A structural steel shaft with an outer diameter of 1.9 inches and an applied torque of 82.7 ft*lbs. Find: The maximum torsional shear stress in the shaft. Select one: a)- 736.88 ksi b)- 61.41 psi c)- 1473.76 ksi d)- 736.88 psi e)- 368.44 psi

Respuesta :

Answer:

Answer is part d -736.88  psi

Explanation:

We know that for a bar subjected to pure torsion the shear stresses that are generated can be calculated using the following equation

[tex]\frac{T}{I_{P} } =\frac{t}{r}[/tex]....................(i)

Where

T is applied Torque

[tex]I_{P}[/tex] is the polar moment of inertia of the shaft

t is the shear stress at a distance 'r' from the center

r is the radial distance

Now in our case it is given in the question T =82.7 ft*lbs

converting T into inch*lbs we have T = 82.7 x 12 inch*lbs =992.4 inch*lbs

We also know that for a circular shaft polar moment of inertia is given by

[tex]I_{P}=\frac{\pi D^{4} }{32}[/tex]

[tex]I_{P}= \frac{\pi\ 1.9^{4} }{32} =1.2794 inch^{4}[/tex]

Since we are asked the maximum value of shearing stresses they occur at the surface thus r = D/2

Applying all these values in equation  i we get

[tex]\frac{992.4 inch*lbs}{1.2794 inch^{4} } \frac{1.9 inches}{2}[/tex] = t

Thus t = 736.88 psi