scholarly journals A modified split Hopkinson torsional bar system for correlated study of τ – γ relations, shear localization and microstructural evolution

2014 ◽  
Vol 372 (2015) ◽  
pp. 20130208 ◽  
Author(s):  
Rong Yang ◽  
Husheng Zhang ◽  
Letian Shen ◽  
Yongbo Xu ◽  
Yilong Bai ◽  
...  
Keyword(s):  
Dynamic Stress ◽  
Shear Localization ◽  
Stress And Strain ◽  
Strain Response ◽  
Micro Structure ◽  
Paper Briefly ◽  
Effective Period ◽  
Split Hopkinson ◽  
Shear Stress And Strain ◽  
Set Up

The conventional split Hopkinson torsional bar (SHTB) system consists of two bars, which can successfully produce the data for the construction of dynamic torsional shear stress and strain relationships. However, the system cannot provide reliable information on the progression of the deformed micro-structure during the test. The reverberation of waves in the bars and the tested specimen can spoil the microstructural pattern formed during the effective loading. This paper briefly reviews a modified version of the SHTB system consisting of four bars that has been developed. This modified system can eliminate the reverberation of waves in the specimen and provide only a single rectangular torsional stress pulse, thus it can properly freeze the microstructure formed during the effective period of loading in the specimen. By using the advantage of the modified SHTB system, together with a new design of specimen, it is possible to perform a correlated study of the dynamic stress–strain response, shear localization and the evolution of the microstructure at a fixed view-field (position) on a given specimen during the sequence of the loading time. The principles, experimental set-up and procedure, calibration and some preliminary results of the correlated study are reported in this paper.

Atomic simulation of mechanical properties of irradiated iron

2019 ◽  
Vol 31 (02) ◽  
pp. 2050027
Author(s):  
Lei Ma ◽  
Changsheng Li ◽  
Ailong Zhang ◽  
Wangyu Hu
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Tensile Test ◽  
Room Temperature ◽  
Stacking Faults ◽  
Dynamics Simulation ◽  
Stress And Strain ◽  
Micro Structure ◽  
Atomic Simulation

The mechanical properties of irradiated iron are studied by molecular dynamics simulation. The initial models are irradiated with the energy of primary knocked-on atoms (PKA) of 10[Formula: see text]keV at 100, 300, 500 and 600 K, and then all the irradiated models are subjected to tensile test. The results reveal that the mechanical properties of irradiated iron are changed compared with un-irradiated iron, the yield stress and strain decrease after irradiation, and the irradiation causes the hardening of micro-structure at low temperature and high temperature, but it results in the softening of structure at room temperature. The plastic reduces for irradiated iron under tensile test, more stacking faults are formed in the crystal structure as the temperature increases.

Research and Experiment on Sleeve Damage Mechanism of Oil Film Bearing in Large-Scale Mill

2005 ◽  
Author(s):  
Qing-Xue Huang ◽  
Jian-Mei Wang
Keyword(s):  
Large Scale ◽  
Damage Mechanism ◽  
Theoretical Research ◽  
Hot Strip Mill ◽  
Stress And Strain ◽  
Axial Thrust ◽  
Oil Film ◽  
Hot Strip ◽  
Set Up ◽  
Thrust Forces

During the process of set up and disassembly and usage period, the sleeve of oil film bearing in the backup roll of some 1580PC hot strip mill has been dramatically damaged, which results in production accidents and decreases the service life of bearing. Aimed at such puzzles, theoretical research has been quantitatively analyzed by BEM with 3D elastic-plastic contact, variable laws of stress and strain under different hydroform pressures and axial thrust forces during the setup and disassembly process of sleeve have been drawn, the reasons that result in sleeve failure have been analyzed as well. Finally, Detailed experiments have been made on the two sample mills, which have been manufactured for research and analysis.

An Energy Approach to the Mechanics of Discontinuous Chip Formation

1964 ◽  
Vol 86 (2) ◽  
pp. 157-162 ◽  
Author(s):  
W. K. Luk ◽  
R. C. Brewer
Keyword(s):  
Shear Stress ◽  
Shear Strain ◽  
Normal Stress ◽  
Chip Formation ◽  
Strain Energy ◽  
Energy Condition ◽  
Stress And Strain ◽  
Rupture Plane ◽  
Shear Stress And Strain ◽  
Shear Strain Energy

After briefly reviewing previous work in this field, the authors propose that rupture of the chip work contact (to give a discontinuous chip) is governed by a limiting shear strain energy condition. Assuming that shear stress and strain at rupture are dependent on the compressive normal stress, a criterion for the direction of the rupture plane is deduced. Using some results given by Field and Merchant, the authors then compare their calculated direction of rupture with that experimentally observed. Some indication that the agreement is not entirely fortuitous is afforded by checking the calculated shear strain energy at fracture with that calculated from force and chip measurements.

scholarly journals A modified split Hopkinson torsional bar in studying shear localization

1995 ◽  
Vol 6 (11) ◽  
pp. 1557-1565 ◽  
Author(s):  
Q Xue ◽  
L T Shen ◽  
Y L Bai
Keyword(s):  
Shear Localization ◽  
Split Hopkinson

scholarly journals Recent Development of the Atomic Line List

Galaxies ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 63 ◽  
Author(s):  
Peter Van Hoof
Keyword(s):  
Transition Probabilities ◽  
Atomic Line ◽  
Spectral Features ◽  
Online Database ◽  
Web Interface ◽  
Paper Briefly ◽  
Line List ◽  
Atomic Lines ◽  
Set Up ◽  
The Web

The Atomic Line List is an online database of wavelengths and transition probabilities of atomic lines. It is primarily set up as a tool to help identify unknown spectral features. This paper briefly describes the web interface, how the line list is constructed, and what development is currently being undertaken for the next release.

scholarly journals Improving Electrical Efficiency of Edm Power Supply

2014 ◽  
Vol 64 (1) ◽  
pp. 88-93
Author(s):  
Emanoil Toma ◽  
Carmen Mihaela Simion
Keyword(s):  
Current Pulse ◽  
Power Supply ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Resonant Converter ◽  
Output Current ◽  
Paper Briefly ◽  
Electrical Efficiency ◽  
Pulse Generators ◽  
Set Up

Abstract This paper briefly presents the principal types of Pulse Generators for Electrical Discharge Machining and ways to improve electrical efficiency. A resonant converter with series-parallel LCC circuit, for EDM applications, was analyzed by PSpice simulation. The performances of EDM Power Supply were improved by adding an energy recovering - voltage limiter circuit. The shape of current pulse was changed by adding a supplementary MOSFET Switch in parallel with the gap. Two or more converters can be parallelized, in this way output current can be changed. A bloc-schema was conceived for EDM experimental set up

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