An Approach for Predicting the Initiation of Ductile Fracture in Plane Strain Rolling

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.827.379 ◽

2019 ◽

Vol 827 ◽

pp. 379-384

Author(s):

Elena Lyamina ◽

Alexander Pirumov ◽

Yeong Maw Hwang

Keyword(s):

Ductile Fracture ◽

Plane Strain ◽

Fracture Criterion ◽

Ductile Fracture Criterion ◽

Axis Of Symmetry ◽

Workability Diagram

The paper extends Orowan’s method to the prediction of ductile fracture in plane strain rolling. In general, any uncoupled ductile fracture criterion can be used in conjunction with the solution found. However, the present paper focuses on a ductile fracture criterion based on the workability diagram. It is assumed that the initiation of fracture occurs at the axis of symmetry.

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Prediction of Strain Path Changing Effect on Forming Limits of AA 6111-T4 Based on A Shear Ductile Fracture Criterion

Metals ◽

10.3390/met11040546 ◽

2021 ◽

Vol 11 (4) ◽

pp. 546

Author(s):

Silin Luo ◽

Gang Yang ◽

Yanshan Lou ◽

Yongqian Xu

Keyword(s):

Ductile Fracture ◽

Uniaxial Tension ◽

Plane Strain ◽

Strain Path ◽

Fracture Criterion ◽

Kinematic Hardening ◽

Isotropic Hardening ◽

Ductile Fracture Criterion ◽

Plane Strain Tension ◽

Strain Paths

Strain path changing is a phenomenon in the stamping of complex panels or multiple-step stamping processes. In this study, the influence of the strain path changing effect was investigated and assessed for an aluminum alloy of 6111-T4 with a shear ductile fracture criterion. Plastic deformation of the alloy was modeled by an anisotropic Drucker yield function with the assumption of normal anisotropy. Then the shear ductile fracture criterion was calibrated by the fracture strains at uniaxial tension, plane strain tension and equibiaxial tension under proportional loading conditions. The calibrated fracture criterion was utilized to predict forming limit curves (FLCs) of the alloy stretched under bilinear strain paths. The analyzed bilinear strain paths included biaxial tension after uniaxial tension, plane strain tension and equibiaxial tension. The predicted FLCs of bilinear strain paths were compared with experimental results. The comparison showed that the shear ductile fracture criterion could reasonably describe the effect of strain path changing on FLCs, but its accuracy was poor for some bilinear paths, such as uniaxial tension followed by equibiaxial tension and equibiaxial tension followed by plane strain tension. Kinematic hardening is suggested to substitute the isotropic hardening assumption for better prediction of FLCs with strain path changing effect.

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Numerical study of chip formation and cutting force in high-speed machining of Ti-6Al-4V bases on finite element modeling with ductile fracture criterion

International Journal of Material Forming ◽

10.1007/s12289-021-01617-9 ◽

2021 ◽

Author(s):

Mehmet Aydın

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Ductile Fracture ◽

Cutting Force ◽

Chip Formation ◽

High Speed ◽

Fracture Criterion ◽

Numerical Study ◽

High Speed Machining ◽

Ductile Fracture Criterion

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Comparison of Modified Mohr–Coulomb Model and Bai–Wierzbicki Model for Constructing 3D Ductile Fracture Envelope of AA6063

Chinese Journal of Mechanical Engineering ◽

10.1186/s10033-021-00549-4 ◽

2021 ◽

Vol 34 (1) ◽

Author(s):

Jianye Gao ◽

Tao He ◽

Yuanming Huo ◽

Miao Song ◽

Tingting Yao ◽

...

Keyword(s):

Ductile Fracture ◽

Fracture Criterion ◽

Fracture Strain ◽

Stress Triaxiality ◽

Ductile Fracture Criterion ◽

Forming Process ◽

Tension Tests ◽

Wide Range ◽

Round Bar ◽

Fracture Envelope

AbstractDuctile fracture of metal often occurs in the plastic forming process of parts. The establishment of ductile fracture criterion can effectively guide the selection of process parameters and avoid ductile fracture of parts during machining. The 3D ductile fracture envelope of AA6063-T6 was developed to predict and prevent its fracture. Smooth round bar tension tests were performed to characterize the flow stress, and a series of experiments were conducted to characterize the ductile fracture firstly, such as notched round bar tension tests, compression tests and torsion tests. These tests cover a wide range of stress triaxiality (ST) and Lode parameter (LP) to calibrate the ductile fracture criterion. Plasticity modeling was performed, and the predicted results were compared with corresponding experimental data to verify the plasticity model after these experiments. Then the relationship between ductile fracture strain and ST with LP was constructed using the modified Mohr–Coulomb (MMC) model and Bai-Wierzbicki (BW) model to develop the 3D ductile fracture envelope. Finally, two ductile damage models were proposed based on the 3D fracture envelope of AA6063. Through the comparison of the two models, it was found that BW model had better fitting effect, and the sum of squares of residual error of BW model was 0.9901. The two models had relatively large errors in predicting the fracture strain of SRB tensile test and torsion test, but both of the predicting error of both two models were within the acceptable range of 15%. In the process of finite element simulation, the evolution process of ductile fracture can be well simulated by the two models. However, BW model can predict the location of fracture more accurately than MMC model.

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