I’m not a mechanical engineer but I’ve played one. Because of the slight bow in the flexible bus cables, as they expand and contract, there will be a very small rotational force on the studs. The serrated flange nuts grab better in one direction and will have a ratchet effect with each heating and cooling cycle. Solid bus bars won’t have this problem.
You are absolutely correct that there is some rotational forces in play. But it’s not the cables that change shape as much as the cell position. The cables have a bit of yield before they get incredibly resistant to flex so I’m not too concerned about that undoing the nut’s torque. I’ve measured the amount of movement per cell (302Ah CATL) in springed compression (550lbs) and it’s initially .025” after a full charge and 100 degrees F worst case. It then subsides during discharge and cooling but never all the way down to original size. The normal cycle travel thereafter is less than .010” (from.015 to the full growth size .025” per cell). If I had to do it over again, I’d probably go with the flexible buss bars despite them having those dang large slots on a small post area. Most of those are resistance welded in that area and that makes that copper “full hard” condition. I’d love to see one after use or get feedback from users. Every connection or cable I make is checked with an internal resistance meter or a sensitive voltage meter across a section under load (when in use). A few times I got surprised so I check.
