03-02ChapGere.0014

# 03-02ChapGere.0014 - A-PDF Split DEMO : Purchase from...

This preview shows page 1. Sign up to view the full content.

Problem 3.7-2 A motor drives a shaft at 12 Hz and delivers 20 kW of power (see figure). (a) If the shaft has a diameter of 30 mm, what is the maximum shear stress t max in the shaft? (b) If the maximum allowable shear stress is 40 MPa, what is the minimum permissible diameter d min of the shaft? Solution 3.7-2 Motor-driven shaft SECTION 3.7 Transmission of Power 217 d 12 Hz 20 kW f 5 12 Hz P 5 20 kW 5 20,000 N ? m/s T ORQUE P 5 2 p fT P 5 watts f 5 Hz 5 s 2 1 T 5 Newton meters (a) M AXIMUM SHEAR STRESS t max d 5 30 mm T 5 P 2 p f 5 20,000 W 2 p (12 Hz) 5 265.3 N . m (b) M INIMUM DIAMETER d min t allow 5 40 MPa d min 5 0.0323 m 5 32.3 mm Ê 5 33.78 3 10 2 6 m 3 d 3 5 16 T p t allow 5 16(265.3 N . m) p (40 MPa) 5 50.0 MPa Ê t max 5 16 T p d 3 5 16(265.3 N . p (0.030 3 Problem 3.7-3 The propeller shaft of a large ship has outside diameter 18 in. and inside diameter 12 in., as shown in the figure. The shaft is rated for a maximum shear stress of 4500 psi. (a) If the shaft is turning at 100 rpm, what is the maximum horsepower that can be transmitted without exceeding the allowable stress?
This is the end of the preview. Sign up to access the rest of the document.
Ask a homework question - tutors are online