The cap of an automotive connecting rod is secured by two class 10.9, M8 x 1.25 bolts with rolled threads. The grip and unthreaded length can both be taken as 16 mm. The connecting rod cap (the clamped member) has an effective cross-sectional area of 250 mm2 per bolt. Each bolt is tightened to an initial tension of 22 kN. The maximum external load, divided equally between the bolts, is 18 kN.
(a) Estimate the bolt-tightening torque required.
(b) What is the maximum total load per bolt during operation?
(c) Figure P10.48 shows free-body diagrams for zero load. Make a similar pair of free-body diagrams when the maximum load of 18 kN is pushing downward on the center of the cap.
(d) What is the safety factor (factor by which the 18-kN load could be multiplied) for fatigue? Assume an idealized stress-strain curve based on Sy.
