A modified elliptical fracture criterion to predict fracture forming limit diagrams for sheet metals

2018 ◽  
Vol 252 ◽  
pp. 116-127 ◽  
Author(s):  
Jun Cao ◽  
Fuguo Li ◽  
Xinkai Ma ◽  
Zhankun Sun
Keyword(s):  
Fracture Criterion ◽  
Forming Limit ◽  
Sheet Metals ◽  
Forming Limit Diagrams ◽  
Elliptical Fracture

Formability of High Strength Sheet Metals with Special Regard to the Effect of the Influential Factors on the Forming Limit Diagrams

2015 ◽  
Vol 812 ◽  
pp. 271-275 ◽  
Author(s):  
Miklós Tisza ◽  
Péter Zoltán Kovács ◽  
Zsolt Lukács ◽  
Antal Kiss ◽  
Gaszton Gál
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Experimental Investigations ◽  
Sheet Metals ◽  
Forming Limit Diagrams ◽  
Research Activities

Car manufacturing is one of the main target fields of sheet metal forming: thus sheet metal forming is exposed to the same challenges as the automotive industry. The continuously increasing demand on lower consumption and lower CO2 emission means the highest challenges on materials developments besides design and construction. As a general requirement, the weight reduction and light weight construction principles should be mentioned together with the increased safety prescriptions which require the application of high strength steels. However, the application of high strength steels often leads to formability problems. Forming Limit Diagrams (FLD) are the most appropriate tools to characterize the formability of sheet metals. Theoretical and experimental investigations of forming limit diagrams are in the forefront of todays’ research activities.

Effect of Plastic Anisotropy on Forming Limit Prediction

2005 ◽  
Vol 495-497 ◽  
pp. 1573-1578 ◽  
Author(s):  
S. He ◽  
Albert Van Bael ◽  
Paul van Houtte
Keyword(s):  
Strain Path ◽  
Plastic Anisotropy ◽  
Yield Locus ◽  
Material Behavior ◽  
Forming Limit ◽  
Sheet Metals ◽  
Forming Process ◽  
Forming Limit Diagrams ◽  
Strain Path Changes ◽  
Complex Strain

A model based on Marciniak-Kuczynski (M-K) theory [1] for the prediction of forming limit diagrams (FLDs) for anisotropic sheet metals is presented. The plastic anisotropy is taken into account by the shape of the yield locus generated on the basis of measured crystallographic texture. As a result, not only the material behavior during the monotonic loading can be well described and predicted, but also the complex strain-path changes during the forming process can be taken into account. Examples of predicted FLDs for two aluminum alloys are given. Comparisons with experimental results are presented.

Fracture Prediction for Sheet Metals Subjected to Draw-Bending Using Forming Limit Stress Criterion

2013 ◽  
Author(s):  
Masazumi Saito ◽  
Toshihiko Kuwabara
Keyword(s):  
Sheet Metal ◽  
Steel Sheet ◽  
Fracture Criterion ◽  
Test Material ◽  
Forming Limit ◽  
Sheet Metals ◽  
Cross Sectional ◽  
Stress Criterion ◽  
Limit Stress ◽  
Draw Bending

Draw-bending is one of the typical deformation modes in sheet metal forming. It causes serious thickness reduction to sheet metals and very often leads to fracture. Therefore, it is crucial to establish a fracture criterion for sheet metals subjected to draw-bending. In this study, a fracture criterion for sheet metals subjected to draw-bending is investigated using the concept of the forming limit stress criterion. The test material used is a dual phase steel sheet (DP590Y) with a thickness of 1.2 mm and a tensile strength of 590 MPa. Draw-bending experiments of a wide specimen are performed using three different die profile radii: 4, 6 and 10 mm. The forming limit stress of the test material under draw-bending, σDB, is precisely determined from the experimentally measured drawing force and the cross sectional area of the specimen, determined from the strain distribution in the vicinity of fracture using a 2 mm square grid. In addition, multiaxial tube expansion tests are performed to measure the forming limit stress under plane strain tension, σPT. It is found that σDB almost coincides with σPT. Thus, it is concluded that σPT can be a fracture criterion for a sheet metal under draw-bending, at least for the high strength steel sheet used in this study.

scholarly journals Forming Limit Diagrams of Perforated St12 Steel Sheets

2021 ◽  
Author(s):  
M. Hossein Sehhat ◽  
Ali Mahdianikhotbesara ◽  
Mohammadjafar Hadad
Keyword(s):  
Forming Limit ◽  
Sheet Metals ◽  
Forming Limit Diagrams ◽  
Maximum Deformation ◽  
Steel Sheets ◽  
Deformation Limit ◽  
Metal Sheets ◽  
Perforated Sheets ◽  
Nakajima Test ◽  
Hemispherical Punch

Abstract One of the unique characteristics of sheet metals is their formability, which is determined by the forming limit diagrams. These diagrams specify the maximum deformation limit before part’s failure. For several applications of metal sheets, they have to be in the perforated format. Existence of holes in the perforated sheets may adversely deteriorate the forming limit of metal sheets. In this study, the effect of perforated sheets’ hole size and hole layout on their formability are investigated. Several specimens of St12 steel with 0.6 mm thickness, different widths, two various hole sizes of 2 and 4 mm, and two layouts of triangular and square were prepared. The specimens were tested using Nakajima test (stretch with a hemispherical punch) to generate the forming limit diagrams. It was observed that both the diameter and layout of the punched holes have a significant effect on the formability of the perforated sheets. The perforated sheets with triangular hole layout showed higher forming limits due to their larger ligament ratios.

scholarly journals The secondary forming limit diagrams of sheet metals.

1985 ◽  
Vol 51 (469) ◽  
pp. 2224-2230 ◽  
Author(s):  
Manabu GOTOH ◽  
Takeshi SATOH ◽  
Kozo TANAKA
Keyword(s):  
Forming Limit ◽  
Sheet Metals ◽  
Forming Limit Diagrams
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