Take a U-shaped wire, bent from 10 mm O.D. stainless steel. You model it as a swept extrusion or a pipe (solid) and when finished, you calculate the required length to cut from your stock material, either by doing the geometry math yourself or by creating an evalute feature. Either way you end up with the same answer, 3 straight lengths and 2 quarter circles.
If you model the same part but now as a square (10x10 mm) section and then declare it as a sheetmetal part you can get the required length by using a flat pattern feature. When a sheet metal part is bent, it stretches and therefore, which ProE recognizes, the total length required is less than the "geometrical answer" above. Its obvious that in reality, the wire stretches when bent just like a strip of sheeet metal and that therefore the second smaller answer is correct.
Now, does anybody know a way of getting a "flat pattern" answer without having to redo the part in square form. This redo can get complicated if there are more bends to the wire that are not all in the same plane.
Bertil