Paradigm Change: Alternate Approaches to Constitutive and Necking Models for Sheet Metal Forming

Stoughton, Thomas B.; Yoon, Jeong Whan

doi:10.1063/1.3623589

Cited by 9 publications

(2 citation statements)

References 31 publications

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“…More recent press shop experience and research results showed that the effect of bending on formability is significantly more pronounced for modern Advanced High Strength Steel (AHSS) sheets than for conventional grades (e.g. [3][4][5][6][7]). Consequently, traditional formability measures (e.g.…”

Section: Introductionmentioning

confidence: 99%

Deformation Scenarios of Combined Stretching and Bending in Complex Shaped Deep Drawing Parts

Kitting

Ofenheimer

Boogaard

et al. 2013

KEM

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Abstract. Bending effects, especially for Advanced High Strength Steels (AHSS), are known to influence the material formability when stretching and bending is combined in sheet forming. Traditional formability measures (e.g. the conventional forming limit curve (FLC)) fail to reliably predict formability when bending is added. Consequently, in order to take full advantage of the available forming potential of AHSS sheets in industrial applications and to ensure a reliable failure assessment at the same time, current research is focusing on the experimental characterization and modeling of the influence of bending effects on the AHSS sheets formability in forming scenarios of combined stretching and bending. It is expected that aside parameters such as bending radius or strain ratio, individual deformation scenarios of combined stretching and bending may affect the material formability too. Due to tool geometry and the resulting material flow in deep drawing various complex scenarios of combined stretching and bending can occur. For example, a material element is subjected to a complex deformation history of in-plane stretching with subsequent stretch-bending over a cylindrical tool contour, followed by unbending under tension. Another material element of the same drawing part presumably starts also with in-plane stretching but is consequently stretch-bent over a doubly curved tool geometry. Consequently, comprehensive knowledge on the stretch-bending deformation scenarios prevailing in deep drawing is crucial for a more reliable formability assessment. This work aims to identify and characterize the stretch-bending deformation scenarios to occur in different complex deep drawing parts (i.e. B-pillar, cross-die test) and small scale tests (i.e. Angular Stretch-Bend Test (ASBT)). For this reason, this investigation uses an innovative approach recently developed by some of the authors and published elsewhere to categorize the stretch-bending scenarios in industrial deep drawing processes. The approach consists of a stretch-bending categorization schema and a procedure to categorize the forming scenarios in deep drawing parts using data of finite element (FE) simulations. Results of the categorization can directly be plotted on the FE mesh of the deep drawing part (i.e. map type plot of deformation scenarios). The categorization approach mentioned uses results of conventional shell-type FE forming simulation and is therefore applicable in an industrial environment. The FE forming simulation results of the parts selected were analyzed using the stretch-bending categorization approach to identify which stretch-bending scenarios occur in deep drawing parts, to quantify which scenarios to prevail and to show that the conventional ASBT does not represent all the relevant deformation scenarios that prevail in typical deep drawing parts. Furthermore, with the use of experimental observations from real part forming, the stretch-bending scenarios which are the most critical (i.e. the scenarios under which failure occurs) in forming the cross-die geometry are identified. Results of these analysis are presented and discussed in detail.

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Section: Introductionmentioning

confidence: 99%

Deformation Scenarios of Combined Stretching and Bending in Complex Shaped Deep Drawing Parts

Kitting

Ofenheimer

Boogaard

et al. 2013

KEM

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“…Considering plane-stress loading conditions and localized necking, the forming limit diagram (FLD) is proven to be an appropriate tool to estimate and predict forming limits. However, the FLD lacks applicability when differing failure modes occur [5]. For example, shear-fracture was observed as the dominating failure mechanism by small curvature bending of AHSS with sharp radii [6,7].…”

Section: Introductionmentioning

confidence: 99%

Methodology for the Analysis of the Process Behaviour of Advanced High Strength Steels in Bending and Shearing Operations

Tsoupis

Hildering

Merklein

2012

KEM

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In the automotive sector the application of advanced high strength steels (AHSS) for structural and safety relevant components plays an important role. Typical manufacturing processes concerning these parts are bending and cutting operations. However, the forming and cutting potential of these steel grades is different compared to conventional steels, as the process behaviour is changing. For an improved workpiece quality the fundamental knowledge of the damage and failure mechanisms is essential. This study presents a methodology for the analysis of AHSS in bending and out-of-plane shearing operations. Two micro alloyed high strength steels are investigated within this work. First results are presented concerning material characterisation by tensile tests, the material performance in air bending tests and the development of a modular punching tool. The study is closed by summarizing the damage behaviour along the process chain considering both bending and cutting. This shows the applicability of the presented methodology for analysing the process behaviour with respect to occurring failure.

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Path Independent Polar Effective Plastic Strain (PEPS) Diagram for Sheet Forming

Yoon

Stoughton

2012

ICAA13: 13th International Conference on Aluminum Alloys

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Paradigm Change: Alternate Approaches to Constitutive and Necking Models for Sheet Metal Forming

Cited by 9 publications

References 31 publications

Deformation Scenarios of Combined Stretching and Bending in Complex Shaped Deep Drawing Parts

Deformation Scenarios of Combined Stretching and Bending in Complex Shaped Deep Drawing Parts

Methodology for the Analysis of the Process Behaviour of Advanced High Strength Steels in Bending and Shearing Operations

Path Independent Polar Effective Plastic Strain (PEPS) Diagram for Sheet Forming

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