Topography Optimization Design Of Less Radiated Noise For A Certain Oil Pan

The oil pan has a large proportion of the surface radiated noise of the internal combustion engine.It is important to optimize the structure of the oil pan to reduce the surface radiated noise and to control the radiated noise of the internal combustion engine.In this paper,the vibration characteristics analysis and acoustic radiation analysis of the diesel engine oil pan are carried out.Based on the important parameters such as sound power,modal participation factor and panel contribution,the optimization mode and optimization area are targeted selected.In order to improve the frequency of multi-order dominance modes,the multi-objective topography optimization is applied to the oil pan.Vibration characteristics and radiated noise are obviously improved after optimization.It summarizes and implements a complete and effective analysis and optimization scheme,which has a certain reference significance for the structure optimization of the oil pan and other thin-walled parts.Mainly to complete the following work:(1)The solid model of the oil pan is established.The finite element model with suitable grid unit size of the oil pan is established by the convergence analysis.The modal analysis and the frequency response analysis are carried out to obtain the modal shape,modal participation factor,vibration response and other results.These lay the foundation for acoustic radiation analysis and structural optimization.(2)The boundary element model of oil pan is established.Through the interpolation mapping,the vibration response on the FEM model is transplanted to the BEM model as the boundary condition for the acoustic solution.The indirect boundary element method is used to analyze the acoustic radiation and panel contribution of the oil pan.These provide basis for the selection of the optimization modal and optimization area.(3)Based on the sound power and modal participation factor,the dominant modal with large contribution to the radiation noise is chosen as the optimization modal.Based on the panel contribution and the surface vibration velocity,the area with large contribution to the radiation noise is selected as the optimization area.The design model is obtained by removing the stiffeners of the optimization area of the original model.Select modals of design model similar to the modals of original model as optimized sub-targets.Through the linear weighting method and analytic hierarchy process,multiple sub-targets are unified into a comprehensive goal.In order to improve the multi-order dominance modals,the topography optimization is applied to the design model of the oil pan.(4)Considering the optimization results and the processing technology,the new oil pan model is established.The modal analysis,frequency response analysis and acoustic radiation analysis of the new model are carried out.In the original range of the analysis frequency,the new model is compared with the original model: the total modals decrease,the first ten natural frequencies increase,the surface vibration decreases and tends to be gentle.The maximum and the total value of the surface radiated sound power are reduced.So the optimization design achieves the expected goal.