# Testing boat structure with FEA

Discussion in 'Boat Design' started by EddieGreen, Feb 13, 2021.

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### gonzoSenior Member

A rigid body can have 6 degrees of freedom. You use a standing man holding a rope as an example. With only his shoes attached to ground, he would have 5 degrees of motion. Is the man in your example a rigid body?

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### Ad HocNaval Architect

Again, please state where I have claimed to be a self-proclaimed expert?

The question is:

This has nothing to do with the question posed.
That - standing man - was an analogy to explain for those wishing to grasp the concept but your response suggests you simply do not understand this concept from the comments you have subsequently made.

Thus, what does rigid body motion mean - in the context of FEA.

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### gonzoSenior Member

Let's take it one small step at a time. You say the man analogy is wrong.

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### Ad HocNaval Architect

Are you able to at least answer this question ?

Despite your endless misdirections... that is what I am attempting to do with you.
One step at a time...

So, back to the question at hand...

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### gonzoSenior Member

Firstly, stop the aggression and stick to FEA.
A rigid body mode is defined as the free translation or rotation of a body without undergoing any significant internal deformation.

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### Ad HocNaval Architect

This is very simple, as this is a statement you made:

Please state where I have claimed to be so?

Progress - even if it is a cut and paste.

So for a model in the FEA...what does this actually mean?

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### gonzoSenior Member

To make sure, your example of a man was not correct?

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### Ad HocNaval Architect

To make sure, can you please state where I have claimed this to be?
Or is this a lie?

Again, for the hard of reading...

Where...This... being rigid body motion.

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### gonzoSenior Member

Can you answer the questions and stop with the personal attacks?
This is ridiculous.

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### Ad HocNaval Architect

So, what you are saying...is that:-
1) You are unable to supply me with the citation of where you claim I am a self proclaimed expert - your words not mine. Yet fail to do so.
In other words a statement you made up to change the narrative.

2) You are unable to follow a simple line of questions - ergo logic - in order to answer the question at hand.
In doing so, again, you simply wish to change the narrative.

If you do not wish to engage and answer questions to subjects you do not understand, which you asked, please say so.

But please do not keep replying with false statements and ad hominem just to obscure your inability to answer a simple question you are seeking and thus concede you do not know what you are talking about.

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### EddieGreenJunior Member

Hey guys, i said earlier i value all inputs but as the OP of this thread (i am no moderator by all means !) i dare say i don't find the latest exchange useful ... this is kind of polluting the discussion...
and not helping getting answers to simple and detailed questions based on very common and rather basic examples (e.g. isotropic material and no composite, etc) in boat design.

Has anyone read the Delft paper mentioned above by @fastwave ?

Could anyone with already hands on experience explain this further to a beginner ? for instance which loads and restraints are applied and where (can take the example of the V1 chainplate -interface to start with)

Thanks !

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### gonzoSenior Member

These are examples of a plate with force applied with and without a reinforcing channel. The other is the stress at the weld. The plate is welded to a pipe.

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### TANSLSenior Member

Good work Gonzo. I see that you have finally managed to learn to use a CAD / CAM package. !! Congratulations!!

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### gonzoSenior Member

Thanks. That was for a job for GE Medical in 2015.

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### an2reirfifty boat designs

I wish all of you a very good day from the south of France

and thank you merci beaucoup for your feedback ,

I consider your postings here very useful

To establish a more precise validation of the structural superyacht design studies I am working on here in France

I did now a very rapid comparative study of FEA software Autodesk Fusion and Scan and Solve for Rhino as follows:

1. I did two FEA simulations in parallel of a single 6061 aluminum plate dimensions 1000mm x 250mm subjected to a vertical load 10kN in Scan and Solve as well as in Autodesk at a resolution of 118,600 finite element units

The total displacement is 6 .571mm identical in Fusion and Scan and Solve

The max stress Von Mises is 241 MPa in Fusion and 287 MPa in Scan and Solve so very close

The difference is because my Aluminum alloy is just a little different in Scan and Solve compared to Fusion but also because the geometry of the finite mesh elements units is uniform in Scan and Solve compared to Fusion where it is not uniform

From my perspective I consider that this sufficiently validates very well the procedure of doing testing with Scan and Solve software.

I can and will do this sort of validation on a boat structure in the third software namely the Bureau Veritas Compose IT

From my perspective the integration of FEA software with Bureau Veritas certification validations software is very useful

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