An investigation into the effect of strain rate on forming limit diagram using ductile fracture criteria

Meccanica ◽  
2011 ◽  
Vol 47 (6) ◽  
pp. 1391-1399 ◽  
Author(s):  
Mehdi Safari ◽  
S. J. Hosseinipour ◽  
H. D. Azodi
Keyword(s):  
Strain Rate ◽  
Ductile Fracture ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria

Cockcroft-Latham Ductile Fracture Criteria for Non Ferrous Materials

2014 ◽  
Vol 782 ◽  
pp. 373-378 ◽  
Author(s):  
Tibor Kvačkaj ◽  
Juraj Tiža ◽  
Július Bacsó ◽  
Andrea Kováčová ◽  
Robert Kočiško ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Ductile Fracture ◽  
Compression Test ◽  
Copper Alloys ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Compression Tests ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria

The determination of ductile fracture criteria as well as friction coefficient, stress-strain curves, constants for Hollomon's equation and a material workability based on analytical methods as a forming limit diagram, a normalized Cockcroft-Latham criteria (nCL)) ring and compression tests for two materials based on aluminum and copper alloys were carried out. A calculation of nCL criteria on the basis of a compression test and numerical simulations was made. The critical values nCL criteria resulting from compression test were determined. Prediction of nCL criteria by numerical simulations were confirmed by laboratory compression tests. The values obtained from numerical simulations and compression tests for both materials show a good coincidence in results.

scholarly journals Evaluation of Varying Ductile Fracture Criteria for 42CrMo Steel by Compressions at Different Temperatures and Strain Rates

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Guo-zheng Quan ◽  
Gui-chang Luo ◽  
An Mao ◽  
Jian-ting Liang ◽  
Dong-sen Wu
Keyword(s):  
Strain Rate ◽  
Ductile Fracture ◽  
Ductile Damage ◽  
Compression Tests ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria ◽  
Bulk Forming ◽  
42Crmo Steel ◽  
Different Temperatures ◽  
Tension Testing

Fracturing by ductile damage occurs quite naturally in metal forming processes, and ductile fracture of strain-softening alloy, here 42CrMo steel, cannot be evaluated through simple procedures such as tension testing. Under these circumstances, it is very significant and economical to find a way to evaluate the ductile fracture criteria (DFC) and identify the relationships between damage evolution and deformation conditions. Under the guidance of the Cockcroft-Latham fracture criteria, an innovative approach involving hot compression tests, numerical simulations, and mathematic computations provides mutual support to evaluate ductile damage cumulating process and DFC diagram along with deformation conditions, which has not been expounded by Cockcroft and Latham. The results show that the maximum damage value appears in the region of upsetting drum, while the minimal value appears in the middle region. Furthermore, DFC of 42CrMo steel at temperature range of 1123~1348 K and strain rate of 0.01~10 s-1are not constant but change in a range of 0.160~0.226; thus, they have been defined as varying ductile fracture criteria (VDFC) and characterized by a function of temperature and strain rate. In bulk forming operations, VDFC help technicians to choose suitable process parameters and avoid the occurrence of fracture.

Ductile Fracture Criteria Based on Mesoscopic Void-Damage of Metals under Plastic Forming

2014 ◽  
Vol 633-634 ◽  
pp. 620-623
Author(s):  
Dao Fu Tang ◽  
Lian Fa Yang
Keyword(s):  
Tensile Stress ◽  
Ductile Fracture ◽  
Maximum Tensile Stress ◽  
Triaxial Stress ◽  
Forming Limit ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria ◽  
Plastic Forming ◽  
Void Damage ◽  
Main Factor

In the process of plastic forming of metals, ductile fracture is an important factor influencing the improvement of forming limit of metals, while ductile fracture criteria can predict when and where ductile fracture occurs. Some conventional ductile fracture criteria based on mesoscopic void-damage and their application in different plastic forming of metals are introduced in this paper. And the ductile fracture criteria will be summarized into two categories: based on triaxial stress degree and based on maximum tensile stress. Because the triaxial stress degree and maximum tensile stress are a main factor deciding the occurrence of the ductile fracture.

Finite Element Analysis of the Hydro-Mechanical Punching Process

2006 ◽  
Vol 505-507 ◽  
pp. 871-876
Author(s):  
Jong Hun Yoon ◽  
Hoon Huh ◽  
Yong Sin Lee ◽  
Seung Soo Kim ◽  
E.J. Kim ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Ductile Fracture ◽  
Sheet Material ◽  
Middle Surface ◽  
Initial Crack ◽  
Fracture Criteria ◽  
Element Analysis ◽  
Final Fracture ◽  
Ductile Fracture Criteria ◽  
Punching Process

This paper investigates the characteristics of a hydro-mechanical punching process. The hydro-mechanical punching process is divided into two stages: the first stage is the mechanical half piercing in which an upper punch goes down before the initial crack is occurred; the second stage is the hydro punching in which a lower punch goes up until the final fracture is occurred. Ductile fracture criteria such as the Cockcroft et al., Brozzo et al. and Oyane et al. are adopted to predict the fracture of a sheet material. The index value of ductile fracture criteria is calculated with a user material subroutine, VUMAT in the ABAQUS Explicit. The hydrostatic pressure retards the initiation of a crack in the upper region of the blank and induces another crack in the lower region of the blank during the punching process. The final fracture zone is placed at the middle surface of the blank to the thickness direction. The result demonstrates that the hydro-mechanical punching process makes a finer shearing surface than the conventional one as hydrostatic pressure increases.

Damage evaluation in tube spinnability test with ductile fracture criteria

2015 ◽  
Vol 100 ◽  
pp. 99-111 ◽  
Author(s):  
Hao Ma ◽  
Wenchen Xu ◽  
Bo Cheng Jin ◽  
Debin Shan ◽  
Steven R. Nutt
Keyword(s):  
Ductile Fracture ◽  
Damage Evaluation ◽  
Fracture Criteria ◽  
Ductile Fracture Criteria

Behavior of Lode Dependent Plasticity at Plane Strain Condition and its Implication to Ductile Fracture

2016 ◽  
Vol 258 ◽  
pp. 213-216 ◽  
Author(s):  
František Šebek ◽  
Jindrich Petruška ◽  
Petr Kubík
Keyword(s):  
Ductile Fracture ◽  
Plane Strain ◽  
Uniaxial Stress ◽  
Complex Materials ◽  
Fracture Criteria ◽  
Dependent Plasticity ◽  
Ductile Fracture Criteria ◽  
Stress States ◽  
Aluminum Alloy 2024 ◽  
Von Mises

Variety of metals are complex materials exhibiting various behavior under different loading. Many metallic materials exhibit Tresca-like behavior rather than von Mises. It means different behavior in tension under plane strain and uniaxial stress conditions. This might be described by Lode dependent plasticity which should result in better prediction in force or torque responses of material tests. Good agreement between computation and experiment is also very important when calibrating the ductile fracture criteria. Several tests under plane strain and uniaxial stress states were carried out on aluminum alloy 2024-T351 where the Lode dependency was significant. The Lode dependent plasticity was implemented along with von Mises and Tresca-like yield criteria, which resulted in improvement of force–displacement responses of plane strain tests simulations. But it also caused significant change in the stress state of tensile flat and grooved plates which wrongly approached uniaxial tension condition. This inconvenience prevents plane strain experiments from using for calibration of ductile fracture criteria under these circumstances.

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