Influence of Ultrasonic Assistance on the Forming Limits of Steel

2021 ◽  
pp. 1281-1290
Author(s):  
Manuel Jäckisch ◽  
Marion Merklein
Keyword(s):  
Forming Limits

Prediction of forming limits and microstructural evolution during warm stretch forming of DP590 steel

2021 ◽  
Vol 21 (3) ◽  
Author(s):  
Sandeep Pandre ◽  
Ayush Morchhale ◽  
Nitin Kotkunde ◽  
Swadesh Kumar Singh ◽  
Sujith Ravindran
Keyword(s):  
Microstructural Evolution ◽  
Stretch Forming ◽  
Forming Limits

scholarly journals Understanding Size Effects and Forming Limits in the Micro-Stamping of Industrial Stainless Steel Foils

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Matthias Weiss ◽  
Peng Zhang ◽  
Michael P. Pereira ◽  
Bernard F. Rolfe ◽  
Daniel E. Wilkosz ◽  
...  
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Size Effects ◽  
Bipolar Plate ◽  
Forming Limits ◽  
Tool Profile ◽  
Steel Processing ◽  
The Individual ◽  
Stainless Steel Foils ◽  
Steel Foils

This study investigates the effect of grain size and composition on the material properties and forming limits of commercially supplied stainless steel foil for bipolar plate manufacture via tensile, stretch forming and micro-stamping trials. It is shown that in commercially supplied stainless steel the grain size can vary significantly and that ‘size effects’ can be influenced by prior steel processing and composition effects. While the forming limits in micro-stamping appear to be directly linked to the plane strain forming limits of the individual stainless steel alloys, there was a clear effect of the tensile anisotropy. In contrast to previous studies, forming severity and the likelihood of material failure did not increase with a decreasing channel profile radius. This was related to inaccuracies of the forming tool profile shape.

Sheet metal forming limits as classification problem

2017 ◽  
Author(s):  
Christian Jaremenko ◽  
Xiaolin Huang ◽  
Emanuela Affronti ◽  
Marion Merklein ◽  
Andreas Maier
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Classification Problem ◽  
Forming Limits

Experimental and Numerical Analysis of Forming Limits in CNC Incremental Sheet Forming

2007 ◽  
Vol 344 ◽  
pp. 511-518 ◽  
Author(s):  
Markus Bambach ◽  
M. Todorova ◽  
Gerhard Hirt
Keyword(s):  
Sheet Metal ◽  
Sheet Forming ◽  
Incremental Sheet Forming ◽  
Negative Slope ◽  
Evaluation Procedure ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve ◽  
Forming Limits ◽  
Straight Line

Asymmetric incremental sheet forming (AISF) is a relatively new manufacturing process for the production of low volumes of sheet metal parts. Forming is accomplished by the CNC controlled movements of a simple ball-headed tool that follows a 3D trajectory to gradually shape the sheet metal blank. Due to the local plastic deformation under the tool, there is almost no draw-in from the flange region to avoid thinning in the forming zone. As a consequence, sheet thinning limits the amount of bearable deformation, and thus the range of possible applications. Much attention has been given to the maximum strains that can be attained in AISF. Several authors have found that the forming limits are considerably higher than those obtained using a Nakazima test and that the forming limit curve is approximately a straight line (mostly having a slope of -1) in the stretching region of the FLD. Based on these findings they conclude that the “conventional” forming limit curves cannot be used for AISF and propose dedicated tests to record forming limit diagrams for AISF. Up to now, there is no standardised test and no evaluation procedure for the determination of FLCs for AISF. In the present paper, we start with an analysis of the range of strain states and strain paths that are covered by the various tests that can be found in the literature. This is accomplished by means of on-line deformation measurements using a stereovision system. From these measurements, necking and fracture limits are derived. It is found that the fracture limits can be described consistently by a straight line with negative slope. The necking limits seem to be highly dependent on the test shapes and forming parameters. It is concluded that standardisation in both testing conditions and the evaluation procedures is necessary, and that a forming limit curve does not seem to be an appropriate tool to predict the feasibility of a given part design.

Spatial Free Plastic Forming of Slender Parts—Machine Design, Forming Limits, and Application

2001 ◽  
Vol 123 (4) ◽  
pp. 524-529 ◽  
Author(s):  
M. Thalmair ◽  
H. Lippmann ◽  
M. Reigl
Keyword(s):  
Laboratory Scale ◽  
Machine Design ◽  
Forming Limits ◽  
Plastic Forming ◽  
Computer Controlled

Free plastic forming of a slender part means that an initially straight bar, clamped at its both ends, is bent and twisted by an appropriate motion of the end supports only. Emphasis is attached on the computer controlled, precise forming of workpieces with prescribed shape. In this paper the design of an appropriate forming machine at the laboratory scale will be presented. Moreover, the forming limits due to replastification of already completed sections of the part will be illustrated geometrically using one or two “cylinders of admissibility.” Finally, the method will be demonstrated by means of actually formed parts.

Prediction of Forming Limits for Anisotropic Sheets with Ellipsoidal Voids

2004 ◽  
Vol 274-276 ◽  
pp. 397-402 ◽  
Author(s):  
Seo Gou Choi ◽  
Hyun Sung Son ◽  
Young Suk Kim
Keyword(s):  
Forming Limits

Evaluation of Biaxial Forming Limits by Bulge Testing

2006 ◽  
Vol 519-521 ◽  
pp. 117-124 ◽  
Author(s):  
S.R. MacEwen ◽  
Y. Shi ◽  
P. Hamstra ◽  
R. Mallory ◽  
Pei Dong Wu
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Rolling Direction ◽  
Major Axis ◽  
Sheet Forming ◽  
Biaxial Strain ◽  
Forming Limits ◽  
Element Modelling ◽  
Bulge Testing

Finite element modelling of sheet-forming operations, such as pressure-ram-forming, (PRF™) requires knowledge of forming limits under biaxial strain conditions. In this work, elliptical bulge tests have been used to evaluate the forming limits of an aluminum bodystock alloy, X309, that is used for PRF™ applications. Limiting dome heights have been determined as a function of pressure-rate and temperature. All tests have been done with the rolling direction, RD, of the sheet aligned with the major axis of the bulge.

scholarly journals Determination of Forming Limits Based on Finite Element Simulations

2021 ◽  
Author(s):  
Fuhui Shen ◽  
Kai Chen ◽  
Junhe Lian ◽  
Sebastian Münstermann
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Tensile Tests ◽  
Finite Element Simulations ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Anisotropic Plasticity ◽  
Forming Limits ◽  
Dog Bone ◽  
Spatio Temporal

Two categories of experiments have been performed to obtain the experimental forming limits of a ferritic stainless steel from uniaxial to equibiaxial tension, including Nakajima tests and tensile tests of flat specimens with different geometries of the central hole as well as the notched dog bone. The plasticity behavior of the investigated material is described using an evolving non-associated anisotropic plasticity model, which is calibrated based on experimental results of uniaxial tensile tests along different loading directions. A damage mechanics model is calibrated and validated based on the global force and displacement response of tensile tests. Finite element simulations of the Nakajima tests and the tensile tests of various geometries have been performed using the anisotropic material model. A novel spatio-temporal method is developed to evaluate the forming limits under different stress states by quantitatively characterizing the plastic strain distribution on the specimen surface. The forming limits have been independently determined from finite element simulation results of tensile specimens and Nakajima specimens using the spatio-temporal evaluation method. The forming limits obtained from numerical simulations of these two types of experiments are in good agreement with experimental results.

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