Simulation of ductile tearing during a full size test using a non local Gurson–Tvergaard–Needleman (GTN) model

Author(s):  
Youbin Chen ◽  
Eric Lorentz ◽  
Anna Dahl ◽  
Jacques Besson
PAMM ◽  
2011 ◽  
Vol 11 (1) ◽  
pp. 157-158
Author(s):  
Geralf Hütter ◽  
Thomas Linse ◽  
Uwe Mühlich ◽  
Meinhard Kuna

2020 ◽  
Vol 229 ◽  
pp. 106817
Author(s):  
Andreas Seupel ◽  
Geralf Hütter ◽  
Meinhard Kuna

Author(s):  
Frederick Reusch ◽  
Christian Hortig ◽  
Bob Svendsen

The purpose of the current work is the application of a recent nonlocal extension (Reusch, F., Svendsen, B., and Klingbeil, D., 2003, “Local and Non-Local Gurson-Based Ductile Damage and Failure Modelling at Large Deformation,” Eur. J. Mech. A∕Solids, 22, pp. 779–792; “A Non-Local Extension of Gurson-Based Ductile Damage Modeling,” Comput. Mater. Sci., 26, pp. 219–229) of the Gurson–Needleman–Tvergaard (GTN) model (Needleman, A., and Tvergaard, V., 1984, “An Analysis of Ductile Rupture in Notched Bars,” J. Mech Phys. Solids, 32, pp. 461–490) to the simulation of ductile damage and failure processes in metal matrix composites at the microstructural level. The extended model is based on the treatment of void coalescence as a nonlocal process. In particular, we compare the predictions of the local with GTN model with those of the nonlocal extension for ductile crack initiation in ideal and real Al–SiC metal matrix microstructures. As shown by the current results for metal matrix composites and as expected, the simulation results based on the local GTN model for both the structural response and predicted crack path at the microstructural level in metal matrix composites are strongly mesh-dependent. On the other hand, those based on the current nonlocal void-coalescence modeling approach are mesh-independent. This correlates with the fact that, in contrast to the local approach, the predictions of the nonlocal approach for the crack propagation path in the real Al–SiC metal matrix composite microstructure considered here agree well with the experimentally determined path.


2021 ◽  
Author(s):  
Kiminobu Hojo ◽  
Takatoshi Hirota ◽  
Naoki Ogawa ◽  
Satoshi Kumagai

Author(s):  
Rémi Lacroix ◽  
Julie Drouet ◽  
Sébastien Gallée ◽  
Stéphane Chapuliot ◽  
Philippe Gilles

The experimental assessment of ductile failure of Dissimilar Materials Welds (DMW) of NPP components can be challenging. For instance, the European project ADIMEW [1] has shown the technical complexity of the bending set-up on a DMW join at 300°C. Such experiments are so scarce that their analysis is highly valuable to quantify the validity of alternative methods for assessing the ductile failure. This paper presents the application of the numerical simulation of ductile failure with a local approach in the case of the ADIMEW mock-up and discusses its validity.


Author(s):  
Zhifeng Shao

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as


Author(s):  
Zhifeng Shao ◽  
A.V. Crewe

For scanning electron microscopes, it is plausible that by lowering the primary electron energy, one can decrease the volume of interaction and improve resolution. As shown by Crewe /1/, at V0 =5kV a 10Å resolution (including non-local effects) is possible. To achieve this, we would need a probe size about 5Å. However, at low voltages, the chromatic aberration becomes the major concern even for field emission sources. In this case, δV/V = 0.1 V/5kV = 2x10-5. As a rough estimate, it has been shown that /2/ the chromatic aberration δC should be less than ⅓ of δ0 the probe size determined by diffraction and spherical aberration in order to neglect its effect. But this did not take into account the distribution of electron energy. We will show that by using a wave optical treatment, the tolerance on the chromatic aberration is much larger than we expected.


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