Papers by Keyword: Boundary

Abstract: The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a beam. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Bars”) that is very similar to this paper except that the geometry considered in that paper is a bar.

Abstract: The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a bar. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Beams”) that is very similar to this paper except that the geometry considered in that paper is a beam.

Abstract: In this work, the authors attempted to consider the influence of the geometry of the crystal lattice on the properties of nanowires, which manifest themselves in the process of uni-axial stretching. This work summarizes and systematizes the results of previous studies of the authors. The first group of samples – are typical FCC metal – Ni₃Al. For these nanowires, deformation processes in directions with different packing densities of atoms <100>, <110> and <111> were investigated. The second material group studied was an alloy with the non-cubic symmetry of the element cell CuAu I. Correspondingly, this sample was examined under deformation in directions corresponding to different lengths of the sides of the unit cell, <001> and <010>. All the investigations described in this paper were carried out by molecular dynamics method on three-dimensional models using the Morse's pair potentials.

Abstract: Using the method of molecular dynamics, FCC Ni nanowires containing hydrogen atoms in octahedral and tetrahedral pores are investigated in the course of high-speed uniaxial tensile loading along the direction <001>. The feature of structural transformations in Ni nanowires containing hydrogen is appearance on the stage of plastic deformation globular (spherical) formations consisting of hydrogen atoms

Abstract: An extensive study was made of the boundary area microstructure between the matrix and dense inner sublayers of the ceramic coating formed on AZ91 magnesium alloy substrate by micro-arc oxidation(MAO).The coating was prepared in an alkaline electrolytic solution composed of 5-20g/l of NaH₂PO₄, 1-5g/l of NaOH, 5-8g/l of KF; 0.5-2g/l of Na₃C₆H₅O₇, and 0.5-2g/l of EDTA , employing a constant-current controlled AC power supply with a current density of 10-30A/dm²; and the microstructure of the coatings was characterized using transmission electron microscopy(TEM) and scanning electron microscopy(SEM). It was found that (1) the main constituent of the coating adjacent to the boundary was microcrystalline and nanocrystalline; (2) the microhardness of the coating adjacent to the boundary was improved than that of the matrix. It was due to the formation of the intermixing of Mg and MgO and their grains were refined, these leaded to fine-crystal strengthen.

Abstract: This paper proposes a study on the workspace of the guiding device mechanism of a parallel topology robot. The kinematical scheme and the geometrical model of the guiding device mechanism of the parallel topology robot are presented. The lengths of binary links between the platforms determine the shape and the volume of the parallel robot’s workspace; different boundaries of the workspace are presented. Thus, variation of the workspace in both volume and shape is studied, depending on the binary link lengths, using for modeling and simulation SolidWorks software.

Abstract: In the paper we analyse the character of spatial boundaries of buildings and examine their correlation with social changes. For a case study we use Holesovice, a quarter of Prague, Czech Republic. This city part is a typical example of originally industrial suburb with a large number of factories, docks and railway station, all built mainly in 19. century. In the last 15 years the area has gone through gentrification that significantly changed its urban and architectural face. The transformation also affected the character of services and cultural facilities available in the area. We compare boundaries of the original construction and boundaries of the new developments built in the last 15 years. The analysis is done at the scale of buildings. Our methodological framework is based on the Space Syntax theory and Urban Morphology. The studied characteristics are integration of accessible spaces and design of boundaries. The paper identifies urban and architectural features that correspond and reflect the lifestyle of the gentrified part of population.

Abstract: s: Jilin university innovation experiment Electrical Simulation Experiment and the Analysis of Thermal Conductivity of Materials aims to solve the problem of thermocouple measuring tenderness in error. Thermocouple is used to measure temperature when measuring unsteady heat conduction in laboratory. The improved measuring method of unsteady heat conduction puts the breakthrough on the electric simulation method. The text bench is constructed by different shapes of conductive plate which is made of the graphite conductive paint, and voltmeter is refitted by diodes and controlled transformer. Through the test bench, we finished the simulation of unsteady heat conduction under the similar thermal conductive boundary conditions. Finally, the error analysis of experiment and the advantages of electric simulation method are given in this paper.

Abstract: We focused on when and how to reorder the Chinese NPs A+(de)+B+(de)+C wherein A,B and C are three separate and smallest chunks for reordering. Based on the types of chunks A, B and C, we analyzed four types for the Chinese NPs A+(de)+B+(de)+C and their grammar structures in theory and summed five reordering patterns by comparing the orders Chinese NPs A+(de)+B+(de)+C with their English orders. We used a rule-based method and built formalized 53 rules to identify the boundaries of chunks A, B and C using the Boundary-Words and developed a strategy on how to reorder the chunks efficiently. At last, we used a rule-based MT system on the SCT model to test our work, and the experimental results showed that our rule-based method and strategy were very efficient.

Abstract: We consider in the present work the fusion laser cutting of stainless steel sheets under a nitrogen laminar gas jet. The molten metal is treated as a laminar and steady viscous incompressible fluid. The mathematical model describing our problem is set in terms of Navier-Stokes equations, solved numerically using the finite differences method, where the effect of the gas jet velocity on the molten boundary layer is considered. The generated shear stress occurring on the gas-liquid interface and its contribution in the momentum is carried out, and it is found that when the skin friction and the shear stress decrease, the thickness and the velocity at the edge of the molten boundary layer increase along the kerf surface. The layer thickness reduces when the assisting gas velocity is increased.