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Structure, physical properties and fractal characteristics of the arc PVD coatings deposited onto the ceramics materials

Kwaśny W.

Archives of Computational Materials Science and Surface Engineering

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2010

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Vol. 2, nr 4

189-200

EN

Purpose: The goal of the presented study was to develop a methodology giving a possibility to predict functional properties of coatings obtained in the arc PVD process onto the ceramics materials, based on fractal and multi-fractal quantities describing their surface. Design/methodology/approach: Effect of process type and deposition conditions on structure and shape of surface, as well as mechanical and service properties of the obtained coatings were determined. Methodology and detailed description of coatings topography obtained in the PVD process on ceramics materials, including use of the fractal- and multi-fractal geometry based on images obtained on the atomic forces microscope were worked out. Relationships between fractal- and multi-fractal quantities and their mechanical and service properties were determined. Findings: The investigation results confirmed the feasibility to predict the service properties defined in the cutting ability test for coatings obtained in the arc PVD process, based on the surface fractal dimension Ds value for their surface topography. Research limitations/implications: The geometrical features description of surfaces of the coatings obtained in the PVD processes. Practical implications: Determining significant quantitative correlations between fractal quantities defining coatings' surfaces, as well as their service and/or mechanical properties provides the opportunity to predict their end-user properties. Originality/value: Fractal and multifractal analysis gives possibility to characterise the extent of irregularities of the analysed surface in the quantitative way.

2

Selected methods of modelling of polymer during the injection moulding process

Koszkul J., Nabiałek J.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

253-259

EN

Purpose: The purpose of present paper was presenting chosen results of investigations on polymer flow during mould cavity filling phase of injection process. Advancement in the simulation software make possible to model more phenomena occurring during polymer flow in injection molding process. Design/methodology/approach: The results of computer simulations of injection process have been compared with the results of video recording for the plastic flow during filling phase. For the simulating investigations a professional computer software Moldflow Plastics Insight ver. 6.1. has been employed. A specialized injection mould which enables observation and registration of the plastic flow during processing has been employed. The mould enables direct monitoring of the course of phenomena inside the mould cavity in two planes. To record the flow, a digital video camera has been employed. As an example the issue of stream flow (jeting) have been described. Findings: The results of the investigations enabled documenting of specific phenomena which occur during plastics or their composites injection process. The registered video sequences have been compared with the results of numerical calculations and then it was estimated to what degree the computer simulation of injection process may be useful in practice. Research limitations/implications: The camera enabled to register the flows with the rate of 25 fps. This reduced the scope of the investigations, since at higher plastic flow speeds the registered image became less clear. The investigations were performed on a wide scale, however, only chosen results have been presented. Practical implications: Deep understanding of the phenomena which occur during filling the injection mould may lead to more effective design of the processing tools and shortening of the time for implementation and production time. Originality/value: The transparent sight-glasses have been used, made of a material called ZerodurŽ which is characterized by the coefficient of thermal expansion close to zero.

3

Validation of computer models of an artificial hip joint

Okrajni J., Plaza M., Ziemba S.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 5

305-308

EN

Purpose: Problems of the modelling of the surgical cement behaviour during implantation have been presented in the paper. The purpose was to validate the FEM model describing the temperature fields in the bone during the surgery treatment. Design/methodology/approach: The physical laboratory modelling has been used to perform validation of the model that makes it possible to predict the temperature influence on the bone tissue during polymerization process. Findings: Due to its non-invasive nature, the computer models' validation method applied in the study seems to be the right solution for the research on surgical procedures of endoprosthesis implantation. However, a particular emphasis should be placed on a correct selection of thermophysical properties of the designed laboratory models. Relying on the calculations and research results, similar local values of maximum temperatures were obtained. Practical implications: The computer modelling methods presented in the paper together with the analytical approach are of great importance to both forecasting the implants' behaviour during a surgical procedure and in their operational conditions, as well as in the selection and modification process of surgical cements' material properties. The analysis carried out makes it possible to determine the location of zones most threatened with an adverse effect of an elevated temperature. They are located in the vicinity of the top of the endoprosthesis stem. Originality/value: The work presents the own method of validation of the FEM model used for heat flow modelling.