Deformation analysis in single-point incremental forming through finite element simulation

Incremental sheet forming (ISF) is a promising manufacturing technology in which complex 3D shapes can be formed with one simple tool. Compared to conventional forming processes, for complex shapes, it is more flexible and economical with higher formability and shorter lead time. Therefore, ISF is ideally suitable to rapid prototype and small-batch production, especially in the aerospace and biomedical sectors. Over the last decade, although the process has been experimentally studied extensively, the associated deformation mechanics is still unclear and intensive investigation is needed. The purpose of this study is to provide further knowledge of the deformation mechanics of the sheet and clarify the deformation mechanism in a typical cone-forming process through finite element (FE) simulation approach. In particular, comprehensive FE models with fine solid elements are utilised, which allow the investigation of deformation modes including stretching, bending and shearing. The FE model is firstly validated with experimental results in terms of forming forces, and then, the evolution history of all the strain components along with the effective strain is presented. The contribution of each strain component to the effective plastic strain during the cone-forming process is discussed. Moreover, the characteristic of each strain component is investigated in detail. It is confirmed from the FE simulation that the deformation modes in the ISF process are a combination of shearing, bending and stretching, although the quantitative contributions in each direction are varied. The effect of step-down size on material plastic deformation as well as formability is also investigated.