Numerical Simulation of a Pyramid Steel Sheet Formed by Single Point Incremental Forming Using Solid-Shell Finite Elements

Abstract

Single Point Incremental Forming (SPIF) is an interesting manufacturing process due to its dieless nature and its increased formability compared to conventional forming processes. Nevertheless, the process suffers from large geometric deviations when compared to the original CAD profile. One particular example arises when analyzing a truncated two-slope pyramid [. In this paper, a finite element simulation of this geometry is carried out using a newly implemented solid-shell element [, which is based on the Enhanced Assumed Strain (EAS) and the Assumed Natural Strain (ANS) techniques. The model predicts the shape of the pyramid very well, correctly representing the springback and the through thickness shear (TTS). Besides, the effects of the finite element mesh refinement, the EAS and ANS techniques on the numerical prediction are presented. It is shown that the EAS modes included in the model have a significant influence on the accuracy of the results.

Damage prediction in single point incremental forming using an extended Gurson model

“…This fact is also supported by previous simulations using the solid-shell element formulation (e.g. Duchêne et al, 2013;Sena et al, 2013). Localization is nonetheless a different aspect of the deformation.…”

“…Guzmán et al (2012a) showed using the SSH3D solid-shell element for a line test simulation, that the element flexibility modified by EAS modes can severely decrease the force level. This was later confirmed by a pyramid test simulation by Duchêne et al (2013). Potential reasons for high forces were studied by Sena et al (2016) (boundary conditions, missing blankholder force modeling, friction coefficient, hardening modeling choice, element stiffness, etc.).…”

Simulation of a two-slope pyramid made by SPIF using an adaptive remeshing method with solid-shell finite element

“…The hardening type adopted is a mixed one, with an isotropic constitutive model. The kinematic part of the hardening is introduced by a back-stress tensor described by non-linear Armstrong-Fredrick model (Duchêne et al, 2013). The plastic domain is described by a von Mises yield surface and the isotropic hardening behaviour is defined by means of a Swift's law.…”

“…The experimental tool path points were given in order to use it in the numerical simulations. These SPIF experiments as well as the shape measurements were performed by the team at KU Leuven (Duchêne et al, 2013) The shape analysis is divided in four sections (A, B, C, D), in order to analyse them separately in the middle section of the mesh model (see Figure 6), to avoid the influence of Boundary Conditions (BC). The material behaviour is elastically described by E = 142800 MPa and ν = 0.33.…”

“…Both authors have used a shell finite element in their FEM analysis. However, Duchêne et al (2013) have used a solid-shell finite element in order to investigate the influence of Enhanced Assumed Strain (EAS) formulation in the accuracy of the shape.…”