6 Ways to BREAK the Ship: Common Methods of Structural Failure
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- เผยแพร่เมื่อ 29 มิ.ย. 2024
- Why are ship structures so labor intensive to design? Engineers need to anticipate multiple methods of failure, which makes a lot of work. The trick of efficient structural analysis focuses on recognizing which methods of failure are likely in each scenario. This article reveals six major methods of structural failure, with examples of common applications. Because it will be the failure mode you didn’t consider that ultimately leads to catastrophe.
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References
[1] Wikipedia Authors, "Elastic Load Method (full)," Wikimedia Commons, 2010 July 27. [Online]. Available: es.m.wikipedia.org/wiki/Archi.... [Accessed 25 Oct 2018].
[2] S. Petrov, "MOL Excellence - Bending of Underdeck Passage," TH-cam, 2 Nov 2012. [Online]. Available: • MOL Excellence - Bendi... . [Accessed 29 Oct 2018].
[3] The Commonwealth of the Bahamas, "Report of the Investigation Into the Sinking of the "MOL Comfort" in the Indian Ocean," Bahamas Maritime Authority, London, UK, September, 2015.
[4] ClassNK, "The Investigative Panel on Large Container Ship Safety," Class NK, September 2014.
[5] M. Ermann, "Column Buckling," TH-cam, 5 Jul 2018. [Online]. Available: • Column buckling . [Accessed 29 Oct 2018].
[6] Wikipedia Authors, "Bolt-In-Shear," Wikimedia Commons, 24 Jan 2012. [Online]. Available: commons.wikimedia.org/wiki/Fi.... [Accessed 29 Oct 2018].
[7] Simon Brand, "Autodesk Nastran In Cad Fatigue Analysis," TH-cam, 3 Nov 2014. [Online]. Available: • Autodesk Nastran In CA... . [Accessed 29 Oct 2018].
[8] VectorPly, "Vectorply's Finite Element Analysis Service," VectorPly, [Online]. Available: vectorply.com/finite-element-a.... [Accessed 29 Oct 2018]. - วิทยาศาสตร์และเทคโนโลยี
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Master Captain/ Local Pilot.. Your videos make me realize how little I know regarding the physics behind ship architecture. Your videos are also expanding my overall level of awareness to some of the forces, sometimes overlooked because “the ship was engineered this way or that way or to withstand this or that..” Thank you for your contributions by sharing your wealth of knowledge in this specialized area of science and please continue to keep our crews and vessels safe.
Im so glad to have stumbled upon your channel... there are many questions i have , to which, you are answering . Continue on, my good sir
"It was fine, until it wasn't" - love your videos!
Enjoy your videos immensely!
Thanks for the video. Very useful to see you talking about this. As a young engineer I come from a field where some companies had adventured on shipbuilding. I always considered the finite element analysis as fundamental for building ships, even though I didn't ever step into a shipyard. The designing softwares which you've shown are actually piece of cake, and the analysis are realistic and true to my opinion. Thank you very much.
Excellent stuff as always. I'm not a fan of the new more conventional attire, but I do agree that it's probably a good idea :-)
The video of the ship flexing is the best thing I've seen on TY in like at least a year.
Thanks for this informative video. keep on!
So informative !
Sharp Right, Medium Left! Concentrate Samir, you are breaking the ship!
hull fatigue made me think of the iowa class battleships that are still around, kinda curious where those might be on metal fatigue
1:53 “Look here” - nice
Derbyshire, Kowloon Bridge, hull girder joint and offset at the engineroom bulkhead... what were they thinking
Building plumb columns but ship 3 or 5 degs lean right or left or north or south may b more sound alternating the patterns like piles driven out of plumb for wharf.
Each water tight balk head can hve a pre engineered break panel & crush zone where a box is just free floating inside a bigger box, allowing water wt natual balancing rather than telling water u can't level out/seek level, or hve any extra load per sq inch.
Nice!!!!
All makes sense to me, But I can think of one ship which is much older and as far as I know - still in service as the MV Astoria. This same ship collided with the Italian liner Andrea Doria in 1948. It was then sailing as The Stockholm. So some magic must have been done to let it survive seventy years.
so at the end the hull of an ship is not that far away of the fuselage of an aircraft. cool!
This man is really smart. I wish I can talk like him.
You can do it!!! Start with "I wish I could* talk like him" :):):)
@@JohnHighmerSmith I did something wrong then! :) :) :) I tried and I tried it always the other way around. Thanks for the positive affirmation feedback.
@@fishme4112 And you can admit when you're wrong! Holy cow you are on your way sir!! :) All folks can learn from you too!!
@@fishme4112 Record urself so that u can listen to urself and hear what u don't like...Most of the great speakers do this. It helps a lot.
your squishing columns fix is simple. tapered columns that r just round or sq 4 or 6" column at top but either added thickness in or out on bottom 1st pnt. If it squishes it will b at top 1st not middle or bottom & 2nd. U sleeve the top so that it can slide down the column (not welded)but as it does the tapered column kicks in & locked the load ever more it slides down. So u allow for ceiling squish movement like a shock up 1/2 a ft or so & same 6" squish load down b4 taper locks it down like a shock on car not designed to come up after a hit. Then u can just jack it back up after storm & make in improvements or repairs in sections needed. Steel doesn't give but it needs to b engineered too do just that.
Could you do a video on old ship hulls? Or the evolution of the hull. From Greek triremes, Viking longships, to Spanish galleons, to Dutch flat-bottomed to English man-of-wars, to clippers and cutters.
Like why did they evolve the way they did. What was their effect on movement and how did they achieve their purpose?
Because we basically went from slender and straight, to round and curved, to wide and straight and back to straight and slender again.
That sounds very interesting. And it would take a lot of research to do it justice. Understanding the limits of construction that went into each ship. Anyone from the History channel want to do a documentary on this?
@@DatawaveMarineSolutions I think this is too niece and technical for a history channel. I remember hearing once about the importance of the invention of the curved ship from the 16 and 17 century wooden ships to allow better structure in a wavy sea. But then in the 18th century wooden ships got straight again even though they got even bigger.
Also in your hull video you only covered sharp bows. But here in the Netherlands a lot of traditional ships I see have complete round bows, I'd love to learn about how hulls like this work at sea. And it there would be any modern use for round bows.
@@DrTheRich Ik denk dat ik begrijp wat je bedoeld met het laatste deel van je comment. De ronde traditionele ronde Boegen in Nederland komen vooral voor op platbodems. de boegen zijn denk ik een resultaat van het ondiepe vaarwater en de aard van de goederen die men vervoerde in deze schepen. De kans dat een schip met een ronde boeg en platte bodem vastloopt is kleiner en de stabiliteit van het schip blijft gewaarborgd. Een nadeel aan de traditionele platbodems is dat het oprichtende vermogen van de boot afneemt naarmate de helling van het schip toeneemt. Deze extreme helling wordt echter alleen bereikt door extreme zeiloppervlaktes bijvoorbeeld bij Skûtsjes. Extreme golfhoogtes komen op Nederlands binnenwater nauwelijk voor. Je zou kunnen stellen dat de vorm van de schip voort komt uit functie (bulk vervoeren) en omstandigheden een ronde boeg verdeeld de krachten van aan de grond lopen beter.
@@plaksie Interesting information. but round bows were not only for flat bottomed ships. sea worthy ships of the renaissance and realy 17th century also had round bows. It doesn't look like it since the bow sprit and the fore castle often make it seem pointy. and the as the time goes forward merchant/war ship bows become more and more pointy.
I often go off-shore with family and children in a fast (+35mph) planing hull fiberglass 24ft boat. Your discussion of fatigue and combined stress got me thinking about all those "slamming events". Do you think small pleasure craft should worry about this type of catastrophic failure? Is there a way to detect fiberglass hull strength degradation?
That is an excellent question, and I can't answer it because so much depends on the individual manufacturer for your boat. I can say that standard design practice reinforces the hulls of high speed boats specifically to handle those slamming events. But we also design yachts with the assumption that they spend most of their life fe at the dock, not daily slamming into waves.
If you are looking for signs of hidden damage to the hull, I don't know any reliable and affordable methods. X-ray radiography would possibly work. We use that to check critical welds on big ships. But it is very expensive. On the cheaper side, a simple surface moisture meter would indicate areas of water absorption into the hull. A local damp spot usually means a crack.
What about the aircraft cariers ? Can they bend also ? Thank you for the video (2nd time...).
Oh yes. In fact, they are so heavy that most aircraft carriers have an entire deck just below the flight deck, which adds strength to the ship hull. Think of it like an I-beam, which places the strong parts on top and bottom. We put an extra deck of structure on the top and bottom to reinforce the ship.
I'm no military expert, but I believe this is also why the defense strategy for the aircraft carriers was very worried about any bomb penetrating through the flight deck. Breaking through those strength decks could possibly cripple the ship's structure. (I believe they specifically added armor and reinforcement to address this vulnerability. But like I said, I'm not a military expert.)
so how long a ship can last depends on how many storms it is in ?
Isn't this all related to gross hull dimensions? If a hull is much wider in relation to its length than is currently the norm, this would enable cross-bracing at deck and keel levels, reducing torsion and bending moments. Additional vertical cross-bracing would counter engine weight. This ignores current lock dimensions, of course.
Gross hull dimensions are rarely the significant factor on ships up to 90ish m. Above that, they can become significant, because global bending dominates more.
But we don't use diagonal braces as much as you imagine, for two reasons. First, every place you put a brace, we frequently need to put a bulkhead as a barrier against internal flooding. And the plate works just as well as the diagonal brace, although it does sadly weigh more.
Second, the end attachments of braces create hard point loads that increase fatigue on the vessel structure and reduce it's life. Remember that the vessel structure constantly flexes, and we need to design to allow that flexure.
how to contain bending forces by limiting the vast difference between ship weight & hull buoyancy??? is it some kind of reinforcement in the torsionally vulnerable sections???
We don't really contain the forces. Instead, we anticipate and prepare for them. Large designs absolutely consider the scenarios you described. We will run detailed simulations to predict the maximum bending forces on the hull. And then we design a hull structure to handle those forces.
In general, hull structures look like a hollow tube. All the strong steel is on the outside. And the hull is not just a single layer of flat plate. We use a layered hull structure, much like a skyscraper. The plate gets supported by small stiffeners,
which intersect large stiffeners,
and the large stiffeners intersect large internal bulkheads that run the entire depth of the hull,
and the bulkheads intersect with massive beams that run along the entire length of the hull.
We put a lot of structure into a ship. The trick to efficient design is putting the structure in the right spot.
I usually just eyeball fatigue analysis 👀👀
how do you minimize bending & other torsional forces in a super carrier (e.g. Gerald Ford class super carriers of the U.S. Navy)??? how do you reinforce a double hulled 110,000 ton super carrier??? please advise . . .
I can't speak with authority since I never worked on the Ford class, and I don't have access to their drawings. But I did work with the BOKA Vanguard, which is similar in size. The short answer is: build massive structure and very thick steel. One of the additional tricks is to add a double top. Most ships have a double bottom (two layers of hull plate, about 5.0 ft apart, but just on the bottom) at a minimum. This is for structural reasons. But for really big ships, you also add a double top. Two layers of hull plate at the top of the hull (main deck). The Ford class appears to have an accommodation deck below the main flight deck and above the hangar deck. That would be a good location to incorporate a double top.
@@DatawaveMarineSolutions @Datawave Marine Solutions thank you!!!!!! I'm not a naval architect as you but I'm very interested in naval engineering, especially large surface combatants like super carriers!!! can a thick double hull span the entire length breadth & height (from the very bottom of the double hull to the flight deck) of a super carrier??? super carriers boasting a length of 1,600 ft is it prudent to add ribs under the lower hull (spanning the width / beam of the lower hull) to reinforce & minimize structural stress on the hull caused by continuous pitching & rolling in rough seas!!! in stormy weather ships literally have to ride over high waves instead of going through due to surface effect!!!
Hi Nick
I would like to build a 48' steel motor boat and I'm interested for structural drawings.
Can you do it.
Thanks
u should when every poss pre bend or pre load so u already hve accounted for it & r saying from this pnt we r locking it down, that way it has to go beyond just extreme loading to hve breakage, bc it's already welded down at bent overload pnt weld this hold this line, not straight & plumb.
It's like a tree growing up to sun vs a tree beach side pre bent every day growing w/coastal breeze pre loaded for big blow.
Pre engineer a fracture pnt to relief stress under extreme + storm loading, we want it to break here & here & here & go no further rather than massive failure no returning home ever again.
@10:36 wait, have customers been asking you for "A quick, easy FEA Hull structural analysis"?!?!
My favorite method is to beach them at Alang.
Uhauls hve milage counter like big rigs on tires & they charge u by the miles bc normal driving & hauling r completely diff & overloaded hauling on regular bases is worst of all. The old under wt bolt is nice guage of long term loading tell. U pick bolts under sized designed to break at know loading & place them on multi key pnt locations all over the ship few turns from tight or hand tight & let them just ride along no real job other than to be a tell, at this pnt time & age & elements & loading hve sheared off 5 of 20 tell bolts in this section & for more in this area here, & most of ship has 1 or 2 missing tell bolts. Lets go look at planes & see why these 2 areas hve more broken tell bolts & if we need to fix on fly or bring it into dry dock fight cancer time.
2:19 free qa
1:55 3:04
Wait no not my custom Lego ferry
this has nothing to do with stopping snapeXhermoine
Build it out of rubber and it wont break.
7:52 Why not whack it with a hammer, if it rings true then it's good, if it doesn't, well you're outta luck.
You shouldn't need computer simulations and such to determine a ship's health.
People always want to take shortcuts when it comes to maintenance.
Fatigue rarely alters the acoustic behavior of ship structure. And by the time it does, you are already in trouble. I once did an analysis for an articulated tug barge (ATB) that used massive pins to attach the tug to the barge. They experienced fatigue failure of the pins. The first warning sign for them: cracks in the welds that were 0.5 m long, and daylight visible through the hull plate.