Mechanical Properties Analysis And Structure Optimization Of Body-in-white Based On Finite Element Method

Integral body structure is widely used in modern cars.Without car frame, themass and the height of vehicle can be reduced, vehicle handling performance and fueleconomy also can be. High stiffness, lighting weight is becoming the goal ofautomobile body-in-white design. As a significant part of CAE, finite elementanalysis has a great calculating ability，and it plays an important role in the field ofvehicle engineering design. Finite element analysis can improve the body designefficiency. The whole body design process became more systematic and standardized.The main content is as follows.1.Established a finite element model of body-in-white with finite elementpre-processing software Hypermesh based on the finite element method. Comprisedsimplification and repair of geometric model, the balance between quantity of gridand economic, and the selection of element type. Research of form of body partsconnection also be done.2. Established the constraints and loads of bending and torsional conditions.Calculated the static stiffness of car body with finite element software Nastran,included the stiffness calculation of ultimate bending and torsional conditions.3. The necessity of modal analysis of white body was discussed. The free modalanalysis of body-in-white was carried out, received low order vibration frequency andtypes of the body-in-white. Avoided low order frequency of body-in-white coupledwith the engine idling frequency and result in resonance.4Sensitivity analysis is completed on the basis of optimization, with the bodymass as the optimized object, body stiffness and modal for the constraints of theoptimization design, body thickness as design variables, selected certain parts of theplate body thickness as design variables, to reduce the body weight. Improved thebody static and dynamic performance.