The shaft, made of aisi 1040 cd steel, rotates at 1600 rpm and is supported in the rolling bearings at a and b. the applied forces are f1=2500 lbf and f2=1000 lbf. determine the minimum fatigue factor of safety based on achieving infinite life. if infinite life is not predicted, estimate the number of cycles to failure. also check for yielding. (hint: use attached charts to calculate static stress concentration factors kt and kts and dynamic stress concentration factors kf and kfs at steps in shaft.)