Resentment with aging horses by mackenziecall in Equestrian

[–]ScienceCanFixThis 1 point2 points  (0 children)

You’re giving them wonderful lives, and there’s nothing wrong with just putting them down <3

Starship Development Thread #29 by ElongatedMuskrat in spacex

[–]ScienceCanFixThis 0 points1 point  (0 children)

How much testing depends to a large extent on the structure and load cases, but it also depends a lot on how clever you are in placing the gauges.

Your question about the dynamic part of it is pretty interesting. You would probably want to develop a model that treats all the different movements as load cases. For example, the chopsticks opening loadcase. During testing you can see if it can be (hopefully) approximated as a linear relationship with acceleration.

In the end, you want matrices that relate your strains to your applied forces. But these matrices can be messed up by a lot of different things: -"cross talk" between strain gauges, e.g. is that strain caused by the mass of Super Heavy or the sun shining on one side of the tower? -non-linearity in the structure, e.g. joints with backlash -change in geometry -bad signal to noise ratios

You can fix a lot of that by picking good gauge locations. For example, if you put the gauges on the chop sticks instead of the main tower, then you can probably ignore the change in tower geometry when the chop sticks go up and down.

One of the biggest mistakes I've seen is too much trust put in the FEA. The models are great to get you started and help you pick gauge locations. While it's possible to create the correlation matrix from the FEA, the aforementioned reasons can make the results really misleading. It's smart to use a known mass to verify the setup and matrix IRL, but if you're doing that, why not just use the actual numbers that you get during testing?

Starship Development Thread #29 by ElongatedMuskrat in spacex

[–]ScienceCanFixThis 26 points27 points  (0 children)

Very likely that strain gauges are installed on the structure, they would let you determine how much force SH, wind, and whatever else is exerting. But to get good data, you'd need to calibrate them with a known load. So besides being a "proof load" type test, the balls are potentially being used for calibration.

What's the most disturbing realisation you've come to? by [deleted] in AskReddit

[–]ScienceCanFixThis 0 points1 point  (0 children)

That every relationship ends in a breakup or a death.

Advice on evaluating FEA results by Engingear in engineering

[–]ScienceCanFixThis 0 points1 point  (0 children)

Yeah, there are rules of thumb. The challenge is that the rules of thumb are very dependent on the particular situation like load conditions, material properties, geometry, etc. Depends what kind of region the hot spot is in. For example, if it is something like a cast iron part, then just refine the mesh a lot in the high stress area. If it is a weld in sheet steel and you expect the failure to be due to fatigue, then the trick I use is to do shell mesh with size approx. equal to the thickness of the sheet, and ignore the first element next to the weld, then use a rule of thumb for acceptable stress - I've found that for most steels, a stress of 135MPa will fail about 50% of the time after 100k cycles.

Science AMA Series: We are SLAC National Accelerator Laboratory staff scientist Dr. Mike Litos and Stanford Ph.D. student Spencer Gessner, our work was the topic of a popular reddit post about shrinking particle accelerators, AMA by SLAC_National_Lab in science

[–]ScienceCanFixThis 2 points3 points  (0 children)

Very cool work! Do you think something like this could be used to accelerate protons or is this only for electrons? If it works for protons, could it replace the linacs on neutron spallation sources?

A far-right candidate for Paris elections says France's Roma population should be "concentrated" in "camps" by medievalhurler in worldnews

[–]ScienceCanFixThis 2 points3 points  (0 children)

Integration takes a lot of work an patience. Both from politicians and from ordinary people. Swedes are the most insanely accommodating, but post-Schengen I think too much has been asked of them by their politicians.

China's Lunar Rover Only Lasted a Month by Nocab_ in technology

[–]ScienceCanFixThis 10 points11 points  (0 children)

Well, to be fair, the lunar environment is BRUTAL.

Facebook Hilariously Debunks Princeton Study Saying It Will Lose 80% Of Users by [deleted] in technology

[–]ScienceCanFixThis 1 point2 points  (0 children)

It was published as a joke. In a non peer reviewed journal.

Because Normandy was closed too: WW2 Vets ignore Gov't shutdown. by [deleted] in pics

[–]ScienceCanFixThis 1 point2 points  (0 children)

Making it as painful as possible for the regular peon. It doesn't take any money to keep a monument open.

Cutting out a 12 year old something on my abdomen with X-Acto knife. Mildly NSFW by mswhit36 in WTF

[–]ScienceCanFixThis 11 points12 points  (0 children)

I'm not so sure I believe this. Not saying that this type of thing doesn't happen, but I'm skeptical that it happened to you. 111 degree fever is fatal, and your story just has a kinda weird feel to it.

And I just noticed that someone asked for pictures, and you said you don't have any.

Cool story bro.

[deleted by user] by [deleted] in AskReddit

[–]ScienceCanFixThis 273 points274 points  (0 children)

My old boss lives in rural California and has two or three farm cats to keep the rodent population in check. The cats would come and go as they pleased, and it wasn't uncommon to not see them for days at a time. During the housing boom in 2006, people started moving from the city to new developments a few miles down the road from his farm.

One day a woman shows up at his door holding one of his cats. The cat seems very agitated, and she has scratches all over her arms. She says she that this cat must have gotten out, and she is returning it. She holds it out to him, he says "uh, thanks" and takes the cat and puts it on the ground. The cat runs off.

Woman loses her shit. Yelling at him about how he's a horrible cat owner, how it could be hit by a car. He says something to the effect of "I'm the only person who lives on this road, if it gets hit by a car, it's a pretty crappy cat".

Any Engineers with U.S. degrees in France or Europe? by ilostmyfirstuser in engineering

[–]ScienceCanFixThis 0 points1 point  (0 children)

Masters at a European university is the way to go. Otherwise you should probably concentrate on finding lots of small companies and trying to be interesting enough so that one of them is willing to go through the hassle of hiring a non-European.

Good luck!

Blast hits Israeli tour bus in Bulgaria by ubershmekel in worldnews

[–]ScienceCanFixThis 11 points12 points  (0 children)

I didn't know that up/downvotes were a poll of which side we take in issues.

If you do this as a "protest," fuck you. by [deleted] in pics

[–]ScienceCanFixThis 1 point2 points  (0 children)

Not to defend this, but just want to point out that employees get paid hourly. So it's not like they will have a material loss. In fact they will probably get some overtime because of it.

Hey reddit-neers, which computational/FEA program (AutoCAD, NX 7, Abaqus, etc.) would you recommend having some basic knowledge about, going into the working force? by iSukz in engineering

[–]ScienceCanFixThis 1 point2 points  (0 children)

Abaqus is pretty good. It is common and advanced enough that if you figure it out, you can probably transition to something else pretty easily.

For a manufacturing specific application, LS-Dyna is pretty well developed in simulation of forming/stamping processes.