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1

Effect of combinative cooled addition of strontium and aluminium on mechanical properties AlSi12 alloy

Lipiński T.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 83, nr 1

5--11

EN

Purpose: The study was to determine the mechanical properties of hypo-eutectic silumin AlSi12 modified with Sr or Al-Sr alloy slow or fast cooled and in the form of a strip or powder. Design/methodology/approach: The experiment performed on EN AB-AlSi12 hypoeutectic alloy. Aluminium and strontium was melted and next fast cooled to room temperature or cooled on a metal plate at rates about 200°C/s. This enabled to produce a different components, which were powdered immediately before adding to the alloy or used as a strip. The scope of this paper was to verify the cooling effect of Sr-Al modifiers and its form (powder or strip) on the microstructure and mechanical properties the AlSi12 alloy. Findings: The use of fast cooled Al-Sr alloy in the modification process and/or powdered alloy contributed to a further increase mechanical properties AlSi12 alloy. Research limitations/implications: The modification alloys with fast cooled powdered modifier are attractive for future research. Practical implications: Widely presented books and research papers on the silumin treatment give not a lot of contents on the effect treatment fast cooled alloy in the form of a strip or powder. Originality/value: The original value of the paper is comparison Sr and Al-Sr alloy modifiers slow and fast cooled and used as a powder or strip.

2

Structure Modelling Based on Percolation Theory

Trzaskowski W., Myszka D.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 3 spec.

71--74

EN

The paper discusses the possibility of application of percolation theory to model the structure of materials in a virtual space. The designed models were transferred to real space using modern incremental manufacturing techniques like 3D printing. Studies of model materials of this type based on percolation theory are expected to provide more accurate knowledge of the problem, which is extremely important from the point of view of the properties of most construction materials. Reference of percolation phenomena to materials science is more and more frequently done in the design of various types of composite materials, such as e.g. conductive composites. In this study, the percolation theory has been used to design in microscale an optimum material through model analysis done in macroscale. Since studies of percolation in polycrystalline materials are difficult, and there are also some technical limitations imposed on the evaluation done in a volume of material, this phenomenon is usually examined in a simplified manner, which means that it is reduced only to statistical analysis of potential percolation with determination of its threshold value. To generate a potential structure based on percolation theory, popular computer programmes for solid modelling were used. Real shapes were conferred to the designed models using a widely known technique of 3D printing. It allows the production of parts in ABS material. The subject of the present study combines modern design techniques with modern manufacturing techniques, relating both to the fundamentals of materials science. Today's software tools enable creating more complex solids, while their transfer to reality allows better understanding of dependencies that exist in the structure of materials. The originality of this study consists in the art of creating new construction materials with planned properties. The article offers a new approach to the capabilities of scheduling modern engineering materials with the help of percolation theory.

3

Methodology of high-speed steels design using the artificial intelligence tools

Sitek W.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 39, nr 2

115-160

EN

Purpose: The main goal of the research carried out was developing the design methodology for the new high-speed steels with the required properties, including hardness and fracture toughness, as the main properties guaranteeing the high durability and quality of tools made from them. It was decided that hardness and fracture toughness KIc are the criteria used during the high-speed steels design. Design/methodology/approach: In case of hardness, the statistical and neural network models were developed making computation possible of the high-speed steel hardness based solely on the steel chemical composition and its heat treatment parameters, i.e., austenitizing- and tempering temperatures. In this case results of own work on the effect of alloy elements on the secondary hardness effect were used, as well as data contained in catalogues and pertinent standards regarding the high-speed steels. In the second case - high-speed steels fracture toughness, the neural network model was developed, making it possible to compute the KIc factor based on the steel chemical composition and its heat treatment parameters. The developed material models were used for designing the chemical compositions if the new high-speed steel, demonstrating the desired properties, i.e., hardness and fracture toughness. Methodology was developed to this end, employing the evolutionary algorithms, multicriteria optimisation of the high-speed steels chemical composition. Findings: Results of the research carried out confirmed the assumption that using the data from catalogues and from standards is possible, which - would supplement the set of data indispensable to develop the assumed model - improving in this way its adequacy and versatility. Practical implications: Solutions presented in the work, based on using the adequate material models may feature an interesting alternative in designing of the new materials with the required properties. The practical aspect has to be noted, resulting form the developed models, which may successfully replace the above mentioned technological investigations, consisting in one time selection of the chemical composition and heat treatment parameters and experimental verification of the newly developed materials to check of its properties meet the requirements. Originality/value: The presented approach to new materials design, being the new materials design philosophy, assumes the maximum possible limitation of carrying out the indispensable experiments, to take advantage of the existing experimental knowledge resources in the form of databases and most effective computer science tools, including neural networks and evolutionary algorithms. It should be indicated that the materials science knowledge, pertaining oftentimes to the multi-aspect classic problems and described, or - rather - saved in the existing, broadly speaking, databases, features the invaluable source of information which may be used for discovery of the unknown so far relationships describing the material structure - properties relations.

4

Analysis of composite structural elements

Baier A., Majzner M.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 2

577--585

EN

Purpose: The themes of the study are composite structural components. For this purpose have been designed and built several research positions. Design/methodology/approach: Using different structural materials to build new device components requires multiple tests of the components. Research posts were designed in the advanced graphical program CAx Siemens NX 7.5. Analysed samples were made from the glass fibre, aramid and carbon of various weights. Due to the specific use of composite materials it focuses on the elements in the form of plates and flat bars. For the examination of experimental strain gauge technique was used bead, the force sensor and displacement sensor. The experimental methods were compared with computer simulation using the FEM. Findings: The aim of this study was to determine the basic material constants and a comparison of the experimental method and the method of computer simulation. Research limitations/implications: Change the number of layers and how to connect the laminate with the steel plate changes mechanical properties of the structural component. Practical implications: The ultimate result will be knowledge on the different forms of laminates, such as material properties, the stresses in all layers, strain and comparing the results obtained by two methods. Originality/value: The expected outcome of the study will be the composition and method of joining composite laminate with a steel plate to the possible application in the repair and construction of structural elements of freight wagons.

5

Artificial intelligence and virtual environment application for materials design methodology

Dobrzański L. A., Honysz R.

Archives of Materials Science and Engineering

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2010

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Vol. 45, nr 2

69-105

EN

Purpose: The purpose of this study is to develop a methodology for material design, enabling the selection of the chemical elements concentration, heat and plastic treatment conditions and geometrical dimensions to ensure the required mechanical properties of structural steels specified by the designer of machinery and equipment as the basis for the design of material components manufactured from these steels, by using a computational model developed with use of artificial intelligence methods and virtual environment. The model is designed to provide impact examinations of these factors on the mechanical properties of steel only in the computing environment. Design/methodology/approach: A virtual research environment built with use of computational model describing relationships between chemical composition, heat and plastic treatment conditions and product geometric dimensions and mechanical properties of the examined group of steel was developed and practical applied. This model enables the design of new structural steel by setting the values of mechanical properties based on material production descriptors and allows the selection of production descriptors on the basis of the mechanical properties without the need for additional tests or experimental studies in reality. Findings: Virtual computing environment allows full usage of the developed intelligent model of non-alloy and alloy structural steel properties and provides an easy, intuitive and user-friendly way to designate manufacturing descriptors and mechanical properties for products. Research limitations/implications:The proposed solutions allow the usage of developed virtual environment as a new medium in both, the scientific work performed remotely, as well as in education during classes. Practical implications: The new material design methodology has practical application in the development of materials and modelling of steel descriptors in aim to improve the mechanical properties and specific applications in the production of steel. Presented examples of computer aid in structural steel production showing a potential application possibility of this methodology to support the production of any group of engineering materials. Originality/value: The prediction possibility of the material mechanical properties is valuable for manufacturers and constructors. It ensures the customers quality requirements and brings also measurable financial advantages.

6

The analysis of the microstructure of steel S460NL1 in the conditions of thermo-mechanical treatment

Markowski J., Knapiński M., Koczurkiewicz B., Dyja H., Kawałek A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 25, nr 2

61-64

EN

Purpose: The application of new technologies requires, however, modern rolling mills. Indeed, in manufacturing plants of older types, strict compliance with the developed rolling regimes is not always feasible. Improving the mechanical properties in such cases in only possible by means of cooling. Design/methodology/approach: The tests carried out in this work was performed using the dilatometer DIL 805 A/D with the internal adapter for the plastic deformation of specimen. Findings: Diagrams of austenite decomposition during continuous cooling of steel have been developed, which are essential for the modernization of the technology of cooling plates of steel S460NL1. Dilatometric tests have been complemented with the results of metallographic examinations. Practical implications: The results of the researches carried out have allowed to project new technology of thermo-mechanical treatment for this steel grade. These results was used for the physical simulation of normalizing rolling process. Originality/value: By controlling cooling conditions, structures differing in mechanical properties can be obtained for the same material. Accurate understanding of a structure forming when different cooling conditions are applied enables the control of the process that assures intended structures and mechanical properties to be achieved.

7

New approach to study tribological properties of polymer materials. A case of car windshield wipers

Bielinski D. M., Glab P., Slusarski L.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 15, nr 1-2

71--78

EN

Purpose: Existing approach to tribology of polymer materials does not take into account their composition and structure. This paper presents the original analysis of friction characteristics, enabling an insight from the material engineering point of view. Design/methodology/approach: Apart friction also dissipation energy spectra have been analyzed. For transformation of friction fluctuations from the force into the frequency domain the FFT methodology has been applied. Parameters for evaluation of friction and wear have been proposed. Results of bench tests have been verified by examinations of wiper blades under conditions simulating real exploitation, adapting a system of car window cleaning. Power consumption by a driving engine has been monitored. Findings: Various kinds of modifications, influencing composition and structure of polymer materials have been studied. Ageing and wear resistance have been found to be the most important from the point of view of working properties of blades. They influence the efficiency of water removal from a car window. Research limitations/implications: Different blade designs have to be checked working under various conditions. Practical implications: A correlation between tribological properties and structure of polymer materials has to be taken into account at the stage of their compounding and processing. The proposed method for testing car windshield wiper blades is more appropriate than standards used so far, enabling quantitative assessment of products. Originality/value: The paper helps to understand materials engineering aspects of tribology. It is of potential value for producers of polymer parts.

8

Mechanical properties of silver matrix composites reinfroced with ceramic particles

Śleziona J., Wieczorek J., Dyzia M.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

165--168

EN

Purpose: Silver, silver alloys, as well as silver matrix based composites have been well known and applied in the electrotechnical and electronics industry for several decades. For many applications in electrotechnology, including electric contacts and brushes, unreinforced sliver alloys do not meet the requirements concerning mainly durability and wear resistance, first of all to tribological and electroerosive wear. These wear processes may be prevented by introducing to silver reinforcement particles and alloys. The target of the research included basic mechanical properties determination of the silver matrix composites reinforced with ceramic particles, manufactured with the use of suspension methods. Design/methodology/approach: In the presented paper the authors demonstrate possibilities of manufacturing of silver matrix composites on the way of casting technology utilization. Findings: The results of the research prove that applied suspension technology, based on introducing of agglomerated foundry alloy which is the carrier for reinforcement particles (SiC lub Al2O3) allows to produce in an effective and, what is important, in an economically attractive way, sliver alloys based composites. Research limitations/implications: The researches on the structure of manufactured composites and their mechanical properties that are presented in the paper prove the possibilities of mechanical mixing technology application for producing mechanical and stable connection between silver matrix and ceramic particles of aluminium oxide and silicon carbide. Originality/value: The manufacturing of this type of composites is based most of all on the utilization of powder metallurgy techniques. However the obtained results of the research prove that there is a possibility of silver matrix composites forming in the casting and plastic working processes. Extrusion process carried out in the hydraulic press KOBO has its favourably influence on ceramic reinforcement distribution, providing even distribution particles in matrix.

9

Friction materials operating under high stress, cryogenic temperature, and in vacuum

Piec Z., Nowacki J.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

15--24

EN

Purpose: of this paper was to select interfacial materials to provide friction coefficients less than μ= 0.3 which remain at this level during the machine lifetime. This material must withstand cycling motion under pressures up to 80 MPa, at 77 K, and in vacuum of 10-4 Pa. Design/methodology/approach: In the described work, experiments were conducted to determine the friction coefficient and the wear of several low friction materials. The test rig consists of a cryogenic sample holder enclosed in vacuum chamber installed into a servo-hydraulic test machine (M.T.S.). The friction coefficients have been measured cycling the samples (1,960 mm2) for about 38,000 cycles at normal pressure up to 80 MPa, sliding speed of 0.1 m/min, at 77 K, and under vacuum of 10-4 Pa. Findings: The Fiberslip B40 (woven multifilament of PTFE and glass) was selected as the best candidate material. It exhibited a friction coefficient of approximately μ = 0.22, and low wear rate was obtained. The maximum value of the friction coefficient is reached after few thousand cycles and then remains fairly constant. Research limitations/implications: Further studies on relative sliding/sticking at magnets interfaces as well as predicting the heating due to frictional forces are required. Practical implications: application of the selected material is possible in large friction interfaces operating under high compression stress, cryogenic temperature, and in vacuum one can meet in nuclear power stations. Originality/value: The experimental program verified the testing methodology, and techniques selected for measurement of coefficient of friction and wear for the friction pairs with large contact area, which are operated at temperature of 77 K, under high contact pressure and in vacuum.