The 60-mm-diameter shaft rotates at 300 rev>min. This motion is caused by the unequal belt tensions on the pulley of 800 N and 450 N. Determine the power transmitted and the maximum shear stress developed in the shaft.

Answer :

Answer:

Power transmitted in the shaft is 3.3 KW

The maximum shear stress developed in the shaft is 157.5 KPa

Explanation:

d = 60 mm = 0.06 m ⇒ r = 0.03 m, N = 300 rev/min, F[tex]_{1}[/tex] = 800 N, F[tex]_{2}[/tex] = 450 N

To calculate the Power (Work done), we have:

Power (Work done per minute) = Force * distance

Power (Work done per minute) = Average torque * Angular displacement

P = T * 2πN/60

T = (F[tex]_{1}[/tex] - F[tex]_{2}[/tex]) * r = (800 - 450) * 0.3 = 105 N·m

Hence, P = 105 * 2π * 300 ÷ 60 = 3298.67 W

P = 3.299 KW ≈ 3.3 KW

To calculate the maximum shear stress, we have:

Maximum shear stress = twisting moment * radius ÷  Polar Moment of Inertia of Area

Mathematically,

τ[tex]_{max}[/tex] = T[tex]_{max}[/tex] · r / J

For this question T ⇔ T[tex]_{max}[/tex]

The formula for Polar Moment of Inertia of a circular solid shaft is  J = π·[tex]r^{4}[/tex] / 2

J = π * [tex]0.06^{4}[/tex] ÷ 2 = 2 x [tex]10^{-5}[/tex] [tex]m^{4}[/tex]

substitute J into formula for τ[tex]_{max}[/tex], we have:

τ[tex]_{max}[/tex] = 105 * 0.03 ÷ 2 x [tex]10^{-5}[/tex] = 157,500 Pa = 157.5 KPa

τ[tex]_{max}[/tex] = 157.5 KPa

Other Questions