The drive shaft AB of an automobile is to be designed as a thin-walled tube. The engine delivers 150 hp when the shaft is turning at 1000 rev/min. Determine the minimum thickness of the shaft’s wall if the shaft’s outer diameter is 3 in. The material has an allowable shear stress of τ allow = 8 ksi.

Respuesta :

Answer:

thickness  0.106 inc

Explanation:

outer radius of shaft is given as [tex]= \frac {d_o}{2} = 3/2 = 1.5 inch[/tex]

power = 150 hp = 150*550 lb- ft/s

angular velocity is given as \omega = [tex]\frac{2 \pi N}{60}[/tex]

[tex]\omega =\frac{2 \pi 1000}{60}  = 104.71 rad/s[/tex]

we know that torque is given as [tex]T =\frac{P}{\omega}[/tex]

[tex]T = \frac{150*550}{104.71}[/tex]

T = 787.89 lb.in

T =9454.67 lb ft

minimum allowable  shear stress is given as

[tex]\tau = \frac{Tr_0}{\frac{\pI}{2}(r_o^4 - r_i^4)}[/tex]

[tex]8 *10^{3}=  \frac{9454.67*1.5}{\frac{\pI}{2}(1.5^4 - r_i^4)}[/tex]

[tex]r_1 =  1.39 inc[/tex]

[tex]thickness = r_o - r_i = 1.5 - 1.39 = 0.106 inc[/tex]