On the other hand, impossible to let that pass:
dedeleco wrote:Every word from chatelot16 is worth its weight of advice to listen to, no offense to Kenny-k [Flytox Moderation] who says without anything all around and shows photos with buildings, etc ... !!
Yes aluminum is vicious with lots of dead like
https://fr.wikipedia.org/wiki/De_Havilland_Comet
as a result of metal fatigue on thousands of small tremors
"these accidents are due to metal fatigue":
https://fr.wikipedia.org/wiki/Fatigue_% ... %A9riau%29
much more serious for aluminum than for steel !!
The wind is very tiring.
Finally, the eddies and whirlpools even at 2 times higher are still disruptive by reducing the efficiency, on a wind turbine, which moreover has an inefficient regulator, which amplifies the speed oscillations instead of stabilizing them !!.
The fine blades are for a steady wind at a fixed speed with a very fixed direction and the slightest fluctuation or direction of a few degrees destroys the yield.
uh no, very bad example and totally false:
At 10'000m altitude (-50 ° C):
- the ferritic structure of iron would become brittle (much more than metal)
- annealed ferritic steels, would suffer from elastic limit anomalies, they would threaten to fall apart (necking).
- only austenitic steels remain ductile.
So the metal is quite unusable at altitude for a structure (compared to aluminum), moreover, when the temperature rises, the resistance of the metals decreases. Aluminum, it gradually lengthens ...
For the elastic limit (that which concerns the mats in the case of this wire) aluminum, iron, magnesium and titanium are in the same category (best performing metals 269 N.mm.Kg-1).
Aluminum alloys are even better in mechanical characteristics than ordinary steels (for a density near 3x less 2,7 Kg / dm3 VS) ... It is therefore not a heresy to make an aluminum mat if the '' we expect that the metal will have to absorb the stresses due to its own weight! otherwise [Flytox Moderation] the mast is an assembly of three uprights assembled by a structure of cremona sketch >>> which gives the whole a titanic resistance almost indestructible. So your words are big salad.
Indeed, it is not therefore:
1) that the metal is free from fatigue problems (on the contrary, see above).
2) that the choice of aluminum would have been inappropriate (otherwise they would not have made any changes they would have changed the alloy.)
To set an admissible fatigue limit (σf), this is calculated taking into account the maximum stresses in service + safety factor.
The fatigue of the aluminum in the case of this airplane, was therefore manifested because of a bad sizing at the point of rupture which placed the part "beyond the admissible threshold" known - and not because the aluminum would have been inappropriate or because of the fatigue of the aluminum relating to its aging - every day airliners are subjected to extreme stresses, rising to approx. 10 meters above sea level and descending at temperatures up to> + 000 ° C, even several times a day without damage. Going from tropical temperatures on the ground, to temperatures of -40 ° C at cruising altitude, reaching ∆ ° of nearly 50 ° C without worry and this for decades ...
[Flytox Moderation]
