Studies On Dynamic Characteristics Of Marine Diesel Engine Crankshafts Via Rigid-flexible Hybrid Model

The diesel engine crankshafts is one of the important moving parts in the diesel engine, which bears complex, alternating gas pressure and inertia force.The traditional crankshafts characteristics study is about rigid model, but the crankshafts parts and components of the actual working condition are elastomer, prone to small elastic deformation with the external load,leading to the complicated of interaction force between different parts and components. The traditional analysis methods is difficult to meet the requirements of increasing calculation accuracy, but the rapid development of virtual prototyping technology and finite element method makes us be able to do the kinematics and dynamics simulation analysis research on the crankshaft system.The marine 6300 C diesel engine crankshafts was taken as the study object in this paper. Firstly, Pro/E modeling software was used to create the entity model of crankshaft system parts and components, and was assembled to get the assembly data model of the crankshaft system. It was imported into Multi-body dynamics simulation software ADAMS, kinematic pair and quality attributes were defined, external load and drive was applied, Multi-rigid-body dynamics model of the crankshaft system was created and the displacement was calculated, velocity, acceleration of every components in anytime and anywhere and the force etc.. Then finite element software ANSYS was used to do calculating modal analysis of the crankshaft and connecting rod of the 6300 C diesel engine respectively, the natural frequency and vibration mode was required, the modal neutral file(MNF) of the crankshaft was generated and rod was connected respectively. The modal neutral file(MNF) of the crankshaft was imported and rod Generated in ANSYS was connected to the Multi-rigid-body dynamics model of the crankshaft system respectively, the crankshaft was made and rod flexible was connected, the simulation results of the Multi-flexible-body dynamics and the Multi-rigid-body dynamics was contrasted, the Athletic performance of The crankshaft system parts and components and the effect of the force between parts of the two different model was got. At last, the dynamic load files of the connecting rod from flexible model was exported, Stress and strain was analysed, the most dangerous part when it is working was found, and reliability was analysed.The simulation analysis work of the crankshaft system dynamics of diesel engine was finished by combination of virtual prototyping technology and finite element analysis tools, The actual working conditions were more closer, very good research results was obtained, support for the precise design of the crankshaft system parts and components of the diesel engine and reference for the follow-up connecting rod optimization work was provided, very important significance for improving the design level and the whole machine performance of diesel engine was supplied.