# Numerical - Diameter of shaft - Maximum principle stress theory

Q.  Calculate diameter of shaft using maximum principle stress theory, when equivalent bending moment of 900 x 103 N-mm acts on the shaft when maximum tensile stress does not exceed 50 N/mm2 and equivalent torque of 700 N-m acts on it.
- Published on 14 Sep 15

a. 56.80 mm
b. 52.24 mm
c. 50 mm
d. None of the above

#### Discussion

• Sravanthi   -Posted on 03 Nov 15
- Maximum principle stress theory: According to this theory, failure occurs when maximum principle stress in complex stress system reaches elastic limit stress in simple tension.

Given: Equivalent bending moment = 900 x 103 N-mm, σ = 50 N/mm2 , torque = 700 N-m

According to maximum principle stress theory,

σ = 32 M / π d3

50 = 32 x 900 x 103 / π d3

d3 = 183346.49

d = 56.80 mm

- Diameter of shaft = 56.80 mm

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