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The article presents a computational model build with the use of artificial neural networks optimized by genetic algorithm. This model was used to research and prediction of the impact of chemical elements and heat treatment conditions on the mechanical properties of ferrite stainless steel. Optimization has allowed the development of artificial neural networks, which showed a better or comparable prediction result in comparison to un-optimized networks has reduced the number of input variables and has accelerated the calculation speed. The introduced computational model can be applied in industry to reduce the manufacturing costs of materials. It can also simplify material selection when an engineer must properly choose the chemical elements and adequate plastic and/or heat treatment of stainless steels with required mechanical properties.
Content available remote Virtual laboratory methodology in scientific researches and education
Purpose: This article is presenting the Material Science Virtual Laboratory. Developed laboratory is an open scientific, investigative, simulating and didactic medium helpful in the realisation of the scientific and didactic tasks in the field of material Science. It is implemented in the Institute of Engineering Materials and Biomaterials of Silesian University of Technology in Gliwice, Poland. Design/methodology/approach: The laboratory is a set of testers and training simulators, set in the Virtuality and created in several languages and the programming techniques, which interprets the properties, functionality and manual rules of actual equipment installed and accessible in the real science labs of scientific universities. Findings: Application of the equipment, that is practically imperishable, cheap in exploitation and ease in the use encourages students and scientific workers to independent audits and experiments in places, where the possibilities of their performance in the real investigative laboratory will be restricted because of the high material costs, difficult access to real equipment or the possible peril of his impairment. Research limitations/implications: The proposed solutions allow the utilisation of the developed virtual environment as a new medium in both, the scientific work performed remotely, as well as in education during classes. Practical implications: The usage possibilities of the virtual laboratory are practically unrestricted; it can be a foundation for any surveys, course or training plan. Originality/value: The project of the virtual laboratory corresponds with the global tendency for expand the investigative and academic centres about the possibilities of training and experiments performance with use of the virtual reality. This enriches investigation and training programmes of the new abilities reserved so far exclusively for effecting only on actual equipment.
Purpose: The work presents the application of the Finite Elements Method in a computer simulation whose aim is to determine the properties of PVD and CVD coatings on various substrates and to optimise parameters of a laser surface treatment process of surface layers of tool steels. Design/methodology/approach: The article discusses the application of the finite elements method for simulating the determination of stresses and microhardness of Ti+TiN, Ti+Ti(CN) and Ti+TiC coatings obtained in a magnetron PVD process on a substrate of sinter high-speed steel, of Ti/Ti(C,N)/CrN, Ti/Ti(C, N)/(Ti, Al)N, Ti/(Ti, Si)N/(Ti, Si)N, Cr/ CrN/CrN, Cr/CrN/TiN and Ti/DLC/DLC coatings obtained in a PVD and CVD process on magnesium alloys, of graded and monolayer coatings (Ti, Al)N, Ti(C,N) produced with the PVD arc technique on a substrate of sintered carbides, cermets and oxide tool ceramics and tool steel remelted and alloyed with a high-performance diode laser (HPDL). Modeling of stresses was performed with the help of finite element method in ANSYS and MARC environment, and the experimental values of stresses were determined based on the sin2Ψ. Findings: The models presented satisfy the assumed criteria, and they can be applied for the determination of properties of surface layers and optimisation of PVD and CVD processes and laser alloying and remelting. The results of a computer simulation correlate with experimental results. The models developed allow to largely eliminate costly, timeconsuming and specialist experiments which have to be done during investigations for the benefit of computer simulations. Research limitations/implications: To be able to assess the possibility of application of surface layers, a computer simulation of other properties of coatings has to be additionally carried out, and a strength analysis has to be made of other coatings coated onto various substrate materials. Originality/value: value Computer simulation and modelling is an interdisciplinary field necessary for the development of science and technology, enabling to perform direct visualisation of properties, which cannot be identified in experimental observations. The purpose of computer simulation and modelling is to improve the ability to predict results and to optimise solutions.
Content available Internal stresses in PVD coated tool composites
The aim of work is the investigation of the internal stresses in PVD coated metal matrix composites (MMC). Sintered MMC substrate is composed of the matrix with the chemical composition corresponding to the high-speed steel, reinforced with the TiC type hard carbide phase. Functionally graded composition of MMC providing of high ductility characteristic of steel in the core zone as well as high hardness characteristic of cemented carbides in the surface zone. Internal stresses were determined with use of finite element method in ANSYS environment. The reason of undertaking the work is necessity of develop the research of internal stresses, occurring in the coating, as well as in the adhesion zone of coating and substrate, which makes it possible to draw valuable conclusions concerning engineering process of the advisable structure and chemical composition of coatings. The investigations were carried out on cutting tools models containing defined zones differing in chemical composition. Modelled materials were characteristic of chemical composition corresponding to the high-speed steel at the core, reinforced with the TiC type hard carbide phase with the growing fraction of these phases in the outward direction from the core to the surface, additionally coated with (Ti,Al)N or Ti(C.N) functionally graded PVD coatings. Results of determined internal stresses were compared with the results calculated using experimental X-ray sin2ψ method. It was demonstrated, that the presented model meets the initial criteria, which gives ground to the assumption about its utility for determining the stresses in coatings as well as in functionally graded sintered materials. The results of computer simulations correlate with the experimental results.
Content available remote On transition functions and nonlinearity measures in gradient coatings
Purpose: In this paper the influence of the shape of transition functions between the single layers of multilayer coating on the final internal stresses states in the coating was investigated. Additionally the degree of nonlinearity and asymmetry of postulated gradient layers was calculated. Design/methodology/approach: Physical and mathematical models of the layers were created basing on classical theory of elasto-plastic materials. Computer model of the object (coating + substrate) describing internal strains and stresses states in layers, after deposition process, was created using FEM method. Findings: New concepts of nonlinearity and asymmetry measurability of transition function were introduced. Using predefined measures the dependence between internal stresses fields in postulated class of gradient layers and values of nonlinearity and asymmetry were obtained. Research limitations/implications: There are an infinite number of possible measures of heterogeneity and nonlinearity of the transition layers. Also there are infinitely many functions with the same measures of asymmetry and nonlinearity, but different mathematical forms, thus a functions of the same measures value form a kind of class of abstraction. So it is convenient to consider specific representatives of the given class and expand the obtained results to remaining representatives which is laborious and ambiguous task. Practical implications: Proposed measures of gradient layers will become a significant components of the PC software in future, which will upgrade the designing process of hard, wear resistant coatings architecture. Originality/value: A class of monotonic and asymmetric transition functions, describing continuous physico-chemical material’s parameters changes in each layer of K-layered coating was created. Also a new measures of nonlinearity and asymmetry of transition function were introduced.
A number of theoretical problems are discovered in the application of degenerated models in punching process of ballistic shields. Insufficient knowledge of dynamic behaviours of these models based on non-linear complex constitutive materials or combination of mixed rheological Maxwell models with linear elastic elements or dissipative is the main reason of the problems. In the engineering application with the influence of rheological forces the element of mass responsible for force ofinertia in dynamic loads is always applied. Taking the forces into consideration in dynamic analysis the degenerated system is necessary to use. It is also utilitarian goal of materiał properties identification in punching process with the use ofparticle mass (projectile). In this paper, the authors present further results ofresearch in this area. Suppression and dispersion of energy is the crucial phenomena in the punching process of ballistic shields with the use of small arms. Therefore the research presented in the paper concerns systems based on viscotic damping with the dry friction parameter (h). As a result ofthe research influence of h parameter on time and frequency characteristics under impact stress was estimated. Analytic calculations and simulations of the examination were validated by experimental test and measurements. With the basis on the results the final conclusions were formulated.
This paper presents a method, which may be used to determine residuaI stress distribution in bodies subject to cyclic loads. A mixed global/local version of the Meshless Finite Difference Method (MFDM) is used to devise a discrete computational formulation of a shakedown based residual stress calculation mechanical model for elastic-plastic bodies subject to cyclic loadings. Several 1D and 2D verification/vaIidation tests are presented, including thorough discussion of results and conclusions regarding the details of computational model. The method developed is applied to determine residual stress distribution in a railroad rail subject to simulated contact load.
W pracy przedstawiono metodę, która może zostać zastosowana do wyznaczenia rozkładu naprężeń resztkowych w ciałach poddanych obciążeniom cyklicznie zmiennym. Mieszana globalno/lokalna wersja Bezsiatkowej Metody Różnic Skończonych (BMRS) została zastosowana do zbudowania dyskretnego sformułowania obliczeniowego modelu mechanicznego służącego do wyznaczania rozkładu naprężeń resztkowych w sprężystoplastycznych ciałach poddanych obciążeniom cyklicznie zmiennym. Model mechaniczny oparty jest na twierdzeniach teorii plastycznego przystosowania. W pracy przedstawiono wybrane jedno- i dwuwymiarowe testy weryfikacyjne i walidacyjne, włączając dyskusję ich rezultatów i konkluzje dotyczące szczegółowych rozwiązań modelu obliczeniowego. Opracowana metoda została zastosowana do wyznaczenia rozkładu naprężeń resztkowych w szynie kolejowej poddanej symulowanym obciążeniom kontaktowym.
Content available remote Numerical analysis of beams on unilateral elastic foundation
Purpose: The main issue of this paper is to present results of finite element analysis of beams elements on unilateral elastic foundation received with a use of special finite elements of zero thickness designated for foundation modelling. Design/methodology/approach: Computer strength analysis with a use of Finite Element Method (FEM) was carried out. Findings: The paper presents possibilities of special finite elements of zero thickness which enable taking into consideration unilateral contact in construction-foundation interaction as well as an impact of surrounding construction environment to its behaviour. Research limitations/implications: Further researches should concentrate on taking into consideration a multi-layer aspects as well as elasto-plasticity of foundation. Practical implications: Modern engineering construction on elastic foundation analyze require not only standard analysis on Winkler (one parameter) foundation but also calculation of construction on two-parameter foundation which will take into consideration a possibility of loosing contact between construction and foundation (unilateral contact). Originality/value: The paper can be useful for person who performs strength analysis of beams on elastic foundation with a use of finite element method.
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