Hi,
Yes, I get the result you quoted at the end of you post. My sign is reversed though, so I get the moment equilibrium when I set boom_total_moment = boom_cylinder_moment - boom_reaction_moment. I think this is because I get the force the nozzle exerts as a result of the moment, not the...
That's awesome, thanks! I just finished the other two. I realised the symmetry meant that the perpendicular vector joined the axis at the mid-plane (to "uncross" M using r to get F). So that also turned out to be fairly trivial too. But it's great to know that you got the same answer for the...
Hi, thanks. I see you're using a different method, using trig instead of matrix algebra. I've managed to get some values for the Yoke contribution, which is fairly trivial since the axis is always vertical so one can work in the horizontal plane. For the other axes I've been trying to get an...
Yes, I see what you did there... Effectively the you're applying moments that result in equal and opposite reaction forces. This would lead to the statically indeterminant case like in my reply to jlnsol above, where there is no contact force at D in the example mechanism pictured. And the way...
Hi jlnsol,
I think the way I'm looking at it, where the nozzle is constrained by contact with the earth to yield the applied force, this stucture can be viewed as not-a-mechanism. At least this is the view from a source I encountered during my recent research. In particular:
You make some...
Hi. Yes, that would be what I'll be doing. What is wrong with that approach, and do you have any suggestions? It's effectively like fixing everything and activating each cylinder pair separately (which is practically possible), then saying "okay, now turn them all on!" Surely since the system is...
Yeah, I was recently getting stuck on solving the fairly trivial problem, M = r x F, with M and r known, and solving for F. I found a solution where
[tab]F = M x r / r • r + k * r, with k = any scalar.
Hence there are an infinite number of solutions, I imagine in a half-plane, since any force...
Okay, so that means the superposition of the reaction force from each cylinder would work. I considered this early on but dismissed the idea after a simple thought experiment, although I can't remember exactly why now. Why then do analyses separate the links and find the reaction forces? Is this...
Just some further information, I just need to provide a quasi-static analysis, and I'm hoping to integrate the solution into an existing spreadsheet. So far I have the below, which I've been generating as I go along (mostly to check that it's all working). I'll probably add a sheet with an array...
Sorry, maybe I wasn't clear enough. All 6 cylinders could be activated together, so it's unlike a backhoe excavator, which is first positioned then has a single activation point, which is probably what you were thinking.
I'm busy with a force analysis of a crawler, pictured below, using Excel. I've colour-coded the main parts into (static) body, yoke, boom and nozzle. I've quickly drawn in the cylinders, but there are 3 pairs: the body/yoke pair swivels the yoke, the yoke/boom pair lifts and lowers the boom, and...
