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In this paper, finite element prediction of sheet metal forming process is investigated using solid elements. A three-dimensional rigidviscoplastic finite element method with linear tetrahedral MINI-elements is employed. This technique has traditionally been used for bulk metal forming simulations. The solid element approach with remeshing capability is applied to simulating a plate metal forming process to reveal its possible problems. The similar approach is also applied to a typical sheet forming process. Both single- and double-layer finite element mesh systems are studied, with particular attention to their effect on the deformed shape of the workpiece and thickness variation of a cold sheet forming process. The procedure is applied to the well-known problem of the NUMISHEET93 international benchmark. The resulting predictions are compared with experimental observations found in the literature, and good agreement is noted. [ABSTRACT FROM AUTHOR]

For sheet metal parts with the vertical-wall partially and irregularly distributed on the sides (VWPIS) that contains both the difficult-form-surface (i.e., vertical-wall) with large forming angle and easy-to-form surface (i.e., gently tilted surface) with small forming angle, a selective multi-stage two point incremental forming (SMTPIF) on the basis of the forming angle was proposed. This SMTPIF method performs multi-stage forming only for the difficult-form-surface and gives different forming strategies and forming parameters to the different surface regions according to the forming angle. The algorithms for surface zoning, generation of the small forming angle surface for vertical-wall, generation of one-stage forming model by combining the easy-form-surface and small forming angle surface were presented. Meanwhile, the algorithm for the generation of the toolpath that is suitable to the SMTPIF was also given. The effectiveness of the proposed algorithm and the SMTPIF was verified by using the case studies, the finite element analysis, and the forming experiments. The results indicate that the SMTPIF can fabricate the VWPIS with short forming time and no sinking phenomenon. [ABSTRACT FROM AUTHOR]