Need help with FEA of a rudder

[pamarine]

I have the following rudder design and am having trouble running deformation tests in SWSim2009.

I keep getting the message "Preconditioner Fails to factor" but am unable to find any information about that error code.

I have attached the necessary files below and was hoping someone would be able to assist.

The Rudder is made from 304 Stainless Steel, the shaft from Aquamet 22, and the Tiller from Maganese Bronze.

The bearings are just blocks of Mahogany with a standard brass Rudder Bearing inserted.

[Raggi_Thor]

If you google the error message you find some others with maybe similar problems?
http://ww3.cad.de/foren/ubb/Forum131/HTML/000481.shtml

[Raggi_Thor]

I tried to look at your attachment, but it seems to be an XT file embeded in a dwg?

[pamarine]

Saw that forum post, wasn't informative in the least

It's just a standard X_t file.

[Ad Hoc]

Perhaps explaining your problem a bit more may help?

Is it just simply a 'command' within the program you need assistance with, or an understanding of what the command does and is for?

[pamarine]

Originally Posted by Ad Hoc

Perhaps explaining your problem a bit more may help?

Is it just simply a 'command' within the program you need assistance with, or an understanding of what the command does and is for?

Mainly what the error message is and how to fix it. Barring that, if someone else can run the analysis and simply tell me when and how it will fail.

[Ad Hoc]

I use cosmos, which was eventually embedded within SW. But I've not come across that command.

Is this for static, dynamic, linear or non-linear analysis?

[pamarine]

Originally Posted by Ad Hoc

I use cosmos, which was eventually embedded within SW. But I've not come across that command.

Is this for static, dynamic, linear or non-linear analysis?

It is a Static Linear Analysis. It's the first Time I've seen it as well.

[Ad Hoc]

Ok, what is it you are trying to 'model' or rather what is the analysis? You say it is a straight forward linear analysis, but what loading and elements have you chosen?...the error message you posted...what command did you execute to get this error message, and what inputs if any affects this?

[pamarine]

I hit "Run". Can't find any meaningful information on the error message that would help me zero in on a fix.

I am trying to see if the Rudder Stock and Rudder Blade will deform at max speed and angle (55 knots and 35 deg). Based on my math, that should be roughly 5200 lbs of force along the longitudinal axis of the hull hitting the rudder blade.

[pamarine]

Well, figured it out on one of the Rudders, The Pin Connecting the Tiller to the Rudder Stock was moving out of place wierd and the program couldn't solve for it.

YeeHaw, I love this stuff

[Ad Hoc]

In linear static analysis, it wont tell you that, you have to interrogate the results.

If you already have the 'expected' load, then it is just a case of My/I, and the deflection, being a standard cantilever.

I can understand if you wish to use the FE to estimate the SCF for a hot-spot stress, but otherwise, your doing an over-kill, it seems to me. Just a thought.

[pamarine]

Fixed the other model, Tiller arm again.

Well, Basically I have a bean counter trying to tell me how to design the rudder. So when I show him the results and all the reds an yellow where the stock has twisted and the rudder blade bent back 10 deg I'm thinking maybe he'll shut up and let me do what I'm being paid for

[Ad Hoc]

aahh...managers...ugh!!!...I do sympathise. I've had my fair share of those "lets blue sky this...or think out of the box"..management bollocks speak....ugh!

Good luck

[Knut Sand]

Originally Posted by pamarine

Well, figured it out on one of the Rudders, The Pin Connecting the Tiller to the Rudder Stock was moving out of place wierd and the program couldn't solve for it.

YeeHaw, I love this stuff

I was gonna suggest that you'd choose the end of the rudder axle as a "Fix" point, either totally fixed or fixed vertically, if you see....

I have not SW/ SWS/ CW here now, but another way to fix the bolt, popping out/ away is to make a split line on the bolt's surface, similar to the surface of the part that this bolt shall be incerted into, then you, in the study can choose to .... Don't remeber the word..... It's not mating, its something else, I believe it's 3 options there, the button for it, in the CW study its just below where you choose the material for the parts... I'll find it later tonight....