Ross McLendon

Christian,
Husband,
Father,
Multiscale Computaional Mechanist,
TAMU '06,
Photographer,
Singer,
Expatriated Texan living in Rhode Island

[Ross McLendon @rossmclendon]

The partially eclipsed sun rises behind the Independent Man statue atop the Rhode Island Statehouse.
#SolarEclipse #RhodeIsland #SolarEclipse2021
@jdesnoyersabc6 @michmuscatello @tony_tpetrarca @NBC10_Mark @tjdelsanto @MelissaSardelli @TedNesi @JimCantore @GovDanMcKee

[Ross McLendon @rossmclendon]

@VictorG64650226 @SnoCoPW This is how we did it when I was in scouts.

[Ross McLendon @rossmclendon]

@Xaraphim Woah.

[Ross McLendon @rossmclendon]

@Xaraphim Beyond failure/damage prediction-
- curing induces warping
- curing induces fixed residual stresses (at various scales)
- laying up over complex geometries impacts ply orientations (fabrics have to shear to accommodate doubly-curved surfaces)
... to name a few.

[Ross McLendon @rossmclendon]

@Xaraphim Aerospace companies design very close to the margins - 1.5x dictated by FAA reqts for commercial planes for most scenarios.

They do lots of analysis and testing at various scales. You'd have to talk to Boeing people to get details on why they missed this mode.

[Ross McLendon @rossmclendon]

@Xaraphim https://t.co/KP3KWJq5Jz

[Ross McLendon @rossmclendon]

@Xaraphim The 777 (aluminum wing) static structural test failed at 154% of the limit load (has to reach 150%, any margin above that is extra weight).

The first 787 (composite wing) test delaminated in the wing box just around the limit load, failing the test and requiring costly redesign.

[Ross McLendon @rossmclendon]

@OnDisasters @CreeCoder Definitely a canary in the coal mine given that the highest level of X leadership has been a vocal fan of the content that he stole and reposted in the past.

[Ross McLendon @rossmclendon]

@Xaraphim The Abaqus docs have some nice summaries of the equations (as the Abaqus PM, I'm a bit biased towards Abaqus)

LaRC05 & Hashin: https://t.co/mQyxzdookd

Other criteria (Tsai-Hill, Tsai-Wu, Max Stress/Strain, etc.): https://t.co/sRfi2u6P56

[Ross McLendon @rossmclendon]

@Xaraphim I read the papers back in the day.

Jones's book that I had back in the day went through quite a few of them, but some of the newer ones like LaRC05 and Puck I read about in papers.

Even Tsai Wu has some deeper things about it, like the F12 term that's hard to pin down.

[Ross McLendon @rossmclendon]

@Xaraphim Also, Tsai-Wu arguably isn't the state of the art for ply failure; it's just a tensor polynomial fit to a bunch of failure tests under different loadings. Many regard LaRC05 (among others) as more current, and it also gives separate indications for different modes of failure.

[Ross McLendon @rossmclendon]

@Xaraphim At some point you learn that Abaqus outputs for Tsai-Wu and other failure criteria isn't the value of the criteria (which are generally nonlinear), but rather the inverse reserve factor, i.e., a value of 0.5 means doubling the stress would cause the criterion to be be met.

[Ross McLendon @rossmclendon]

@asynchronous_x As someone who worked in a backend FEA mechanics support team, one of my first thoughts when I saw this was "my gosh that would be impossible to troubleshoot". However, users in export-restricted nations who pirate FEA software usually don't qualify for support.

[Ross McLendon @rossmclendon]

@StephanSturges I have my doubts that much serious FEA was done on Titan *before* the disaster. As far as I'm able to tell, OceanGate wasn't an Abaqus customer (the contour you're showing appears to be Abaqus). And as has been alluded to, fast16 seems to target a different type of analysis.

[Ross McLendon @rossmclendon]

@DJSnM @rhizomaticthot EOS meets NSA

[Ross McLendon @rossmclendon]

@DJSnM That shoe fits what's being shown here.

[Ross McLendon @rossmclendon]

@DanielDiMartino It keeps getting worse if you zoom in further!

There are probably some interesting stories about treaties and surveying that figure into this.

[Ross McLendon @rossmclendon]

@consumer_crnbrd Additive for investment casting would be an interesting approach...

[Ross McLendon @rossmclendon]

It'll be interesting to see how these hold up under repeated uses. I've seen reports they extensively use additive manufacturing techniques to get this cleaner design. I've also heard from multiple non-rocket sources that 3D printed parts can exhibit poor fatigue lives.

[SpaceX @SpaceX]

Raptor 3 (sea level variant)

Thrust: 280tf
Specific impulse: 350s
Engine mass: 1525kg
Engine + vehicle-side commodities and hardware mass : 1720kg

[Ross McLendon @rossmclendon]

Circuit breakers are electromagneto-thermomechanical devices.

Are there any simpler things that make up everyday life that depend on coupling this many fields?

[Ross McLendon @rossmclendon]

More here
https://t.co/z8Yaq73IWJ

[Ross McLendon @rossmclendon]

Of the four RS-25 engines on Artemis II, three of them - 2047, 2059, and 2061 previously flew on shuttles, with 22 missions between them. Only engine 2062 had never been to space. All are now wrecked somewhere at the bottom of the Atlantic.

[Max Evans @_MaxQ_]

@NASA has just released some EXTRAORDINARY tracking footage from Artemis II's launch just one week ago.

Mesmerizing exhaust flow interaction between all four RS-25's & twin SRB's.