1. Two identical steel members are clamped with a single 1/2-20 UNF grade 7 bolt, with the left member fixed. The members are subjected to an external load that reverses between 0 and 14,000 lb repeatedly. The length of the bolt is two threads beyond the nut. The bolt is initially tightened to 75% of its full proof load. Determine the factors of safety against yielding, overloading, and separation, respectively. Also, estimate the torque necessary to develop the preload.
Steel Bolt Reversing Load 0 to F
Sheet member
2. For Problem 1, it is suspected that the fatigue life of the bolt is finite. Suppose the stiffness of the joint has been adjusted to 0.2, i.e., C=0.2. After the fluctuating load has been applied for 200,000 cycles, one decides to lower the load so that the bolts can have an infinite fatigue life. Estimate the new endurance limit of the bolts, after 200,000 cycles of the fluctuating load applied, using the Manson's method and based on the Goodman fatigue criterion.
