Concept explainers
A vertical pole of solid, circular cross section is twisted by horizontal forces P = 5kN acting at the ends of a rigid horizontal arm AB (see figure part a). The distance from the outside of the pole to the line of action of each force is c = 125 mm (sec figure part b) and the pole height L = 350 mm.
(a)
If the allowable shear stress in the pole is 30 MPa, what is the minimum required diameter dminof the pole?
(b)
What is the torsional stiffness of the pole (kN · m/rad)? Assume that G = 28 GPa.
(c) If two translation al springs, each with stiffness k =2550 kN/m, are added at 2c/5 from A and B (see figure part c), repeat part (a) to find dmin.
Hint: Consider the pole and pair of springs as "springs in parallel."
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