4 ms·

You test at the extremes so you know it'll perform in the usual.

Maursault 4y ago
I'm sure that isn't always true, that if something performs at the extreme it necessarily means it performs in the usual. I find it difficult to believe that, if normal operating temperatures are going to be somewhere between the upper and lower limit temperatures of sea water and the upper and lower limits of air temperature at sea level, that a metal batch that failed at -100°F would need to be rejected. It's one thing for the purposes of science, to know, but my understanding is that engineering and material specifications for an actual thing needs to be more practical, especially for something that already costs $3.5B.
- kergonath 4y ago
  > I'm sure that isn't always true, that if something performs at the extreme it necessarily means it performs in the usual. That’s why we test over the operating range for the different parameters, not just at the limits. > It's one thing for the purposes of science, to know, but my understanding is that engineering and material specifications for an actual thing needs to be more practical, especially for something that already costs $3.5B. You need to be pessimistic about operating conditions if you don’t want it to fail unexpectedly. That is absolutely critical in engineering. Now, you set the boundary differently depending on the field and the importance of the widget you engineer (tolerances are quite different for a phone than for an aircraft), but the concept itself is part of engineering. There are cases where practicality is less important than reliability. Things like space probes and a lot of things related to national security. That is one of the reason why they cost billions in the first place.
- mrguyorama 4y ago
  The big reason for these kind of "extreme" tests is that they help you verify the models and simulations you've done. If your model breaks down at -40f, you want to know that, and figure out why, what that means for the actual material, what that means for the specs you promise, and what that means for the product. It also can be useful if these extreme test are better at revealing manufacturing defects. Maybe you literally only want the most perfect 1% of steel coming out of the foundry to actually be used, because you believe that will make a better submarine. In that case, sure maybe -100f is overkill for the specific application but you have to remember these objects are literally designed to have explosives near them. Being EXTREMELY GOOD at resisting brittleness literally will save sailors lives when it comes to close calls from depth charges.

I'm sure that isn't always true, that if something performs at the extreme it necessarily means it performs in the usual. I find it difficult to believe that, if normal operating temperatures are going to be somewhere between the upper and lower limit temperatures of sea water and the upper and lower limits of air temperature at sea level, that a metal batch that failed at -100°F would need to be rejected. It's one thing for the purposes of science, to know, but my understanding is that engineering and material specifications for an actual thing needs to be more practical, especially for something that already costs $3.5B.

kergonath 4y ago
> I'm sure that isn't always true, that if something performs at the extreme it necessarily means it performs in the usual. That’s why we test over the operating range for the different parameters, not just at the limits. > It's one thing for the purposes of science, to know, but my understanding is that engineering and material specifications for an actual thing needs to be more practical, especially for something that already costs $3.5B. You need to be pessimistic about operating conditions if you don’t want it to fail unexpectedly. That is absolutely critical in engineering. Now, you set the boundary differently depending on the field and the importance of the widget you engineer (tolerances are quite different for a phone than for an aircraft), but the concept itself is part of engineering. There are cases where practicality is less important than reliability. Things like space probes and a lot of things related to national security. That is one of the reason why they cost billions in the first place.
mrguyorama 4y ago
The big reason for these kind of "extreme" tests is that they help you verify the models and simulations you've done. If your model breaks down at -40f, you want to know that, and figure out why, what that means for the actual material, what that means for the specs you promise, and what that means for the product. It also can be useful if these extreme test are better at revealing manufacturing defects. Maybe you literally only want the most perfect 1% of steel coming out of the foundry to actually be used, because you believe that will make a better submarine. In that case, sure maybe -100f is overkill for the specific application but you have to remember these objects are literally designed to have explosives near them. Being EXTREMELY GOOD at resisting brittleness literally will save sailors lives when it comes to close calls from depth charges.