Comparison of stresses at locations c and d resulting
from loading in direction 1 in Figure 7 show symmetric
stress values from FEA, experiment, and analytical
method. The results from these three methods are close
to each other. However, stresses obtained form FEA
results and experiment show different stresses (i.e. nonsymmetric) at locations a and b, resulting from loading in
direction 2 in Figure 7. On the other hand, stresses
calculated from the analytical method are symmetric at
these two locations (+/-72 MPa) and different from the
obtained values from FEA and experiment. Therefore,
the use of FE model in the analysis is necessary due to
geometry complexity.
Stress results from FE and analytical results have similar
symmetric values for stresses on the main bearing away
from fillet areas. FE results show different stress values
on the fillet area of main bearing. The reason is the
eccentric cylinders geometry which will result in changes
in Kt value around the fillet area.
Load variation over a cycle results in variation of stress.
For proper calculations of fatigue damage in the
component there is a need for a cycle counting method
over the stress history. Using the rainflow counting
method [11] on the critical stress history plot (i.e.
location 2 in Figure 9) shows that in an entire cycle only
one peak is important and can cause fatigue damage in
the component. The result of the rain count flow over the
stress-time history of location 2 at the engine speed of
2000 rpm is shown in Figure 13. It is shown in this figure
that in the stress history of the critical location only one
cycle of loading is important and the other minor cycles
have low stress amplitudes.