Research On Gravity And Binder Wrap Algorithm Of Sheet Forming Simulation Based On DKT12 Shell Elements

As one of important manufacturing methods in the modern industrial system,sheet forming is widely used in the field of aerospace and automobile manufacturing.With the development of computer technology,multi-step quick forming enable products to obtain preliminary evaluation of formability efficiently.To ensure this method analyzes large complex parts accurately and steadily,this article researches gravity algorithm in consideration of bend effect and binder wrap algorithm based on curved binder surface in order to accord with actual production conditions.In consideration of bend effect,multi-step quick forming adopts DKT12 shell elements as finite element model.Firstly,element coordinate transformation matrix between local coordinate system and global coordinate system is deduced.Then element stiffness matrix and node internal force are deduced according to the Kirchhoff theory.Study geometric penetration judgment algorithm between sheet configuration nodes and die mesh and research contact search algorithm based on bounding box in gravity algorithm.Confirm geometrical relationship between sheet configuration nodes and die master surface element and project penetration nodes to die master surface.In the binder wrap stage,determine the basic idea of binder wrap of complex parts based on curved binder surface and research critical technology to solve sheet configuration after binder wrap based on direct projection method.Firstly,Confirm the projection range of sheet nodes by global search algorithm.Then,determine specific projection position by local search algorithm based on arc length method.Finally,obtain intermediate configuration on bend binder surface by iterative computations.Finally,take three complex automobile covering parts as examples to verify effectiveness?accuracy and stability of multi-step quick forming that combines gravity algorithm and binder wrap algorithm.