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| Berlin AquaDom explosion - what went wrong? |
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| rdl:
I'm not exactly sure why, but this seems a little odd to me. --- Quote from: ebastler on December 19, 2022, 03:40:21 pm ---The interview stresses a couple of times that there was a risk of the 20 cm thick acrylic drying out if it is no longer in contact with water from the inside, which could cause cracks. They applied adhesive foils to the acrylic to avoid this. --- End quote --- |
| ebastler:
--- Quote from: rdl on December 19, 2022, 04:23:35 pm ---I'm not exactly sure why, but this seems a little odd to me. --- Quote from: ebastler on December 19, 2022, 03:40:21 pm ---The interview stresses a couple of times that there was a risk of the 20 cm thick acrylic drying out if it is no longer in contact with water from the inside, which could cause cracks. They applied adhesive foils to the acrylic to avoid this. --- End quote --- --- End quote --- Yes, that surprised me too, and is counterintuitive. But despite being hydrophobic, PMMA (= acrylic) can absorb water, up to 2% by weight: https://pubmed.ncbi.nlm.nih.gov/22799564/ Surprising that thin adhesive foils should be enough to prevent the PMMA drying out. But the application of these foils was nicely visible in the refurbishment video someone share earlier in this thread. Maybe they only need to slow down the evaporation, so it happens slowly and without causing excessive stress in the material. |
| ebastler:
--- Quote from: imo on December 19, 2022, 04:17:03 pm ---This kind of funny stuff like the AquaDom shall be designed and constructed such way that in case of a failure the water has the free way to escape without causing catastrophic damages or dead bodies. An assumption such that specific construction will last forever would be pretty naive one, imho.. --- End quote --- Right. Just like it's good practice to design towers, bridges and cranes in a way where they gently sink down in case of a collapse, provide an emergency exit to the occupants, and sort the rubble into neat piles in the process. ::) |
| AndyBeez:
--- Quote from: tom66 on December 19, 2022, 03:30:21 pm ---I wonder if "modernize" is a poor translation. I have heard other Europeans use that word when they mean "refurbish". As far as I know they didn't replace the actual panels themselves. That would require the roof structure to be removed (at the very least) and would be extremely disruptive. --- End quote --- During refurb, the panels were wrapped in plastic film and shrouded in a giant curtain; maybe to ensure the acrylic didn't dry out or go out out of geometry. Modernized; in the UK we say, "in need of updating", so what was updated? Someone clearly felt the need to rearrange the rocks on the bottom of the ocean, but was there a more fundamental motivation? Was the Aqaudom out of it's OEM guarantee? And was the 'modernizing contractor' the same firm as the OEM installer? Until someone puts the broken pieces together like an air crash investigation, no-one will know where the fail started. Either way, this spectacular fail will be a memorable case study for structural engineering students for decades to come. |
| tooki:
FYI to our German-speaking friends, in English, “folie” translates to “film” for plastics, while “foil” is for metals. We never say “plastic foil”, while “metal film” is possible, but then means a thin layer on some substrate (i.e. “Metallbeschichtung”). What I wondered from the start is whether they use scratch-resistant films on acrylic aquaria. Many of the public transit vehicles here in Switzerland are now having films applied to the windows to stop vandals from scratching the glass. The film is essentially sacrificial. |
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