A cast-steel C frame as shown in the figure has a rectangular cross section of 1.25 in by 2 in, with a 0.5-in-radius semicircular notch on both sides that forms midflank fluting as shown. Estimate A, rc, rn, and e, and for a load of 2000 lbf, estimate the inner and outer surface stresses at the throat C. Table 3€“4 can be used to determine rn for this section. From the table, the integral ˆ« dA/r can be evaluated for a rectangle and a circle by evaluating A/rn for each shape [see Eq. (3€“64)]. Subtracting A/rn of the circle from that of the rectangle yields ˆ« dA/r for the C frame, and rn can then beevaluated.

0.5-in R. 4.5 in 2000 lbf 1.25 in 1.25-in R. 0.5 in 0.5 in