plates tutorial

[fabio]

I recently buy the pro.
There is a tutorial in the forum or topic of the web plates developing step by step?:blush:

[otaku]

Hi Chiossul,

Are you trying to create shell stringers/sideshell stiffeners? That is, are you trying to create T or L stiffeners, such as web/flange plate?

I don’t think you can do that in Delftship.

What I did was to create my hull and fair it. Then, I added waterlines and stations, at various intervals where I thought I later on *might* need or want to add stiffeners.

After much fairing, i exported the DXF 3D Polylines and the DXF mesh. I then opened my CAD application and imported those files.

I assigned various waterlines and stations to conveniently named layers.

I color-coded things to make it easier to work.

Do you have a CAD application that can work with solids or create solids? I’m not talking about meshes. If you do not, then consider something you can afford. You have many choice, ranging from Rhino to Autocad, and Rhino with various add-ons.

If you find them to be too expensive (as I have) and are not generating cashflow from your drawings (as is my case), then you may want to try Punch! ViaCAD Pro. It is less than $300, and it has some pretty good 3D modeling tools. It is what I use. I like the look of the solids when I properly construct them. And, I like the reasonably-laid out and exportable CGs and Moments information that is calculated for individual and multiple solids in the model.

To create stringers, I sweep the profile or the web and the flange separately along a waterline.

Quickly, to generate stiffeners…

— Pick a waterline that will be your stringer’s path
— Find the stern (in my case i have transom sterns)intersection
— Draw a line that will be the web
— Draw a line that will be the flange
— Use one of the rail sweep tools you find works with the ending profile you’re wanting

— Thicken the surface using the “Thicken” tool. Before leaving the Thicken mode, zoom in to make sure it is where you want it. Use the “Ctrl” key to “throw” or shift the thickness to above, below, or exactly on the waterline.

If you like it, keep it. If not, then look at the angle at which you created the web and the flange. Nicely, the sweep tool will follow the line/curve even though it bends 90 degrees in the case of a transom stern of waterlines.

If you need to break those waterlines because later you want stringers interrupted by the bulkheads you might install, just break the solid with the trim or another tool. But, for that solid, some associative information may be lost. If you have to re-thicken the stiffener, it should still be possible later, but you might in some cases want to re-sweep the surface and re-thicken the solid.

Swept surfaces are associative to the curve used, so if you activate control points and move them around, you can force the surface to be reshaped. But, don’t get crazy — dramatic displacement of points could lock up the drawing due to calculations, since in 3D you might think you’ve moved a point only an inch or some number of millimeters, but if you are incorrectly using snaps, you might actually be moving a point by meters or kilometers in the drawing.

If you are creating sideshell stiffeners/panel stiffeners/bulkhead stiffeners, you can use the same or similar techniques.

* But, keep in mind that you want an app that allows you to export the solids information as some sort of dxf or delimited (comma, tab, etc) format. And, you want this format to appear STRUCTURED, not in some time-wasting mixed format that forces you to copy, paste, splice, and eliminate stuff that won’t neatly align into columnar format. Why? Well, you might later on want to run reports in a spreadsheet or a database app and don’t want to become a scripting expert just to untangle an insane or obtuse layout that is set up for visual use rather than analytical use.

—-
* Clarification: I wanted to clarify that I am not criticizing DELFTSHIP’s hydros outputs and CGs/Moments info. I’m speaing of a well-known, very expensive, CAD app that requires some amount of scripting to get some decent formatting out of the mass properties information.

[otaku]

As for PLATES…

If by plates you mean shell plating, you need to ask yourself whether you want smoothly curving, unbroken hull mesh surfacing or if you want to have the hull “broken” in convenient places where the waterlines and stations intersect.

As for one big half-breadth hull surface, you can turn on the mesh and then export it. Depnding upon the CAD program or hull modeler you’re using outside of Delftship, you may or may not be able do much with the mesh. Since I’ve already mentioned that I am using Punch! ViaCAD Pro, I can tell you how I use the mesh. I export the mesh model to DXF 3D Mesh. Then, in VCP, I import that model. In my early forays into DelftShip, I realized i did NOT want one huge hull, since I am doing detail design and I want to account for weights of EVERYTHING I draw — not just the equipment, ducts, pipes, and so on, but the specific region of the hull and its bulkheads and decks, too.

So, I created waterlines and stations not for (well, not JUST for) hydros reasons, but to “break up” my hull. By creating stations at convenient intervals (matching my paper drawing in general, but adjusted when I found out the 3D model gave me more space than my pencil lead at 1″=20″ did), I found that I could assign mesh areas to specific layers. So, I created layers that were named for the hull compartment. I color-coded each so that in and out of DS, I could more easily see where I was in the model space.

When I imported those into ViaCAD, I realized I could thicken each compartment’s plate more realistically. Instead of going on some “average plate thickness” notion, I could by compartment thicken the plate. But, later, when I CREASED waterlines, I realized that I ended up with individual rectangular plating that I could more gradually thicken or thin in a more refined way to realistically deal with thinning the plate as it got higher or more near an extremity. I could thicken plates in zones needing more protection.

Now, where some may leave that to a hydrodynmics and weight specialist, this is MY model. *I* am all of the departments. So, I am not going to just use a hand-wave and declare or use rules of thumb or wrack my brain trying to calculate weight of x square meters of y type of steel of z thickness. I just tell Delftship the density information so that I can sanity check it against what ViaCAD later will calculate.

In ViaCAD, I assigne the MESH to a sublayer of its compartment, namely MESH. I copy and then transform that mesh into a SURFACE. I assign the surface to a layer in that compartment, and I then create a layer called Plate/Solid/etc as convenient, and then thicken the sideshell and assign it to its appropriate layer. I then go into “properties” and tell VCP to make it 1020 steel and then VCP shows me the CGs and moments of that steel. Later, when I add stiffening, decks, cutouts, ladders, partitions, pipes, and bunks, and so on, I can over time see know with more confidence what my hull region is WEIGHING, not just displacing.

CREASES AT WATERLINES

If you’ve created your points and made the general hull (or if you open one of the demo hulls), create waterlines and stations at convenient intervals just for experimentation.

Crease the waterlines. Note that creasing WILL slightly modify the hydros results. Creasing will likely force you to make more manual adjustments, but the positive side effect is you may end up with more planar plating if you re reasonably careful. Un-creasing can, however, re-introduce multiple problems since DS is not one of those $10,000-per-drafter-seat programs that will automatically re-fair within a tight tolerance close to what you had prior to fairing. DS WILL automatically fair for you, but YOU probably will want a shape of your own, not one of the interated farings.

Now, if you export those creased areas, you can play around and realise the things creasing can do for you besides making single and double chines.

You will probably spend WEEKS interactively iteratign your Delftship to CAD app drawings, looking for excessive sheer, camber, and twists, and reversals that you might not notice in DS if you’re not using the histogram tools correctly. If you’re creating stealthy corvetts or just want to exploit all that buzz around “steath shaping”, then creases can be your friend very quickly.

Remember, though, the manual process can be fun if time is no issue. But, it CAN take a good deal of time if you’re very demanding and perfectionist.

[fabio]

many thanks for the reply.
I wanted to know how I can have a shell panel divided as casual example:

http://delftship.net/designdatabase/showdetails.php?DetailsID=178

I can not figure out how to turn a corner in a normal face end plates.

I read the manual but maybe I do not understand an important step that I try here

how do you build a deck panels like this and how do you separate the panels where I want
grazie

[fabio]

ok this is perfect for my :

http://www.modelboatmayhem.co.uk/forum/index.php?topic=19208.50

[Author]

Posts