sheet metal tool adaptions?

john_doubleday

Has anyone tried to design a simple style monocoque  body for velomobile type vehicles. Interested to know how far this tool can be pushed.

dirk_van_der_vaart

The design of the alu monocoque from Lotus can be done in Onshape and creating a shell around that for a velomobile is also not so difficult, you don.t need a class A freeform shape. The body in the picture is not made in Onshape, but a shape like this is not difficult.
This sound's like a project.

matthew_stacy

@john_doubleday CAD (Onshape included) sheet metal tools are generally limited to bends in a single plane.  The fundamental requirement is uniform thickness.  A folded box is an acceptable example.  Basically we're limited to origami style parts.  These are called developable surfaces because the mathematics to unfold them into a flat pattern is relatively simple.  Sometimes we'll cheat a little bit to add features like dimples (forming tools in SolidWorks-speak), but strictly speaking those lie beyond the capabilities of sheet metal design tools.

Compound curved surfaces (e.g. monocoque vehicle) are more in the realm of surface modeling tools (FILL & LOFT), which Onshape also has.  Some CAD packages can flatten complex curved surfaces to create patterns, but Onshape cannot ... yet (3wk update cycle!!!).

There are some great surface modeling tutorials in the Onshape Learning Center.

dirk_van_der_vaart

How about Rubber pressing in a mold, or vacuumforming.Making 
The shape you want must be very light, so most design's have a shell and some sort of frame.



Making mold's for something like this is not that difficult in Onshape

john_doubleday

Thanks and very interesting. Was this done on Onshape? I was just wondering if anyone had pushed the 'Sheet Metal Tool' to it's limit.
Yes have built HPV tube designs  before but wondering if Onshape can produce designs like the light weight Lotus https://www.carmagazine.co.uk/car-news/industry-news/lotus/extreme-dieting-how-lotus-saved-207kg-from-its-cars-in-2016/

dirk_van_der_vaart

The design of the alu monocoque from Lotus can be done in Onshape and creating a shell around that for a velomobile is also not so difficult, you don.t need a class A freeform shape. The body in the picture is not made in Onshape, but a shape like this is not difficult.
This sound's like a project.

john_doubleday

matthew_stacy said:

@john_doubleday CAD (Onshape included) sheet metal tools are generally limited to bends in a single plane.  The fundamental requirement is uniform thickness.  A folded box is an acceptable example.  Basically we're limited to origami style parts.  These are called developable surfaces because the mathematics to unfold them into a flat pattern is relatively simple.  Sometimes we'll cheat a little bit to add features like dimples (forming tools in SolidWorks-speak), but strictly speaking those lie beyond the capabilities of sheet metal design tools.

Compound curved surfaces (e.g. monocoque vehicle) are more in the realm of surface modeling tools (FILL & LOFT), which Onshape also has.  Some CAD packages can flatten complex curved surfaces to create patterns, but Onshape cannot ... yet (3wk update cycle!!!).

There are some great surface modeling tutorials in the Onshape Learning Center.

Thanks for replying. OK what about a series of linked boxes to create a frame, like the Lotus aluminum chassis made to take a light weight outer skin.  A 'no weld' chassis design. The project I am thinking of is for student kit assemble and no welding     

dirk_van_der_vaart

Or make the shell like the first airplanes, a wooden structure with a fabric cover, glued together.
Most part's can be made as sheetmetal shape's only a few need to have a freeform shape.

john_doubleday

dirk_van_der_vaart said:

The design of the alu monocoque from Lotus can be done in Onshape and creating a shell around that for a velomobile is also not so difficult, you don.t need a class A freeform shape. The body in the picture is not made in Onshape, but a shape like this is not difficult.
This sound's like a project.

Ahh thanks as I thought. Yes it is a Kit project for a student challenge. Often teachers find themselves with no access to welding equipment ...and aluminum is difficult to weld anyway. If sections were not to long could be folded up and mechanically fastened together into a light weight frame.  A coreflute shell could then be added over the top.....fancy joining the team:)). Check out my linkedin profile   for more info