Shenoy and Fatemi [6] conducted dynamic analysis of
loads and stresses in the connecting rod component,
which is in contact with the crankshaft. Dynamic analysis
of the connecting rod is similar to dynamics of the
crankshaft, since these components form a slide-crank
mechanism and the connecting rod motion applies
dynamic load on the crank-pin bearing. Their analysis
was compared with commonly used static FEA and
considerable differences were obtained between the two
sets of analysis. Shenoy and Fatemi [7] optimized the
connecting rod considering dynamic service load on the
component. It was shown that dynamic analysis is the
proper basis for fatigue performance calculation and
optimization of dynamically loaded components. Since a
crankshaft experiences similar loading conditions as a
connecting rod, optimization potentials of a crankshaft
could also be obtained by performing an analytical
dynamic analysis of the component.
A literature survey by Zoroufi and Fatemi [8] focused on
durability performance evaluation and comparisons of
forged steel and cast iron crankshafts. In this study
operating conditions of crankshaft and various failure
sources were reviewed, and effect of parameters such
as residual stress and manufacturing procedure on the
fatigue performance of crankshaft were discussed. In
addition, durability performance of common crankshaft
materials and manufacturing process technologies were
compared and durability assessment procedure, bench
testing, and experimental techniques used for
crankshafts were discussed. Their review also included
cost analysis and potential geometry optimizations of
crankshaft.
In this paper, first dynamic load analysis of the
crankshaft investigated in this study is presented. This
includes a discussion of the loading sources, as well as
importance of torsion load produced relative to bending
load. FE modeling of the crankshaft is presented next,
including a discussion of static versus dynamic load
analysis, as well as the boundary conditions used.
Results from the FE model are then presented which
includes identification of the critically stressed location,
variation of stresses over an entire cycle, and a
discussion of the effects of engine speed as well as
torsional load on stresses. A comparison of FEA
stresses with those obtained from strain gages of a
crankshaft in a bench test is also presented. Finally,
conclusions are drawn based on the analysis preformed
and results presented.