Research On Lightweight Design Of Composite Body Side Based On Stochastic Finite Element

Sandwich structure has a high ratio of bending stiffness to weight,it has less lateral deformation,higher buckling resistance,and higher natural frequency than a single layer of metal plate.Therefore,by rationally designing the thickness of the sandwich panel,we can obtain a lower-weight sandwich structure similar to the static,strength and buckling properties of a single-layer metal plate.At the same time,considering the spatial randomness of material properties,this thesis uses the stochastic finite element method to study the work of lightweight vehicle body.The main research contents include:(1)Single layer and sandwich plate model and analysisBased on the theoretical analysis of single-layer and sandwich panels,the finite element solution of the displacement and natural frequency of the plate is calculated by using MATLAB software to fully mesh the plate structure,and compared with the analytical solution to verify the accuracy of the finite element method.On this basis,the effects of different properties of sandwich plates on displacement,natural frequency,critical load and sensitivity are studied.(2)Stochastic finite element method and its applicationBy taking the Exponential type random field as an example,the Karhunen-Loeve expansion method of Gaussian random field is studied.By using the function approximation theory,the Galerkin method for solving the eigenvalue problem of random fields is studied.By establishing the random field of the body’s elastic modulus and density,and combining with the finite element method,a numerical method of stochastic finite element analysis is studied to calculate the body response of the vehicle body side considering the material randomness.(3)Study the light weight of vehicle body by using composite sandwich plateBy studying the characteristics of the single-layer metal plate,the suitable sandwich plate material is selected,and the response surface of the composite sandwich plate thickness to displacement,mass and first-order natural frequency is established.The sandwich structure optimization model is established with different objective functions,and the deterministic,stochastic optimization and reliability optimization are carried out.The structural design of the vehicle body side is obtained.On this basis,the effects of different reliability indicators and different coefficient of variation of random field on the optimization results are analyzed.The results show that the sandwich structure can replace the single-layer metal plates.In the project,suitable parameters can be selected according to the requirements to obtain a suitable composite sandwich vehicle body side structure.