Wyniki wyszukiwania - Biblioteka Nauki

1

Strain state and strength of acetabular component of total hip-joint endoprosthesis.

100%

Jira J. , Jirova J. , Micka M.

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1999

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tom Vol. 1, nr 2

79-83

EN

The paper deals with the new cementless acetabular cup of the Beznoska type. This cup is made of 1 mm thick titanium covering and polyethylene inner layer. Good initil implant stability is ensured by titanium projections on the outer surface. The purpose of the experimental research was to measure strains at selected points on the outer surface of the artificial cup. A computation model enables us to analyse the strain state generated not only by concentrated load, but also by uniformly distributed load or by varing load. The aim of the research was to analyse the strain state of the acetabular component and to find out the limit loading for assesment of strength and the loss of stability of the cup structure.

2

Experimental modeling of large scale gas fuel injector for IC piston engines

84%

Bocian P. , Wojciechowski J. , Rychter T.

Research Bulletin / Warsaw University of Technology, Institute of Aeronautics and Applied Mechanics

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1998

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tom nr 8

81-84

EN

Supplying 1C piston engines with gaseous fuels is one of well known approaches to reduce the content of polluting components in exhaust gases. One of methods for gaseous fuel supply considered is a high-pressure direct gas injection, which is currently studied in a number of laboratories. The successful application of this method requires the proper organisation of the combustion system and particularly - the careful treatment of the gas injection process and its mixing with the surrounding air. Very important is also the location of the choice of the ignition point in order to assure repeatable combustion initiation. The mixing process strongly depends on the shape and the direction of the injected gas which, in turn, depends on the injector tip geometry. The main objective of the presented experimental analysis is to determine the best of the gaseous fuel single-nozzle injector, would be able to assure the proper mixing of the gas with air. The investigations were performed under "cold" conditions with the use of the model gas injector in geometrical scale 10:1. The conventional-like form of the nozzle was with annular gas flow area created by the gap between the pintle and the nozzle wall. The element as well as experimental conditions be easily changed in the wide range This made it possible to select jet geometry (the form, length and convergence angle of the pintle, nozzle outlet and divergence angle etc.). It also for the longitudinal vorticity control: from axial flow to the flow with strong velocity component, or any form. The injection gas pressure was 0.5 MPa, which allowed for the rough simulation engine conditions, for a large spectrum of flow geometries (pintle, nozzle, vorticity). The CO2 was as a working medium. There were used: flow visualisation by schlieren method, the hot-wire technique for determination of velocity especially designed hot-wire probe and the infrared energy apparatus to measure - respectively - the high and low or very low injected gas local concentration. Some interesting injector configurations were chosen for posterior measurements of velocity field in the free circular jet of gas past the injector. The study allowed for drawing the optimal schema of the single-nozzle gas fuel injector, which has become the base for the combustion tests in a normal-scale injection system.

3

Modelling of semi-liquid aluminium flow in extrusion

84%

Skorulski G. , Piwnik J.

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2007

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tom Vol. 7, iss. 2

31-36

EN

Experimental modeling using substitute materials is usually a simply way to obtain satisfacted results. This kind of experiment is characterizing by low cost. The significant results may be quickly applying using theory of probability. The way of modelling the deformation mechanisms during extrusion of aluminium alloys in semi - liquid phase, the way of preparing samples and experimental technique has been analysed in the following work. On the ground of received results (i.e. registrations of consecutive process steps) the grid of the flow velocity vectors on a flat sample surface was done. It allowed to draw conclusions which one of the basic deformation mechanisms is dominant in particular stage of the process. The technique of measurement has been shown as well. Experiments are made using plasticine and rape oil as a substiute materials. Some kind of different variants have been investigated. To ensure that such model experiments provide useful information it is essential to select model materials and prepare samples that would exhibit (preferably at room temperature) similar behaviour and similar deformation mechanisms as those present during the actual deformation process of aluminium alloys in a semi-liquid state. In particular the FLS, SS and PDS mechanisms should be adequately reproduced.

4

Modelling of semi-liquid aluminium flow in extrusion with temperature effect

84%

Skorulski G. , Piwnik J.

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2007

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tom Vol. 7, iss. 2

25-30

EN

During thixoforming, when the material is in the semi-liquid state, it exhibits thixotropic properties, i.e. the unsupported material remains stiff and holds its shape so it can be readily handled, but rapidly thins and flows like a liquid when sheared. It is this behaviour that is the key to the thixoforming process where material flows as a semi-liquid slurry into a die, as in conventional die-casting. Modelling the influence of the temperature distribution heterogeneity on deformation mechanisms during extrusion of the aluminium alloys in semi-liquid phase, the way of preparing samples and experimental technique has been analysed in the following work. There were made an analysis on the influence of the possible temperature distribution in recipient obtained during heating it on the extrusion process proceedings. The conclusions concerning stability of the process and appearing during it deformation mechanisms had been drawn on the ground of the received results. The plasticine and rape oil have been choosen as a substitute materials. Some kind of different variants have been investigated used a special experimental stand. The results of the tests presented below prove that the proposed technique can provide valuable insight into the material flow during deformation of aluminium alloys in the semi-liquid state and thus can give some guidance concerning the desirable temperature distribution within the workpiece.