Research On Layout Optimization Of Welding Spot For Automobile Body On The Topology Optimization

Resistance spot welding is the most commonly used connection method in the manufacture of vehicle body structure.Generally,there are thousands of welding spots throughout the body structure.In the mass production,even a welding spot is saved,the over cost will be significantly reduced.The reasonableness of the welding spots is not only related to the manufacturing cost of the vehicle,but also to the stiffness,strength,modal frequency and collision performance of the vehicle body structure.In conventional process of vehicle body design and manufacture,the layout of the welding spots depends heavily on the personal experience of the engineers and lacks of systematic guidance program.The number of welding spot are artificially increased to meet the performance of the vehicle,meanwhile this also increases the design and manufacturing costs.On the other hand,the method of the layout of the vehicle body's welding spots based on the experience may lead to the shortage of welding spots in some parts of the vehicle body.So it cannot give full play to the structure and material performance and result in the waste of materials.The unreasonable layout method of the welding spots may also lead to overlarge local tension stress,or even failure of the connection,affecting vehicle safety performance.In this paper,to meet the multi-disciplinary requirements of the vehicle body,the advanced structure topology optimization theory and method were applied to the research on layout optimization of welding spot for automobile body.The static stiffness analysis and modal analysis of the body structure were carried out in the work condition of bending and torsion.The mathematical expression for the weighted coupling objectives and the constraints for the welding spots layout topology optimization problem were pursued.The problem of discrete optimization design of welding spots layout was transformed into the continuous optimization design problem of the welding spots material distribution in the design domain where the welding spots may be arranged.The finite element model of body welding spots topology optimization were established.Based on the result of the welding spots layout topology optimization,the density-spacing interpolation method of welding spots was firstly proposed.The results of the optimization of the welding spots under different interpolation functions was analyzed and compared,selection rules based on the welding spots topology optimization were established to meet multi-disciplinary performance requirements and the solderability.The method of this paper was verified by the B-pillar of the vehicle body,and the number of welding spots were reduced by 16.4% without reducing the structural performance.The optimization model,method,flow and strategy of welding spots layout topology optimization developed in this paper are general utility and good operability.It will be widely applied to the vehicle body and all kinds of welding parts of welding spots layout optimization work.