Low Vibration Design Analysis Of Diesel Engine Block Based On The Virtual Technology

The power, fuel economy and emission characteristics of the diesel engine lead to be used more and more widely. However, with the improvement of diesel engines'power density, it causes excessive vibration, which makes the applied range be limited. This thesis combines multi-body dynamic analysis, finite element analysis and topography optimization design to explore methods of predicting the diesel engine's vibrating level and improvement measures of decreasing the entire diesel engine's vibrating intensity.The paper considers a diesel engine with six-cylinders in-line as its research object. Firstly, it analyses the rationality of geometric parameter design of the diesel engine simulation model by adopting Pro/ENGINEER software on assembly modeling of the diesel engine's major components. Through mesh generation it sets up the finite element analysis model of major components to achieve the modal neutral files of its crank axle, body and head. Through exact restrain and combustion pressure-driven exerted by flexible dynamics diesel engine simulation model and Mechanism Dynamics Simulation Analysis it achieves the body's major mechanical excitation forces by the motion structure in order to lay foundations of finite element dynamic response analysis.Secondly, it builds the finite element computation model of the diesel engine dynamic response analysis. Through the finite element computation mode analysis on the major components, body and crank axle of the diesel engine, the result of experiment modal analysis verifies the correctness of finite element computation mode analysis and the validity of the set-up dynamic analysis model. Through the mechanical excitation force by reasonably exerting boundary condition, combustion pressure-driven burdening and mechanism dynamics, it takes use of finite element dynamic response analysis to calculate the response of diesel engine surface vibration. The testing results of the entire diesel engine vibrating intensity demonstrate the correctness of simulation analysis results and the validity of infinite element dynamic response analysis method on complicated diesel engine structure dynamic response analysis.Finally, it considers a diesel engine with four cylinders in-line as the research object. By using topography optimization it makes improvement design on low-vibration structure of the body, especially taking the more-intensive vibrating crank case as design object. The comparison between the computation results of vibrating intensity of before-and-after improving designs shows that the improved diesel engine vibration, especially the vibrating level of the crank case, makes obvious improvement, which achieves low-vibration design goal of the body.