Wyniki wyszukiwania - Biblioteka Nauki

1

On transition functions and nonlinearity measures in gradient coatings

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Ratajski J. , Szparaga Ł.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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tom Vol. 54, nr 1

83--92

EN

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.

2

Internal stresses in PVD coated tool composites

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Śliwa A. , Mikuła J. , Gołombek K. , Kwaśny W. , Pakuła D.

Archives of Metallurgy and Materials

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2016

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tom Vol. 61, iss. 3

1371--1378

EN

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.

3

Optimization of Ferrite Stainless Steel Mechanical Properties Prediction with artificial Intelligence Algorithms

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Honysz R.

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2020

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tom Vol. 65, iss. 2

749-753

EN

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.

4

On estimation of residual stresses in rails using shake-down based method

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Pazdanowski M.

Archives of Transport

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2010

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tom Vol. 22, iss. 3

319-336

EN

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.

PL

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.

5

Numerical analysis of beams on unilateral elastic foundation

72%

Torbacki W.

Archives of Materials Science and Engineering

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2008

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tom Vol. 29, nr 2

109-112

EN

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.