Research On Vibration Performance And Structure Optimization Of Vehicle Roof Based On Variable Density Method

The way to travel of human was changed by the birth of automobile.With the high speed development of automotive technology,performance and fuel economy of automobile have already reached its peak value,both performance and fuel economy could meet the requirements of the majority of consumers.So in recent year.The comfort of vehicle has become the another one standard of consumers to purchase vehicles.The vehicle roof is the largest metal parts of the white vehicle body.Easily radiation noise to inside of car caused by the resonance in low frequency.As the same time.The vehicle roof act as a role whos need to protect the driver and passengers,Its safety perfomance also should not be ignored.So it is necessary to study on the vibration performance and structure optimization of vehicle roof.A domestic cars act as the research object in this article.This paper focuses on the proplem of booming noise when the engine working in 1600r/min~1800r/min.The reason was gotten through the analysis of this noise problem that is caused by abnormal roof vibration,Therefore the vehicle roof structure was optimized based on the variable density method.Multi-objective optimization analysis was performed for the roof mode frequency、anti-dent performance and crushing performance by the ISIGHT softwar.The main research content is as follows to the booming noise problem:(1)The modal test of vehicle roof was tested by the LMS.Test.Lab softwar,To obtain the natural frequencies and natural modal shape.(2)Using a 3D software to building the CAD mode of vehicle roof and its connect parts.Import the CAD mode to the HyperMesh software and pre-processing to it,such as: meshin、set materials and properties、add boundary conditions and difine contact.Statics analysis of the vehicle roof was calculated by the solver of OptiStruct.Prove the validity of the CAE model by compared he simulation data and experimental data.Do some dynamic analysis on the roof according with some related corporate standards and national standards.To get the anti-dent performance and crushing performance of vehicle roof.(3)Set the vehicle roof to the design area except the sun-roof and optimize the design area by using SIMP topology optimization.Combined with topology optimizaion results and engineering application.Forming the optimized vehicle roof stiffener layout,Then the statics and dynamics simulation analysis was complete according to the above research works.(4)Using th ISIGHT software combined the OptiStruct solver and Abaqus software,Set the thickness of stiffeners as variables,Getting the sample data of variables by using the Optimal Latin hypercube design method,and forming the RSM approxination models of a multi-objective optimization problem of the vehicle roof.(5)The calculation results show that:the vehicle roof-optimized avoid the resonance range of the second-order frequency of engine,as the same time,The anti-dent perfomance and crushing performance of optimized roof has got a obvious improve.The research methods and results in this paper can provide some related experience to the vibration perfomance study of similar vehicle roof,and has a certain practical application value.