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A flywheel is mounted on a vertical shaft. The both ends of a shaft are fixed and its diameter is 50 mm. The flywheel has a mass of 500 kg, the modulus of rigidity for the shaft material is 80 GN/m2 and its radius of gyration is 0.5 m. Find the natural frequency of torsional vibrations.

A flywheel is mounted on a vertical shaft. The both ends of a shaft are fixed and its diameter is 50 mm. The flywheel has a mass of 500 kg, the modulus of rigidity for the shaft material is 80 GN/m2 and its radius of gyration is 0.5 m. Find the natural frequency of torsional vibrations. Correct Answer 5.32

We know that J = πd4/32 = 0.6×10-6 m4 q1 = 56×103 q2 = 84×103 q = 140×103 therefore using the formula for fn we get fn = 5.32 Hz.

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