IJmuiden, Netherlands
IJmuiden, Netherlands

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Emmens W.C.,CORUS RD and T | Sebastiani G.,TU Dortmund | van den Boogaard A.H.,University of Twente
Journal of Materials Processing Technology | Year: 2010

This paper describes the history of Incremental Sheet Forming (ISF) focusing on technological developments. These developments are in general protected by patents, so the paper can also be regarded as an overview of ISF patents in addition to a description of the early history. That history starts with the early work by Mason in 1978 and continues up to the present day. An extensive list of patents including Japanese patents is provided. The overall conclusion is that ISF has received the attention of the world, in particular of the automotive industry, and that most proposed or suspected applications focus on the flexibility offered by the process. Only one patent has been found that is explicitly related to the enhancement of formability. Furthermore, most patents refer to TPIF (Two-Point Incremental Forming) as a process. Besides simply presenting a historical overview the paper can act as an inspiration for the researcher, and present a rough idea of the patentability of new developments. © 2010 Elsevier B.V. All rights reserved.

Swart A.E.,CORUS RD and T | Karamanos S.A.,University of Thessaly | Scarpas A.,Technical University of Delft | Blaauwendraad J.,Technical University of Delft
Heron | Year: 2010

The present paper describes a numerical formulation for the analysis of damage in steel pipeline bends. In particular, the numerical implementation of Gurson plasticity model is described in the framework of a special element, referred to as "tube element". This is a three-node element, which simulates pipe behavior combining longitudinal deformation with cross-sectional ovalization and warping. The numerical results obtained with the tube elements are compared with results obtained with selective integrated Heterosis elements. The constitutive equations are integrated through an Euler-backward numerical scheme, enforcing the condition of zero stress in the radial direction of the pipe. Results for isotropic hardening have been obtained.

Ghadbeigi H.,University of Sheffield | Pinna C.,University of Sheffield | Celotto S.,Corus RD and T | Yates J.R.,University of Sheffield
Materials Science and Engineering A | Year: 2010

The evolution of local plastic deformation in a dual-phase (DP) steel has been studied using Digital Image Correlation (DIC) and in-situ tensile testing inside a scanning electron microscope. Tests were performed using specially designed samples to study the initiation and evolution of damage in DP1000 steel by measuring the strains at the scale of the microstructure. Micrographs have been analysed using DIC at different stages throughout a tensile test to measure local strain distributions within the ferrite-martensite microstructure. The results show progressive localisation of deformation into bands orientated at 45° with respect to the loading direction. Strain magnitudes are higher in the ferrite phase with local values reaching up to 120%. Several mechanisms for damage initiation are identified and related to the local strains in this steel. The procedure used and the results obtained in this work may help the development of models aimed at predicting the properties of new generation automotive steels. © 2010 Elsevier B.V.

Ghadbeigi H.,University of Sheffield | Pinna C.,University of Sheffield | Celotto S.,Corus RD and T | Yates J.R.,University of Sheffield
Applied Mechanics and Materials | Year: 2010

Digital Image Correlation (DIC) together with in-situ tensile testing has been used to measure in DP1000 steel the evolution of plastic strains at the microstructure scale. Interrupted tensile tests were performed on specially designed samples and scanning-electron micrographs were taken at regular applied strain intervals. Patterns defined by the microstructural features of the material have been used for the correlation carried out using LAVision software. The full field strain maps produced by DIC show a progressive localisation of deformation into bands at about 45 o with respect to the loading direction. Plastic strains as high as 130% have been measured within the ferrite phase. © (2010) Trans Tech Publications, Switzerland.

Fictorie E.,University of Twente | van den Boogaard A.H.,University of Twente | Atzema E.H.,Corus RD and T
International Journal of Material Forming | Year: 2010

Forming limit curves are usually determined for membrane type deformations. Recently, the influence of simultaneous bending deformation on the forming limits has attracted renewed attention. In this paper, FLCs are determined for a DC06 steel and an AA5051 aluminium alloy by the standard Nakazima test procedure with different punch diameters. The difference in FLC obtained with punch diameters of 100 mm and 75 mm is negligible. For aluminium, the FLC is shifted upwards slightly for a Ø50 mm punch and significantly for a Ø20 mm punch. For DC06, only the experiments with a Ø20 mm punch show a relevant increase in formability. The increased formability cannot be explained by simply transforming the measured (outer) strains to the mid-plane or inner-plane, as proposed by the so-called concave-side-rule. The experimentally observed and numerically validated high pressure on the inner surface for small punch diameters may be responsible for the increased stability of the deformation. © 2010 Springer-Verlag France.

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