Constitutive Modeling of Nanocrystalline Materials with Shear Band

2011 ◽  
Vol 311-313 ◽  
pp. 512-515
Author(s):  
Jian Qiu Zhou ◽  
Shu Zhang ◽  
Ying Wang
Keyword(s):  
Shear Band ◽  
Nanocrystalline Materials ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Deformation Behaviors ◽  
Band Deformation ◽  
Two Phases ◽  
Softening Stage ◽  
Insight Into ◽  
Main Deformation

In hardening stage, a model was used to study the plastic deformation behaviors of nanocrystalline materials. The material was considered as a composite of grain interior phase and grain boundary (GB) phase. The constitutive equations of the two phases were determined in term of their main deformation mechanisms. In softening stage, a shear band deformation mechanism and the corresponding constitutive relation were presented. Calculation results have shown that the predications fit well with experimental data. The investigation using the finite-element method (FEM) provided a direct insight into quantifying shear localization effect in nanocrystalline materials.

Constitutive Model for Large Plastic Deformation of Nanocrystalline Materials

2011 ◽  
Vol 682 ◽  
pp. 139-144
Author(s):  
Hua Jiang ◽  
Jian Qiu Zhou ◽  
Rong Tao Zhu
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Constitutive Model ◽  
Nanocrystalline Materials ◽  
Metallic Materials ◽  
Large Plastic Deformation ◽  
Phase Mixture ◽  
Band Deformation ◽  
Softening Stage ◽  
Good Agreement

A constitutive model was presented for nanocrystalline metallic materials that can experience large plastic deformation with shear band. The model was composed of two parts for different deformation stage: hardening stage and softening stage. In the hardening stage, the phase mixture model was used, and in the softening stage, a shear band deformation mechanism was proposed. Based on the model presented, numerical simulations were carried out to prove that the predications kept in good agreement with experimental data.

Strength and Plastic Deformation Behavior of Nano-Scale Au/Cu and Cr/Cu Multilayers

2008 ◽  
Vol 41-42 ◽  
pp. 3-8 ◽  
Author(s):  
Y.P. Li ◽  
G.P. Zhang ◽  
Z.G. Wang
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Layer Structure ◽  
Individual Layer ◽  
Nano Scale ◽  
Dislocation Plasticity ◽  
Plastic Deformation Behavior ◽  
Deformation Behaviors ◽  
The Difference ◽  
Band Deformation

Nano-scale Au/Cu multilayers were investigated by nano/microindentation. It was found that the hardness of the multilayers increases with decreasing individual layer thickness (λ), and shear band deformation can occur more easily in the multilayer with small λ. For comparison, the same experiments were also performed on Cr/Cu multilayers with the same layer structure. The results show that the Cr/Cu multilayer can be more effective in resisting shear band deformation than the Au/Cu multilayer. Finally, the λ dependence of shear band deformation and the difference between plastic deformation behaviors of the two multilayers were analyzed based on dislocation plasticity.

scholarly journals An Insight into Amorphous Shear Band in Magnetorheological Solid by Atomic Force Microscope

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4384
Author(s):  
Mohd Aidy Faizal Johari ◽  
Asmawan Mohd Sarman ◽  
Saiful Amri Mazlan ◽  
Ubaidillah U ◽  
Nur Azmah Nordin ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Shear Band ◽  
Shear Bands ◽  
Test Duration ◽  
Phase Imaging ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Matrix ◽  
Relaxation Stress ◽  
Band Deformation

Micro mechanism consideration is critical for gaining a thorough understanding of amorphous shear band behavior in magnetorheological (MR) solids, particularly those with viscoelastic matrices. Heretofore, the characteristics of shear bands in terms of formation, physical evolution, and response to stress distribution at the localized region have gone largely unnoticed and unexplored. Notwithstanding these limitations, atomic force microscopy (AFM) has been used to explore the nature of shear band deformation in MR materials during stress relaxation. Stress relaxation at a constant low strain of 0.01% and an oscillatory shear of defined test duration played a major role in the creation of the shear band. In this analysis, the localized area of the study defined shear bands as varying in size and dominantly deformed in the matrix with no evidence of inhibition by embedded carbonyl iron particles (CIPs). The association between the shear band and the adjacent zone was further studied using in-phase imaging of AFM tapping mode and demonstrated the presence of localized affected zone around the shear band. Taken together, the results provide important insights into the proposed shear band deformation zone (SBDZ). This study sheds a contemporary light on the contentious issue of amorphous shear band deformation behavior and makes several contributions to the current literature.

Dynamic assessment and requesting: Assessing the development of Japanese EFL learners’ oral requesting performance interactively

2020 ◽  
Vol 17 (5) ◽  
pp. 545-575
Author(s):  
Allan Nicholas
Keyword(s):  
Conversation Analysis ◽  
Dynamic Assessment ◽  
Task Type ◽  
Efl Learners ◽  
Coding Scheme ◽  
Dynamic Methods ◽  
Two Phases ◽  
Japanese Learners ◽  
Development Analysis ◽  
Insight Into

AbstractThis study investigates the use of dynamically-administered strategic interaction scenarios (D-SIS) in identifying Japanese EFL participants’ difficulties with requesting-in-interaction, and tracking their development. Informed by conversation analysis research, six Japanese EFL learners at a university in Japan carried out D-SIS tasks in two phases, with the aim of both identifying specific aspects of requesting-in-interaction that were challenging, and learner development. Analysis focuses on three particular areas of difficulty that arose for participants during the dialogic interactions—connecting request turn utterance linguistic choices to social context; pre-request expansions of requesting talk, and pre-closing sequences. A coding scheme was applied that analyzed mediation sequences in terms of the efficiency with which participants oriented to and resolved problems, allowing ZPD movement to be quantified. In combination with close qualitative analysis of the transcript data, mediation sequences provided insights into the participants’ knowledge and understanding of these areas that would not have been gained through non-dynamic methods. Results therefore provide insight into areas of difficulty for Japanese learners with regards to requesting, and provide support for the use of the D-SIS task type as a diagnostic tool in regards to request-based talk-in-interaction.

scholarly journals NUMERICAL ANALYSIS OF CORRUGATED STEEL PLATE BRIDGE WITH REINFORCED CONCRETE RELIEVING SLAB

2015 ◽  
Vol 22 (5) ◽  
pp. 585-596 ◽  
Author(s):  
Damian BEBEN ◽  
Adam STRYCZEK
Keyword(s):  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Steel Plate ◽  
Numerical Models ◽  
Experimental Tests ◽  
Bridge Engineering ◽  
Steel Plates ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Rc Slab

The paper presents a numerical analysis of corrugated steel plate (CSP) bridge with reinforced concrete (RC) relieving slab under static loads. Calculations were made based on the finite element method using Abaqus software. Two computation models were used; in the first one, RC slab was used, and the other was without it. The effect of RC slab to deformations of CSP shell was determined. Comparing the computational results from two numerical models, it can be concluded that when the relieving slab is applied, substantial reductions in displacements, stresses, bending mo­ments and axial thrusts are achieved. Relative reductions of displacements were in the range of 53–66%, and stresses of 73–82%. Maximum displacements and bending moments were obtained at the shell crown, and maximum stresses and axial thrusts at the quarter points. The calculation results were also compared to the values from experimental tests. The course of computed displacements and stresses is similar to those obtained from experimental tests, although the absolute values were generally higher than the measured ones. Results of numerical analyses can be useful for bridge engineering, with particular regard to bridges and culverts made from corrugated steel plates for the range of necessity of using additional relieving elements.

scholarly journals Cause Analysis and Countermeasures of a Breakdown Failure of Flexible 110 kV Cable Terminal

2018 ◽  
Vol 38 ◽  
pp. 04004
Author(s):  
Feng Huang
Keyword(s):  
Electric Field ◽  
Electric Field Intensity ◽  
Field Model ◽  
Semiconductor Layer ◽  
Mechanism Analysis ◽  
The Finite Element Method ◽  
Cable Insulation ◽  
Cause Analysis ◽  
Breakdown Mechanism ◽  
Calculation Results

disintegration examination and analysis are employed in flexible terminal breakdown of 110 kV XLPE insulated cables. It is considered that the main reason of breakdown is the separation of the stress cone of the terminal and the fracture of the semi- conductive layer of the cable insulation. Therefore, the finite element method is used to electric field model and simulate the dislocation fault of internal stress cone and outer semiconductor layer of cable insulation. The distribution of the electric field intensity is calculated and compared. The simulation and calculation results verify the validity of the breakdown mechanism analysis, and put forward some practical suggestions.

scholarly journals INFORMATIZATION OF CONSTRUCTION MANAGEMENT AS A BASIS FOR PREVENTING MAN-MADE ACCIDENTS

2021 ◽  
Vol 4 (4) ◽  
pp. 11-31
Author(s):  
S. Koryagina
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Definition Of ◽  
Deep Pits ◽  
Geotechnical Problems ◽  
Seismic Impacts ◽  
Base Structure ◽  
Element Method

the article presents the principles and algorithms of the finite element method in solving geotechnical prob-lems taking into account seismic impacts for determining the stress-strain state of structures and slope stabil-ity, implemented in the Midas GTS NX software package. GTS NX allows you to perform calculations of various types of geotechnical problems and solve complex geotechnical problems in a single software envi-ronment. GTS NX covers the entire range of engineering and geotechnical projects, including calculations of the "base-structure" system, deep pits with various mounting options, tunnels of complex shape, consolida-tion and filtration calculations, as well as calculations for dynamic actions and stability calculations. At the same time, all types of calculations in GTS NX can be performed both in 2D and in 3D. The author does not claim to be the author of the finite element method, but he cannot do without pointing out the basic equa-tions, as this affects the definition of the boundaries of use, the formulation of algorithms for constructing calculation schemes and the analysis of calculation results.

Analysis by the mixed method of statically indeterminate frames with elements of increased rigidity and numerical verification of the calculation results using the finite element method

2021 ◽  
Vol 14 (2) ◽  
pp. 54-66
Author(s):  
Svetlana Sazonova ◽  
Viktor Asminin ◽  
Alla Zvyaginceva
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Initial Data ◽  
Mixed Method ◽  
Numerical Verification ◽  
Bending Moments ◽  
The Finite Element Method ◽  
Calculation Results ◽  
Internal Forces ◽  
Element Method

The sequence of application of the mixed method for calculating internal forces in statically indeterminate frames with elements of increased rigidity is given. The main system is chosen for the frame with one kinematic and one force unknown. The canonical equations of the mixed method are written, taking into account their meaning. Completed the construction of the final diagram of the bending moments and all the necessary calculations and checks. When calculating integrals, Vereshchagin's rule is applied. The solution of the problem is checked by performing the calculation using the computer program STAB12.EXE; the results of the calculations are numerically verified using the finite element method. An example of the formation of the initial data for the STAB12.EXE program and the subsequent processing of the calculation results, the rules for comparing the numerical results and the results obtained in the calculation of the frame by the mixed method are given.

Electrowetting Induced Droplet Generation in T-junctions

2021 ◽  
Author(s):  
Arshia Merdasi ◽  
Ali Moosavi
Keyword(s):  
Shear Stress ◽  
Continuous Phase ◽  
Droplet Breakup ◽  
Droplet Generation ◽  
The Finite Element Method ◽  
Fluidic Channel ◽  
Generation Frequency ◽  
Two Phases ◽  
Breakup Time ◽  
Good Agreement

Abstract In the current study, droplet generation in a T-junction fluidic channel device was studied through using electrowetting actuation with the consideration of different droplet forming regimes. For this purpose, the finite element method (FEM) was used to solve the unsteady Naiver-Stokes equation. In addition, the level set method was applied to capture the interface between two phases. It was shown that there was a good agreement between obtained data and other work during the process of droplet generation in the absence of electrowetting actuation which results in decrease in the size of droplet with increasing the velocity ratios. In shearing regime, the effectiveness of electrowetting on the droplet generation frequency as well as droplet size is visible in a T-junction fluidic channel since after applying voltages, specified with non-dimensional electrowetting numbers of ?=0.5 and 1.2, dispersed phase is pulled out into the oil phase. In fact, with applying the voltage on the top wall, the droplet breakup time was decreased and smaller droplets were produced. Finally, different important parameters such as pressure difference across the interface as well as Shear Stress exerted from the continuous phase shear stress were examined in a detail.

Failure mechanisms in two-layer undrained slopes

2020 ◽  
Vol 57 (10) ◽  
pp. 1617-1621
Author(s):  
Shuangfeng Guo ◽  
D.V. Griffiths
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Slope Angle ◽  
Strength Ratio ◽  
The Finite Element Method ◽  
Stability Analyses ◽  
Shallow Failure ◽  
Insight Into

This note presents results of stability analyses of two-layer undrained slopes by the finite element method. The study focuses on the circumstances under which either deep or shallow failure mechanisms occur, as a function of the strength ratio of the layers, slope angle, and foundation depth ratio. Improved knowledge of the location of the critical failure mechanism(s) in two-layer systems will give engineers better insight into where to focus their attention in terms or remediation or reinforcement to preserve stability.

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