Granted, we don't have many picture to go by, but in what we do have, I don't see anything like spalling or shoddy "repair" by buttering over defects.
This looks like a compression failure.
So, if this column worked fine for long time, and now suddenly failed, wouldn't that mean that the load...
A few scribbles on a post-it show that the hoop stress is trivially small, and thus the deflections and bolt bending will also be trivial.
Given any choice at all, nobody would purposely design a pressure vessel with a flat end. Your seemingly arbitrary choice of shell thickness bludgeons the...
There is a big mismatch between fastener strength, tapped material strength and joint capacity vs. load. That's not in and of itself a problem, but in the context of the overall design it's leading to a sub-optimal outcome isn't it?
Your entire design seems dictated by external constraints...
Durability comes from applying materials appropriately, and maintaining them.
If that's a precondition, then there will be no difference in durability between industrialized modular construction using GRC panels and "traditional construction".
"Drive rivets" will likely be faster and easier to install.
Drill, place, wack.
One size hole though both pieces.
https://www.hansonrivet.com/rivets/drive-rivets-steel/
How many of those arms are there between the pod and the ring? What is is made of?
I can imagine that setup hitting a resonance at some conditions, leading to fatigue failures.
Try these guys.
https://www.gobigbolt.com/
I have no affiliation, but they've supplied to a lot of train manufacturers that I've worked with over the years.
Too bad, as with so many things these days, they are "available", on paper, until you ask for them.
Some possible alternatives to Tef-Gel:
https://next.henkel-adhesives.com/us/en/products/industrial-lubricants/central-pdp.html/loctite-lb-8023/BP000568.html...
I'll assume the green axis is horizontal.
The center of mass appears offset from the green axis, so torque will vary over each rotation. You need to calculate how much.
You need to select a drive and brake with suitable torque in both modes, and backlash that meets your needs.
You need to...
Stacks become unstable when the weight vector at the CG moves father than the center of pressure at the base, in response to small perturbations.
It's mostly about stiffness and geometry.
This NASA paper presents a conservative calculation for pullout strength, and tabulates it for various materials.
https://ntrs.nasa.gov/api/citations/20170003491/downloads/20170003491.pdf
The pullout strength formula presented is:
Note that the 3 is an arbitrary factor of safety.
1/2"-13...
So, the folks that wrote the standard weren't worried about hydrogen embrittlement with these three finish options.
Looks like your screws have one of the two black oxide finishes.
The shape of the fracture looks most like stress corrosion cracking from the pictures at the link provided by...
