A camshaft rotates 650 rpm, causing a follower to raise and lower once per revolution. The follower is to be held against the cam by a helical compression spring with a force that varies between Fmin = 300 and Fx 600 N as the spring length varies over a range of AZ = 25 mm. Ends are to be squared and ground. The material is chrome-vanadium wire, ASTM A232, with Young's modulus E = 203 GPa and shear modulus G = 77 GPa. The wire diameter to be used is d=6 mm. Squared and ground ends ASTM A232 spring wire S S + S S 650 600 N 600 N 300 N 300 N 25 mm a) Determine the spring rate k. b) Estimate the ultimate tensile strength S for the spring material using Table 10-4 at the end of the document. Also estimate the endurance fimit as S. S/2. Finally, calculate the ultimate shear strength as SS/3 and the shear endurance limit as S = S/3 (according to von Mises criterion). c) Using Goodman's rule for shear stress, S determine the maximum allowable midrange shear stress as r where Sum is the midrange shear strength component, S., is the shear strength amplitude, and is the safety factor. Use n = 1.2. n Hint: Observe that S/SFF, where F-F-Fi and Fm = (Fax +Fmin)/2 are the amplitude and midrange of the cyclic loading.