Extension of the Backward Tracing Scheme of the Rigid-Plastic FEM in Three-Dimensional Deformation

1997 ◽  
Vol 119 (4A) ◽  
pp. 556-562 ◽  
Author(s):  
B. S. Kang ◽  
J. H. Lee ◽  
H. H. Choi
Keyword(s):  
Plastic Deformation ◽  
Metal Forming ◽  
Three Dimensional ◽  
Preform Design ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Critical Fields ◽  
Rigid Plastic ◽  
Process Sequence ◽  
Cylindrical Workpiece

Preform design is one of the critical fields in metal forming. The finite element method (FEM) has been effective in designing preforms and process sequence, for which the backward tracing scheme of the rigid-plastic FEM has been explored. In this work a program using the backward tracing scheme of the rigid-plastic FEM is developed for three-dimensional plastic deformation, which is an extension of the scheme from two-dimensional cases. The calculation of friction between workpiece and die, and handling of boundary conditions during backward tracing require sophisticated treatment. The developed program is applied to upsetting of a rectangular block and to side pressing of a cylindrical workpiece. The results of the two applications show feasibility of the program on three-dimensional plastic deformation.

Bereziskii-Kosterlitz-Thouless transition in the Weyl system PtBi2

2021 ◽  
Author(s):  
Arthur Veyrat ◽  
Valentin Labracherie ◽  
Rohith Acharya ◽  
Dima Bashlakov ◽  
Federico Caglieris ◽  
...  
Keyword(s):  
Condensed Matter ◽  
Three Dimensional ◽  
Spin Orbit Coupling ◽  
Two Dimensional ◽  
Pairing Mechanism ◽  
Critical Fields ◽  
Weyl Semimetal ◽  
Superconducting Coherence Length ◽  
Low Dimensional ◽  
Strong Spin

Abstract Symmetry breaking in topological matter became, in the last decade, a key concept in condensed matter physics to unveil novel electronic states. In this work, we reveal that broken inversion symmetry and strong spin-orbit coupling in trigonal PtBi2 lead to a Weyl semimetal band structure, with unusually robust two-dimensional superconductivity in thin fims. Transport measurements show that high-quality PtBi2 crystals are three-dimensional superconductors (Tc≈600 mK) with an isotropic critical field (Bc≈50 mT). Remarkably, we evidence in a rather thick flake (60 nm), exfoliated from a macroscopic crystal, the two-dimensional nature of the superconducting state, with a critical temperature Tc≈370 mK and highly-anisotropic critical fields. Our results reveal a Berezinskii-Kosterlitz-Thouless transition with TBKT≈310 mK and with a broadening of Tc due to inhomogenities in the sample. Due to the very long superconducting coherence length ξ in PtBi2, the vortex-antivortex pairing mechanism can be studied in unusually-thick samples (at least five times thicker than for any other two-dimensional superconductor), making PtBi2 an ideal platform to study low dimensional superconductivity in a topological semimetal.

scholarly journals Numerical simulation of the dimensional transformation of atomization in a supersonic aerodynamic atomization dust-removing nozzle based on transonic speed compressible flow

2020 ◽  
Vol 7 (3) ◽  
pp. 597-610 ◽  
Author(s):  
Tian Zhang ◽  
Deji Jing ◽  
Shaocheng Ge ◽  
Jiren Wang ◽  
Xiangxi Meng ◽  
...  
Keyword(s):  
Flow Field ◽  
Axisymmetric Flow ◽  
Three Dimensional ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Speed Flow ◽  
Complex Process ◽  
Study Results ◽  
Laval Nozzles

Abstract To simulate the transonic atomization jet process in Laval nozzles, to test the law of droplet atomization and distribution, to find a method of supersonic atomization for dust-removing nozzles, and to improve nozzle efficiency, the finite element method has been used in this study based on the COMSOL computational fluid dynamics module. The study results showed that the process cannot be realized alone under the two-dimensional axisymmetric, three-dimensional and three-dimensional symmetric models, but it can be calculated with the transformation dimension method, which uses the parameter equations generated from the two-dimensional axisymmetric flow field data of the three-dimensional model. The visualization of this complex process, which is difficult to measure and analyze experimentally, was realized in this study. The physical process, macro phenomena and particle distribution of supersonic atomization are analyzed in combination with this simulation. The rationality of the simulation was verified by experiments. A new method for the study of the atomization process and the exploration of its mechanism in a compressible transonic speed flow field based on the Laval nozzle has been provided, and a numerical platform for the study of supersonic atomization dust removal has been established.

Three Dimensional PDMA Assembly: Design, Process, and Applications

2002 ◽  
Author(s):  
C. Liu ◽  
J. Chen ◽  
J. Zou ◽  
Z. Fan
Keyword(s):  
Plastic Deformation ◽  
Design Methodology ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Assembly Process ◽  
Hot Wire ◽  
Assembly Design ◽  
Magnetic Assembly ◽  
Micromechanical Structures ◽  
Rf Inductors

This paper discusses a recent three-dimensional assembly process called the Plastic Deformation Magnetic Assembly (PDMA) method. The PDMA method allows three dimensional micromechanical structures to be realized efficiently using surface micromachining and wafer-scale, post-sacrificial-release assembly. We will discuss the principle of the PDMA method, along with the design methodology. The PDMA process has been used for a number of applications, including vertical micro RF inductors, micromachined hot wire anemometers, artificial lateral line sensors, and two dimensional neuron probes. The process for these applications will be discussed to illustrate the usefulness of the PDMA process.

Finite-element analysis of axi-symmetric rotors

1969 ◽  
Vol 4 (3) ◽  
pp. 163-168
Author(s):  
H Stordahl ◽  
H Christensen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Three Dimensional ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Engineering Problems ◽  
Symmetric Rotor ◽  
Practical Engineering ◽  
Element Method

The finite-element method (1) (2)∗ is increasingly used in the stress analysis of mechanical-engineering problems. It is the purpose of this paper to described how the finite-element method can be used as an effective tool in the design of rotors. Up to the present time this method has mainly been used in the analysis of two-dimensional problems. However, a special class of three-dimensional problems, namely axi-symmetric rotors, can be treated as a nearly two-dimensional problem. This paper summarizes the development of the finite-element method as applied to the analysis of the axi-symmetric rotor. A computer programme is then briefly described, and the application of the method to the solution of three examples taken from practical engineering experience are presented.

Three-Dimensional Rigid-Plastic FEM Simulation of Metal Forming Processes

2006 ◽  
Vol 15 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Young-Suk Kim ◽  
Seung-Han Yang ◽  
Debin Shan ◽  
Seog-Ou Choi ◽  
Sang-Mok Lee ◽  
...  
Keyword(s):  
Metal Forming ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Rigid Plastic

Investigation into the Effect of the Nut Thread Run-Out on the Stress Distribution in a Bolt Using the Finite Element Method

2003 ◽  
Vol 125 (3) ◽  
pp. 527-532 ◽  
Author(s):  
J. W. Hobbs ◽  
R. L. Burguete ◽  
E. A. Patterson
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Element Model ◽  
Two Dimensional ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Dimensional Models ◽  
Three Dimensional Models

By means of comparing results from finite element analysis and photoelasticity, the salient characteristics of a finite element model of a nut and bolt have been established. A number of two-dimensional and three-dimensional models were created with varying levels of complexity, and the results were compared with photoelastic results. It was found that both two-dimensional and three-dimensional models could produce accurate results provided the nut thread run-out and friction were modeled accurately. When using two-dimensional models, a number of models representing different positions around the helix of the thread were created to obtain more data for the stress distribution. This approach was found to work well and to be economical.

Three-Dimensional Finite Element Analysis on Open-Die Block Forging Design

1992 ◽  
Vol 114 (4) ◽  
pp. 459-464 ◽  
Author(s):  
Chinghua Hung ◽  
Shiro Kobayashi
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Rigid Plastic ◽  
Flat Bottom ◽  
Element Analysis ◽  
Dimensional Finite Element ◽  
Die Set ◽  
Cylindrical Workpiece ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Three-dimensional rigid-plastic finite element method was used to analyze the practice of open-die block forging, focusing on the effects of die configurations and forging pass designs. Four combinations of die configurations were investigated: conventional flat dies, top flat/bottom V-shaped dies, and double V-shaped dies with 120 and 135 deg included angles. Two different pass designs, 90 and 180 deg rotation angles between succeeding passes, were applied to each die set. The results include the magnitude and distribution of effective strains along the center line of the cylindrical workpiece and the final shape of the workpiece. Good agreement was observed in comparison with experimental data from physical modeling method, and several suggestions were made for choosing suitable dies.

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