Build 2D Shell Mesh inwardly from external CAD surface geometry

Gabriele Rosso

Good morning,

I am currently working on a frame model constituted by multiple thin-walled beams which are joined together. Since I need to vary several parameters in the model, among which the thickness of the different elements and their shape, I have modelled directly the CAD geometry as a surface geometry to avoid the mid-surfacing and the consequent cleanup procedure. My problem now is how to deal with the thickness changes. I would ideally design the standard external geometry and assign the shell thickness inwardly. In this way, I could easily change the thickness of the components without the need of changing the dimensions of the CAD surface geometry. In fact, with the normal shell elements assigning 1/2 thick upward and 1/2 downward if one beam is modelled with a surface section 100x100 mm with a shell thickness of 2 mm the represented beam will be 102x102 mm, and if I increase the thickness of the elements to 4 mm the represented beam will be 104x104 mm, which is not what I want to obtain since I would like to keep constant the external size of the represented cross-section.

Have you any advance on an efficient way to proceed?

Thanks in advance for your support 

Adriano_Koga

Hi,

 

you can make usage of OFFSET into your property to adjust this.

In OptiStruct. OFFSET can be defined into the PSHELL property, under the ZOFFS control.

Please take a look also at the documentation of the PSHELL card for more details.

OFFSET will essentially shift your thickness assignment from the mesh, in positive or negative direction.

You can check the effects by toggling on the thickness visualization in HyperMesh as well.