Problem 5-28/5-29/5-30/ Engineering Mechanics Materials

Engineering Mechanics problem with solution
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5-28. The assembly consists of the solid rod AB , tube BC , and the lever arm. If a torque of T = 20 kip in. is applied to the rod and couple forces of P = 5 kip are applied to the
lever arm, determine the required diameter for the rod, and the outer and inner diameters of the tube, if the ratio of the inner diameter di
to outer diameter do, is required to be
di Ndo = 0.75. The rod and the tube are made of material having an allowable shear stress of tallow = 12 ksi.
5-29. The steel shafts are connected together using a fillet weld as shown. Determine the average shear stress in the
weld along section a - a if the torque applied to the shafts is T = 60 N · m. Note: The critical section where the weld fails is along section a - a .
5-30. The shaft has a diameter of 80 mm. Due to friction at its surface within the hole, it is subjected to a variable torque described by the function t = 125xex2
/2 N
mNm, where x is in meters. Determine the minimum torque T0 needed to overcome friction and cause it to twist. Also, determine the
absolute maximum stress in the shaft.