Originally Posted by
Kontact
That's a dumb analogy, not a fun one. A spoke is in tension, not compression. It is not analogous to a spring compressed until the coils are touching each other, because that is a mechanical limit. A spoke or spring in tension doesn't have a mechanical limit - it can keep stretching until it breaks. A fully compressed spring can't break from compression.
I'm fairly certain the elbow gets pulled in place way before maximum elongation for the final tension is reached. That'll of course will depend on the butting etc.
A sprung elbow can "move" for exactly the same reason that the rest of the spoke can elongate - because tension changes the shape of everything based on where the forces are applied. A straight section - like the end of the butt - is going to elongate in proportion to the amount of material. The butt isn't a stress riser because there is no bending force against it. The spoke is equally weak right next to the butt as it is mid spoke.
That's not the definition of a stress riser. In fact not even close. You should know this if you've been a crash investigator.
The sprung elbow is touching the flange, but is not necessarily at its mechanical limit in how short a distance it can make that curve. So as tension increases, that partially collapsed curve does get smaller and flatter, trying to compress into the flange, and it is doing that under a strain that is greater on the outside of the curve than the inside. So as tension changes, the bend experiences changes in that relative strain.
And if spokes cycled anywhere near their fatigue limit that might count for something. But as established above, they don't, so it doesn't. Also if you bend the elbow prior, how would that change things? The bend is still there so the asymmetric strain in your example remains.
At this point I would like to remind you of Occam's razor and the dangers of inventing complex elaborate theories just to explain your point of view.
Which is why we are having a conversation about elbows breaking, instead of having a conversation about why elbows never break. If you actually believed your BS, you would say that there is no force that could break an elbow.
What...?