| The use of new lightweight materials has become a key technology for the automotive industry to cope with the problems of energy shortage and environmental pollution.In this paper,two commonly used lightweight materials,High Strength Steel plate(HSS)and Carbon Fiber Reinforced Polymer(CFRP)were combined to obtain Steel/CFRP laminates car body components with more excellent comprehensive performance.At present,a lot of research has been done about stamping springback problems of single metal sheet,but the research on springback of Fiber-Metal Laminates is rare.Therefore,based on the springback problems often occurring in the stamping forming of automobile body components,the Steel/CFRP laminates constituted by alternately laying steel sheet and Carbon Fibre Reinforced Polymer were subjected to warm bending forming experiment to study the springback behavior of the bending components after forming.The main research contents are as follows:(1)The bending forming and springback theory of single metal sheet and FMLs were analyzed.The experimental research scheme of Steel/CFRP laminates bending forming was designed,and based on the forming requirements and experimental scheme,bending forming die with the functions of forming,heating,temperature control and punch changeability was developed independently.U-bending experiments of pure steel plate,pure CFRP and Steel/CFRP laminates were completed by using the designed die;(2)The bending springback of Steel/CFRP laminates U-shaped parts,which are influenced by the fiber direction,CFRP layers and the punch fillet radius,were quantitatively compared and qualitatively analyzed.The influence law and mechanism of the above factors on bending springback of Steel/CFRP laminates U-shaped parts were investigated.The results show that Steel/CFRP laminates U-shaped parts with high shape accuracy and forming quality can be achieved by increasing CFRP layers of[0°] fiber direction,increasing total CFRP layers and adopting appropriate punch fillet radius;(3)The forming ability of pure CFRP bending parts and Steel/CFRP laminates bending parts were compared.The forming characteristics of the above bending components and the interface bonding state of bending areas of Steel/CFRP laminates bending parts were described,and the reasons of producing related forming characteristics and interface bonding state were analyzed;(4)The constitutive relationship model of Steel/CFRP laminates was established,and the model parameters,the basic performance parameters were determined by unidirectional tensile test.The bending forming and springback process were simulated on ABAQUS software platform,and the simulation springback values were compared with the experimental measurement values.The results show that the variation trend of simulation springback values affected by different factors is highly consistent with the variation trend of the springback values obtained from the experiments;(5)Based on the theory of bending springback of sheet metal and relevant reasonable assumptions,the bending springback prediction model of Steel/CFRP laminates was proposed.Combined with the springback values obtained from the experiments,the model parameters affected by fiber direction,CFRP layers and punch fillet radius were determined by curve fitting method,and the bending springback prediction model of Steel/CFRP laminates affected by the above factors was established.Comparing the calculated values of the prediction model with the springback values obtained from the experiments,the results show that the prediction model has good prediction accuracy,and the coincidence between the predicted values and the experimental values is over 88%. |
