scholarly journals Modeling of a Ductile Fracture Criterion for Sheet Metal Considering Anisotropy

2016 ◽  
Vol 25 (2) ◽  
pp. 91-95 ◽  
Author(s):  
N. Park ◽  
H. Huh
2014 ◽  
Vol 23 (8) ◽  
pp. 1189-1210 ◽  
Author(s):  
HS Liu ◽  
MW Fu

A modified ductile fracture criterion is proposed based on the traditional Ayada criterion and coded into the finite element simulation platform of VUMAT/ABAQUS for prediction and analysis of ductile fracture in metal plastic strain processes. In this modified ductile fracture criterion, stress triaxiality is taken into account, and more importantly, the exponential effect of the equivalent plastic strain on the damage behavior, which is generally ignored in other ductile fracture criteria, is also considered. The material related constants in the modified ductile fracture criterion are determined by tensile tests together with finite element simulations. The applicability and reliability of the ductile fracture criterion in ductile fracture prediction in two types of classic stress states, viz. shear stress, tensile stress in sheet metal forming, are investigated based on the deformation behavior and fracture occurrence in two case studies with two typical types of materials, i.e. Al 6061 and T10A. The materials have a wide range of plasticity. The simulation and experimental results verify the applicability and reliability of the developed ductile fracture criterion in prediction of the ductile fracture with and without necking in different stress states of plastic strain.


2015 ◽  
Vol 639 ◽  
pp. 543-550
Author(s):  
Rong Zeng ◽  
Liang Huang ◽  
Jian Jun Li

Sheet metal stamping is an important manufacturing process because of its high production rate and low cost, so the fracture prediction of stamping parts has become important issues. Recent experimental studies have shown that the quality of stamping parts can be increased by using ductile fracture criteria. This paper proposed a modified ductile fracture criterion based on the macroscopic and microscopic continuum damage mechanics (CDM). Three-dimensional (3D) explicit finite element analysis (FEA) are performed to predict the fracture behaviors of sheet metal stamping process. An approach to determine the material constants of modified ductile fracture criterion is presented with the help of uniaxial tensile tests and compressive tests. The results show that the modified ductile fracture criterion enables precise cup depth and fracture location of sheet metal stamping under nonlinear paths. Compared with typical ductile fracture criteria, the results predicted with modified ductile fracture criterion correlate the best with the experimental data.


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianye Gao ◽  
Tao He ◽  
Yuanming Huo ◽  
Miao Song ◽  
Tingting Yao ◽  
...  

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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