Some locations on the geometry were considered for
depicting the stress history. These locations were
selected according to the results of FE analysis, and as
expected, all the selected elements are located on
different parts of the fillet areas due to the high stress
concentrations at these locations. Selected locations are
labeled in Figure 8 and the von Mises stresses with sign
for these elements are plotted in Figure 9. The critical
loading situation is at the crank angle of 355 where the
combustion exerts a large impact on the piston. At this
time all stresses are at their highest level during stress
time history in a cycle. As can be seen, location number
2 experiences the highest stress at this moment.
Therefore, element number 2 was selected as the critical
element. Figure 10 shows the maximum stress, mean
stress, and stress range at the engine speed of 2000
rpm at different locations. It can be seen that element
number 2 not only has the maximum von Mises stress,
but it also carries the largest stress range and mean
stress among other locations. This is important in fatigue
analysis since the range and mean stress have more
influence than the maximum stress. This is another
reason for why having the stress history of critical
elements are more useful than static analysis of the
crankshaft.