Theoretical Analysis And Finite Element Simulation Of Residual Stress On Cold-Formed Profiled Steel

In the cold bending process,there are two kinds of processing methods that direct bending forming and multi-stand continuous bending forming.In this paper,the residual stress produced by the two kinds of bending methods was studied by theoretical analysis and finite element method respectively.In this paper,the elastic-plastic bending theory was used to analyze the various processes that may affect the cold bending residual stress,including the process of coiling,uncoiling,flattening,bending and rebounding.Then,the residual stress of cold bending by different uncoiling modes was calculated depend on the assumption that the materials is the ideal elastic-plastic body and the kinematic hardening body,and the algebraic expression of cold bending residual stress was obtained.Based on this theory,the residual stress of Q345 steel and WYS600 high strength steel blanks with thickness of 4mm,6mm,8mm and 10 mm were calculated.By comparing the calculated results with the measured results,it shows that the theoretical method is verified.Then,the residual stress distribution along the thickness direction was obtained.And the influence law of the material constitutive relation model,the relative bending radius,the uncoiling method and the steel type on the cold bending residual stress were researched.The ABAQUS/Explicit dynamic display algorithm was used to simulate the three-step continuous roll forming of the Q345 steel blank with the thickness of 8mm by using the finite element analysis software ABAQUS.The blank was bent into 90 degree forming piece.Then,the ABAQUS/Standard static implicit algorithm was used to analyze the springback of the forming parts,and the distribution of the cold bending residual stress was obtained.The simulation results are basically the same as the measured results.