| As a most important part of the vehicle, the frame connects the assembly of thecar and remains the relatively correct position. It aslo bears all kinds of complex loadsfrom the process of moving. Therefore, the structure design of the frame is crucial inautomotive design. The finite element method (FEM) is the key technique of theframe design. At present, the frame structure design based on finite element methodfocuses on how to achieve the lightest quality on the condition that the frame hasenough strengh, sufficient stiffness and the reasonable vibration chatacteristics.In this paper, taking the QJJW50mobile police station as research object, wemake use of the finite element theory to study the characteristics of the frame. First ofall, after simplifying the frame reasonably, we establish the three dimensional solidmodel by UG. And then by using HyperMesh and ANSYS software, the finite elementmodel which applied for analysis is built. According to the actual use of electric cars,the paper carries out static analysis of frame structure. After that the stress andstrain,which in the two conditions of bend with full load, torsion with full load,areobtained. The results shows that the stiffness and stength of frame meet the designrequirements.To avoid the occurrence of resonance, the paper analyses the dynamic responseof the frame on free boundary conditions, and the thirteen natural frequencies andmode shapes of the frame are received. Then we evaluate the mode results, it showsthat the dynamic performance of electric vehicles is reasonable.By using the optimization module of ANSYS, the frame model is conductedparametrically.The design variable is the cross-sectional dimensions of the girder, theconstrain condition is the deformation of frame, the objective function is the totalweight of frame, then optimization design of frame is carried out. Finally, the mass offrame is reduced when the requirement of strength and stiffness condition are met. |
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