Research Of The Equivalent Drawbead Model Based On The Deformation Characteristics

In the numerical simulation of deep drawing,due to the small size of drawbead comparing with mould,if the real drawbead is implied in the finite element model,the elements should be divided into small enough to establish the drawbead structure,thus increase the difficulties to solve the problem,so the equivalent drawbead model is carried out in the finite element analysisi software.Now the method to establish the equivalent drawbead model include resistance line method,spring element method and projection plane method,but these methods did not consider the deformation characteristics of sheet when the blank go through drawbead,and the calculation precision should be improved.In this article,the deformation process that sheet go through the drawbead are studied by using ABAQUS software,to reveal the deformation characteristics that the blank repeated bending-straightening when it go through the drawbead,found the thinning occurs mainly at the upper and die fillet,and using the orthogonal design,the influence of structural parameters of drawbead on the drawbead resistance force and deformation of sheet when it go through drawbead.Based on resistance line method for equivalent drawbead model,programming by user subroutine in ABAQUS software which provid the interface of second-developement,established a dual-line drawbead model that contain drawbead resistance force and the characteristics of deformation that the sheet go through drawbead.In the model,drawbead is simplified as two lines,the sheet units on two lines which are impied resistance force and tensile force,respectively,and the resultant force is equal to the drawbead resistance force,also the tangential strain of sheet after equivalent drawbead is equal to that calculated by real drawbead.In ABAQUS software,using resistance line method and dual-line method the two kinds of equivalent drawbead model,the deformation process that sheet go through the equivalent drawbead is simulated,comparing the numerical simulation results,the result error of thickness and tangential strain of the sheet after deformation by using the resistance line method is large,but the tangential strain error after sheet deformation that calculated by using dual-line method is small compared with the resistance line method,the calculation accuracy is obviously improved.Choosing three kinds of drawbead structure,using the dual-line method of equivalent drawbead model to simulate the box deep drawing,contrast with the experiment results,the steel thickness error after deep drawing is 9.65%,the resistance line method equivalent draw bead model calculation precision is improved obviously,dual-line method of equivalent draw bead model can be well applied to the numerical simulation analysis of sheet metal stamping forming.