Finite elements

[nemo]

Hi,
does anybody out there use finite elements programmes in naval applications? If yes, which are the most suitable for that?

[SailDesign]

Nemo,
I have to admit that I don't use any. But people I have talked to that have tried to use them for marine applications all say the same thing - "It is not a problem creating the mesh, but it is really difficult to decide on the worst-case loadings."
Steve

[Dim]

Dear Nemo,

The set of programs from SRAC:
http://www.cosmosm.com/cosmosm.htm or

I can recommend page of web-site:
http://www.bodrum-bodrum.com/vorteks/arsenal/feacodes.htm

On my sight - one of best about software for all of us.

Dim.

[EmilSB]

Hi,
I try something like that with Nemecheck and with Posseidon.
I think both are good if you know how it works. But, also I think the best softwear in this category is the software which you know best.
Emil

[dionysis]

hi EmilSB,

While I have had limited experience with finite element software, all applications have a steep learning curve. After having an opportunity to look at Nastran, Ansys and Algor finite element packages in use, I think the best value and the easiest learning curve is Algor. Be warned, you need to learn a lot to use these packages properly; they are complex and there will be steep learning curve.

Bear in mind you wll need a way to be able to compare results so you can validate them. Get a good engineering book.

Good luck, Dionysis.

[Dim]

Will not say more precisely. In any case to work with any FEA-software, it is necessary to have specialized education.
First and most important during usage FEA-software - whether is for the person understanding that happens in PC.

Dim.:)

[EmilSB]

Hi,
If you want to see some stuff about finite elements see this site:
http://swath.com/maritech.htm(correction:http://www.swath.com/maritech.htm)
There you will find some pictures with result of analyse with Nastran.
Emil

[Dim]

Sorry, EmilSB,

but attribution is
http://www.swath.com/maritech.htm

Dim.

[EmilSB]

Sure Dim, I never said It's my!

[Dim]

Good pictures, EmilSB.

Dim.

[EmilSB]

Dim, a saw your gallery on this forum and your 3D Models are very good and I am woner what soft for hull form, for rendering and for detail design you use?

[Dim]

My answer - at PM, EmilSB.

Well also was lucky me with number of posts!

Dim.

[Jeff]

Sure Dim, I never said It's my!
I think Dim was simply pointing out that the site doesn't work without the www because of the way they have their server set...

P.S. thanks (to both of you) for posting the images in the gallery - I really enjoy looking at them - they're great :)

[Dim]

Yes, Jeff and thank you for your words.

Dim.

[Thomas Ask]

I use Algor and wrote a paper on FEA analysis of hulls for the International Institute of Marine Surveyors a few months ago. I could forward you a copy of this paper if you would like.

The problem with FEA is modeling wave behavior. I used multiple surfaces on a solid model to achieve a reasonable model.

[dionysis]

hi Thomas,

I would be interested in reading your paper:)

cheers dionysis.

[Dim]

I join judgement Dionysis.

Dim.

[Guest]

I will email you a copy of the paper. Unfortunately, my office is being moved right now so everything is in disarray. I will send it as soon as I can findi it.

Tom

[Dim]

No problems. We will wait your.
Dim.

[dionysis]

thanks again, take it easy, cheers dionysis.

[burakreis]

hi,

with general purpose fea software it is not easy to solve a floating thing. a local analysis on ship structures can be easliy done with any modern fea tool.

the problem is global ship structural analysis. defining the boundary contidions will be very hard and then modeling these boundary conditions with a general purpose fea is also very hard if it is not impossible.

so there are some special tools developed for ship hull structural analysis such as maestro, trident, nauticus system etc. but these are very expensive for design and a little harder to use and learn.

best regards,

[EmilSB]

burakreis,
Can you post links for maestro, trident,....?
Thanks.

[Guest]

http://www.proteusengineering.com

[burakreis]

EmilSB,

you can find (nearly) all ship structural analysis stuff at my site;

http://www.bodrum-bodrum.com/vorteks/arsenal/feacodes.htm

regards,

[Dim]

Dear Burakreis,

I am happy, that even I can meet the creator of my loved site.
Let to express you sincere gratitude for Your job. Exist, on my sight, only two resources in www. It is that Forum, on which we with you are also Your site.

Sincere thanks.
Dim.

P.S.
How are Your gallery of a 3D model?
I am waiting, waiting. It's very powerfull !
Dim.

[burakreis]

hi Dim,
first, thanks for your comments...
actually i am working on some major updates on VMA, new sections many new software links etc. indeed i have been working on some technical articles specially on cfd and fea applications for marine vehicles also but it takes more and more time to do then i thought in the beginning :)

by the way if there are some people who want to share their knowledge with the community via VMA they are always welcome for cfd, fea, surface and solid modeling articles & tutorials etc.

i hope will release some of the updates in 2 weeks. but for the rest (i mean articles) can take 6-12 months! (i am a little busy in these days)

for the free 3d models; the problem is a little different. as you can see VMA does not stand on its server but a friend's server as a subdomain for today. in the past after heavy downloads of 3d models the server exceed the monthly file transfer limits so when i find a suitable server to put these files i can reactivate it...

in the beginning i was thinking to put a forum in VMA but after finding this forum there is no need for that, this forum is excellent...

best regards,

burakreis

[Dim]

Dear Burakreis,

Always with large pleasure I open Your site, because I know, that I am waited with interesting news. With the large interest has studied yours free 3D models in Iges-format.
Good luck to You in Your job and more of time the large thanks!

Yours faithfully
Dim.

[dionysis]

Hi burakries,

Just a note to say how much I found your site to be excellent and I highly recomend it to all forum members.

For those who do not know about the site here it is:



Viryual Marine Arsenal (http://www.bodrum-bodrum.com/vorteks/arsenal/homepage.htm)

cheers, dionysis.

[dionysis]

read "Virtual Marine Arsenal

[EmilSB]

Burakreis,
Your site is goooood, very gooooooood.
Thanks for all. I'm impressed.
To all members of this forum and guests visit Burakreis's site. Is the best and links are good.
Best Regards,
EmilSB

[burakreis]

dionysis and EmilSB, thanks for your comments...

burakreis

[ClarkT]

Thomas,
I use Algor also, and I find the multiple layer method of applying a pressure distribution a pain the the A$$! I've been on them for years about this, but it seems there are not enough boat/ship/platform designers using Algor for global analysis to make it worth their while.

ANSYS is miles ahead in this respect. You can apply an individual pressure load to individual elements. I have a program that I used some time ago to bring an ANSYS mesh into WAMIT (MIT diffraction theory software), then take the wave pressures from WAMIT and apply them to my ANSYS file. Using this software, we were able to cycle the waves through our hull and do a very good global fatigue analysis.

I can't imagine doing this with Algor and all those layers. I'd have as many layers as I do wetted elements.

[kosmich]

Hi! I'm Constantine from Greece and i am a candidate PhD in Aristotle univercity of Thessaloniki in floating breakwaters. I try to link ANSYS and WAMIT without any other programme and it doesnt work. Is there any other programme to link ANSYS and WAMIT? When i say link i meen to bring an ansys mesh into wamit and then take the wave pressures from wamit and apply them to the ansys model. I'm looking forward hearing from you!

[jamac]

Hi there,

We use Strand7 in our office. Very good for ship structures as it allows you to import nurbs surfaces, then loft beams to that surface transversely and longitudinally and very quickly you can build your basic hullform and stiffeneing from the original nurbs surface.

We are extremely pleased with it and you can find more at www.strand7.com.

HTH

JA