Critical Thickness for Strained Quantum Wires

1995 ◽  
Vol 379 ◽  
Author(s):  
T. J. Gosling ◽  
L. B. Freund
Keyword(s):  
Finite Element ◽  
Critical Thickness ◽  
Quantum Wires ◽  
Lattice Mismatch ◽  
Threading Dislocations ◽  
Element Analysis ◽  
Strained Layers ◽  
Strained Layer ◽  
The Finite Element Analysis ◽  
The Stability

ABSTRACTThe stability of strained quantum wires against the propagation of threading dislocations is considered, using a critical thickness criterion due to Matthews and Blakeslee that is extensively used for strained layers. Given first are results for the critical mismatch at which a buried wire of a given thickness becomes susceptible to degradation. It is found that a wire, once buried, is extremely stable, being able to support, without loss of coherency, around five times the lattice mismatch that can be supported by a buried strained layer of the same thickness. It is concluded that if a strained wire contains dislocations then those dislocations must have been introduced during its growth, when the top surface of the wire is exposed. To investigate this, the results of finite element calculations are presented that give the critical relationship between mismatch and thickness during the growth of a triangular quantum wire being deposited in a [110]-oriented V-groove in a patterned (001) substrate. The results may be approximately expressed through an expression of the same form as that derived by Matthews and Blakeslee for a strained layer, but with modified coefficients obtained via the finite element analysis. Contact is made with the limited experimental evidence available.

Fatigue Strength Study on Radial Bogie Vice Frame Based on Finite Element Analysis

2015 ◽  
Vol 723 ◽  
pp. 96-99
Author(s):  
Xiao Wei Wang ◽  
Mao Xiang Lang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Structural Strength ◽  
Simulation Software ◽  
Experimental Result ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Stability

The vice frame bears and transfers the forces and loads between the bogie and the vehicle body.The strength of the vice frame relates directly to the stability and smoothness of the vehicle. In this study, finite element analysis is utilized first to analyse the structural strength and fatigue life of the vice frame, and the recognize the weak parts of its structure in order to enhance its structural strength in the following design work.The finite element analysis is performed on a simulation software Ansys. Then an experiment is designed to test the fatigue strength of the vice frame. The experimental result indicates that the fatigue strength of the object corresponds to the standards and the finite element analysis has high feasibility in solving this kind of problem.

K-Type, Inverse K-Type and X-Type Legs Stability Analysis of Jack-Up Offshore Platform

2013 ◽  
Vol 312 ◽  
pp. 205-209
Author(s):  
Wen Xian Tang ◽  
Jun Cao ◽  
Jian Zhang ◽  
Chao Gao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Offshore Platform ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Design Requirements ◽  
The Stability ◽  
Jack Up ◽  
Survival Condition

The force situation of truss legs has an important impact on the jack-up offshore platform. The finite element analysis on three types truss leg was made, and the stability of the three types truss leg under preload, operating and storm survival condition was discussed. The result showed that the maximum stress was in the chord; they met the design requirements; K type, inverse K type can save material, and they both met resonance requirements. The former had a better stability under preload condition, and the later had the best stability under operating, storm survival condition.

Finite Element Thrust Line Analysis (FETLA) of Axisymmetric Masonry Dome with Meridian Cracks

2017 ◽  
Vol 865 ◽  
pp. 397-402 ◽  
Author(s):  
Mahesh Varma ◽  
Siddhartha Ghosh ◽  
Gabriele Milani
Keyword(s):  
Finite Element ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Tensile Forces ◽  
Ring Mechanism ◽  
Masonry Domes ◽  
Tension Cracks ◽  
The Stability ◽  
Masonry Dome ◽  
Line Analysis

Many masonry domes in their lower portion are subjected to hoop tensile forces which mostly lead to vertical cracks appearing along the dome's meridian planes. A close inspection of any such dome reveals these hoop tension cracks. The dome stands as a series of arches with common key stone, with cracks as a matter of non-structural consequences. Different strategies have been considered historically to arrest these cracks. The provision of tension ring mechanism adds to the stability of these domes, and hence many masonry domes are retrofitted with the provision of the tension rings using steel and FRP rings. The challenge in such retrofitting will remain to analyze its effect on stability of these masonry domes, more specifically in absence of reliable mechanical properties of such masonry domes. This paper presents a simplified analysis procedure combining thrust line analysis with the finite element analysis called here as Finite Element Thrust Line Analysis (FETLA). The development of a new element suitable for masonry dome analysis to include the effect of hoop tension cracks is demonstrated. The orthotropic material properties are utilized for penalty approach to allow redistribution of the forces from meridian direction to the hooping rings, with thrust line approaching the extrados or intrados of the dome. The analysis results of FETLA are validated with the previously available results. The analysis method proposed in this paper gives the rational estimates for the failure load without utilizing inelastic properties of the material to model the hoop tension cracks and its propagation.

scholarly journals Design and strength analysis of C-hook for load using the finite element method

2020 ◽  
Vol 313 ◽  
pp. 00034
Author(s):  
Pavol Lengvarský ◽  
Martin Mantič ◽  
Róbert Huňady
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Strength Analysis ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Deformation State ◽  
The Finite Element Analysis ◽  
Stress And Deformation ◽  
The Stability

The special type of C-hook is investigated in this paper. The C-hook is designed to carry a special load, where is not possible to use classical hooks or chain slings. The designed hook is consisted of two arms that ensure the stability of the load being carried. The finite element analysis is performed for the control of the stress and deformation state in the whole hook. The fatigue analysis is performed for the check of a lifetime of C-hook.

Influence of Bridging Arrangement Location on the Mechanical Characteristics of the High-Formwork Support System

2014 ◽  
Vol 580-583 ◽  
pp. 2232-2234
Author(s):  
Li Liu ◽  
Ya Nan Liu ◽  
Bo Wang ◽  
Ju Chao Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Support System ◽  
Mechanical Characteristics ◽  
Lateral Migration ◽  
Analysis Method ◽  
Element Analysis ◽  
Finite Element Analysis Method ◽  
The Finite Element Analysis ◽  
The Stability

Bridging play a important role in guarantee the stability of the high-formwork support system as a whole, its arrangement location will affect the force of the frame body. This paper used the finite element analysis method to compare the bridging arrangement location under the beam with the bridging under the board which was arranged according to certain modules. the results show, the arrangement spacing of the bridging under the beam is greater than the bridging under the board, but its frame body lateral migration is smaller, sharing part of the axial force of beam bottom rod at the same time, that means the bridging under the beam is more beneficial for the stability of high-formwork support system.

The Finite Element Analysis of Ultimate Bearing Capacity of Initial Bending on the T-Axis Compression Component

2013 ◽  
Vol 690-693 ◽  
pp. 1914-1918
Author(s):  
Yang Yang Han ◽  
Cai Xia Zhang ◽  
Ya Qin Li ◽  
Si Yu Chen ◽  
Chun Shan Liu
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Cross Section ◽  
Element Calculation ◽  
Element Analysis ◽  
Cross Sectional ◽  
Buckling Behavior ◽  
The Finite Element Analysis ◽  
Axis Compression ◽  
The Stability

There is little research about the stability of T-stub steel axial compression component at home and abroad, and it remains to further investigation. On the basis of taking initial bending and other factors into consideration, through theoretical analysis and finite element calculation, this paper studies the T-stub steel axial compression buckling behavior and carrying capacity mainly using three different cross-section and different lengths ZC cross-sectional specimens.

Thrust Line Using Linear Elastic Finite Element Analysis for Masonry Structures

2010 ◽  
Vol 133-134 ◽  
pp. 503-508 ◽  
Author(s):  
Mahesh Varma ◽  
R.S. Jangid ◽  
Siddhartha Ghosh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Masonry Structure ◽  
Masonry Structures ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Structural Engineer ◽  
The Stability ◽  
Line Analysis

Failure of masonry structures are generally studied in terms of the formation of unstable mechanisms and the thrust line approach is considered to be the most useful tool for this. Thrust line analysis is a simple technique for studying the stability of masonry structures, although its applicability is limited to specific types of structures because of various implicit assumptions. Finite element analysis, on the other hand, is versatile but computationally more intensive. This paper presents a linear elastic finite element analysis based method of obtaining the thrust line of a masonry structure. The proposed method allows the application of the thrust line analysis to structures with any complicated geometry while retaining the simplicity of this approach for studying the stability of a masonry structure. The proposed method is applied to various case study structures and the sensitivity of the results to the adopted material property data in the finite element analysis is studied. The proposed method also allows a structural engineer, who is usually familiar with the finite element analysis, to easily migrate to the stability analysis of masonry systems.

Bearing Capacity of Fastener Steel Tube Full Hall Formwork Support Base on Stability of Pressed Pole with Multiple Point Restraint against Rotation

2012 ◽  
Vol 166-169 ◽  
pp. 1404-1415
Author(s):  
Zheng Ran Lu ◽  
Xiao Min Sui ◽  
Zhi Hua Chen
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Horizontal Tube ◽  
Steel Tube ◽  
Future Research ◽  
Multiple Point ◽  
Simplified Models ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Stability

Through advanced non-linear finite element models in different geometric parameters that considering the semi-rigid character of the couplers, the critical loads and failure modes of many fastener steel tube full hall formwork supports (FFS) with and without bridging were evaluated. Thirteen FFS specimens were tested to failure in order to examine the stability behavior and failure modes of them. The finite element analysis (FEA) results were well consistent with those of the test what could prove its validity. On the basis of FEA and experimental research, simplified models and corresponding calculation formulas were established for the FFS under uniform load through choosing different buckling modes, which were verified by the experimental and analytical results and turned out to be accurate enough in predicting the strength. The simplified models presented here considering the semi-rigid character of right-angle coupler, effect of adjacent horizontal tube which provided a very useful reference for the industry as well as academia for design and future research.

Study on Dynamic Response and the Effect to Center Level Height of Periodic Symmetric Struts Support

2011 ◽  
Vol 462-463 ◽  
pp. 1013-1018
Author(s):  
Mamtimin Gheni ◽  
Wei Bing Liu ◽  
Lie Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Response ◽  
Thermal Condition ◽  
Technical Difficulty ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Parametric Effects ◽  
The Stability ◽  
Level Height

In this paper, in order to overcome the technical difficulty of center level height of Periodic Symmetric Struts Support (PSSS) by using the test in the field and reduce the high cost of testing, the method of the finite element analysis by considering thermal condition and the dynamic response is used and the center level height of PSSS is evaluated. Some relations for center level height changing process of PSSS were found and some parametric effects are obtained for the stability analysis of gas turbine by changing the number of struts support and angle.

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