Multi-pass deformation design for incremental sheet forming: Analytical modeling, finite element analysis and experimental validation

Abstract

Abstract:Incremental sheet forming (ISF) is a promising rapid prototyping technology with high potential to shape complex three-dimensional parts. However, a common technical problem encountered in ISF is the non-uniform thickness distribution of formed parts; particularly excessive thinning on severely sloped regions. This may lead to fracture and limit the process formability. Design of multi-stage deformation passes (intermediate shapes or preforms) before the final part, is a desirable and practical way to control the material flow in order to obtain a more uniform thickness distribution and avoid forming failure. In the present paper, a systematic methodology for designing multi-stage deformation passes considering the predicted thickness strains given the design shape is proposed based on the shear deformation and the strain compensation mechanism. In this methodology, two analytical models (M1 and region used in the forming (M2), respectively. The feasibility of the proposed design methodology is validated by finite element analysis (FEA) and experimental tests using an Amino ISF machine. The results show that a more uniform thickness strain distribution can be derived using M2. The incurrence of the highest strains can be delayed in the intermediate stages and the flow of material is allowed into the deformed region, thereby allowing a compressive stress state to develop and enabling steeper shapes to be formed. Therefore, the process formability can be enhanced via the optimized design of deformation passes.

Parameters for the FEA simulations of single point incremental forming

“…Complicated shell theories are required to consider thickness and to make up for the developmental assumptions. In addition, the two-dimensional material law and the assumptions employed in the shells lead to inaccuracies in the description of through thickness variables (Arfa, Bahloul, and Belhadjsalah, 2014;Bahloul et al, 2013;Computational Finite Element Methods in Nanotechnology, 2012;Liu, Daniel, Li, Liu, & Meehan, 2014;Petek & Kuzman, 2010).…”

Part precision improvement in incremental sheet forming of not axisymmetric parts using an artificial cognitive system

“…Recently some authors suggested a multi pass forming strategy [19] which consists of several forming stages, each one giving a partial deformation to the part. Multipass forming allows to obtain 90 • wall angles [20], to form complex parts [21] and to improve the accuracy [22,23].…”

Process Investigation of Incremental Sheet Forming: The Evolution Towards Multi-Pass Deformation Design

“…In Paper E, (Liu, Z.B., Li, Y.L., Daniel, W.J.T., Meehan, P.A., 2014 noting that the results of this study will indicate a further direction on how to optimize process parameters to find a balance between forming efficiency (forming time) and forming quality (forming accuracy and surface roughness).…”

“…In Paper D, (Lu, H.B., Li, Y.L., Liu, Z.B., Liu, S., Meehan, P.A., 2014. Study on step depth for part accuracy improvement in incremental sheet forming process.…”

“…In Paper F, (Liu, Z.B., Liu, S., Li, Y.L., Meehan, P.A., 2014 results. It is demonstrated that the strategic combination A+B is the optimal way to achieve the forming target.…”