minimum of the mass after 33hz ?

Thank you.

Best regards

• peteroznewman
Subscriber

I can answer the question on damping. Open Engineering Data and add the damping ratio to each material. Then in Mechanical, you can leave the damping section of the solution controls empty.

• MJol
Subscriber

Thank vou very much.

• MJol
Subscriber

How should I model the fluid inside?

I created a body for fluid in spaceclaim because I'd like to perform a modal and response spectrum analysis and take into account the mass of fluid. I shared the topology with the shells. I merged the nodes between shell and body. Is it the right thing to do or not?

Best regards.

MJol

• peteroznewman
Subscriber

You can read this discussion about how I performed a Transient Structural model of a water filled cylinder.

Here is another discussion on modeling fluid motion inside a structure.

If you have new questions, open a New Discussion because this one is marked as Solved and some members will not open discussions that are solved.

• MJol
Subscriber

Thanks