CPE - Few Questions

[VN1981]

I got a couple of questions in Catia V5 CPE...

Firstly, I am trying to generate a solid laminate using Grid methodology for a UAV wing skin. Typical wing skin with "pads" (beefed up region) at locations where ribs & spars attach & "pockets" between the stiffeners. I using a combination of Catia V5 help as well as CPE training material from Dassualt.

From what I understand, there are two ways to generate solid geometry.
1. Generating Solids directly from Plies
2. Generating Solid after defining Iso-thickness

What is the difference between the two of them?

Secondly, I was able to generate solid for my laminate definitions using both the above methods. For my ramp definition, I had defined a drop-off total length of 10 mm. If I change the length to 25m m, I get all kinds of errors during iso-thickness process however solid generation from plies go through smoothly. Most of the errors in Iso-thickness says "Non-relimited edge" & "Non-manifold curve" kinds of messages (I could be paraphrasing errors). Any ideas on what they mean & how to trouble shoot them? Neither Catia V5 help nor Dassualt training material has any topics covering trouble shooting.

Pointers are deeply appreciated.
Thanks,
-V

 

[Macm_020171]

Generating solid from plies is a dead solid, if there is a modification in your plies EOPs or sack up (more or less plies) the solid is not editable, you have to create it again. Catia internally does thick surfaces for each plies stack up EOPs, and the result is a rough solid with steps on drop offs areas when a thinner laminate transition to a thicker laminate. This is not good to be used as a IML surface to design a frame or a rib sitting on top of a drop off.

Solid from Iso-thickness areas is a more refined construction method, where the drop offs are more realistic, represented by continuous surfaces. But you have to do more work to get it right, by connecting the ISA with lines. And when surfaces are too complex this tool might not work properly. If it works properly, the resulting IML surface is a good support to design a frame or a rib that is sitting on the drop offs areas. This process is parametric so if your laminate design changes, the ISA can changes downstream.

I have had to do lots of GSD work to get a clean IML to design the internal structure, when surfaces are complex with lots of double curvature and facets.

These automated solid/surfaces generation works fine when the OML is simple, with minimum facets and double curvature slopes. Otherwise you need decent GSD kills to work with multi-section surfaces, sweeps etc.

The errors you're seeing might be due to the fact that you created Iso-thickness areas with boundaries. This is quite unstable, because when you change the drop off parameter, the edges of the surfaces in the ISA are recreated, and when there are facets in the surface those boundaries need to be edited individually reselecting the ISA edges. You have to go through each of the boundaries that have a yellow dot, double click on them and reselect the edge of the ISA. Normally the edge that needs to be re-selected is highlighted in a dotted yellow curve.

Try to uncheck the boundaries generation when creating the ISAs.