Forming Limit Curves for the AA5083 Alloy under Quick Plastic Forming Conditions

2011 ◽  
Author(s):  
Fadi Abu-Farha ◽  
Louis Hector ◽  
Paul Krajewski
Keyword(s):  
Forming Limit ◽  
Aa5083 Alloy ◽  
Plastic Forming ◽  
Quick Plastic Forming ◽  
Forming Limit Curves

Sheet Orientation Effects on the Hot Formability Limits of Lightweight Alloys

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Fadi Abu-Farha ◽  
Louis G. Hector
Keyword(s):  
Rolling Direction ◽  
Superplastic Forming ◽  
Strain Ratio ◽  
Forming Limit ◽  
Specific Strain ◽  
Plastic Forming ◽  
Lightweight Alloys ◽  
Quick Plastic Forming ◽  
The Relationship ◽  
5083 Aluminum Alloy

The formability curves of AZ31B magnesium and 5083 aluminum alloy sheets were constructed using the pneumatic stretching test at two different sets of forming conditions. The test best resembles the conditions encountered in actual hydro/pneumatic forming operations, such as the superplastic forming (SPF) and quick plastic forming (QPF) techniques. Sheet samples were deformed at (400 °C and 1 × 10−3 s−1) and (450 °C and 5 × 10−3 s−1), by free pneumatic bulging into a set of progressive elliptical die inserts. The material in each of the formed domes was forced to undergo biaxial stretching at a specific strain ratio, which is simply controlled by the geometry (aspect ratio) of the selected die insert. Material deformation was quantified using circle grid analysis (CGA), and the recorded planar strains were used to construct the forming limit curves of the two alloys. The aforementioned was carried out with the sheet oriented either along or across the direction of major strains in order to establish the relationship between the material’s rolling direction and the corresponding limiting strains. Great disparities in limiting strains were found in the two orientations for both alloys; hence, a “composite FLD” is introduced as an improved means for characterizing material formability limits.

Forming Limit Diagrams for AA5083 under SPF and QPF Conditions

2007 ◽  
Vol 551-552 ◽  
pp. 129-134 ◽  
Author(s):  
Mary Anne Kulas ◽  
Paul E. Krajewski ◽  
John R. Bradley ◽  
Eric M. Taleff
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Superplastic Forming ◽  
Forming Limit ◽  
Forming Limit Diagrams ◽  
Commercial Grade ◽  
Bulge Testing ◽  
Macroscopic Fracture ◽  
Plastic Forming ◽  
Quick Plastic Forming

Forming Limit Diagrams (FLD’s) for AA5083 aluminum sheet were established under both Superplastic Forming (SPF) and Quick Plastic Forming (QPF) conditions. SPF conditions consisted of a strain rate of 0.0001/s at 500°C, while QPF conditions consisted of a strain rate of 0.01/s at 450°C. The forming limit diagrams were generated using uniaxial tension, biaxial bulge, and plane strain bulge testing. Forming limits were defined using two criteria: (1) macroscopic fracture and (2) greater than 2% cavitation. Very little difference was observed between the plane strain limits in the SPF and QPF conditions indicating comparable formability between the two processes with a commercial grade AA5083 material.

Effect of the Constitutive Law on the Accuracy of Prediction of the Forming Limit Curves

2012 ◽  
Vol 504-506 ◽  
pp. 77-82 ◽  
Author(s):  
Liana Paraianu ◽  
Dan Sorin Comsa ◽  
Ioan Pavel Nicodim ◽  
Ioan Ciobanu ◽  
Dorel Banabic
Keyword(s):  
Sheet Metal ◽  
Mechanical Response ◽  
Yield Criterion ◽  
Plastic Anisotropy ◽  
Equivalent Stress ◽  
Point Of View ◽  
Constitutive Law ◽  
Forming Limit ◽  
Accuracy Of Prediction ◽  
Forming Limit Curves

The accuracy of the forming limit curves predicted by the Marciniak-Kuczynski model depends on the type and flexibility of the constitutive equations used to describe the mechanical response of the sheet metal. From this point of view, the yield criterion has the most significant influence. The paper presents a comparative analysis referring to the quality of the forming limit curves predicted by the Marciniak-Kuczynski model for the case when the plastic anisotropy of a DC04 sheet metal is described by the BBC2005 yield criterion. The coefficients included in the expression of the BBC2005 equivalent stress are evaluated using different identification strategies (with 4, 6, 7, and 8 mechanical parameters). The forming limit curves predicted by the Marciniak-Kuczynski model in each of the cases previously mentioned are compared with experimental data.

Forming Limits Under Stretch-Bending Through Distortionless and Distortional Anisotropic Hardening

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Ji He ◽  
Bin Gu ◽  
Yongfeng Li ◽  
Shuhui Li
Keyword(s):  
Detailed Comparison ◽  
Forming Limit ◽  
Anisotropic Hardening ◽  
Hardening Model ◽  
Stretch Bending ◽  
Bending Process ◽  
Hardening Models ◽  
Out Of Plane ◽  
Forming Limit Curves ◽  
Insight Into

The necking behavior of sheet metals under stretch-bending process is a challenge for the forming limit prediction. State-of-the-art forming limit curves (FLCs) allow the prediction under the in-plane stretching but fall short in the case under out-of-plane loading condition. To account for the bending and straightening deformation when sheet metal enters a die cavity or slide along a radius, anisotropic hardening model is essential to reflect the nonproportional loading effect on stress evolution. This paper aims to revisit the M-K analysis under the stretch-bending condition and extend it to accommodate both distortionless and distortional anisotropic hardening behavior. Furthermore, hardening models are calibrated based on the same material response. Then the detailed comparison is proposed for providing better insight into the numerical prediction and necking behavior. Finally, the evolution of the yield surface and stress transition states is examined. It is found that the forming limit prediction under stretch-bending condition through the M-K analysis strongly depends on the employed anisotropic hardening model.

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