scholarly journals Plastic instability and texture modification in extruded Mg-Mn-Nd alloy

2021 ◽  
Author(s):  
Sang Kyu Woo ◽  
Risheng Pei ◽  
Talal Al-Samman ◽  
Dietmar Letzig ◽  
Sangbong Yi
Keyword(s):  
Plastic Instability ◽  
Texture Modification

Optimization of Tube Hydroforming Process Using Probabilistic Constraints on Failure Modes

2011 ◽  
Vol 62 ◽  
pp. 21-35 ◽  
Author(s):  
Anis Ben Abdessalem ◽  
A. El Hami
Keyword(s):  
Failure Modes ◽  
High Reliability ◽  
Thickness Distribution ◽  
Tube Hydroforming ◽  
Forming Limit Diagram ◽  
Plastic Instability ◽  
Probabilistic Constraints ◽  
Forming Limit ◽  
Reliability Based Design ◽  
Hydroforming Process

In metal forming processes, different parameters (Material constants, geometric dimensions, loads …) exhibits unavoidable scatter that lead the process unreliable and unstable. In this paper, we interest particularly in tube hydroforming process (THP). This process consists to apply an inner pressure combined to an axial displacement to manufacture the part. During the manufacturing phase, inappropriate choice of the loading paths can lead to failure. Deterministic approaches are unable to optimize the process with taking into account to the uncertainty. In this work, we introduce the Reliability-Based Design Optimization (RBDO) to optimize the process under probabilistic considerations to ensure a high reliability level and stability during the manufacturing phase and avoid the occurrence of such plastic instability. Taking account of the uncertainty offer to the process a high stability associated with a low probability of failure. The definition of the objective function and the probabilistic constraints takes advantages from the Forming Limit Diagram (FLD) and the Forming Limit Stress Diagram (FLSD) used as a failure criterion to detect the occurrence of wrinkling, severe thinning, and necking. A THP is then introduced as an example to illustrate the proposed approach. The results show the robustness and efficiency of RBDO to improve thickness distribution and minimize the risk of potential failure modes.

Plastic instability of a cylindrical angle-ply shell in biaxial tension

1995 ◽  
Vol 30 (5) ◽  
pp. 474-483
Author(s):  
P. A. Zinov'ev ◽  
S. V. Tsvetkov
Keyword(s):  
Biaxial Tension ◽  
Plastic Instability

Prediction of Defects in Multistage Cold Forging by Using Finite Element Method

2014 ◽  
Vol 622-623 ◽  
pp. 659-663 ◽  
Author(s):  
Fabio Bassan ◽  
Paolo Ferro ◽  
Franco Bonollo
Keyword(s):  
Radial Flow ◽  
Surface Defects ◽  
Plastic Instability ◽  
Cold Forging ◽  
Formation Mechanisms ◽  
Fe Model ◽  
Pipe Fitting ◽  
Tooling Design ◽  
Simulated Flow ◽  
Good Agreement

In this work, the formation mechanisms of surface defects in multistage cold forging of axisymmetrical parts have been studied through FEM simulations. As case history, the industrial production of an heating pipe fitting by cold forging has been analyzed. Based on simulated flow behaviour of material, several types of surface defects are identified and attributed to plastic instability of the work-material, inappropriate axial/radial flow ratio, excessive forming-pressure and uncorrect tooling design. The results of the FE model are finally compared with those obtained from real forging process and good agreement is observed.

Microstructure Evolution and Deformation Mechanisms of Harmonic Structure Designed Materials

2016 ◽  
Vol 879 ◽  
pp. 145-150
Author(s):  
Kei Ameyama ◽  
Sanjay Kumar Vajpai ◽  
Mie Ota
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Powder Metallurgy ◽  
Early Stage ◽  
High Strength ◽  
Plastic Instability ◽  
Structure Design ◽  
Harmonic Structure ◽  
Homogeneous Microstructure ◽  
Macro Scale

This paper presents the novel microstructure design, called Harmonic Structure, which gives structural metallic materials outstanding mechanical properties through an innovative powder metallurgy process. Homogeneous and ultra-fine grain (UFG) structure enables the materials high strength. However, such a “Homo-“ and “UFG” microstructure does not, usually, satisfy the need to be both strong and ductile, due to the plastic instability in the early stage of the deformation. As opposed to such a “Homo-and UFG“ microstructure, “Harmonic Structure” has a heterogeneous microstructure consisting of bimodal grain size together with a controlled and specific topological distribution of fine and coarse grains. In other words, the harmonic structure is heterogeneous on micro-but homogeneous on macro-scales. In the present work, the harmonic structure design has been applied to pure metals and alloys via a powder metallurgy route consisting of controlled severe plastic deformation of the corresponding powders by mechanical milling or high pressure gas milling, and subsequent consolidation by SPS. At a macro-scale, the harmonic structure materials exhibited superior combination of strength and ductility as compared to their homogeneous microstructure counterparts. This behavior was essentially related to the ability of the harmonic structure to promote the uniform distribution of strain during plastic deformation, leading to improved mechanical properties by avoiding or delaying localized plastic instability.

scholarly journals Studying the Effects of Nucleating Agents on Texture Modification of Puffed Corn-Fish Snack

2014 ◽  
Vol 79 (2) ◽  
pp. E178-E183 ◽  
Author(s):  
Hamid Reza Shahmohammadi ◽  
Jamilah Bakar ◽  
Russly Abdul Rahman ◽  
Noranizan Mohd Adzhan
Keyword(s):  
Nucleating Agents ◽  
Texture Modification

Antibiofilm properties of model composites containing quaternary ammonium methacrylates after surface texture modification

2017 ◽  
Vol 33 (10) ◽  
pp. 1149-1156 ◽  
Author(s):  
Guilherme Ferreira Rego ◽  
Marina Lermen Vidal ◽  
Gil Mendes Viana ◽  
Lucio Mendes Cabral ◽  
Luis Felipe Jochims Schneider ◽  
...  
Keyword(s):  
Surface Texture ◽  
Quaternary Ammonium ◽  
Texture Modification
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