International Journal of Mechanics

   
E-ISSN: 1998-4448
Volume 15, 2021

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of NAUN Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

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Volume 15, 2021


Title of the Paper: Investigation of Physical Properties of Fe(III) Containing Metal-Organic Polymers

 

Authors: A. Yu. Ershova, Minggong Sha

Pages: 204-210

DOI: 10.46300/9104.2021.15.24     XML

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Abstract: In this work, we studied the properties of a specially synthesized organometallic coordination polymer - a porous coordination polymer with biocompatible structural elements based on oxoclusters of iron muconate (III). The samples were investigated by scanning electron microscopy, thermogravimetric analysis combined with differential scanning calorimetry, and the study of low-temperature nitrogen adsorption of a sample obtained by a modified solvothermal technique. It is shown that most of the pores of the sample have an average radius of 18,8 Å ~ 1,88 nm. Also, as a result of the study, it is necessary to conclude that the synthesized material has a developed surface area - it is 512,1 m2/g and the pore volume is ~ 0,48 cm3/g. It should be concluded that such materials are promising as components for a new generation of various kinds of functional materials with improved or unique characteristics. It is obvious that further research in this area is important from both fundamental and applied points of view.


Title of the Paper: Mathematical Modeling of Heat and Mass Transfer in Heat Pipes in a One-Dimensional Formulation when Cooling Active Phased Antenna Arrays

 

Authors: S. Radaev

Pages: 196-203

DOI: 10.46300/9104.2021.15.23     XML

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Abstract: The work proposes test one-dimensional models of heat and mass transfer in heat pipes during cooling of active phased antenna arrays, which can be used in processing the test results of flat heat pipes in order to determine their performance characteristics and identify the parameters required for modeling in a more complex setting (for example, in flat and taking into account the presence of several localized sources of heat supply). To take into account the influence of the heat release power on the equilibrium temperature inside the heat pipe, the model has been added to take into account the dependence of the steam saturation temperature on the pressure, which is realized inside the steam pipeline when the heat pipe is heated. Numerous calculations carried out made it possible to refine the mathematical model. In particular, a significant effect on the temperature distribution along the heat pipe is shown, taking into account the dependence of the steam saturation temperature on the pressure in the parawire. It is shown that the introduction of standard functions for the characteristics of the coolant (water) in the liquid and vapor state, as well as taking into account the capillary pressure on temperature, makes it possible to refine the resulting solution.


Title of the Paper: Tribological Properties of Polymer Composite with Impregnated Quasicrystal Nanoparticles

 

Authors: Y. A. Utkin, A. A. Orekhov, Thant Zin Hein

Pages: 189-195

DOI: 10.46300/9104.2021.15.22     XML

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Abstract: In this work, a study is carried out on the introduction of quasicrystal particles into a thermoplastic polymer and it is shown that this leads to changes in the structure of polyethylene. The introduction of quasicrystal particles into a thermoplastic polymer leads to changes in the structure of polyethylene: the degree of crystallinity decreases from 42% (PE) to 27% (10AlCuFe/PE) with increasing concentration of the filler, the ratio of bands corresponding to amorphous and crystalline regions in the IR spectra changes, which indicates on the amorphization of the PE structure. The specimens have improved wear resistance (the wear rate decreased by 96% compared to the original PE), but the friction coefficient remained practically unchanged. It is shown that the addition of quasicrystal nanoparticles in a small amount (up to 10 wt.%) leads to an increase in hardness, but does not have a noticeable effect on the surface roughness. The results obtained indicate that quasicrystals can serve as effective fillers for promising polymeric materials in products for aerospace, instrument making, and other industries.


Title of the Paper: Investigation of Mechanical Properties of Low-Density Polyethylene with Copper Nanoparticles

 

Authors: M. V. Klychnikova, Kyaw Ye Ko

Pages: 181-188

DOI: 10.46300/9104.2021.15.21     XML

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Abstract: In this work, it is shown that the method of the in situ preparation of Cu/LLDPE by combining the formation of a composite and a nanodispersed phase in the viscous-flow state of a polymer makes it possible to achieve a uniform distribution of nanoparticles in the matrix and effectively regulate their mechanical and functional properties. The optimal concentration of Cu nanofiller was found to be 2-5%, allowing to achieve the best mechanical properties. Comparative analysis of the physical and mechanical properties of Cu/LLDPE nanocomposites obtained by various methods shows that the deformation and strength characteristics of the 3CuLLDPE nanocomposite obtained by the in situ method are improved in comparison with the properties of the 3CuLLDPE nanocomposite, prepared by ex situ method. The relationship between the filler content and the modulus of elasticity/tensile strength has been determined. With an increase in the filler content, the elastic modulus increases by 10-20%, and the tensile strength decreases by 30%. Elongation at break for samples with nanofiller content up to 3 wt. % higher than unfilled polymer


Title of the Paper: Numerical and Analytical Modeling of Permanent Deformations in Panels Made of Nanomodified Carbon Fiber Reinforced Plastic with Asymmetric Packing

 

Authors: S. Radaev

Pages: 172-180

DOI: 10.46300/9104.2021.15.20     XML

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Abstract: In this paper, a mathematical model of a multilayer panel made of nanomodified carbon fiber reinforced plastic with asymmetric packing is proposed. The introduction of nanosized particles into the composition of the composite or its components (fiber or binder) allows not only to increase its physical and mechanical properties, but also to improve the picture of the residual stress-strain state. The paper investigates the effect of nanomodification of carbon fiber reinforced plastic on the residual stress-strain state after molding using numerical and analytical methods. Numerous results of computational experiments have been obtained. The results of numerical and analytical modeling are compared with experimental data. Conclusions are drawn about the possibility of reducing the residual stress-strain state in structures with asymmetric reinforcement schemes when using a matrix containing carbon nanoparticles. A mathematical model of a multilayer panel made of nano-modified carbon fiber with asymmetric packing has been built. Investigation of the residual stress-strain state of structural elements made of carbon fiber reinforced plastic made it possible to reveal the possibility of reducing the residual stress-strain state and leash in structures with asymmetric reinforcement schemes when using a matrix containing carbon nanoparticles.


Title of the Paper: Thermophysical and Magnetic Properties of Magnetite – Polyethylene Composite

 

Authors: N. M. Bugaev, Ekaterina L. Kuznetsova, Kyaw Ye Ko

Pages: 165-171

DOI: 10.46300/9104.2021.15.19     XML

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Abstract: In this work, it is shown that the advantage of using matrix-stabilized magnetic nanoparticles to obtain polymer nanocomposites based on them is that such nanoparticles retain their dispersion and stability of size and shape in the technological modes of obtaining polymer nanocomposite materials, and thus ensured stable ferro- and superparamagnetic properties of the obtained target products. For the production of films by the method of hot pressing from blanks obtained in an injection molding machine or a mechanochemical mixture, a manual electrically heated hydraulic press was used. The magnetic properties of nanocomposite samples (about 50 mg on average) were studied using a vibration magnetometer. The character of the dependence of the magnetization on the magnitude of the magnetic field confirms the ferromagnetic character of the behavior of the obtained nanocomposites. The resulting film nanocomposites exhibit ferromagnetic properties at room temperature.


Title of the Paper: Energy Absorption Characteristics of Foam Filled Tri Circular Tube under Bending Loads

 

Authors: Fauzan Djamaluddin

Pages: 159-164

DOI: 10.46300/9104.2021.15.18     XML

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Abstract: In this study, the researcher carried out a comparative investigation of the crashworthy features of different tubular structures with a quasi-static three bending point, like the foam-filled two and tri circular tube structures. Energy absorption capacities and failure modes of different structures are also studied. Furthermore, the general characteristics are investigated and compared for instance the energy absorption, specific energy absorption and energy-absorbing effectiveness for determining the potential structural components that can be used in the field of vehicle engineering. Experimental results indicated that under the bending conditions, the tri foam-filled structures were higher crashworthiness behaviour than the two foam-filled circular structures. Therefore, this study recommended the use of crashworthy structures, such as foam-filled tri circular tubes due to the increased bending resistance and energy-absorbing effectiveness.


Title of the Paper: A New Hybrid Method for Solving Inverse Heat Conduction Problems

 

Authors: M. R. Shahnazari, F. Roohi Shali, A. Saberi, M. H. Moosavi

Pages: 151-158

DOI: 10.46300/9104.2021.15.17     XML

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Abstract: Solving the inverse problems, especially in the field of heat transfer, is one of the challenges of engineering due to its importance in industrial applications. It is well-known that inverse heat conduction problems (IHCPs) are severely ill-posed, which means that small disturbances in the input may cause extremely large errors in the solution. This paper introduces an accurate method for solving inverse problems by combining Tikhonov's regularization and the genetic algorithm. Finding the regularization parameter as the decisive parameter is modelled by this method, a few sample problems were solved to investigate the efficiency and accuracy of the proposed method. A linear sum of fundamental solutions with unknown constant coefficients assumed as an approximated solution to the sample IHCP problem and collocation method is used to minimize residues in the collocation points. In this contribution, we use Morozov's discrepancy principle and Quasi-Optimality criterion for defining the objective function, which must be minimized to yield the value of the optimum regularization parameter.


Title of the Paper: Modification of the Stamp Topological Optimization Taking into Account Cyclic Fatigue based on the Finite Element Approach

 

Authors: Ivan K. Andrianov

Pages: 145-150

DOI: 10.46300/9104.2021.15.16     XML

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Abstract: The study is devoted to optimizing the volume of stamping tools used in pressure processing processes. The relevance of the research is due to the active development of additive technologies and the possibility of producing stamping tools from plastic of optimal shape, which has an important practical significance in the manufacture of thin-walled products in the aviation and automotive industries. The purpose of the study was to carry out a mathematical formulation of the problem of topological optimization of a forming die made of a polymer material with restrictions on fatigue durability and minimum volume. The task of topological optimization was to maximize the stiffness of the die under multicyclic loading. The vector description of topological optimization was based on the finite element approach. The optimization model was built on the basis of the solid isotropic material penalization method with the introduction of additional restrictions in the model of searching for pseudo-densities of the material, taking into account the duration of the force action on the stamp under multicyclic loading. In view of the nonlinearity of the resulting system of equations, the solution of the conditional optimization problem is proposed to be carried out by constructing the Lagrange objective function and using the Lagrange multiplier method. The result of the study is the proposed approach to the topological optimization of the stamp, taking into account the multicyclic loading and restrictions on the desired volume.


Title of the Paper: Effects of the Porous Microstructure on the Drag Coefficient in Flow of a Fluid with Pressure-Dependent Viscosity

 

Authors: M.S. Abu Zaytoon, S. Jayyousi Dajani, M.H. Hamdan

Pages: 136-144

DOI: 10.46300/9104.2021.15.15     XML

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Abstract: Equations governing the flow of a fluid with pressure-dependent viscosity through an isotropic porous structure are derived using the method of intrinsic volume averaging. Viscosity of the fluid is assumed to be a variable function of pressure, and the effects of the porous microstructure are modelled and included in the pressure-dependent drag coefficient. Five friction factors relating to five different microstructures are used in this work


Title of the Paper: The Combination of Taguchi and Proximity Indexed Value Methods for Multi-criteria Decision Making When Milling

 

Authors: Nguyen Lam Khanh, Nguyen Van Cuong

Pages: 127-135

DOI: 10.46300/9104.2021.15.14     XML

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Abstract: Milling is a commonly used method in mechanical machining. This is considered to be the method for the highest productivity among cutting methods. Moreover, the quality of the machined surface is increasingly improved as well as the machining productivity is increasingly enhanced thanks to the development of machine tool and cutting tool manufacturing technology. Therefore, in each specific processing condition (about machine, tool and part material, and other conditions), specific studies are required to determine the value of technological parameters in order to improve productivity and machining accuracy. Only in this way can we take full advantage of the capabilities of modern equipment. The process parameters in the milling method in particular and in the machining and cutting methods in general can be easily adjusted by the machine operator as the parameters of the cutting parameters or the change of tool types. In this article, the combination of Taguchi and Proximity Indexed Value (PIV) methods is presented for multi-criteria decision making in milling. An experimental matrix was designed according to Taguchi method with five input parameters, including the insert materials (TiN, TiCN, and TiAlN), nose radius, cutting velocity, feed rate and depth of cut. The total number of experiments that were performed was twenty-seven. The workpiece used during the experiment was SCM440 steel. At each experiment, the surface roughness was measured and the Material Removal Rate (MRR) was calculated. The weights of these two parameters have been chosen by the decision maker on the basis of consultation with experts. The PIV method was applied to determine the experiment at which the minimum surface roughness and the maximum MRR were simultaneously guaranteed. In addition, the influence of input parameters on surface roughness was also found in this study.


Title of the Paper: Calculation of Collision Probability Matrix of Nuclear Fuel Cell as a Function of Neutron Energy Group using Flat Flux Model

 

Authors: Mohammad Ali Shafii, Dian Fitriyani, Seni H J Tongkukut, Zaki Su’ud

Pages: 121-126

DOI: 10.46300/9104.2021.15.13     XML

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Abstract: One of the methods that widely used in solving neutron transport equations in the nuclear fuel cell is the collision probability (CP) method. The neutron transport is very important to solve because the neutron distribution is related to the reactor power distribution. The important thing in the CP method is the CP matrix calculation, better known as has an important role in determining the neutron flux distribution in the reactor core. This study uses a linear flat flux model in each cell region for each energy group with white boundary condition. Although the type of reactor used in this study is a fast reactor, the matrix calculation still carried out in fast and thermal group energy. The matrix depends on the number of mesh in each cell region. The matrix formed from the mesh distribution will produce a matrix for each energy group. Because the boundary condition of the system is assumed that there are no contributions neutron source from the outside, the sum of the matrix must be less than one. In general, the results of the calculations in this study are following the theory.


Title of the Paper: Two Dimensional Static Mechanical Analysis of Laminated Composite Tube using ABCDE Matrix with No Correction Factor

 

Authors: Arno Roland Ngatcha Ndengna, Joel Renaud Ngouanom Gnidakouong, Achille Njomoué Pandong, Ekmon Mbangue

Pages: 107-120

DOI: 10.46300/9104.2021.15.12     XML

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Abstract: Accurate modeling and prediction of materials properties is of utmost importance to design engineers. In this study, newly developed two-dimensional laminate constitutive equations (LCE) were derived directly from an existing shell model without using a classical correction factor. The resulted LCEs were subsequently used for the first time to analyze a laminated composite tube (LCT) subjected to in plane-loading. This led to additional composite-shell stiffness coefficients which are not currently available in some LCEs. The strains and stresses distribution fields were computed via Matlab. The accuracy and robustness of our analytical method were proven by opposing the as-obtained results of thick and thin LCTs with that of existing theories which use a correction factor. An excellent convergence was observed. Whereas a lower convergence was observed in the case of a laminated shell plate. Results also showed that the thickness ratio χ (2χ=h/R ) considerably influences the mechanical behavior of the LCT. In fact when χ<0.1, the distribution of stresses and strains of the tube were the same for the two opposed theories. When χ>0.1, the distribution of stresses and strains were not the same, hence the contribution of our ABCDE matrix. The new mechanical couplings in our LCE could be well illustrated in a finite element package with visualization tools to observe some intricate deformations which are yet to be seen. Thus the outcome of this work will be of particularly interest to promote advanced scientific and structural engineering applications.


Title of the Paper: Electromechanical Study the Wind Energy Conversion System Based DFIG and SCIG Generators

 

Authors: Samir Bellarbi

Pages: 102-106

DOI: 10.46300/9104.2021.15.11     XML

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Abstract: Generally speaking, asynchronous generators are used more frequently in medium power in wind energy conversion systems WECS applications. Depending on the power electronics converter used in the specific application, the operation of the asynchronous machine can be controlled in nested speed torque loops, using different torque control algorithms. Because WECS are highly nonlinear systems, but with smooth nonlinearities, a possible optimal control design solution can be the maximum power point tracking MPPT in this paper. This research describes a comparison of the power quality for wind power systems based on two generators: the squirrel-cage induction generator (SCIG), the doubly fed induction generator (DFIG). At first, we simulated SCIG and DFIG in MATLAB/Simulink and investigates the impact of this generators on the power system stability for compare the results and to comment on the best option based on the output characteristics of the generator and wind turbine. The technical objective of this research is to choose the most suitable generator adaptive with changing wind speeds and the most energy production


Title of the Paper: Import-mixing Sorbents for Purification of Waste Production Water of Gas Processing Industry for re-use

 

Authors: Yusupov Farkhod, Nuriddinova Dilfuza, Yakhsheva Yulduz, Yusupov Sukhrob, Mamanazarov Murodali

Pages: 95-101

DOI: 10.46300/9104.2021.15.10     XML

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Abstract: Currently, there are a variety of methods and technologies for water purification. One of them is the adsorption method. Today the adsorption method is widely used in the water treatment industry. The aim of the research is to create an effective multifunctional filtering composition suitable for complex physical and chemical water purification. For this, a cation exchanger developed on the basis of local raw materials, activated alumina and other local materials was used. The adsorption properties of the cation exchanger and aluminum oxide in the composition of this filter have been studied. Also, the parameters of the filter for water purification are determined.


Title of the Paper: Numerical Simulation for the Honeycomb Core Andwich Panels in Bending by Homogenization Method

 

Authors: Luong Viet Dung, Dao Lien Tien, Duong Pham Tuong Minh

Pages: 88-94

DOI: 10.46300/9104.2021.15.9     XML

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Abstract: Nowadays, with the continuous development of science and technology, computer software has been widely applied and is increasingly popular in many fields such as the automobile, aviation, space, and shipbuilding industries. Numerical simulation is an important step in finite element analysis and product design optimization. However, it is facing challenges of reducing CAD model building time and reducing computation time. In this study, we have developed a homogenization model for the honeycomb core sandwich plate to reduce the preparation of the CAD model as well as the computational times. The homogenization consists of representing an equivalent homogenized 3D-solid obtained from the analysis calculation in-plane properties of honeycomb 3D-shell core sandwich plate. This model was implemented in the finite element software Abaqus. The simulations of tensile, in-plane shear, pure bending, and flexion tests for the case of the 3D-shell and 3D-solid models of the honeycomb core sandwich will be studied in this paper. Comparing the results obtained from the two models shows that the 3D-solid model has close results as the 3D-shell model, but the computation time is much faster. Thereby the proposed model is validated.


Title of the Paper: Local Elasto–plastic Buckling of Isotropic Plates with Cutouts under Tension Loading Conditions

 

Authors: Marek Barski, Adam Stawiarski, Paweł J. Romanowicz, Bogdan Szybiński

Pages: 69-87

DOI: 10.46300/9104.2021.15.8     XML

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Abstract: The motivation of the presented study was the observation of the existence of local loss of stability “tension buckling” in the experimental tests of composite and metallic plates with cut-outs subjected to tension. Because of this, the numerical analyses of the aluminum plate with elliptical or circular cutouts at the center and subjected to tensile load are studied in the paper. Although the whole structure is uniformly stretched, the circumferential compressive stresses in the vicinity of the cutout edge are observed. First of all, the linear buckling analysis is carried out for different sizes of the holes. Based on these results, the size of the hole is chosen, where the circumferential stress magnitude in the vicinity of the cutout is the lowest or even comparable to the yield stress of the material. The computations are made for three different values of thickness. Finally, the nonlinear buckling analysis is carried out without and with the plasticity effects included. Generally, in the case of the circular and vertically oriented elliptical cut-out, the loss of stability in the tensed plate is always observed. However, in elastic-plastic analyses, the values of the critical parameters significantly differ from the results obtained for elastic buckling. Finally, the critical geometries for further experimental tests were defined.


Title of the Paper: Numerical Calculation of the Diffusion Process in Multicomponent Hydrocarbon Gas Mixtures

 

Authors: Beketayeva Meruyert

Pages: 61-68

DOI: 10.46300/9104.2021.15.7     XML

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Abstract: Knowledge of the laws of diffusion is necessary in the description, design and calculation of the mass transfer process in the production, operation and transportation of gaseous fuels. In this article, the calculation of diffusion processes for five natural hydrocarbon gas mixtures into the air was carried out. The effective diffusion coefficients and matrix coefficients of multicomponent diffusion were determined. Also the advantages of using effective coefficients in the description of mass transfer were shown.


Title of the Paper: Dynamic Analysis of Mechanical Systems using Image Processing

 

Authors: Juan D. Pérez, Diego A. Hincapié, Jonathan A. Graciano

Pages: 56-60

DOI: 10.46300/9104.2021.15.6     XML

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Abstract: Thanks to the fact that nowadays substantial progress has been made in new ways of analyzing our environment using image processing techniques, it is imperative to highlight the importance of applying this methodology to mechanisms, which are our object of study and these elements are present in various sectors, such as industrial, automotive, academic, etc. In the previously mentioned sectors, the mechanisms are a fundamental element for the correct operation of the devices that each sector has. Therefore, knowing the dynamic behavior of the mechanisms is an essential task, since, if any type of failure occurs, it could cause damage to an entire process. The article proposes to develop a methodology that allows the analysis of dynamic variables in different types of mechanisms, through the use of image processing techniques specifically the detection, filtering and tracking of objects, using filters such as the Gaussian filter and background subtraction in order to improve the quality of the information to be analyzed. The results obtained through the application of the proposed methodology were compared with a simulation of a CAD/CAM/CAE software, in this case Siemens NX 12®, these results were satisfactory under certain criteria that will be exposed in the analysis section, thanks to this it can be affirmed that the proposed methodology is acceptable at the time of knowing the dynamic variables in mechanisms.


Title of the Paper: Numerical Approximation of Coupled 1D and 2D Non-linear Burgers’ Equations by Employing Modified Quartic Hyperbolic B-spline Differential Quadrature Method

 

Authors: Mamta Kapoor, Varun Joshi

Pages: 37-55

DOI: 10.46300/9104.2021.15.5     XML

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Abstract: In this paper, the numerical solution of coupled 1D and coupled 2D Burgers' equation is provided with the appropriate initial and boundary conditions, by implementing "modified quartic Hyperbolic B-spline DQM". In present method, the required weighting coefficients are computed using modified quartic Hyperbolic B-spline as a basis function. These coupled 1D and coupled 2D Burgers' equations got transformed into the set of ordinary differential equations, tackled by SSP-RK43 scheme. Efficiency of the scheme and exactness of the obtained numerical solutions is declared with the aid of 8 numerical examples. Numerical results obtained by modified quartic Hyperbolic B-spline are efficient and it is easy to implement.


Title of the Paper: Study of Dynamic Impact of Speed Trains on Bridge Structures

 

Authors: Hakim Siguerdjidjene, Leonid Konstantinovich Dyachenko

Pages: 30-36

DOI: 10.46300/9104.2021.15.4     XML

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Abstract: This research presents a study of the dynamic impact of high-speed trains moving on continuous and discontinuous span bridges. As an example of this study, a continuous span ballast bridge project with a total length of 174 m has been adopted, according to the scheme 27+ 3 × 40+ 27 m, allows us to analyze the dynamic impact of displacement of different trains at a speed range of 100km / h to a maximum speed of 300km / h, as well as to make a comparison of the dynamic behavior of this continuous-span HSR bridge from the discontinuous span bridge systems with lengths of 27m and 40m, and draw conclusions about the dependence of the maximum dynamic coefficients and the vertical accelerations at the midpoints of the span bridges as a function of the moving speed of the deferent trains. The resolution of the dynamic problem of moving loads during design and calculation is based on the modeling of the Bridge-Train system by the complex program, realized by the finite element method (FEM). In this work, for the numerical simulation of dynamic problems, Sofistik software was used. The results show that the increase of train speed up to 300 km / h, it is possible to manifest resonant vibration modes of the structures in span. The results show that the increase of train speed up to 300 km / h, it is possible to manifest resonant vibration modes of the structures in span.


Title of the Paper: Design of PLC based Automated Food Processing Machine

 

Authors: Vidya S. Rao, Praveen Shenoy K., Santhosh K. V.

Pages: 22-29

DOI: 10.46300/9104.2021.15.3     XML

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Abstract: Ever-changing work expects technological advancement in all the tasks carried out by humans. Cooking is one such process, which is presently majorly carried out by human beings. Though a lot of automation has been happening in the area of food processing, involving a larger quantity of food production in a commercial or institutional setup. But very less automation is adapted in domestic or household cooking. In the proposed work, we propose to manufacture a system involving computers and electro-mechanical components for cooking two of the most widely consumed Indian delicacies Dosa (Pancake) and Idli (Rice cake). Reported work discusses the detailed mechanical fabrication of the device, including the process of automation implemented on Programmable Logic Controller (PLC). A detailed comparison is tabulated comparing the similar product to highlight the working of the proposed system


Title of the Paper: The Kirchhoff Transformation for Convective-radiative Thermal Problemsin Fins

 

Authors: Jonatas Motta Quirino, Eduardo Dias Correa, Rodolfo do Lago Sobral

Pages: 12-21

DOI: 10.46300/9104.2021.15.2     XML

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Abstract: The present work describes the thermal profile of a single dissipation fin, where their surfaces reject heat to the environment. The problem happens in steady state, which is, all the analysis occurs after the thermal distribution reach heat balance considering that the fin dissipates heat by conduction, convection and thermal radiation. Neumann and Dirichlet boundary conditions are established, characterizing that heat dissipation occurs only on the fin faces, in addition to predicting that the ambient temperature is homogeneous. Heat transfer analysis is performed by computational simulations using appropriate numerical methods. The most of solutions in the literature consider some simplifications as constant thermal conductivity and linear boundary conditions, this work addresses this subject. The method applied is the Kirchhoff Transformation, that uses the thermal conductivity variation to define the temperatures values, once the thermal conductivity variate as a temperature function. For the real situation approximation, this work appropriated the silicon as the fin material to consider the temperature function at each point, which makes the equation that governs the non-linear problem. Finally, the comparison of the results obtained with typical results proves that the assumptions of variable thermal conductivity and heat dissipation by thermal radiation are crucial to obtain results that are closer to reality.


Title of the Paper: Experiences with using of Loading Tests and the “Design Assisted by Testing” Method for the Determination and Verification of Structural Members and Details

 

Authors: Michal Štrba, Marcela Karmazínová, Pavla Bukovská

Pages: 1-11

DOI: 10.46300/9104.2021.15.1     XML

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Abstract: This paper describes experiences with use of different types of experiments (i.e. loading tests) as well as with use of so-called “Design assisted by testing” method given in the standard “Eurocode 1”. Both these mentioned ways are useful in case of a determination and verification of important design parameters, material properties and load-carrying capacities (in case of different types of stresses, used materials or geometric configurations of designed constructions or their elements and details). In this area, during recent years, large number of miscellaneous loading tests have been performed at the authors’ workplace. Therefore, all presented information and all described experiment results in this article are directly based on solved experimental (and theoretical) research programs carried out at Institute of Metal and Timber Structures at the Faculty of Civil Engineering at Brno University of Technology in cooperation with research institutes and companies in the Czech Republic. Most of all research projects were focused on the load-carrying capacity determination as well as on the knowledge about an actual behaviour and failure mechanisms of steel and steel-concrete structural members and details (recently of members made of FRP or GFRP composite, too), usually in case of verification of either existing or newly designed building or bridge structures.