Loft Intersect Distorted Results

[JFried]

This is my first post, forgive me if it's not the best.

 

I am trying to create the rib structure of an aircraft wing. For FEM reasons, it's best to create as a single component. However, the simplest process for creating the feature gives some very strange distorted results.

 

I have created a series of spaced plates of appropriate thickness for my ribs, I have the root airfoil sketched on one endplate and the tip airfoil on the opposing endplate. Ideally, I would loft these two sketches using the intersect selection which would result in correctly spaced ribs of the correct thickness. However, when I do this, the ribs come out distorted, for lack of a better word. All of the ribs have seemingly random and curved faces (see picture).

 

This problem also occurs if I do this process in reverse, i.e. loft to form the wing, then slice through to form ribs. I'm baffled and have not been able to find any solutions to this problem. Any help would be greatly appreciated.

 

Edit:

I would upload the .ipt but it is too large, even after compression(412kb).

I have linked to it through a Google group, just save the link as an ipt

http://groups.google.com/group/aero-51501-r-1x/web/Ribs%20rev_D.ipt?hl=en

[JD Mather]

Attach ipt file here.

[shift1313]

If you just loft the foil without using intersect, does the shape come out right? it would appear so from the preview.

[JFried]

Yeah, the problems only arise when I try to form ribs with a lofted shape.

[JD Mather]

Yeah, the problems only arise when I try to form ribs with a lofted shape.

 

Attach the file here.

[JFried]

I have created the simple loft between root and tip airfoils for comparison, as expected Inventor forms the loft perfectly.

 

I would upload the file, but it is too large, and the forum will not allow me to post any more hyperlinks.

[JD Mather]

I would upload the file, but it is too large, .

 

In the part browser find the red End of Part (EOP) marker at the bottom of the feature tree. Drag it to the top of the browser hidding all features. Save the file.

 

In Windows Explorer right click on the file name and select Send to Compressed (zipped) Folder. Attach the resulting *.zip file here.

 

Your ribs are going to be as simple as offset outside surface in (what is the thickness of the skin?) and Sculpt or Split rib thickness (Extrude - Instersect might work as well).

[JFried]

I have tried suppressing and hiding all features, the files are still to large. The airfoil sketches are imported from a point cloud, I believe that is what is causing the large file size.

 

Right now, I am modelling the wing without any skin. I have tried using the split feature yielding the same distorted results. My only guess here is that the relative dimensions of the ribs are too small compared to the overall wing.

[JFried]

When I perform the same process using ellipses rather than airfoils, this distortion does not occur. The file is also much smaller.

Loft Example2.zip

[JD Mather]

The airfoil sketches are imported from a point cloud, ...

 

From an Excel sheet? If so attach the xls file.

 

or

 

ipt file without anything except the point cloud.

 

BTW - way too many dimensions, use equal = constraints.

 

Do the Loft before the extrude (actually I think there is a better way as I would think you want multi-body solids for pushing out the individual parts.

[JFried]

I've attached the root and tip airfoil coordinates as well as an ipt with the point clouds and splines imported.

 

I have tried doing the loft first with identical results. I know in a manufacturing setting individual components would be preferred, but this is for an FEM project and a single component is preferable there.

 

Thanks for the tip on the = constraint.

Airfoil Coords.zip

Point Cloud.zip