A ductile fracture criterion under warm-working conditions based on the multiscale model combining molecular dynamics with finite element methods

Author(s):  
Liqun Niu ◽  
Qi Zhang ◽  
Yingsong Ma ◽  
Yujie Chen ◽  
Bin Han ◽  
...  
1998 ◽  
Vol 84 (3) ◽  
pp. 182-187 ◽  
Author(s):  
Hirohiko TAKUDA ◽  
Ken-ichiro MORI ◽  
Masashi KANESHIRO ◽  
Natsuo HATTA

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.


2012 ◽  
Vol 472-475 ◽  
pp. 781-786
Author(s):  
Duc Toan Nguyen ◽  
Young Suk Kim ◽  
Dong Won Jung

The FEM simulation results of deep drawing process are carried out to create training cases for the artificial neural network (ANN), and then the well-trained ANN(s) is used to predict the formability of aluminum alloy A1100-O sheets. The OYANE’ s ductile fracture criterion equation [J. Mech. Work. Technol. 4 (1980), pp. 65-81] was implemented to predict the formability of deep drawing process. This ductile fracture criterion is introduced and evaluated from the histories of stress and strain calculated by means of finite element analysis in order to get the ductile fracture value (I). The resolution of the results of ductile fracture criterion equations is carried out via a VUMAT user material, using ABAQUS/Explicit finite element code. From the calculative results of FEM simulation with the changing of various parameters, the formability predictions using ANN methodology was investigated by comparing with random case studies of FEM results and shown good agreements


2007 ◽  
Vol 340-341 ◽  
pp. 665-670 ◽  
Author(s):  
Jong Sup Lee ◽  
Yoon Ki Ko ◽  
Hoon Huh ◽  
Hong Ki Kim ◽  
Sung Ho Park

This paper is concerned with hole flangeability of steel sheet, which is evaluated by experiment and finite element analysis with respect to the hole processing condition. The hole flangeability of a material as a forming limit needs to be verified to predict and prevent the undesirable fracture during a flanging process. Hole expanding tests are carried out to identify the effect of hole processing conditions on the hole expanding ratio (HER), which is an indicator of the hole flangeability. Specimens with two different hole conditions are prepared: one is produced with punching process; and the other is reamed after punching to get smoother hole surface. Experimental results show that the facture mechanism and the HER are quite different with respect to the hole conditions. Thorough investigation of those effects is carried out with tensile tests of a specimen with notches. From the experiments, the fracture strain is obtained with different hole conditions and is used to determine the material constants of a new proposed ductile fracture criterion which is applied to finite element analyses of the hole flanging process for prediction of the HER. The experimental results are confirmed and reevaluated by the finite element analysis with the ductile fracture criterion.


Author(s):  
Michael F. Macri

In this paper, we assess the ability of three interpolation functions in a discretized continuum model to capture and accurately represent the solution. In particular we examine the differences between the partition of unity, moving least squares and finite element methods in the continuum part of the multiscale model.


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