How to get Midsurface for part?

ncmbhckpl

I want to get Middle surface (horizontal) for this part, but i couldnt. 



I need help emergency.
Thank u.

NeilCooke

Do you mean the mid-surface of the entire part (for simulation)? Or the mid-plane (use midplane option in Plane feature)?

mahir

Midplane option of the plane feature will work fine if you just want to get a plane in between two planar surfaces. If you want a middle surface for the entire part you'll need to use Offset with a value equal to half the thickness.

ncmbhckpl

Yes i mean mid-surface of the entire part for shell meshing, i tried Offset all part but left and right ears of part was drawn on different planes. So i could not.

NeilCooke

If it’s all one part you should be able to use offset surface. Can you share the URL?

ncmbhckpl

Of course, 
https://cad.onshape.com/documents/f589283433b1cc79810c0cea/w/44b01ef8477209e41d340e1a/e/a4424649c3d2921fe34a2c09

mahir

This part looks like it's sheet metal, but it's not really modeled like sheet metal, which makes shell meshing a bit sketchy. The material thickness varies anywhere from .77mm to 4.2mm. So if you wanted a true midsurface, you'd have to stitch together multiple Offset surfaces. 

Paul_15

mahir said:

Midplane option of the plane feature will work fine if you just want to get a plane in between two planar surfaces. If you want a middle surface for the entire part you'll need to use Offset with a value equal to half the thickness.

How would the offset work if the opposing faces are not a constant distance apart?

EvanReese

Paul_15 said:

How would the offset work if the opposing faces are not a constant distance apart?

I think if the part itself isn't an even thickness, it will have to get more manual. Here's an example with two thicknesses, and also one where the opposing faces are at an angle. These are generic examples of how to expand on the workflows above, but not how I'd actually model the parts below.

For anything more complex (like compound curved surfaces that are different), then it's not something Onshape is set up for aside from just manually modeling the middle surface, but something like the Tween command in Rhino would do it. One could also make a custom onshape feature to approximate it, but that sounds pretty tough to me.

billy2

Which FEA program are you using?