Timeline for ISS Destiny Module inner wall: thickness set by internal atmospheric pressure or by mass density needed for meteor shielding?
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 3, 2018 at 5:43 | comment | added | Tom Spilker | @MagicOctopusUrn A Whipple shield has a 2nd layer (and sometimes more than 2) such that the shrapnel impacting the 2nd layer isn't energetic enough to penetrate it, or cause secondary shrapnel. ISS Destiny walls use a "stuffed Whipple shield" that has a layer of Nextel (6 sheets bonded together) and a layer of Kevlar fabric (another 6 sheets) between the two metallic walls. | |
| Dec 3, 2018 at 5:38 | comment | added | Tom Spilker | @MagicOctopusUrn I think the quoted part isn't saying that thickness protects against a 7 km/s impactor, but that a 7 km/s aluminum sphere completely penetrates through a plate of that thickness. You can have interior damage even if the impactor doesn't penetrate the plate (wall). At those speeds, the collision launches a shock wave through the wall. When that shock wave hits the wall's inner surface it spalls off pieces of wall material—at high speeds, just smaller and slower than the initial impactor— that then cause shrapnel damage... | |
| Dec 3, 2018 at 5:30 | comment | added | Tom Spilker | @Hobbes Yes, I did the same calculation and wound up with a similar indicated minimum thickness (used a slightly different value for Young's modulus of 2219-T87 I found on the web), but I couldn't find anything about what safety factor NASA applies, and I couldn't rule out anything, even if I considered it absurdly high. | |
| Nov 28, 2018 at 20:05 | comment | added | Hobbes | I'll see if I can find a source that has more detailed calculations. | |
| Nov 28, 2018 at 19:59 | comment | added | Magic Octopus Urn | Excuse me, it protects against 7km/s MMODs?! Not sure I understood the quoted part, how big can the MMOD be before this rule doesn't apply? Is it that the shield is thicker than the sphere is in diameter? | |
| Nov 28, 2018 at 19:46 | history | edited | Hobbes | CC BY-SA 4.0 |
added more info
|
| Nov 28, 2018 at 13:58 | comment | added | Uwe | The pressure vessel is calculated using Barlow's formula. But you have to use a design factor of about 0.4. Some excess for corrosion and tolerances are necessary. The force in axial direction of the cylinder is unattended. But the result is still less than 1 mm. Bending and warping stress is not considered. | |
| Nov 28, 2018 at 11:59 | history | answered | Hobbes | CC BY-SA 4.0 |