A Forming Limit Curve Measurement of Sheet Metal Based on Digital Image Correlation

2017 ◽  
Author(s):  
J. Li ◽  
J. Liang ◽  
Y. Z. Jiang ◽  
H. L. Yu ◽  
T. S. Cui ◽  
...  
Keyword(s):  
Digital Image Correlation ◽  
Sheet Metal ◽  
Digital Image ◽  
Image Correlation ◽  
Forming Limit ◽  
Limit Curve ◽  
Forming Limit Curve

Determination of Forming Limit Strains Using Marciniak-Kuczynski Tests and Automated Digital Image Correlation Procedures

2012 ◽  
Vol 504-506 ◽  
pp. 17-22 ◽  
Author(s):  
Dmitry Vysochinskiy ◽  
Terence Coudert ◽  
Aase Reyes ◽  
Odd Geir Lademo
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Forming Limit Diagram ◽  
Image Correlation ◽  
Forming Limit ◽  
Forming Limit Curve ◽  
Strain Space ◽  
Automated Methods ◽  
Dic Technique

Forming limit strains are used to construct a forming limit diagram (FLD), which is a diagram in the principal strain space, traditionally used for designing forming operations of sheet metals. A line indicating the boundary between safe and unsafe strains is often called the forming limit curve (FLC). FLDs are also used to evaluate results from finite element simulations. Therefore consistency and reproducibility are important. This paper deals with the experimental determination of forming limit strains from Marciniak-Kuczynski (MK) tests. The material tested is AA6016 aluminum alloy in three different conditions: virgin material and material subjected to 5% and 8% deformation by rolling. Strains were measured by the use of digital image correlation (DIC) technique. Forming limit strains were determined by the use of two automated methods. The results from the two methods are compared and evaluated regarding their applicability to the Marciniak-Kuczynski test and ability to capture actual forming limit strains.

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.

Measuring forming limit strains with digital image correlation analysis

2014 ◽  
Vol 214 (5) ◽  
pp. 1120-1130 ◽  
Author(s):  
Kaifeng Wang ◽  
John E. Carsley ◽  
Baiyan He ◽  
Jingjing Li ◽  
Lianhong Zhang
Keyword(s):  
Digital Image Correlation ◽  
Correlation Analysis ◽  
Digital Image ◽  
Image Correlation ◽  
Forming Limit ◽  
Digital Image Correlation Analysis

Sheet-Metal Assessment at Medium Strain-Rates by Digital Image Correlation

Strain ◽  
2010 ◽  
Vol 46 (4) ◽  
pp. 396-403 ◽  
Author(s):  
G. B. Broggiato ◽  
D. Ferrari ◽  
M. Fischer ◽  
V. Veglianti
Keyword(s):  
Digital Image Correlation ◽  
Sheet Metal ◽  
Digital Image ◽  
Image Correlation ◽  
Strain Rates
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