The Research Of Triangular Shell Elements And Its Application On Vehicle Body Design And Manufacturing

Plate and shell structure has been widely used in the automobile engineering,as for automobile body,more than 90%of its structural components are composed of plates and shells.The accuracy and efficiency of the plate and shell element directly affects the accuracy and efficiency of the body's strength,stiffness,modal,and stamping process simulation analysis.Triangular element is particularly attractive for its simplicity in automatic meshing.The Discrete Shear Gap method(DSG3)effectively eliminates the parasitic shear strains.However,the solution of DSG3 is influenced when the sequence of node numbers changes.In order to solve the shortages of DSG3 method,this thesis presents an effective plate and shell element based on central point discrete shear gap method.The dissertation includes:(1)Plate element based on center point discrete shear gap(CP-DSG3)method is proposed.Based on the Reissner-Mindlin hypothesis,a novel plate element is proposed to cure the shortages of DSG3.Moreover,without any increase of internal variables or degree of freedoms,the novel plate element can guarantee the high precision and high efficiency at the same time.The novel plate element analysis code is compiled using Matlab language.The performance of CP-DSG3 plate element is verified by the standard example.(2)Novel shell element is presented based on center point discrete shear gap method.Based on the basic equations of shell and coordinate transformation,the CP-DSG3 shell element is proposed to cure shortages of DSG3.Based on Visual FORTRAN platform,the CP-DSG3 shell element analysis program is compiled to solve the linear problem of the shell and the static stiffness of the vehicle body.The calculation results are compared with the results of DSG3 and CAE software.(3)The proposed CP-DSG3 shell element is utilized to simulate the sheet metal forming process.The yield criterion,elastic-plastic updating algorithm and nodal force are presented for the large deformation analysis.On this basis,the CP-DSG3 shell element is used to simulate sheet metal forming processes,which involve's material,geometric,and contact non-linear.The obtained numerical results are compared with the experimental results.It can be found that the proposed shell element can be utilized efficiently for the sheet metal forming problem and has good practical value in engineering.