In a connection using 5/8-inch Φ (UNF-18, SAE Grade 8) bolts,each bolt is subjected to a varying axial load between 10 Kips to20 Kips. Bolts can be preloaded between 0% (none) and 100%, at 10%intervals, of their proof strength.
What range of preload is ideal so that the fatigue life of thisjoint is infinite without join separation?
Use Modified Goodman Criteria for fatigue and showcalculations for the preload levels between 0% and 100% (or atleast the two cases of 0% and 50%). Calculate max stress and factorof safety for infinite life vs. preload as % of proof strength;find gross yielding & joint separation of bolts; thenestablish a workable range and ideal value forpreload.
