Question

Select a diameter of a steel driveshaft that transmits 250 hp at 5000 rpm. Bending and axial load are negligible. Note: Select the diameter as 3 inches What is the nominal shear stress at the surface? If a hollow shaft of inside diameter 0.9 times outside diameter is used, what outside diameter would be required to give the same outer-surface stress? How do the weights of the solid and hollow shaft compare? Rotation unknown diameter 250 hp, n = 5000 rpm

Answer 1

Given po 250 hp = 250% 74% Watts N = 5000 rpm. , line 25.4 mm. P = TWT 2504 7462 T* 2T (5000) 60 To 356.1887 nmn Bending and axial load are negligible.. so Torsional shear stress acts, O I = Į » equation of shear stress. ( r= dolz 23 Ja Id", Given d=3in = 342504 mm d=76.9 mm Ie 16x (356.1887 *103) T = 16T * (762) F = 4.1 Mpe] (ths) ; - 0.9do for Hollow shaft ( az dole 1. Je I (dotad) 7+ (do C219) вт 4% o du 3(1-c") Tai tida)
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4.1 = 108.16 mm 1 t = 4.1 Hpa a same outer surface stress - 16x ( 356-1887*103) Tx dost (12.9") [do= 108.16 mm/ (ams) % we mq szequal sug 1 - гара dia a do do = 97.884 mm/ * 1d7af de cdo- d; 2)*& = (76.272 (108.76²- 97.8842) Ws = us WH - 2.58 WH