General > General Technical Chat
Berlin AquaDom explosion - what went wrong?
james_s:
--- Quote from: rf-messkopf on December 19, 2022, 10:31:34 pm ---On German TV a guy from Deutsches Meeresmuseum Stralsund was interviewed who said that in large aquariums it is general practice to regularly check polymer panes for scratches from visitors, and to polish them out as soon as possible. Happens easily when people scrape their backpacks along the pane.
--- End quote ---
I'm surprised there isn't a non-structural protective layer on the outside for that reason. Something similar to the adhesive film used to protect car headlights.
tom66:
Of course, in this case it's unlikely that the aquarium was scratched by a normal member of the public, except if someone climbed onto it... which is probably something you'd notice. But, could divers accidentally damage it during the routine feeding and cleaning that was performed? A heavy SCUBA tank hitting the walls of the tank accidentally could damage it - and if you weren't paying attention, maybe it would go unnoticed? I can't see how you could spot the kind of damage that leads to unexpected failure unless you vigorously inspect the tank regularly. The safety factor is around 11x for these types of tanks, so if the scratch/fracture damage is beyond about 5mm deep (out of a total of 200mm) it sounds like you lose that factor altogether and unzipping is all but guaranteed. How many acrylic aquaria are there out there where divers regularly have access to the interior space? I can think of larger ones, but they are only part acrylic, like around viewing windows and so on.
rf-messkopf:
--- Quote from: james_s on December 19, 2022, 10:40:51 pm ---I'm surprised there isn't a non-structural protective layer on the outside for that reason. Something similar to the adhesive film used to protect car headlights.
--- End quote ---
I can only guess but a protective layer would surely degrade the optical properties of the pane and distort. Maybe the visual impression is supposed to be particularly spectacular. However, scratches from visitors probably weren't a problem in the case of the AquaDom, because it seems that the public had no way to touch the panels.
I have walked past that building countless times, but I never knew that tank inside even existed. From the pictures it does not look too aesthetically pleasing though, but more like a hydrodynamic test facility. :)
tooki:
--- Quote from: rf-messkopf on December 19, 2022, 10:31:34 pm ---
--- Quote from: tom66 on December 19, 2022, 06:03:35 pm ---The slides linked in a prior post indicate pedestrian scratches and impacts are just something that has to be accounted for in the design, but it's amazing how little damage is needed to weaken the structure. The indication (chart on slide 27) is that the entire material strength is reduced by around 5x for a 2.5mm deep scratch, which seems utterly mad to me, but material physics is weird. I am not sure whether this is just for the 'wet' side (with the greatest pressure) or if any part of the material could be susceptible.
--- End quote ---
On German TV a guy from Deutsches Meeresmuseum Stralsund was interviewed who said that in large aquariums it is general practice to regularly check polymer panes for scratches from visitors, and to polish them out as soon as possible. Happens easily when people scrape their backpacks along the pane.
--- End quote ---
Sure. But in this case the aquarium was 8m off the ground, so no contact with visitors.
james_s:
--- Quote from: bigfoot22 on December 19, 2022, 11:59:13 pm ---This is exactly why I refuse to fly in an airplane.
Most failure modes of an aircraft is to fall out of the sky and bury itself into the ground.
In a car at least you can jump for your life or slam on the brakes or give the finger to whoever is crashing into you.
You cannot do that to a wasp, a ground mechanic thousands of kms away who decided to be incompetent that day, or a design flaw.
Some things were just not meant to be built, the commercial aircraft is one such thing.
i'm not lucky enough to roll that dice. I was born into a family of luddite schitzoaffective parents and every single thing in my life which would affect my career has had a catch 22.
--- End quote ---
In other words you either lack an understanding of math and statistics, or you are more driven by emotional feeling than by logic.
Yes if a crash occurs you are more likely to survive in a car, however per mile driven you are many times more likely to get into a crash in a car. Per mile traveled, flying is much safer, that is not an opinion, it is an objectively true fact. Commercial aircraft are extremely safe, there are thousands of them in the air at any given time and crashes are so incredibly rare that they make front page news any time they happen. Fatal car accidents happen every single day, they are so common that they don't even make the local news most of the time.
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