Two plates X and Y are to be clamped together using a Metric hexagonal bolt-nut system (12 mm nominal diameter, coarse pitch with ISO property class 10.9) as illustrated in Figure 1. Two-washer mechanism is used to distribute the clamping load onto the joined members more evenly (underside of bolt head and upper side of the washer face, respectively). Both nut and washer are specified to be of regular size. The bolt initial tightening is set to be preloaded to 85% of its proof strength. The joint is expected to be a load-bearing for a structure subjected to a fatigue load oscillating in between P = 0 N and P = 16,000 N. The ambient properties at which the joint will normally operate is summarised as in Table 1. Take the elastic modulus for each component in the joint to be steel, E = 207,000 MPa. From the given technical specifications, design the prescribed joint system by first specifying a suitable length for the bolt (to the nearest next 5 mm) and subsequently, determine; 1) Fatigue design safety factor according to modified-Goodman criterion, (nf) Goodman 2) Design safety factor against first-cycle yielding, nyield and 3) Design safety factor against joint separation, nseparation [CO2, PO2, C5] d = 12 mm P12 P12 Y L = 80 mm D = 34 mm P/2 P/2 Figure 1 Table 1 Factor No. Service factor Technical requirement legend 1. Surface preparation ka Machined/cold-drawn 2. Size effect kb 12 mm (round) 3. Loading effect kc Purely in tensile 4. Operating temperature kd 5. Design reliability ke 150 C 99%