iges trimmed surface problem in maxsurf

[hasicktear]

Helo, i've just signed up the forum, it's very amazing..

In rhino, i modelled a gulet hull, an aegean sailing hull. I use non uniform sections depends on general gulet hull characteristic while modelling. i draw a layout and plan, make surface from network of layout curves, take isocurves on the generated surface, adjust them and then regenerate the surface from the current isocurves . Anyway, finally I've generated the shape using Patch command because NetworkSrf command didnt create the hull shape that i expect in the beginning. but patch command created a trimmed surface maxsurf cant read. Maxsurf shows a silly shape. so finally i want to convert my trimmed surface into untrimmed surface as the same hull shape. I should do some fairings but this problem is so boring. I can't see forward. if i take enough longitudinal or transvere sections then how could i create the same shape as a single surface using NetworkSrf command in spite of there are 5 edge curves and interior curves aren't lined up as the form NetworkSrf command could work? I think it is very difficult to model a single surface square stern hull that its keel starts front of stern....Or is there an other easy way to convert trimmed into untrimmed? Also i'd prefer not to create the hull as polysurface because while modeling the construction and optimizing the hull along feedback engineering process, there will be fitting and continuity problems on the hull. I think single surface is better. for example, if hydrostatic result shows less displacement than i anticipate, so i should be able to adjust the hull shape to increase displacement as a good result of gaussian and any curvature without changing main dimensions and draft.

Thanks for the reply.

[CGN]

Hi,

Have a look to the attached file, I think this is a good way to do the surface without using trimmed surfaces, in rhino try to match the surface sections with the sections that you have already, I think you can have a very good approximate, is not going to be 100% but I think the results can be acceptable, after this export the surfaces to Maxsurf, once on maxsurf you can use:

BondEdges>StrictTangency, I think it should give you the best continuity between surfaces.

Is tricky, but I think is better to have simple surfaces and not deal with trimmed surfaces, and once in maxsurf should be easier to tweak.

[hasicktear]

Thanks for your suggestions;

But i want to create the hull as a single surface because when i calculate hydrostatic and speed-power analyses, working on single surface is make me flexible then i have no problem about continuity and curvature. if i can solve this problem, design and product process accelerate. instead of polysurface modelling, isn't there any way to make maxsurf able to read trimmed surface correctly? because the shape is there, and mathematicaly formed, so i see it

[archnav.de]

If we have a Rhino file we prefer to save the file as ACIS 4.0 or Step. With this surfaces we normally have not any problems in other CAD-Systems. I have saved the file from CGN as ACIS 4.0 combined the patches with our ACIS based software to one surface and saved the file as ACIS 4.0 again.

You can look at the file under Autocad in the following way. Insert ACIS.

Cheers

Bernd

[hasicktear]

how can i use acis surface in maxsurf?

İ tried to save .stp as acis surface but it minimizes surface trimming to boundary. It is the same thing that i use untrim command.

here is the model.

[DaveB]

Hey CGN,

Could you describe what you did in a bit more detail... The result seems good but I'm not sure how you did it...

Did you start with curves and then build surfaces from edge curves?

Cheers,

Dave

[hasicktear]

it is very simple to model a hull as polysurface. first of all ,

first picture 1. step: draw plans , layout

second picture 2.step : draw a water line approximately

third picture 3.step : now you have four edge and an interior curve

fourth picture 4.step: split the edges to create two network has 4 edges

fifth picture 5.step: use _NetworkSrf command to generate upper shape of the hull. and adjust edge matching for position

sixth picture 6.step: do the same process for the lower shape

finally picture you have the result.

and then by adjusting isocurves on surfaces, you can give the form that you expected. but there may be fitting matching and continuity problem.

[hasicktear]

here is the final picture and model. i think it is useless for engineering

[CGN]

no, hasicktear, that's not a good approach.

I created 3 separate surfaces and use "push and pull" to shape the hull, once I have the hull close to a shape that I'm looking for; a software like maxsurf can be use to match the edges,
using: BondEdges>StrictTangency, this in maxsurf will give you a nice continuity between surfaces and then finish the fairing there.

the surfaces used on rhino can be 6 columns by 1 intermediate row (6x1) that way you don't have as many points as the "other" method and is easier to manipulate and control.

the file that I uploaded has more rows but again you can use the top as a 6x2 the one on the middle as 6x1 and the one the bottom 6x2 or 1 it depends on how much control you want, at the end you can even use the "match" command to match the surfaces in rhino should work fine. this is one way it may be more but IMO I think this give you some advantages: better surfaces, more control of the surface, and better results on the fairness of the surface.

This type of hulls are not easy to model (when is about matching an existing offsets table, or an old drawing), but I think the results can be more than satisfactory.

[hasicktear]

why isnt it a good approach?

eventually, i dont suggest multisurface modellig when there is a way to model hull as a single surface. actually i'm searching for converting my model trimmed into untrimmed as the same shape. although i formed the hull shape that i want, why cant i use it in maxsurf? that is my primary question. if i take enough markers on the hull and export into maxsurf how could i create the shape again in maxsurf? the trouble is making hull as a single surface.

[CGN]

becouse it leaves more room to mistakes and is not editable, at least the way i do it i can edit my surface and modified or reshape it with no much problem. of course must be a way to do it right, but for now i think is a good solution to such task.

Andrew Manson reads and gives response to some of the questions on the forum i'm quite sure he will have a good comment on what you are looking to achieved.

cheers

[hasicktear]

oh finally i create my model top of the page as a single surface and untrimmed! , by sectioning and fairing in a long way. here is the gaussian curvature in maxsurf. is it acceptable?

[CGN]

cool, you got it hasicktear, it looks nice i don't know about the gaussian, but i'm glad that you got it, you can do this in rhino and then export to maxsurf, but i will stick to maxsurf.

[hasicktear]

tomorrow i will share this my experience how it is modelled. it is not so difficult but now im going to sleep. i havent any time to sleep for two days

[urisvan]

dear hasiktir,
i have tried to designed something and i want to share my opinions with you. i will be glad if you you give your e-mail.