The Increased Forming Limits of Incremental Sheet Forming Processes

By Julian M. Allwood, D. R. Shouler, A. Erman Tekkaya. 2007

189 citations recorded by the source corpus.

Incremental sheet forming is known to give higher forming limits than conventional sheet forming processes, but investigation of this effect has been impeded by the computational cost of process models which include detailed predictions of through thickness behaviour. Here, a simplified process is used to gain insight into the mechanics of a broad class of incremental forming processes. The simplified process is described and shown to give increases in forming limits compared to a conventional process with the same geometry. A model of the process is set up with a commercial finite element package, validated, and used to trace the history of a ‘pin’ inserted perpendicularly into the workpiece. The history of the deformation of the ‘pin’ demonstrates significant through thickness shear occurring in the direction parallel to tool motion. This insight is used to modify an existing analysis used to predict forming limit curves. The analysis shows that for a sheet with uniform proportional loading, the forming limit is increased when through thickness shear is present, and this is proposed as an explanation for the increased forming limits of incremental sheet forming processes.

Subfields: Computational Mechanics, Mechanical Engineering, Mechanics of Materials

View Paper: https://www.semanticscholar.org/paper/47c857acc0140d5a087ff3585196246fa883b582

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In Computational Mechanics

In Mechanical Engineering

In Mechanics of Materials

Citations in the corpus

Marciniak–Kuczynski type modelling of the effect of Through-Thickness Shear on the forming limits of sheet metal (2009, background): “(2007)) and experimental studies (Allwood et al. (2007), Eyckens et al.”
Advances in anisotropy and formability (2010, background): “The experimental researches of the Single Point Incremental Forming (SPIF) [3, 154, 230, 246] showed that the formability of the sheet in this process increases (the FLC is beyond the traditional FLC).”
Research and Progress in Incremental Sheet Forming Processes (2011, background): “In what concerns the formability limits, some authors explain the high formability of SPIF, and the corresponding raise of the forming limit curve (FLC), as a consequence of through thickness shear [45] or serrated strain paths arising from cyclical, local plastic deformation [46].”
Review on the influence of process parameters in incremental sheet forming (2016, background): “curs due to shearing [21], whilst others believe it is through stretching [22].”
Failure mechanisms in single-point incremental forming of metals (2011, background): “deep drawing and stretch forming) [3] and (c) that the raise in formability is due to a stabilizing effect caused by large amount of through thickness shear [7, 8] or by serrated strain paths arising from cyclic, local plastic deformation [9].”
Single point incremental forming of polymers (2009, background): “Local necking and ductile fracture are competitive modes of failure in metallic materials [6] but in the case of PVC necking seems to be suppressed.”
Mechanism investigation of friction-related effects in single point incremental forming using a developed oblique roller-ball tool (2014, background): “[20] investigated the throughthe-thickness-shear caused by the friction in the direction of tool motion.”
The mechanics of incremental sheet forming (2009, background): “Similar was found by experimental measurements of the relative movement of surfaces of 1 mm aluminium 5251-H22 formed to 45◦ by SPIF by Allwood et al. (2007).”
Single point incremental forming: An assessment of the progress and technology trends from 2005 to 2015 (2017, background): “[70] which predicts no effect of the direction of TTS on formability.”
Incremental Forming of Sandwich Panels (2007, background): “[22] proposed that the increased forming limits observed in ISF of monolithic sheet metal in comparison to the conventional bulge formability test is due to the increased through-thickness shear.”