Kind of OT, but you know what’s interesting? The round that exploded the barrel was loaded with 30% LESS powder than it should have been (it was a .700 Nitro). An internal ballistics expert where I worked back then told me that, while less propellant generates less pressure, in certain unfortunate circumstances, it generates a brisant shockware that’s quite powerful enough to blow up a barrel.
Not familiar,
Is this the “detonation” vs “rapidly burn”
I know the how and why it’s bad, but not the technical aspects
It has something to do with detonation, yes. The layman’s explanation I was given was that the powder has too much empty space to expand freely before encountering the back of the projectile and that creates a shockwave. Or something to that effect. I’m really not an internal ballistics specialist - only external.
Yea that’s what I was thinking, I know various powders are specifically designed to take up different amounts of volume per boom unit to help prevent this
There are very few ammo combinations I would ever be willing to deal with the hassle and risk of loading it myself, lest it go boom, as discussed I know enough to know the various ways I COULD fuck up, which is more then enough
However, one would require a very very fluffy powder to prevent detonation,
6.5cm loaded to a sub sonic, could be a lot of fun with some of the new crazy efficient bullets,
And a can of course
Think the numbers I was looking at was maybe 500 yards out of it?
Ok I’ll stop derail
Well, in the case of the failure I witnessed, it was a proof load. Kinda hard to do without loading it yourself. The guy should have overloaded the round by 30%, but they got the math wrong and underloaded it instead. It’s so easy to hit that minus button on the calculator instead of plus 
Quick update: all the chips are still alive:
- Drop tester: 1205 cycles
2351835146 - OK
2351835172 - OK
2351835143 - OK
- Temp chamber #1: 6 x +65C cycles, 7 x -35C cycles
2351835210 - OK
2351835149 - OK
2351835227 - OK
Temp chamber #2: 1 x +65C cycle, 1 x -35C cycle
2351835168 - OK
2351835214 - OK
2351835160 - OK
- Temp chamber #3: 6 x +65C cycles, 6 x -35C cycles:
2351835163 - OK
2351835142 - OK
2351835194 - OK
The temperature chambers haven’t been used all that much for the past two weeks, because we’re in the build phase of our production process - i.e. we build entire batches of devices that will be tested all at the same time later.
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Interesting, that’s a lot more drops than I expected, glad they are still going strong
(Any degradation of the glass housing?)
(Any idea what what g load they get each drop?)
Soo school us on temperature damage
I understand just enough to be dangerous
Does most damage result from expansion/contraction and different thermal expansion rates of dissimilar materials?
Or is there some other cause also?
What generally matters more, the total depth of the cold, or how violently you get there?
No damage that I can see. The implants are under a layer of clear tape though: they might well be cracked and held together by the tape, I wouldn’t know. I doubt it though. I’ll untape them at some point and take a look.
About 1,200G with one of our devices on the carrier. But it’s not the acceleration that matters, it’s the mass of the object. Implants are far too light to sustain major damage from that.
Pretty much. crimped connections work themselves loose, and solder cracks. That’s the reason why manufacturers of products that are subjected to high intensity shocks, vibrations or extreme temperatures can apply for a variance to keep using leaded solder, which is normally forbidden now in Europe.
Shocking them repeatedly on the drop tester tries to achieve the same sort of failure.
Themal shocks are the worst. Same reason why you can slowly bent a tree branch quite a lot and also snap it against something hard fast.
We temperature-cycle our products at 10C per minute above 0C, and 1C per minute under 0C (simply because the refrigeration unit can’t keep up with the demand).
On the testing page you can see we tossed chips into liquid nitrogen… read fine after… I was amazed by that. Truly.
Yeah but… (putting my quality assurance guy hat here). It’s like fatigue failure vs stress resistance: low-level thermal cycling can be - and often is - more destructive than a huge thermal shock applied once. Because essentially, thermal cycling is fatigue failure: it’s repeated shrinking/expansion of the material. That’s what I’m testing here. Not the same test.
Mind you, this is all quite academic, considering no implanted chip will ever experience any of what I’m testing Still, like I said, if they survive those tests as well as yours, that’ll be proof enough that they’ll survive anything in-vivo.
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Hmm,
I feel like this is on topic
I’m suddenly curious (and maybe a smidge concerned) about an x series getting hit but a simunition round (utm or sim) possibly even a paintball, but those have a much greater surface area to disperse their energy
Got a call into my force on force guy, to see if I can get some energy numbers
5.5mm diameter projectile
6.9grain / .45gram
310-375 FPS depending on delivery instrument
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Most of the projectile’s energy will be dispersed into your meat.
Think of it as hitting your implant with a rubber mallet, or something that would leave a similar bruise on your skin: will it break a glassie? Possibly if you’re unlucky, but probably not.
I seem to recall Amal implanting a frozen chicken and hitting it with a hammer rather forcefully, but I can’t find it now. Do I recall wrong?
not sure there’s much meat between the implant and a projectile that small of it hits the mark
I get that… but you’re talking about a broad force versus a very precise force
I’m talking about getting hit on an implant with a projectile the same size as the implant
You can hit a car window with a bat and usually not break it, but hit it with a punch and it fails,
Surface area of impact is far lower with my concern
It doesn’t matter because the implant isn’t backed against a hard surface: there’s squishy meat behind it also that tends to get out of the way.
But before it has a chance to “get out of the way” isn’t all force going to be transferred to the glass implant?
Amal, it seems to me it’s time for you to get the .50 out of the safe and hit the range. Testing is definitely needed here
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It would be if the implant had enough mass and inertia to resist the acceleration. But an implant is very, very light - less than a gram. It won’t oppose anymore resistance than the meat behind it.
Thing is, if you apply enough force to break it, chances are you’ll have a significant injury yourself anyway.
