Equivalent Drawbead Model Research Articles

A robust and accurate geometric model for automated design of drawbeads in sheet metal forming

A robust and accurate geometric model of real drawbeads that can be used for the automated design of drawbeads is presented in the paper. A three-dimensional geometric drawbead is a lofted surface, of which the section curves are constructed parallel to the stamping direction on the control points. Adaptive control point interpolation is introduced to simplify the management of the drawbead geometry and avoid unexpected shapes. Given primitive control points on a drawbead curve, dominant control points are adaptively obtained with the shapes of both the drawbead curve and the binder considered. An a priori heuristic parameter adjustment strategy is proposed to correct the parameter errors of section curves, which improves the accuracy and consistency of the drawbead geometry. By incorporating the proposed geometric drawbead with a previously developed intelligent drawbead optimization algorithm, a fully automated design process for drawbeads is realized that includes geometric modeling, finite element analysis, intelligent optimization of the drawbead geometry, and die manufacturing. Finally, a fender example is presented to verify the feasibility and validity of the fully automated drawbead design process. The simulation results with the optimized geometric drawbeads and equivalent drawbeads are compared with the experimental results. The proposed geometric drawbead shows remarkable practicability and accuracy in the automated design of drawbeads in sheet metal forming and demonstrates good consistency with the experimental results while the equivalent drawbead model introduces unneglectable deviations.

Comparing Study on Real Drawbead and Equivalent Drawbead Based on Finite Element Analysis

The dynamic explicit finite element software DYNAFORM was used to simulate the real and equivalent drawbead model. Analyzed the influence of the blank hold force (BHF) and virtual velocity on blank’s deformation behavior after passing through drawbead, compared the results of the FE simulation. The simulation results were confirmed by experiments. The study shows that the equivalent drawbead model can’t simulate the blank’s behavior precisely when it passing the real drawbeads, the effect of BHF on real drawbead model is larger than equal drawbead model; the proper range of virtual velocity was obtained at the same time.

등가 드로비드 모델의 실험적 검증 및 차체 스탬핑 해석에 적용

An equivalent drawbead model(EDM) for sheet metal forming analysis, which replaces complex drawbead geometries with drawbead forces in modeling the stamping dies with finite elements, is experimentally verified and applied to the numerical simulation of auto-panel stamping process. The drawbead restraining and opening forces of elliptical drawbead, circular drawbead, square drawbead, and step drawbead are obtained by performing the drawbead pulling test and compared with those of EDM and commercial code models(CCM). Better agreement with experimental measurements is found in EDM than CCM. Furthermore, the excellence of EDM is demonstrated in its application to the auto-body stamping analysis.

Computational characterization of drawbeads: A basic modeling method for data generation

The purpose of this investigation is to better understand the behaviour and effects in modeling of drawbeads in sheet metal forming simulation. A finite element model is developed to examine how various modeling aspects, such as element size, number of integration points, material hardening, influence the results. Furthermore, some process parameters such as friction and tool geometry are also discussed. In the modeling of drawbeads in large-scale sheet metal forming analysis using finite element methods it is common to use an equivalent drawbead model. This is due to the need for very dense finite element meshes resulting in demands for extreme computer resources. Generation of input data for an equivalent drawbead model has to be reliable and simple. Herein one method is presented on how to use a plane strain model using actual bead geometry to derive data for the equivalent drawbead model as it is implemented in LS-DYNA TM.

An improved equivalent drawbead model and its application

In this work, an improved equivalent drawbead model is presented to replace the actual drawbead shape. Three-dimensional finite element analysis of the deep drawing process was performed to determine the optimum distribution of drawbead restraining force for the stamping of the joint panel of a gate pillar. The optimum design of the drawbead geometry was executed by means of nonlinear constraint optimization in conjunction with the improved equivalent drawbead model. The drawbead geometry parameters obtained from the optimization design were validated by the achievement of defect-free production panels. The simulation results correspond well with those observed in actual practice, which demonstrates that the restraining force can be reflected effectively by the improved equivalent drawbead model.

Three-Dimensional Finite Element Analysis for the Stamping of a Motorcycle Oil Tank

The three-dimensional finite element analysis was performed to determine an optimum die design and the corresponding sheet-blank shape for stamping a part of motorcycle oil tank. To save the computation time, an equivalent drawbead model was adopted to replace the actual drawbead shape in the finite element simulations. The forming limit diagram constructed from stretching tests was also used in conjunction with the finite element results to predict the occurrence of fracture. The optimum die design and the corresponding sheet-blank shape obtained from the finite element analysis was validated by the achievement of defect-free production panels. The advantage of using the finite element analysis for the stamping die design was thereby confirmed.

The implementation of an equivalent drawbead model in a finite-element code for sheet metal forming

Drawbeads are applied in the deep-drawing process to improve the control of the material flow during the forming operation. In numerical methods these drawbeads can be simulated with an equivalent drawbead. In this paper the implementation of an equivalent drawbead model in a finite-element code is described. The input for the equivalent drawbead consists of a drawbead restraining force, a plastic thickness strain and a drawbead lift force, which are obtained from a two-dimensional drawbead simulation or from an experiment. Two different mathematical descriptions of the implementation of the plastic thickness strain are pointed out. The correlation between the simulation results gained with the different algorithms is presented in this work.

Analysis of an equivalent drawbead model for the finite element simulation of a stamping process

In order to facilitate the three-dimensional finite element analysis for the stamping process, an equivalent drawbead model was adopted to simulate the restraining effects produced by the real drawbead. In the present study, the restraining force exerted by the real drawbead was first computed by the finite element simulation, and the optimum pseudo drawing speed and mesh sizes for both the drawbead and sheet metal employed in the computation were determined through a systematic approach. The computed restraining force was then assigned to a regular mesh which replaced the mesh of the real drawbead. This constitutes the equivalent drawbead model, which avoids the extremely fine mesh required to describe the deformation of sheet blank in the drawbead area. In consequence, a huge amount of computation time can be saved. The accuracy of the finite element simulations using the equivalent drawbead model was validated by both the experimental data and the theoretical predictions.