Attachment Ship Hull - FE Boundary Condition
Attachment Ship Hull - FE Boundary Condition
(OP)
I'm looking into an attachment on the deck of ship/hull subjected to wind and wave loads (as it sits on the deck of the hull). If I know what sea-state(wave loads/accelerations) the ship has been designed to, is it necessary to model the complete ship model to know what's going on, on the attachment at the deck or would it be more/less make sense to just model the attachment with the specified acceleration at the support between the attachment and the deck?





RE: Attachment Ship Hull - FE Boundary Condition
RE: Attachment Ship Hull - FE Boundary Condition
Sure, if the attachment is "big enough" (mass / inertia / stiffness / dimensions) to potentially be significant as far as the ship's sea motion is concerned, then yes, you might need to analyse the whole ship / attachment system.
But for "small" attachments whose mass / inertia / stiffness / dimension is insignificant as far as the ship's motion is concerned, then you should be able to get the characteristic movements of the ship ignoring the attachment, and use these as base excitation inputs into a separate analysis model for the attachment. (You may need to model an appropriate sub-section of the ship's structure to ensure the load paths between the ship and the attachment are modelled reasonably.)
Would you analyse the complete ship / attachment system for a Heavy Lift Vessel with a 10,000 tonne off-shore oil rig as its deck cargo? Almost certainly!
Would you do the same to analyse a one-tonne deck crane? Probably not!
http://julianh72.blogspot.com
RE: Attachment Ship Hull - FE Boundary Condition
RE: Attachment Ship Hull - FE Boundary Condition
"On the human scale, the laws of Newtonian Physics are non-negotiable"
RE: Attachment Ship Hull - FE Boundary Condition
If you don't, bad things may happen.
1. The part (its attachment and its frame or casing) may fail because it is not strong enough to "hang on" to the deck plates and their frames due to the wave impact. Modeling the wave impact will be tough enough on its right!
2. Your attachments (bolting or welding) to the deck plate and its frames may be the weak point. The part is fine. But it ends up breaking free of the deck because the welds or bolts failed. Or pulled through the deck plate.
3. Your attachment is fine, the bolts and welds holding it on are fine, but the deck section underneath pulls out and rips off.
But the whole ship? Almost certainly not warranted.