Question

Question 2 [Shaft design] (10 Marks) The shaft shown is supported by two smooth journal bearings at A and B. Due to the transmission of power to and from the shaft, the belts on the pulleys are subjected to the tensions shown. Determine the smallest diameter of the shaft using the maximum- shear-stress theory, with t,llow = 50 MPa. The radius of the shaft can be obtained 1/3 VM2T2 2 using c JETallow

Answer 1

Heve, the most Ctical Point o ccuYs at since, obending A at that Point, because maximum we know that Mmax y Omark EDistance brom neutal-axiS to heve, the POnt (cVitical) iS at the Pertphery Point =Constant T = Constnt tov a Particulay I=Moment ob inerta GYO -section al mtmbfy S0, MT bgure the brom Now, C w-clock wise CiCw= Coutey clackwise N. Ym T, = 20 N.nm 400 x 0.05 n 71 T2 550 x0.05 - C CoW N m T2 27. 5 = 300x0.075 Nm CW , n Tニ22.5 N.m - 200x0.075 Nim TH C&C.W T4-15 N. m in = tet

that Know we shear StreM maximum at outer phepery TXC C = 2 2 Crnax bor Pav ticular 1o-sechonal T Felar momet of K-d members J C are eonstant sheay nevtia. to get maximum when T i mentimum SO heve out o 나 toveues Max T is . T2 27,5 Nm. boYces NOw 나00 mement due 550 + cM M, M,237.5 Nim 950x0 25 300+ 200 oYces 500x (o.15 +0.25+0.25) due. to moment

MZ =M2 325 N,m here, Mmax 325 Nm M Mmax N.m デ=27.5 M=325 N.m, given bovmua, the brom 2 Yadius, C TT Zaos ソラ 3252+27.52 2. Cこ x 50x10 C 0.01607 m C= 16.07 mm