Civil Engineering MCQJE Level Civil Engineering
A hollow circular shaft with outer dia D = 80 mm and inner dia d = 60 mm carries torque T = 2 kN·m. The maximum shear stress is:
Strength of MaterialsStrength of MaterialsMEDIUM
Choose the correct answer
A
15 MPa
B
29 MPa
C
50 MPa
D
10 MPa
Correct Answer
B. 29 MPa
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τmax = T·R/J. J = π/32×(D⁴−d⁴) = π/32×(80⁴−60⁴) = π/32×(40,960,000−12,960,000) = π×28,000,000/32 = 2,748,893 mm⁴ ≈ 2.749×10⁶ mm⁴. R = 40 mm. τmax = 2×10⁶ N·mm × 40 mm / 2.749×10⁶ mm⁴ ≈ 29.1 MPa. Hollow shaft is more efficient than solid (same J with less material).
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