transmission shaft size

[kikko088]

hello to all, I am new to the forum and my name is francesco.
I have some questions to ask, I have to size a transmission shaft consisting of pulley, bearing, toothed wheel, bearing.
I have to find the diameter of the shaft at the height of the first bearing (between pulley and toothed wheel).
to find the diameter use the following formula:

(d)(32*mf*bk)/(3.14*critical puzzle*c1*c2))^2+(16*mt)/(3.14*th yield)^2)^1/6

the moments I know them, while bk (carving factor), c1 (surface finishing coefficient), c2 (scale factor) are unknown.
I'll take it 0,9-0,95, but c2 and bk?
c2 depends on the smaller diameter of the shoulder, bk instead depends on alfak (form coefficient d/d) and nk (intellect sensitivity coefficient that depends on the shoulder connection radius for me unknown).
How do I proceed for the calculation of the diameter?
Do I decide the bracket radius according to the law 0.017<r/d<0,07? and subsequently the d/d ratio according to law 1,05<d/d<1,4?
I thought I'd find a diameter of first tentative using bk=c2=1 but I don't know how to continue. . .
If it wasn't in the middle of c2 and knowing the connection radius of the shoulder, I wouldn't have a problem, but so I have a lot of confusion in my head.

Can you help me?



♪

 

[meccanicamg]

kikko... found the solution?

I would have done the following:
- pre-size for trees (with mf and mt both present)
>= 2.17 * (mfeq/symgma,adm)^1/3
con mfeq = (mfmax^2 + k^2*mtmax^2)^0.5 where k^2=0.25 for high bending, button torsion or constant and k^2=0.75 for high bending and torsion, sigma,sdm = rm/6- static verification with von mises in the section

- test hard, I put the fittings and carvings I want, hypothesize geometric values, I look at the curves of the carvings and I check with goug pollard.

Why complicate my life with a mixed formula between static analysis and carving analysis where I don't know anything? that could also be ok, but then fatigued?

How did you solve it since it's been a few months?