Wyniki wyszukiwania - Biblioteka Nauki

1

Crushing behaviour of the PVC foam loaded with beaters of various shapes

100%

Bogusz P. , Gieleta R. , Stankiewicz M. , Konarzewski M.

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tom Vol. 12, no. 1

23--30

EN

Statistically, at least 50% of all injuries experienced by police officers in the line of duty are due to assaults with blunt objects. Therefore, vests used by the police should provide not only good ballistic resistance, but also good protection against such threats. Foamed materials are possible to be used for body protectors or inserts of protective clothes. The effects of dynamic impact with beaters of different shapes onto behaviour of polymeric foamed material were determined. There were used four types of beaters: flat, cylindrical, edgy and cornered. Strikes with blunt objects such as a flat board, baseball bat, edgy brick, pavement brick or a sharp stone, to which a protective ware can be subjected, were simulated. The impact load was applied to the rectangular specimens, made of polyvinyl chloride foam, with a usage of a drop hammer. Plots of force versus compression for all the tested samples were obtained and analysed. The effects of impacts with beaters of different shapes onto foamed material samples were presented. A shape of the blunt object significantly influences crushing behaviour of the foamed material. The impact energy of a flat beater is absorbed effectively on a short distance, since it is spread on a relatively large surface. The cylindrical and edgy beaters did not cause fragmentation of the samples, however, on the upper surfaces of the samples, permanent deformations mapping the beaters shapes as well as some cracks occurred. An impact with a sharp object, for example, a cornered beater is very difficult to be neutralized by the foam material, because it is cumulated on a small area.

2

Weryfikacja młotów udarnościowych w świetle wymagań normy ASTM E23 i procedury NIST

84%

Stankiewicz M. , Cęckiewicz S.

Dozór Techniczny

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2001

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tom z. 5

111--113

3

Identification of dynamic parameters in the context of diagnostics of steel tank with different level of liquid

84%

Rucka M. , Zielińska M.

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tom Vol. 16, No. 1

9--14

EN

The paper presents an experimental study to identify the dynamic parameters of a water-filled tank model. The experimental modal analysis approach involving the excitation at one point of the structure and acquisition of vibrations at selected points distributed over the tank surface allowed to determine the resonance frequencies, mode shapes and damping ratios. The main aim of the research was to examine the influence of the level of liquid on the modal parameters. The experimental study showed that the level of water in the tank had an important impact on the values of natural frequencies and damping ratios.

PL

Praca przedstawia badania doświadczalne przeprowadzone w celu identyfikacji parametrów dynamicznych modelu stalowego zbiornika do przechowywania cieczy. Jako techniki badawczej użyto eksperymentalnej analizy modalnej wywołując drgania obciążeniem impulsowym przyłożonym w jednym punkcie konstrukcji i mierząc przyspieszenia drgań w wybranych punktach rozłożonych na powierzchni zbiornika. W badaniach zidentyfikowano częstotliwości drgań własnych, postacie drgań własnych oraz współczynniki tłumienia. Głównym celem pracy była analiza wpływu poziomu cieczy na parametry modalne zbiornika. W pracy wykazano, że stopień napełnienia cieczą znacząco wpływa na częstotliwości drgań własnych oraz współczynniki tłumienia.

4

Resistance of bimetallic plates on the dynamic cracking

84%

Rydz D. , Stradomski G. , Wierzba A.

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tom Vol. 62, nr 1

19--24

EN

Purpose: In this paper was set the aim to determine energy breaking during the impact test. As part of the work, the strength of the bimetallic plates exposed to cracking as a result of dynamic bending forces from the two layers as well as across the connection area of bimetallic plate was analyzed. Design/methodology/approach: To determine the technological properties of this group of materials are specially intended standards but none of them do not determine how to test the impact energy of such group of materials. In this paper are presented results of such test, with macro and microscopic analysis of fracture and merging area. Findings: Based on the results of laboratory tests can be concluded that the most exposed, X6CrNiMoTi17-12-2 - PN355NH bimetallic material, to the dynamic breaking are samples arranged according to variant a3 (i.e.. across the height of the bimetal layers merging zone). Research limitations/implications: This work aimed to highlight the problem of the bimetallic material resistance to cracking according to different initialization direction. Originality/value: The study attempts to identify how the material must be placed in the finished product to reduce as far as possible its exposure to crack. An important element in the correct determination of the impact of the material according to PN-EN ISO 148-1:2010 is the appropriate cutting of notch. For this purpose, a single-pass cutter guarantying to obtain uniform parameters of fracture initiation was developed.

5

Zagrożenia związane z ochroną odgromową stadionu piłkarskiego : wyzwania naukowe w procesie projektowania sieci i instalacji elektrycznych

67%

Koźbiał T.

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tom nr 3

60--63

PL

W pracy przedstawiono zagadnienia problematyczne ochrony odgromowej pojawiające się w trakcie procesu projektowania. Zwrócono uwagę na zagadnienia, które poprzez wyliczenia matematyczne nie dają jednoznacznych rozwiązań. Wówczas należy posiłkować się empirycznym rozwiązaniem problemu. W pracy streszczono zatem problematykę projektową wraz z wynikami badań przeprowadzonych w laboratorium.

EN

The paper presents issues problematic lightning protection arise during the design process. Attention was paid to the issues, which, through mathematical calculations do not provide clear solutions. Then you should make use empirical solution to the problem. The paper summarized therefore the problems of design, together with the results of research carried out in the laboratory.