Oil Bearing Calculations in Ship Diesel Engines Using
MotionSolve
Steen Cosmus Thaning, MAN Diesel
MAN Diesel design large two-stroke Diesel in-line multi cylinder
engines with a crosshead bearing for ship propulsion and power
plants. In this work, the moving parts of a 98 cm bore engine
have been modeled using MotionSolve. The parts were meshed
in HyperMesh and some parts, e.g. the crankshaft were treated
as elastic bodies in the simulation. Two versions of the main
bearings have been simulated. One version is made with constant
spring stiffness in all directions. Another version is modeled
by varying the deflection response with the applied forces
as found by use of a contact FE analysis of the bedplate.
Furthermore, as all bearings are lubricated an oil film analysis
was done simultaneously by use of a user subroutine. Loading
to the system was made by adding the gas forces on top of
the pistons while balancing the speed by a torsional damping
element. Here, we will present some results for the crankshaft
deflection for both the constant stiffness main bearings and
the variable flexibility main bearings. The results show that
the influence is varying throughout an engine. It is also
shown that an oil film analysis can be run together with a
MotionSolve analysis.
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