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Abstract

The use of periodic structures as noise abatement devices has already been the object of considerable research seeking to understand its efficiency and see to what extent they can provide a functional solu- tion in mitigating noise from different sources. The specific case of sonic crystals consisting of different materials has received special attention in studying the influence of different variables on its acoustic performance. The present work seeks to contribute to a better understanding of the behavior of these structures by implementing an approach based on the numerical method of fundamental solutions (MFS) to model the acoustic behavior of two-dimensional sonic crystals. The MFS formulation proposed here is used to evaluate the performance of crystals composed of circular elements, studying the effect of varying dimen- sions and spacing of the crystal elements as well as their acoustic absorption in the sound attenuation provided by the global structure, in what concerns typical traffic noise sources, and establishing some broad indications for the use of those structures.
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Authors and Affiliations

Mário Martins
Luís Godinho
Luís Picado-Santos
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Abstract

The residual stress analysis is discussed in the paper. However, the author has not intended to present, even partially, all aspects of this very broad problem. The aim of this work has been limited to a review of conternporarily used experimental, numerical and hybrid methods, and to outline the directions of possible developments.
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Authors and Affiliations

Marek Bijak-Żochowski
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Abstract

Several methods can be applied for analyses of the acoustic field in enclosed rooms namely: wave propagation, geometrical or statistical analysis. The paper presents problems related to application of the boundary elements method to modelling of acoustic field parameters. Experimental and numerical studies have been combined for evaluation of acoustic impedance of the material used for the walls of a model room. The experimental studies have been carried out by implementing a multichannel measuring system inside the constructed model of an industrial room. The measuring system allowed simultaneous measurements of the source parameters - the loudspeaker membrane vibration speed, the acoustic pressure values in reception points located inside the model space as well as phase shifts between signals registered in various reception points. The numerical modelling making use of the acoustic pressure values measured inside the analyzed space allowed determination of requested parameters of the surface at the space boundary.

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Authors and Affiliations

Janusz Piechowicz
Ireneusz Czajka
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Abstract

This paper deals with an inverse magnetostatic problem related to the reconstruction of a permanent magnet encapsulated inside the cathode of a magnetron sputtering device. The numerical analysis is aimed to obtain the estimation of a short solenoid equivalent to the unknown magnet. Least squares approach has been used to solve the functional defined as squared sum of the residuals. A comparison of the results obtained with Genetic Algorithm approach and nonlinear system of equations is performed. A regularized solution, which is in good agreement with the experimental data, was found by applying a Newton adapted regularization technique.

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Authors and Affiliations

O. Miron
D. Desideri
D.D. Micu
A. Maschio
A. Ceclan
L. Czumbil
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Abstract

The aim of the present work is to verify a numerical implementation of a binary fluid, heat conduction dominated solidification model with a novel semi-analytical solution to the heat diffusion equation. The semi-analytical solution put forward by Chakaraborty and Dutta (2002) is extended by taking into account variable in the mushy region solid/liquid mixture heat conduction coefficient. Subsequently, the range in which the extended semi-analytical solution can be used to verify numerical solutions is investigated and determined. It has been found that linearization introduced to analytically integrate the heat diffusion equation impairs its ability to predict solidus and liquidus line positions whenever the magnitude of latent heat of fusion exceeds a certain value.
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Authors and Affiliations

Tomasz Wacławczyk
Michael Schäfer
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Abstract

For solving a partial different equation by a numerical method, a possible alternative may be either to use a mesh method or a meshless method. A flexible computational procedure for solving 1D linear elastic beam problems is presented that currently uses two forms of approximation function (moving least squares and kernel approximation functions) and two types of formulations, namely the weak form and collocation technique, respectively, to reproduce Element Free Galerkin (EFG) and Smooth Particle Hydrodynamics (SPH) meshless methods. The numerical implementation for beam problems of these two formulations is discussed and numerical tests are presented to illustrate the difference between the formulations.

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Authors and Affiliations

V.E. Rosca
V.M.A. Leitão
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Abstract

The impact of the transversely-oriented sinusoidal wall corrugation on the hydraulic drag is investigated numerically for the flow through the channel of finite width and with flat sidewalls. The numerical method, based on the domain transformation and Chebyshev-Galerkin discretization, is used to investigate the flow resistance of the laminar, parallel and pressure-driven flow. The obtained results are compared to the reference case, i.e., to the flow through the channel with rectangular cross section of the same aspect ratio. Simple explanation of the gain in the volumetric flow rate observed in the flow through spanwise-periodic channel with long-wave transversely-oriented wall corrugation is provided. In the further analysis, pressure drop in the flows with larger Reynolds numbers are studied numerically by means of the finite-volume commercial package Fluent. Preliminary experimental results confirm the predicted tendency.

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Authors and Affiliations

Jacek Szumbarski
Slawomir Blonski
Tomasz Kowalewski
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Abstract

In this paper, a class of linear Boolean functions is analyzed. The Boolean function can be represented as disjoint cubes or in the form of a truth vector. The primary purpose of this analysis is to decide whether an incompletely defined function can be extended to a complete linear form. A simple algorithm for generating all states of this function has been proposed if the Boolean function can have a full representation. The algorithm is beneficial for large functions. The proposed approach can be applied to completely and incompletely defined Boolean functions.
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Authors and Affiliations

Piotr Porwik
1

  1. Faculty of Science and Technology, University of Silesia, Bedzinska 39, 41-200 Sosnowiec, Poland
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Abstract

High-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is

evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex

series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both

from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented

in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel.

The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as

in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich

chemical composition and phenomena occurring during crystallization, must be known to the technologists.

The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated

using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative

analysis.

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Authors and Affiliations

G. Stradomski
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Abstract

The results of experimental investigations of heat transfer and a friction factor in an air channel of the minichannel heat exchanger are presented. The main aim of the analysis was to examine an influence of geometrical parameters of the fin shape with two geometries on heat transfer and flow characteristics of the air channel. The test rig was designed to monitor the parameters of the airflow during cooling by the minichannel heat exchanger. The analysis was conducted with the airflow in the range of 1–5 m/s. The temperature of the evaporation in a refrigeration system was set at 288.15 K. The energy balance of the refrigeration system was carried out. A numerical model describes the airflow through a part of the heat exchanger. Numerical simulations were validated with the experimental data. Numerical methods were used to evaluate the performance of the system and possibilities to improve the fin geometry. The characteristics of the friction factor (a measure of the pressure loss in the airflow) and the Colburn j-factor (heat transfer performance) were calculated. For the maximal velocity of the airflow, the Colburn factor was equal to 0.048 and the evaporator capacity equaled 1914 W.
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Bibliography

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[5] Gunnasegaran P., Shuaib N.H., Abdul Jalal M.F.: The effect of geometrical parameters on heat transfer characteristics of compact heat exchanger with louvered fins. ISRN Thermodyn. (2012), 1–10.
[6] Djamal H.D., Woon Q.Y., Suzairin M.S., Hisham Amirnordin S.: Effects of geometrical parameters to the performance of louvered fin heat exchangers. Appl. Mech. Mater. 773-774(2015), 398–402.
[7] Amirnordin S.H., Didane H.D., Norani Mansor M., Khalid A, Suzairin M.S., Raghavan V.R.: Pressure drop and heat transfer characteristics of louvered fin heat exchangers. Appl. Mech. Mater. 465-466(2014), 500–504.
[8] Chan Kang H., Jun G.W.: Heat transfer and flow resistance characteristics of louver fin geometry for automobile applications. J. Heat Transfer. 133(2011), 1–6.
[9] Okbaz A., Olcay A.B., Cellek M.S., Pinarbasi A.: Computational investigation of heat transfer and pressure drop in a typical louver fin-and-tube heat exchanger for various louver angles and fin pitches. EPJ Web Conf. 143(2017), 02084.
[10] Park J.S., Kim J., Lee K.S.: Thermal and drainage performance of a louvered fin heat exchanger according to heat exchanger inclination angle under frosting and defrosting conditions. Int. J. Heat Mass Transf. 108(2017), 1335–1339.
[11] Liu X., Chen H., Wang X., and Kefayati G.: Study on surface condensate water removal and heat transfer performance of a minichannel heat exchanger. Energies 13(2020), 5, 1065
[12] Saleem A., Kim M.H.: CFD analysis on the air-side thermal-hydraulic performance of multi-louvered fin heat exchangers at low Reynolds numbers. Energies 10(2017), 6, 1–24.
[13] Bohdal T., Charun H., Sikora M.: Heat transfer during condensation of refrigerants in tubular minichannels. Arch. Thermodyn. 33(2012), 2, 3–22.
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[16] Jasinski P.B., Kowalczyk M.J., Romaniak A., Warwas B., Obidowski D., Gutkowski A.: Investigation of thermal-flow characteristics of pipes with helical micro-fins of variable height. Energies 14(2021), 8, 2048.
[17] Kang, Hie-Chan & Jun, Gil.: Heat transfer and flow resistance characteristics of louver fin geometry for automobile applications. J. Heat Transf. 133 (2011), 101802.
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Authors and Affiliations

Michał Jan Kowalczyk
1
Marcin Łęcki
1
Artur Romaniak
1
Bartosz Warwas
1
Artur Gutkowski
1

  1. Lodz University of Technology, Institute of Turbomachinery, Wólczanska 217/221, 93-005 Łódz, Poland
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Abstract

Identification of working fluids and development of their mathematical models should always precede construction of a proper model of the analysed thermodynamic system. This paper presents method of development of a mathematical model of working fluids in a gas turbine system and its implementation in Python programming environment. Among the thermodynamic parameters of the quantitative analysis of systems, the following were selected: specific volume, specific isobaric and isochoric heat capacity and their ratio, specific enthalpy and specific entropy. The development of the model began with implementation of dependencies describing the semi-ideal gas. The model was then extended to the real gas model using correction factors reflecting the impact of pressure. The real gas equations of state were chosen, namely due to Redlich–Kwong, Peng–Robinson, Soave– Redlich–Kwong, and Lee–Kesler. All the correction functions were derived analytically from the mentioned equations of real gas behaviour. The philosophy of construction of computational algorithms was presented and relevant calculation and numerical algorithms were discussed. Created software allowed to obtain results which were analysed and partially validated.

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Authors and Affiliations

Paweł Trawiński
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Abstract

In this article, an analytical-numerical approach to calculating a stationary thermal field in the elliptical region is presented. The eigenfunctions of the Laplace operator were determined analytically, whereas the coefficients of the eigenfunctions were obtained numerically. The cooling was modeled with 3rd kind (Hankel’s) boundary condition, where the total heat transfer coefficient was the sum of the convective and radiative components. The method was used to analyze the thermal field in an elliptical conductor and a dielectrically heated elliptical column. The basic parameters of these systems, i.e. their steady-state current rating and the maximum charge temperature, were determined. The results were verified using the finite element method and have been presented graphically.
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Bibliography

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Authors and Affiliations

Jerzy Gołębiowski
1
Marek Zaręba
1

  1. Faculty of Electrical Engineering, Bialystok University of Technology, Wiejska 45D, 15-351 Bialystok, Poland
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Abstract

Mathematical description of alloys solidification in a macro scale can be formulated using the one domain method (fixed domain approach). The energy equation corresponding to this model contains the parameter called a substitute thermal capacity (STC). The analytical form of STC results from the assumption concerning the course of the function fS = fS (T) describing the changes of solid state volumetric fraction and the temperature at the point considered. Between border temperatures TS , TL the function fS changes from 1 to 0. In this paper the volumetric fraction fS (more precisely fL = 1- fS ) is found using the simple models of macrosegregation (the lever arm rule, the Scheil model). In this way one obtains the formulas determining the course of STC resulting from the certain physical considerations and this approach seems to be closer to the real course of thermal processes proceeding in domain of solidifying alloy.

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Authors and Affiliations

B. Mochnacki
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Abstract

A numerical model of the high-speed train carriage fire is established in this study. The influence of ceilings, sidewalls, luggage racks, seats, and floors on the heat release rate (HRR) of the high-speed train is studied by numerical methods. The results indicate that the heat release rate per unit area (HRRPUA) of ceiling and seat material dramatically influences the peak HRR and the time to peak HRR of train carriage fire. When the peak HRRPUA of interior ceiling material 1 decreases from 326 to 110 kW/m2, the peak HRR of the high-speed train fire decreases from 36.4 to 16.5 MW, with a reduction ratio of 54.7%. When seat materials with low HRRPUA are used, the peak HRR reduction ratio is 44.8%. The HRRPUA of the sidewall, luggage rack, and floor materials has little effect on the peak HRR of the carriage fire. However, the non-combustible luggage rack can delay the time when the HRR reaches its peak.
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Authors and Affiliations

Yuanlong Zhou
1
Haiquan Bi
2
Honglin Wang
2

  1. University of Science and Technology of China, State Key Laboratory of Fire Science, Hefei, Anhui 230026, China
  2. Southwest Jiaotong University, School of Mechanical Engineering, Chengdu 610031, China
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Abstract

The non-stationary problem of temperature distribution in a circular cylindrical channel of infinite length filled with a homogeneous biomass material moving with a constant velocity in the axial direction was investigated. The heat source was a shaftless helical screw (or auger), which was heated with an electric current due to the Joule–Lenz effect and rotated uniformly around the axis of symmetry of the channel. Similar problems arise in the thermal processing of biomaterials using screw conveyor in pyrolysis and mass sterilization and pasteurization of food products. The problem is solved using the expansion of given and required functions in Fourier series over angular coordinate and integral Fourier and Laplace transforms over axial coordinate and time, respectively. As a result, the temperature field is obtained as the sum of two components, one of which, global, is proportional to time, and the other, which forms the microstructure of the temperature profile, is given by Fourier–Bessel series. The coefficients of the series are determined by the integrals calculated using the Romberg method. Based on the numerical calculations, the analysis of the space-time microstructure of the temperature field in the canal was performed. A significant dependence of the features of this microstructure on the geometric, kinematic and thermodynamic characteristics of the filling biomass and the screw was revealed.
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Bibliography

Abramowitz M., Stegun I.A. (Eds), 1972. Handbook of mathematical functions with formulas, graphs, and mathematical tables. Dover Publ., Inc., New York.

Aramideh S., Xiong Q., Kong S.C., Brown R.C., 2015. Numerical simulation of biomass fast pyrolysis in an screw reactor. Fuel, 156, 234–242. DOI: 10.1016/j.fuel.2015.04.038.

Biogreen, 2016. The pyrolyzer Spirajoule®. Available at: https://www.biogreen-energy.com/spirajoule.

Bortolamasi M., Fottner J., 2001. Design and sizing of screw feeders. PARTEC 2001, International Congress for Particle Technology. Nuremberg, Germany, 27–29 March 2001.

Campuzano F., Brown R.C., Martínez J.D., 2019. Auger reactors for pyrolysis of biomass and wastes. Renewable Sustainable Energy Rev., 102, 372–409. DOI: 10.1016/j.rser.2018.12.014.

Carleton A.J., Miles J.E.P., Valentin F.H.H., 1969. A study of factors affecting the performance of screw conveyers and feeders. J. Eng. Ind., 91, 329-333. DOI: 10.1115/1.3591565.

Carslaw H.S., Jaeger J.C., 1959. Conduction of heat in solids. Clarendon Press, Oxford.

Cheney W., Kincaid D., 2008. Numerical mathematics and computing. Thomson Brooks/Cole, Belmont.

ETIA S.A.S., 2019. Thermal processing of bulk and powders powered by electricity. Available at: https://etiagroup. com/operations-for-thermal-processing.

Evstratov V.A., Rud A.V., Belousov K.Y., 2015. Process modelling vertical screw transport of bulk material flow. Procedia Eng., 129, 397–402. DOI: 10.1016/j.proeng.2015.12.134.

Guda V.K., Steele P.H., Penmetsa V.K., Li Q., 2015. Fast pyrolysis of biomass: Recent advances in fast pyrolysis technology, In: Pandey A., Bhaskar T., Stöcker M., Sukumaran R. (Eds.), Recent advances in thermochemical conversion of biomass. Elsevier, Amsterdam etc., 175-211.

Henan Pingyuan Mining Machinery, 2015. What factors that affect the screw conveyor conveying efficiency? Available at: https://www.pkmachinery.com/faq/factors–affect–screw-conveyor-conveying-efficiency.html.

Korn G.A., Korn T.U., 2000. Mathematical handbook for scientists and engineers: Definitions, theorems and formulas for references and review. Dover Publ., Inc., Mineola, New York.

Kovacevic A., Stosic N., Smith I., 2007. Screw compressors: Three dimensional computational fluid dynamics and solid fluid interaction. Springer-Verlag, Heidelberg, Berlin, New York. DOI: 10.1007/978-3-540-36304-0.

Krein S.G. (Ed.), 1972. Functional analysis. Wolters-Noorhoff Publ., Groningen.

Ledakowicz S., Stolarek P., Malinowski A., Lepez O., 2019. Thermochemical treatment of sewage sludge by integration of drying and pyrolysis/autogasification. Renewable Sustainable Energy Rev., 104, 319–327. DOI: 10.1016/j.rser.2019.01.018.

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Martelli F.G., 1983. Twin-screw extruders: A basic understanding. Van Nostrand Reinhold Co, New York.

Martínez J.D., Murillo R., Garcia T., Veses A., 2013. Demonstration of the waste tire pyrolysis process on pilot scale in a continuous screw reactor. J. Hazard. Mater., 261, 637–645. DOI: 10.1016/j.jhazmat.2013.07.077.

Nachenius R.W., Van De Wardt T.A., Ronsse F., Prins W., 2015. Residence time distributions of coarse biomass particles in a screw conveyor reactor. Fuel Process Technol, 130, 87–95. DOI: 10.1016/j.fuproc.2014.09.039.

Shi X., Ronsse F., Roegiers J., Pieters J.G., 2019a. 3D Eulerian-Eulerian modeling of a screw reactor for biomass thermochemical conversion. Part 1: Solids flow dynamics and back-mixing. Renewable Energy, 143, 1465-1476. DOI: 10.1016/j.renene.2019.05.098.

Shi X., Ronsse F., Nachenius R., Pieters J.G., 2019b. 3D Eulerian-Eulerian modeling of a screw reactor for biomass thermochemical conversion. Part 2: Slow pyrolysis for char production. Renewable Energy, 143, 1477-1487. DOI: 10.1016/j.renene.2019.05.088.
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Authors and Affiliations

Stanisław Ledakowicz
1
ORCID: ORCID
Olexa Piddubniak
1

  1. Faculty of Process and Environmental Engineering, Lodz University of Technology, Wolczanska St. 215, 90-924 Lodz, Poland
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Abstract

The high pressure die casting (HPDC) is a technique that allows us to produce parts for various sectors of industry. It has a great application in such sectors as automotive, energy, medicine, as the HPDC allows us to produce parts very fast and very cheaply. The HPDC casting quality depends on many parameters. The parameters among others, are cast alloy alloy metallurgy, filling system design, casting technology elements geometry and orientation, as well as, machine operation settings. In the article, different plunger motion schemes of the HPDC machine were taken into account. Analyses lead to learning about plunger motion influence on the casting porosity and solidification process run. Numerical experiments were run with the use of MAGMASoft® simulation software. Experiments were performed for industrial casting of water pump for automotive. Main parameter taken into account was maximal velocity of the plunger in the second phase. The analysis covered porosity distribution, feeding time through the gate, temperature field during whole process, solidification time. Cooling curves of the casting in chosen points were also analysed. Obtained results allow us to formulate conclusions that connect plunger motion scheme, gate solidification time and the casting wall thickness on the solidification rate and porosity of the casting.
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Authors and Affiliations

Katarzyna Żak
1
ORCID: ORCID
Rafał Dańko
1
ORCID: ORCID
Paweł L. Żak
1
ORCID: ORCID
Wojcich Kowalczyk
2

  1. AGH University of Krakow, Faculty of Foundry Engineering, al. Mickiewicza 30, 30-059 Kraków, Poland
  2. Frech Poland Sp. z o.o., Przedmos´c, Główna 8, 46-320 Praszka, Poland
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Abstract

In the paper, the numerical method of solving the one-dimensional subdiffusion equation with the source term is presented. In the approach used, the key role is played by transforming of the partial differential equation into an equivalent integro-differential equation. As a result of the discretization of the integro-differential equation obtained an implicit numerical scheme which is the generalized Crank-Nicolson method. The implicit numerical schemes based on the finite difference method, such as the Carnk-Nicolson method or the Laasonen method, as a rule are unconditionally stable, which is their undoubted advantage. The discretization of the integro-differential equation is performed in two stages. First, the left-sided Riemann-Liouville integrals are approximated in such a way that the integrands are linear functions between successive grid nodes with respect to the time variable. This allows us to find the discrete values of the integral kernel of the left-sided Riemann-Liouville integral and assign them to the appropriate nodes. In the second step, second order derivative with respect to the spatial variable is approximated by the difference quotient. The obtained numerical scheme is verified on three examples for which closed analytical solutions are known.
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Bibliography

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Authors and Affiliations

Marek Błasik
1

  1. Institute of Mathematics, Czestochowa University of Technology, al. Armii Krajowej 21, 42-201 Czestochowa, Poland
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Abstract

In the last 20 years, a new meshless computational method has been developed that is called peridynamics. The method is based on the parallelized code. The subject of the study is the deformation of open-cell copper foams under dynamic compression. The computational model of virtual cellular material is considered. The skeleton structure of such a virtual cellular material can be rescaled according to requirements. The material of the skeleton is assumed as the oxygen free high conductivity (OFHC) copper. The OFHC copper powder can be applied in additive manufacturing to produce the open-cell multifunctional structures, e.g., crush resistant heat exchangers, heat capacitors, etc. In considered peridynamic computations the foam skeleton is described with the use of an elastic-plastic model with isotropic hardening. The dynamic process of compression and crushing with different impact velocities is simulated.

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Authors and Affiliations

E. Postek
R.B. Pęcherski
Z. Nowak

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