Purpose -Incremental sheet forming represents a promising process in the manufacturing of metallic components, particularly its variant known as single point incremental forming (SPIF). The purpose of this paper is to test and validate the results coming from numerical simulation of SPIF processes using the reduced enhanced solid-shell formulation, when compared to the solid finite elements available in ABAQUS software. The use of SPIF techniques in the production of small batch components has a potential wide application in fields such as rapid prototyping and biomechanical devices. Design/methodology/approach -Incremental forming processes differ from conventional stamping by not using a press and by requiring a lower number of tools, since no dedicated punches and dies are necessary, which lowers the overall production costs. In addition, it shows relative simplicity and flexible setup for complex parts, when compared with conventional technologies. However, the low speed of production and low-dimensional accuracy levels are still the main obstacles for a wider application of this technique in the context of large production batches. Findings -In this sense, the use of numerical simulation tools based on the finite element method (FEM) can provide a better understanding of the process' peculiarities. However, there are differences on using distinct finite element formulations, regarding accuracy as well as CPU times during simulations, which can be prohibitive in some cases. Originality/value -Aiming to provide sounding improvements in these two fields (robustness and cost effectiveness of FEM solutions), the present work encloses a preliminary study about some relevant parameters in the FEM simulation of SPIF. Special focus is given to the use of solid-shell and solid finite elements, for the sake of generality in modelling, as well as implicit solution schemes for the sake of accuracy. Finally, results coming from both experimental data and commercial FEM packages are compared to those obtained by a reliable and cost-effective solid-shell finite element formulation developed and implemented by the authors.

Single Point Incremental Forming (SPIF) is a dieless manufacturing process in which a sheet is deformed by using a tool with a spherical tip. This dieless feature makes the process appropriate for rapidprototyping and allows for an innovative possibility to reduce overall costs for small batches, since the process can be performed in a rapid and economic way without expensive tooling. As a consequence, research interest related to SPIF process has been growing over the last years.Numerical simulation of SPIF process can be very demanding and time consuming, mainly due to the the high non-linearity and constantly changing contact conditions between the tool and the sheet surface, as well as the nonlinear material behavior combined with non-monotonic strain paths. To reduce the simulation time, in the present work an adaptive remeshing technique is proposed being implemented in the in-house implicit finite element code LAGAMINE. This remeshing technique automatically refines only a portion of the sheet mesh at the tool's vicinity, therefore following the tool's motion. As a result, uniformly refined meshes required for accuracy purposes are avoided and consequently, the total CPU time can be drastically reduced.In this work, the proposed automatic refinement technique is applied developed within a Reduced Enhanced Solid-Shell (RESS) framework to further improve numerical efficiency. Finally, validations by means of benchmarks are carried out, with comparisons against experimental results. Keywords

No abstract

Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and small batch production, which enables dieless production of sheet metal parts. This research area has grown in the last years, both experimentally and numerically. However, numerical investigations into SPIF process need further improvement to predict the formed shape correctly and faster than current approaches.The current work aims the use of an adaptive remeshing technique, originally developed for shell and later extended to 3D "brick" elements, leading to a Reduced Enhanced Solid-Shell formulation. The CPU time reduction is a demanded request to perform the numerical simulations. A two-slope pyramid shape is used to carry out the numerical simulation and modelling. Its geometric difficulty on the numerical shape prediction and the through thickness stress behaviour are the main analysis targets in the present work. This work confirmed a significant CPU time reduction and an acceptable shape prediction accuracy using an adaptive remeshing method combined with the selected solid-shell element. The stress distribution in thickness direction revealed the occurrence of bending/unbending plus stretching and plastic deformation in regions far from the local deformation in the tool vicinity.