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Title: Forming Limit Predictions for the Serrated Strain Paths in Single Point Incremental Sheet Forming

Abstract

The forming limits of sheets subjected to the Single Point Incremental Forming process (SPIF) is generally several times higher than those found in the Forming Limit Curve (FLC). In this paper it is shown that the non-monotonic, serrated strain paths to which the material is subjected to during the SPIF process, play a role in the high formability, compared to the monotonic loading in the traditional FLC. The deformation history of an aluminium alloy truncated cone formed with the SPIF process is retrieved through a finite element (FE) model, and discussed. Subsequently, the strain paths at three different depths in the sheet are used as input into a Marciniak-Kuczynski (MK) forming limit model. The usage of different constitutive models in this analysis shows that anisotropic hardening contributes to the delay of the onset of necking in the SPIF process. The large difference in the predicted forming limits that were obtained from the different layers indicates that an interaction between these layers should be taken into account for more accurate forming limit predictions of sheets subjected to the SPIF process.

Authors:
; ;  [1];  [1];  [2];  [3]
  1. MTM, Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium)
  2. (Belgium)
  3. PMA, Katholieke Universiteit Leuven, Celestijnenlaan 300 B, B-3001 Heverlee (Belgium)
Publication Date:
OSTI Identifier:
21057365
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM '07: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740802; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; ANISOTROPY; DEFORMATION; FINITE ELEMENT METHOD; HARDENING; LAYERS; LOADING; MATERIALS WORKING; SHEETS; STRAINS

Citation Formats

Eyckens, P., He, S., Van Houtte, P., Bael, A. van, IWT, Katholieke Hogeschool Limburg, Campus Diepenbeek, Agoralaan Gebouw B, bus 3, B-3590 Diepenbeek, and Duflou, J. Forming Limit Predictions for the Serrated Strain Paths in Single Point Incremental Sheet Forming. United States: N. p., 2007. Web. doi:10.1063/1.2740802.
Eyckens, P., He, S., Van Houtte, P., Bael, A. van, IWT, Katholieke Hogeschool Limburg, Campus Diepenbeek, Agoralaan Gebouw B, bus 3, B-3590 Diepenbeek, & Duflou, J. Forming Limit Predictions for the Serrated Strain Paths in Single Point Incremental Sheet Forming. United States. doi:10.1063/1.2740802.
Eyckens, P., He, S., Van Houtte, P., Bael, A. van, IWT, Katholieke Hogeschool Limburg, Campus Diepenbeek, Agoralaan Gebouw B, bus 3, B-3590 Diepenbeek, and Duflou, J. Thu . "Forming Limit Predictions for the Serrated Strain Paths in Single Point Incremental Sheet Forming". United States. doi:10.1063/1.2740802.
@article{osti_21057365,
title = {Forming Limit Predictions for the Serrated Strain Paths in Single Point Incremental Sheet Forming},
author = {Eyckens, P. and He, S. and Van Houtte, P. and Bael, A. van and IWT, Katholieke Hogeschool Limburg, Campus Diepenbeek, Agoralaan Gebouw B, bus 3, B-3590 Diepenbeek and Duflou, J.},
abstractNote = {The forming limits of sheets subjected to the Single Point Incremental Forming process (SPIF) is generally several times higher than those found in the Forming Limit Curve (FLC). In this paper it is shown that the non-monotonic, serrated strain paths to which the material is subjected to during the SPIF process, play a role in the high formability, compared to the monotonic loading in the traditional FLC. The deformation history of an aluminium alloy truncated cone formed with the SPIF process is retrieved through a finite element (FE) model, and discussed. Subsequently, the strain paths at three different depths in the sheet are used as input into a Marciniak-Kuczynski (MK) forming limit model. The usage of different constitutive models in this analysis shows that anisotropic hardening contributes to the delay of the onset of necking in the SPIF process. The large difference in the predicted forming limits that were obtained from the different layers indicates that an interaction between these layers should be taken into account for more accurate forming limit predictions of sheets subjected to the SPIF process.},
doi = {10.1063/1.2740802},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}
  • A characteristic of incremental sheet metal forming is that much higher deformations can be achieved than conventional forming limits. In this paper it is investigated to which extent the highly non-monotonic strain paths during such a process may be responsible for this high formability. A Marciniak-Kuczynski (MK) model is used to predict the onset of necking of a sheet subjected to the strain paths obtained by finite-element simulations. The predicted forming limits are considerably higher than for monotonic loading, but still lower than the experimental ones. This discrepancy is attributed to the strain gradient over the sheet thickness, which ismore » not taken into account in the currently used MK model.« less
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  • The current paper refers to one of the new non-conventional forming procedures for sheets metal, namely incremental forming. Problems occurring during calculation of stress, thinning and the forces in the process of incremental sheet metal forming have been analyzed in this paper. The paper presents a comparison study based on the simulation by the finite element method of incremental sheet metal forming and experimental researches referred on the same process.
  • Within the scope of this article a decoupling algorithm to reduce computing time in Finite Element Analyses of incremental forming processes will be investigated. Based on the given position of the small forming zone, the presented algorithm aims at separating a Finite Element Model in an elastic and an elasto-plastic deformation zone. Including the elastic response of the structure by means of model simplifications, the costly iteration in the elasto-plastic zone can be restricted to the small forming zone and to few supporting elements in order to reduce computation time. Since the forming zone moves along the specimen, an updatemore » of both, forming zone with elastic boundary and supporting structure, is needed after several increments.The presented paper discusses the algorithmic implementation of the approach and introduces several strategies to implement the denoted elastic boundary condition at the boundary of the plastic forming zone.« less