Artykuły (CN-cmms)

Permanent URI for this collectionhttps://repo.agh.edu.pl/handle/AGH/102779

Artykuły czasopisma Computer Methods in Materials Science

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Now showing 1 - 20 of 93

Access status: Open Access ,
Identification of the average and local boundary condition of heat transfer during cooling with a water spray under surface boiling
(Wydawnictwa AGH, 2020) Jasiewicz, Elżbieta; Hadała, Beata; Malinowski, Zbigniew
The study determined the local and average heat transfer coefficient and the heat flux on the surface of a cylinder cooled with a water nozzle. The inverse method was used to identify the heat transfer coefficient. An objective function was defined to determine the distance between the measured and calculated temperatures. Two models describing the heat transfer coefficient on the cooled surface were considered. The first model described changes in the heat transfer coefficient as a function of the sample radius and cooling time, and the second one assumed the dependence of the heat transfer coefficient solely on time. Numerical simulations showed significant differences in the determined heat transfer coefficients depending on the adopted model of the boundary condition. The performed tests included experimental temperature measurements at selected points of the sensor, numerical simulations of temperature changes, and the inverse solution.
Access status: Open Access ,
On the method of changing the temperature of liquids and gases in a transportation system by local heating or cooling
(2020) Pankratov, Evgenij L.
In this paper, we consider an approach to changing the temperature of liquids and gases in apipeline by local heating and cooling. The concept is based on the introduction of changes in the temperature series of the pipeline sections due to the external modification these sections’ temperature. This situation could be used as a heat sink or to increase temperature. A developed heat transfer model in apipeline also accounts for convection due to liquid/gas transport. An analytical approach for the analysis of liquid/gas transport that takes into account the transport of heat due to convection was also introduced. The approach allows the spatial and temporal variation of parameters of transport to be taken into account as well as considerations of the nonlinearity of the investigated processes.
Access status: Open Access ,
Numerical investigation of the influence of explosive welding process setup on the Ti/Cu interlayer morphology
(2020) Mojżeszko, Mateusz; Setty, Mohan
Explosive welding is a complex process involving various phenomena influenced by a series of parameters in a noticeably short span of time which affect the morphology and eventually the quality of the weld. Therefore, this paper aims to investigate the influence of these parameters on material behavior with a series of numerical simulations based on a meshless approach. The developed model is based on the SPH (Smoothed Particle Hydrodynamics) method and is used to investigate Ti/Cu system behavior as a case study. Examples of the resulting temperatures and pressures as a function of process setup are presented within the paper. The results obtained demonstrate how weld morphology is related to the process conditions.
Access status: Open Access ,
The effect of the assumed thermophysical properties of steel on the heat transfer calculation result in contact phenomena
(Wydawnictwa AGH, 2020) Rywotycki, Marcin; Malinowski, Zbigniew; Przyłucka, Aleksandra; Sołek, Krzysztof
The article presents a model of heat transfer between two solid surfaces remaining in contact under the effect of the force applied. The presented results were obtained from the authors' own studies conducted with the application of a new method of determining the heat flux transferred between these surfaces. The method consists of two stages: the experiment and numerical calculations. The experimental tests include temperature measurements in specific points in two samples remaining in contact with each other. The numerical part uses the inverse solution and the finite element method for the calculation of the heat flux on the contact surface. An analysis was performed on the effect of the steel grade used in the tests on the result of heat transfer determination in contact phenomena. The calculations were conducted with the application of proprietary software using the inverse method integrated with FEM.
Access status: Open Access ,
A hybrid statistical approach for texture images classification based on scale invariant features and mixture gamma distribution
(2020) Benlakhdar, Said; Rziza, Mohammed; Oulad Haj Thami, Rachid
Image classification refers to an important process in computer vision. The purpose of this paper is to propose a novel approach named GGD-GMM and based on statistical modeling in the wavelet domain to describe textured images and rely on a number of principles that give its internal coherence and originality. Firstly, we propose arobust algorithm based on the combination of the wavelet transform and Scale Invariant Feature Transform. Secondly, we implement the aforementioned algorithm and fit the result using the finite mixture gamma distribution (GMM). The results, obtained for two benchmark datasets show that the proposed algorithm has a good relevance as it provides higher classification accuracy than some other well-known models (Kohavi, 1995). Moreover, it shows other advantages relied upon Noise-resistant and rotation invariant.
Access status: Open Access ,
The influence of coolant velocity on the local heat transfer coefficient during steel quenching
(Wydawnictwa AGH, 2020) Szajding, Artur; Gołdasz, Andrzej; Telejko, Tadeusz
The results of the calculations of the local heat transfer coefficient HTC and a heat flux HF on the face of a cylindrical sample made of 1.0503 steel are presented. The sample was cooled from a temperature of approx. 930°C in a mineral oil having a temperature equal to 50°C. The experiments were performed for three speeds of the oil stream (0.2 m/s, 0.4 m/s and 0.6 m/s). The oil stream was directed perpendicularly to the cooled surface. The temperature of each sample was measured with 4 thermocouples and recorded with a frequency of 10 Hz. The maximum values of HTC always occurred in the axis of the sample and were in the range of 8000 to 10,000 W/(m2 ?K). The results are presented in the form of useful graphs showing the dependence of HTC and HF on the surface temperature for various velocities of cooling oil. The calculations were made with self-developed software using the inverse solution of the boundary heat conduction problem.
Access status: Open Access ,
An efficient Monte Carlo Potts method for the grain growth simulation of single-phase systems
(2020) Maazi, Noureddine; Lezzar, Balahouane
The choice of the lattice sites to be reoriented in the Monte Carlo Potts algorithm for grain growth simulation is repeated in a non-homogeneous way. Therefore, some grains are favorably growing than others. This fact may seriously affect the simulationresults. Soa modified MC method is presented. Lattice sites are selected for reorientation one by one following their positions in the matrix in each Monte Carlo step (mcs). This approach ensures that the various selections of one lattice site within every mcs are eliminated, and no favorable growth of grains at the expense of others. The calculation time considerably decreases. The effect of real-time and physical temperature on the grain growth kinetics is discussed.
Access status: Open Access ,
Development and verification of the scale growth model during high temperature oxidation for S235 steel
(Wydawnictwa AGH, 2020) Przyłucka, Aleksandra; Cebo-Rudnicka, Agnieszka; Rywotycki, Marcin; Augustyn-Nadzieja, Joanna; Malinowski, Zbigniew
Every year rapid industrialization and the following urbanization fuel the global demand for steel. The use of steel products contributes to the sustainable development of society. The scale growth mechanism accompanies the high-temperature plastic working of metals and alloys. The article focuses on the thickness of the scale formed as a result of annealing steel samples in a furnace. Samples made of S235 (A283C) steel were heated at two temperatures, 1100°C and 1200°C, for 8 minutes. The amount of scale formed was determined on the basis of photos taken with a light microscope. The transformed equations of steel oxidation kinetics were used in the computational part. The scale thickness obtained numerically corresponded to the scale formed in real conditions. The aim of the research was to adjust the scale growth model on steel so that it gives correct results in relation to the actual thickness of the formed oxidized layer.
Access status: Open Access ,
Mean field and full field modelling of microstructure evolution and phase transformations during hot forming and cooling of low carbon steels
(2020) Szeliga, Danuta; Bzowski, Krzysztof; Rauch, Łukasz; Kuziak, Roman; Pietrzyk, Maciej
The paper describes a critical comparison of mean field and full field approaches to modelling hot deformation/controlled cooling sequences for steels. Classification of the models, based on the balance between predictive capabilities and computing costs, is presented. Mean field models, which describe microstructure evolution and phase transformations were connected with thermomechanical finite element program and applied to simulation of the hot strip rolling process and cooling of tubes after hot rolling. Full field model described in the paper is a connection of the finite element (FE) and level set (LSM) methods. These methods were used to simulate heating/cooling sequence in the continuous annealing line. A suggestion to use a stochastic model as a bridge between mean field and full field approaches is made.
Access status: Open Access ,
An accuracy analysis of the cascaded lattice Boltzmann method for the 1D advection-diffusion equation
(Wydawnictwa AGH, 2020) Straka, Robert; Sharma, Keerti Vardhan
We analyze higher order error terms in a modified partial differential equation of a cascaded lattice Boltzmann method (CLBM) for one conservation law - the advection-diffusion equation. To inspect the behavior of the error terms we derived an equivalent finite difference equation (EFDE), this approach is different from other techniques like the Chapman-Engskog expansion, equivalent partial differential equations or the Maxwell iteration used in the literature. The resulting EFDE is obtained from the recurrence formulas of the lattice Boltzmann equations for the CLBM and is subsequently analyzed by standard analytical techniques. We have found relations of the LBM parameters which could cancel some of the higher order terms, making the method more accurate. The detailed derivation of the EFDE and higher order terms' pre-factors is the main result of this paper. The resulting explicit form of the error terms are derived and presented.
Access status: Open Access ,
Artificial intelligence approach for detecting material deterioration in hybrid building constructions
(Wydawnictwa AGH, 2021) Česnokov, Andrej Vladimirovič; Mihajlov, Vitalij Vital?evič; Dolmatov, Ivan Viktorovič
Hybrid constructions include heterogeneous materials with different behaviors under load. The aim is to achieve a so-called synergistic effect when the advantages of particular structural elements complement each other in a unified system. The building constructions considered in the research include high-strength steel cables, fiberglass rods, and flexible polymer membranes. The membrane is attached to the rods which have been elastically bent from the initially straight shape into an arch-like form. Structural materials inevitably deteriorate during a long operational period. The present study focuses on detecting material deterioration using Artificial Neural Networks (ANNs), which belong to the scope of intelligent techniques for data analysis. Appropriate ANN structures and required features are proposed. A semi-supervised learning strategy is used. The approach allows the training of the networks with normal data only derived from the construction without defects. Material degradationis detected by the level of reconstruction error produced by the network given the input data. The work contributes to the field of structural health monitoring of hybrid building constructions. It provides the opportunity to detect material deterioration given the forces in particular structural elements.
Access status: Open Access ,
Considering semi-crystallinity in molecular simulations of mechanical polymer properties - using nanoindentation of polyethylene as an example
(Wydawnictwa AGH, 2021) Fritz, Susanne
Molecular dynamic (MD) simulations have been used to investigate the response of semi-crystalline polymers in nanoindentation tests, using polyethylene (PE) as an example. To that purpose, semi-crystalline simulation boxes of linear PE with various chain lengths up to C2000 were created by homogeneous nucleation during the non-isothermal cooling of melts. The final crystallinity depended on the chain length and the cooling rate used and could be estimated using various parameters like density, fraction of bonds in trans conformation, and energy terms. The simulation boxes were transferred into surface models and subjected to nanoindentation tests using non equilibrium MD. This allowed the deformation behaviour of the material to be analysed directly. Strong dependencies on the crystallinity of the PE were found, which underlines the importance of considering crystallinity when investigating the mechanical properties of semi-crystalline polymers by means of simulations.
Access status: Open Access ,
On the prognosis of the growth of a heterostructure from a gas phase to analyze the possibility of decreasing mismatch-induced stresses
(Wydawnictwa AGH, 2021) Pankratov, Evgenij Leonidovič
An approach to decreasing mismatch-induced stress in a heterostructure by radiation processing during growth from the gas phase is introduced in this paper. Within the framework of the approach with decreasing mismatch-induced stresses, one can find the acceleration of the recombination and diffusion of radiation defects generated during radiation processing. An analytical approach for analyzing mass and heat transfer is also introduced. The approach provides the opportunity to simultaneously take into account spatial and temporal variations of mass transfer parameters. At the same time, the approach allows the nonlinearity of the considered processes to be taken into account.
Access status: Open Access ,
A new BEM for modeling and simulation of 3T MDD laser-generated ultrasound stress waves in FGA smart materials
(Wydawnictwa AGH, 2021) Fahmy, Mohamed Abdelsabour
The goal of this study is to present a new theory known as the three-temperature memory-dependent derivative (MDD) of ultrasound stress waves in functionally graded anisotropic (FGA) smart materials. It is extremely difficult to address the difficulties related to this theory analytically due to its severe nonlinearity. As a result, we suggest a new boundary element method (BEM) to solve such equations. The suggested BEM technique incorporates the benefits of both continuous and discrete descriptions. The numerical results are visually represented to demonstrate the impacts of MDD three temperatures and anisotropy on the ultrasound stress waves in FGA smart materials. The numerical findings verify the proposed methodology's validity and accuracy. We may conclude that the offered results are useful for comprehending the FGA smart materials. As a result, our findings contribute to the advancement of the industrial applications of FGA smart materials.
Access status: Open Access ,
The influence of material aging on the structural behavior of a flexible roof with a polymer membrane shell
(Wydawnictwa AGH, 2021) Česnokov, Andrej Vladimirovič; Mihajlov, Vitalij Vital?evič; Dolmatov, Ivan Viktorovič
The roof structure considered in the research consists of continuous cables and a number of spreaders forming a three-dimensional frame. The frame is covered with a polymer membrane made of flexible architectural fabrics. The elements of the roof are compact and suitable for transportation to remote construction sites. The roof also has advantages for developing areas with harsh climatic conditions. The flexible elements of the roof, however, only provide transmission of tensile forces. Under compression, cables slacken and the membrane becomes wrinkled. Pre-tension of the flexible elements, which is introduced to retain the operability of the roof, tends to gradually diminish due to material aging. The aging results in the alteration of strength properties and creep elongation of the structural elements. It induces membrane tearing on local areas. Force alteration in primary structural members is examined in the present study, with statistical methods used for data analysis. They include significance hypothesis testing and correlation coefficients estimation. The data are obtained by the Finite Element simulation of the roof using EASY-2020 software. The results of the work may be used for life expectancy assessment of flexible roof structures, providing important information for the preliminary design stage. The work contributes to the safety enhancement of cable-membrane structures and the expansion of their scope in permanent building constructions.
Access status: Open Access ,
Processes simulations with multiscale materials models using a dedicated interface
(Wydawnictwa AGH, 2021) Smyk, Grzegorz; Szeliga, Danuta
The main goal of this work is the integration of in-house software with commercial numerical software based on the finite element method (FEM). The main idea is to develop a universal interface to perform process simulations with multiscale models. The interface allows the combination of external procedures with commercial software with minimum programmer's work putting in integration. As an example, the model of material recrystallization of steel was implemented, added to the commercial application, and the software was tested for a process defined as a sequence of compression and cooling. The material model takes into consideration each type of recrystallization that occurs during a sequence of thermal and mechanical processing such as static recrystallization (SRX), dynamic recrystallization (DRX), and meta-dynamic recrystallization (MDRX). It allows the prediction of recrystallized volume fraction (X) and grain growth on each step of numerical simulation for each Gauss point in the computation domain. The presented multiscale model of process sequences not only allows to calculate microscale model parameters such as grain growth and recrystallized volume fraction, but also reflects the impact of the microscale model on macroscale parameters.
Access status: Open Access ,
The role of neighborhood density in the random cellular automata model of grain growth
(Wydawnictwa AGH, 2021) Czarnecki, Michał; Sitko, Mateusz; Madej, Łukasz
The paper focuses on adapting the random cellular automata (RCA) method concept for the unconstrained grain growth simulation providing digital microstructure morphologies for subsequent multi-scale simulations. First, algorithms for the generation of initial RCA cells alignment are developed, and then the influence of cells density in the computational domain on grain growth is discussed. Three different approaches are proposed based on the regular, hexagonal, and random cells' alignment in the former case. The importance of cellular automata (CA) cell neighborhood definition on grain growth model predictions is also highlighted. As a research outcome, random cellular automata model parameters that can replicate grain growth without artifacts are presented. It is identified that the acceptable microstructure morphology of the solid material is obtained when a mean number of RCA cells in the investigated neighborhood is higher than ten.
Access status: Open Access ,
Evolutionary data driven modelling and many objective optimization of non linear noisy data in the blast furnace iron making process
(Wydawnictwa AGH, 2021) Mahanta, Bashista Kumar; Chakraborti, Nirupam
The optimization of process parameters in modern blast furnace operation, where both control and accessing large data set with multiple variables and objectives is a challenging task. To handle such non-linear and noisy data set deep learning techniques have been used in recent time. In this study an evolutionary deep neural network algorithm (EvoDN2) has been applied to derive a data driven model for blast furnace. The optimal front generated from deep neural network is compared against the optimal models developed from bi-objective genetic programming algorithm (BioGP) and evolutionary neural network (EvoNN). The optimization process is applied to all the training models by using constraint based reference vector evolutionary algorithm (cRVEA).
Access status: Open Access ,
A repeatability study of artificial neural network predictions in flow stress model development for a magnesium alloy
(Wydawnictwa AGH, 2021) Siewior, Hubert; Madej, Łukasz
This work is devoted to an evaluation of the capabilities of artificial neural networks (ANN) in terms of developing a flow stress model for magnesium ZE20. The learning procedure is based on experimental flow-stress data following inverse analysis. Two types of artificial neural networks are investigated: a simple feedforward version and a recursive one. Issues related to the quality of input data and the size of the training dataset are presented and discussed. The work confirms the general ability of feedforward neural networks in flow stress data predictions. It also highlights that slightly better quality predictions are obtained using recursive neural networks.
Access status: Open Access ,
On the approach to the analysis of the growth of epitaxial layers by pulsed laser deposition
(Wydawnictwa AGH, 2021) Pankratov, Evgenij Leonidovič
This paper considers an analytical approach for the prognosis of mass and heat transport during the growth of epitaxial layers by means of pulsed laser deposition. The approach provides the opportunity to make a prognosis which takes into account the spatial and temporal variations of their parameters and, at the same time, the nonlinearity of these processes. Based on this approach, the influence of the variation of several parameters on the growth process is investigated.