Numerical Study of Localized Necking in the Strain Path of Copper Hydroformed Tube: Effect of Friction

Author(s):  
Abir Abdelkefi ◽  
Noamen Guermazi ◽  
Nathalie Boudeau ◽  
Pierrick Malécot ◽  
Gerard Michel
Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 26
Author(s):  
Krzysztof Muszka ◽  
Mateusz Sitko ◽  
Paulina Lisiecka-Graca ◽  
Thomas Simm ◽  
Eric Palmiere ◽  
...  

The experimental and numerical study of the effects of the recrystallization behavior of austenite model alloys during hot plate rolling on reverse rolling is the main goal of the paper. The computer models that are currently applied for simulation of reverse rolling are not strain-path-sensitive, thus leading to overestimation of the processing parameters outside the accepted process window (e.g., deformation in the partial austenite recrystallization region). Therefore, in this work, a particular focus is put on the investigation of strain path effects that occur during hot rolling and their influence on the microstructure evolution and mechanical properties of microalloyed austenite. Both experimental and numerical techniques are employed in this study, taking advantage of the integrated computational material engineering concept. The combined isotropic–kinematic hardening model is used for the macroscale predictions to take into account softening effects due to strain reversal. The macroscale model is additionally enriched with the full-field microstructure evolution model within the cellular automata framework. Examples of obtained results, highlighting the role of the strain reversal on the microstructural response, are presented within the paper. The combination of the physical simulation of austenitic model alloys and computer modeling provided new insights into optimization of the processing routes of advanced high-strength steels (AHSS).


2013 ◽  
Vol 81 (5) ◽  
Author(s):  
Y. Shi ◽  
P. D. Wu ◽  
D. J. Lloyd ◽  
D. Y. Li

An elastic-viscoplastic based finite element model has been developed to study the necking behavior of tube expansion for rate independent materials, rate dependent monolithic materials, and laminated materials during dynamic loading. A numerical study shows that for rate independent materials, the dynamic loading will not delay diffused necking but localized necking; for rate dependent materials, high strain rate sensitivity can significantly delay the onset of localized necking for both monolithic and laminated sheets and affect the multiple-neck formation in high-speed dynamic loading. The model also shows that a higher volume fraction of a clad layer with positive rate sensitivity material in a laminated sheet improves the sheet ductility.


2006 ◽  
Vol 524-525 ◽  
pp. 511-516
Author(s):  
D. Gloaguen ◽  
Jamal Fajoui ◽  
Bruno Courant ◽  
Ronald Guillén

A two-level homogenisation approach is applied to the micro-mechanical modelling of the elasto-plasticity of polycrystalline materials during various strain-path changes. The model is tested by simulating the development of intragranular strains during different complex loads. Mechanical tests measurements are used as a reference in order to validate the model. The anisotropy of plastic deformation in relation to the evolution of the dislocation structure is analysed. The results demonstrate the relevance of this approach for FCC polycrystals.


2018 ◽  
Vol 920 ◽  
pp. 223-229
Author(s):  
Chi Zhou ◽  
Wen Tao Zhang ◽  
Sai Jun Zhang ◽  
Jun Jie Deng ◽  
Qin Xiang Xia

The effect of strain path change on formability of TRIP590 and TRIP780 was investigated experimentally. Two-step uniaxial tension tests, which consist of the first loading in the rolling direction (RD) and the second loading in the directions varied from RD to transverse direction (TD) in every 15º, were conducted. The evolution of strain rates inside and outside the localized necking zone were inspected by using DIC measuring technique. When the angle between the two loading directions was increased from 0º to 90 º, the subsequent hardening behavior in second step was transited from cross-loading type to Bauschinger type. The total elongation was increased when the two loading directions are close to each other and then it was decreased with the increase of angle. When the angle further increased to 90 º, the total elongation is increased again. It is believed that both of the martensite transformation and Bauschinger type transient has a positive impact on the formability of TRIP steels.


Author(s):  
Mohamed Ben Bettaieb ◽  
Farid Abed-Meraim

This paper deals with localized necking in stretched metal sheets using the initial imperfection approach. The first objective is to study the effect of kinematic hardening on the formability of a freestanding metal layer. To this end, the behavior of the metal layer is assumed to follow the rigid-plastic rate-independent flow theory. The isotropic (respectively, kinematic) hardening of this metal is modeled by the Hollomon (respectively, Prager) law. A parametric study is carried out in order to investigate the effect of kinematic hardening on the formability limits. It is shown that the effect of kinematic hardening on the ductility limit is noticeably different depending on the strain path considered. The second aim of this paper is to analyze the effect of an elastomer substrate, perfectly bonded to the metal layer, on the formability of the whole bilayer. It is found that the addition of an elastomer layer substantially enhances the formability of the bilayer, in agreement with earlier studies.


1978 ◽  
Vol 100 (3) ◽  
pp. 303-309 ◽  
Author(s):  
A. S. Korhonen

The history and the present state of the theory of sheet metal forming limits are reviewed. The theory of necking and plastic instability (Swift-Hill and Marciniak-Kuczyn´ski models) is discussed and theoretical limit strains are calculated. The influence of the strain path on the theoretical limit strains is discussed with computational examples. At the present no theory can fully explain the localized necking in stretch forming.


1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,

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