Abstract
Single point incremental forming (SPIF) is a process with the capability to form complex geometries using a tool of very simple geometry, without the need for a matching die. At present, through-thickness modes of deformation and the existence of through-thickness shear are not clear. The objectives of this report are firstly, to establish a computational methodology to study the deformation mechanism of SPIF and secondly, to provide a clear description of the deformation modes that take place through the sheet thickness. The methodology is, in essence, a multi-level approach, although in this example only two levels are necessary. In this paper, a 3-D implicit finite-element (FE) model of the complete sheet being formed, with two elements through the thickness and a second-level FE model of a smaller segment of the sheet, with seven elements through its thickness, are used in a dual-level approach. The results show that the full model is capable only of exploring the principal characteristics of the deformation, normal strains and the final product geometries. The second-level model demonstrates a capability to predict more accurately the deformation modes through the sheet thickness and shows the influence of tool friction and diameter on the through-thickness shear strains. A combination of bending, stretching and thinning modes of deformation in addition to through thickness shear is found. The results obtained provide a more complete description of through-thickness deformation mechanisms.