Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ postaci konstrukcyjnej zespołów korpusowych obrabiarek na rozkłady nacisków w połączeniach prowadnicowych oraz sztywność układu nośnego

100%

Biedunkiewicz W. , Kuligowski G.

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tom Vol. 19, Nr 2

147-160

PL

W artykule przeanalizowano wpływ postaci konstrukcyjnej (grubość ścianek oraz sposób rozmieszczenia żeber usztywniających) zespołu korpusowego na jego sztywność oraz rozkład nacisków w połączeniu prowadnicowym stół-sanie stołu frezarki FYD-32. W tym zakresie analizowano również wpływ mocowania przedmiotu obrabianego do stołu frezarki. Oszacowano wpływ masy zespołu korpusowego na wartości maksymalne i rozkłady nacisków w połączeniu prowadnicowym.

EN

The influence of the machine body shape (the wall thickness of the body and positions of reinforcing ribs) on the stiffness of the machine as well as load distribution in the guideway connection between the cross-slide and the table of milling machine FYD-32 were analysed in the paper. Also the influence of forces fixing the workpiece to the table was analysed. The influence of construction mass on maximum values and on the form of the pressure distribution in guideway connection was estimated.

2

Ocena rozkładu obciążeń stóp kobiet ciężarnych na podłoże podczas chodu

86%

Swinarska D.

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tom z. 12

75--80

PL

Ciąża jest stanem fizjologicznym, podczas którego zachodzi wiele przemian biochemicznych oraz biomechanicznych. Zmiany te znacząco wpływają na kondycję fizyczną kobiety ciężarnej. Powiększający się brzuch oraz zmiany temu towarzyszące znacząco wpływają na komfort poruszania się kobiety. Fizjologiczne zmiany zachodzące w czasie ciąży mogą być przyczyną nieprawidłowego ustawiania stopy, co może powodować bóle pleców i kończyn dolnych. Celem niniejszej pracy jest ocena rozkładu obciążeń stóp kobiet ciężarnych na podłoże podczas chodu.

EN

Pregnancy is a very special period in women's life. Anatomical, biomechanical and hormonal changes are characteristic for this period and may have impact on incorrect posture or affect musculoskeletal balance. Twenty-one pregnant women were recruited in three semesters pregnancy. Measurements included in-shoe plantar pressure distribution. Results suggest higher plantar pressure magnitude in all trimesters pregnancy. Especially, in the third trimester the changes in magnitude of pressure distribution were observe under the forefoot, medial arch and heel (p<0,05).

3

Pressing Speed, Specific Pressure and Mechanical Properties of Aluminium Cast

86%

Gaspar S. , Pasko J.

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tom Vol. 16, iss. 2

45--50

EN

Recent research in the process of aluminum alloy die castings production, which is nowadays deeply implemented into the rapidly growing automobile, shipping and aircraft industries, is aimed at increasing the useful qualitative properties of the die casting in order to obtain its high mechanical properties at acceptable economic cost. Problem of technological factors of high pressure die casting has been a subject of worldwide research (EU, US, Japan, etc.). The final performance properties of die castings are subjected to a large number of technological factors. The main technological factors of high pressure die casting are as follows: plunger pressing speed, specific (increase) pressure, mold temperature as well as alloy temperature. The contribution discusses the impact of the plunger pressing speed and specific (increase) pressure on the mechanical properties of the casting aluminum alloy.

4

Wpływ wybranych parametrów eksploatacyjnych na pola powierzchni śladów opon na podłożu twardym

86%

Walczyk M. , Walczyk J.

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tom R. 6, nr 1

23-30

PL

Pomiary pola powierzchni śladów przedniego i tylnego koła ciągnika MF 235 wykonano dla 3 różnych ciśnień w oponach i 5 obciążeń. Zastosowana metoda wideo-komputerowa pozwala na dokładne określenei mierzonych powierzchni dla różnych warunków eksploatacyjnych. Przedstawione wykresy oraz sformułowane równania regresji wskazują, iż powierzchnia śladów wzrasta proporcjonalnie do obciążeń i ciśnienia.

EN

The contact area of tracks left by front and rear tyred wheels of the MF235 tractor were measured for 3 different tyre pressure and 5 loads. The video-computer measuring method used in research enabled exact determination of measured contact areas at different operation conditions. The diagrams presented and formulated regression equations showed that the area of tyred wheel tracks increased pr

5

Thermoelastic analysis of pressurized hollow spherical vessels with arbitrary radial non-homogeneity

72%

Rani P. , Singh K.

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tom Vol. 26, no. 4

192--205

EN

In this study, a general analysis of one dimensional steady-state thermal stresses of a functionally graded hollow spherical vessel with spherical isotropy and spherically transversely isotropy is presented with material properties of arbitrary radial non-homogeneity. The material properties may arbitrarily vary as continuous or piecewise functions. The boundary value problem associated with a thermo-elastic problem is converted to an integral equation. Radial and tangential thermal stress components distribution can be determined numerically by solving the resulting equation. The influence of the gradient variation of the material properties on the thermal stresses is investigated and the numerical results are presented graphically.

6

Ciśnienie i docisk oraz szerokość strefy kontaktu między cylindrami i wałkami w drukującej maszynie offsetowej – przegląd literatury

72%

Jurkiewicz A. , Pyr'yev Y.

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2016

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tom Vol. 8

9--27

EN

The printing literature provides different values of pressure between cylinders in the printing unit and between rollers in the ink unit of the offset printing machine. Very often there is no information on whether a given value of pressure is maximum or average. Another frequent problem referred to in the printing literature is that authors do not reveal the source of theorems, equations or other important information. This article includes a set of values collected for pressure, line pressure, press clamping and the contact zone width that have been presented by other authors in their specific articles and books. It also includes definitions of pressure, line pressure, press clamping, indentation of blanket and metric clamping. In addition, the article briefly presents findings of the experimental research related to the contact zone between cylinders and rollers was carried out in the printing unit and in the ink unit until present. This article also gives publication references which provide for different equations concerned with the clamping force of cylinders, their compression or indentation, the contact zone width and the impact the specific stress-strain has on blankets.

7

The Effects of Pressure During the Crystallization on Properties of the AlSi12 Alloy

72%

Pastirčák R. , Ščury J. , Moravec J.

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tom Vol. 17, iss. 3

103--106

EN

The paper deals with the impact of technological parameters on the mechanical properties and microstructure in AlSi12 alloy using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. From the experiments we can conclude that operating pressure of 100 MPa is sufficient to influence the structural characteristics of the alloy AlSi12. The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. At a pressure of 100 MPa was increased of tensile strength on average of 20%. At a pressure of 150 MPa was increased of tensile strength on average of 30%. During the experiment it was also observed, that increasing difference between the casting temperature and the mold temperature leads to increase of mechanical properties.

8

Assessment of distribution of plantar pressures and foot characteristics during walking in pregnant women

72%

Mikeska O. , Gimunová M. , Zvonař M.

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2019

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tom Vol. 21, no. 3

49--56

EN

The main purpose of this research was to analyse the distribution of plantar pressures and foot characteristics during walking between weeks 27 and 36 of pregnancy. The secondary purpose was to test the effect of the customized orthopaedic shoes that were worn by the experimental group. Methods: Pregnant women (n = 73) were divided into 2 groups, control group (n = 38) and experimental group (n = 35) which completed 5 gait trials on a walkway (1.55m) at a self-selected velocity of gait, where force, pressure and remaining foot characteristics were sampled and displayed by Novel database pro m (version 25.3.24). Results: Analysis of foot characteristics did not reveal important changes. Analysis of the distribution of plantar pressures revealed few changes in the pre- and post-measurement of the experimental and control groups between weeks 27 and 36 of pregnancy. In the last measurement, there is a significant increase of peak pressure only in the midfoot area of the left foot (151.1 ± 41.2 kPa) and in the hindfoot area of the right foot (346.3 ± 104.1) of the experimental group. The control group exhibits similar pressure development for both of foot. Conclusions: Monitored parameters demonstrated in certain areas notably development of force and contact area. Results of foot characteristics did not reveal a significant changes. As both groups registered similar values in certain areas in a comparison of pre/post measurement characteristics, the influence of specific orthopaedic shoes cannot be conclusively demonstrated in the experimental group.

9

Nacisk wywierany przez glebę w wybranych miejscach powierzchni roboczej lemiesza płużnego podczas uprawy gleby pylastej

72%

Kostencki P. , Borowiak P.

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tom Vol. 56, nr 2

94-97

PL

Ustalono w trakcie uprawy gleby pylastej wartość nacisku wywieranego przez glebę w czterech miejscach powierzchni natarcia lemiesza płużnego, przy czterech prędkościach zabiegu (5,21, 6,52, 7,33 i 7,78 kmźh-1). W warunkach badań występowało duże zróżnicowanie oddziaływania gleby na powierzchnię lemiesza. Największe wartości nacisku występowały w miejscu pomiarowym zlokalizowanym na dziobie lemiesza (od 123,9 do 191,2 kPa), a najmniejsze - w początkowym obszarze części trapezowej lemiesza (od 1,4 do 3,7 kPa). W miejscu pomiarowym zlokalizowanym na dziobie zwiększaniu prędkości orki odpowiadał wyraźny wzrost wartości nacisku gleby (o około 14, 23 i 54% wraz ze zwiększeniem prędkości orki odpowiednio o około 25; 41 i 49%). W pozostałych miejscach pomiarowych nie stwierdzono jednoznacznych prawidłowości w tym zakresie.

EN

The values of pressure exerted by the soil in four points of attack surface at four plough velocities (5.21, 6.52, 7.33 and 7.78 kmźh-1) during cultivation of silty soil were stated. Under test conditions a large diversification of soil impact on ploughshare surface had a place. The highest values were in the measurement point localized at the tip of share (from 123.9 to 191.2 kPa) and the lowest - within the initial area of trapezoidal part of ploughshare (from 1.4 to 3.7 kPa). In the measurement point localized at the ploughshare tip an increase of plough speed responded to an important increase of soil pressure (approximately 14; 23 and 54% along with increasing plough speed of circa 25; 41 and 49%). In remaining measurement points distinct regularities have not been found.

10

Effect of Technological Parameters on the AlSi12 Alloy Microstructure During Crystallization Under Pressure

72%

Pastirčák R.

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tom Vol. 17, iss. 2

75--78

EN

The paper deals with the impact of technological parameters on the heat transfer coefficient and microstructure in AlSi12 alloy using squeeze casting technology. The casting with crystallization under pressure was used, specifically direct squeeze casting method. The goal was to affect crystallization by pressure with a value 100 and 150 MPa. The pressure applied to the melt causes a significant increase of the coefficient of heat transfer between the melt and the mold. There is an increase in heat flow by approximately 50% and the heat transfer coefficient of up to 100 fold, depending on the casting conditions. The change in cooling rate influences the morphology of the silicon particles and intermetallic phases. A change of excluded needles to a rod-shaped geometries with significantly shorter length occurs when used gravity casting method. By using the pressure of 150 MPa during the crystallization process, in the structure can be observed an irregular silica particles, but the size does not exceed 25 microns.

11

Wpływ nacisku, prędkości ślizgania i twardości na zużycie przy suchym tarciu stali na obręcze kół kolejowych

58%

Witaszek M. , Witaszek K.

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tom nr 4

267-274

PL

W artykule przedstawiono wyniki badań zużycia wybranych trzech stali węglowych. Badania przeprowadzono na zmodyfikowanym stanowisku Timkena, przy suchym tarciu ślizgowym. Wyniki badań pozwoliły na określenie zależności intensywności zużywania badanych stali od wybranych parametrów charakteryzujących własności materiału (twardość stali) i warunki współpracy (nacisk i prędkość ślizgania). Zależności te opisano za pomocą równania wykładniczego. Wykorzystano je wraz z wynikami badań metalograficznych do analizy merytorycznej otrzymanych wyników badań zużycia.

EN

In this article, wear test results of three carbon steels (B6, C54 and C55) are presented. These tests have been performed on a modified Timken wear-testing machine in dry sliding conditions. To obtain an initial point contact (like in wheel – rail system), two cylinders with perpendicular axes have been used as elements of the tested pair. One of them had a motionless specimen, and the second one had a counter-specimen rotated around its axis. Volume loss and apparent contact area vs. load, sliding speed, and sliding distance were determined. On the basis of these results, the linear wear rate and contact pressure were calculated. Results of these calculations have been utilised to determine the influence of pressure, sliding speed, and material hardness on the wear rate of the tested steels. These influences have been mathematically described with an exponential function, which was used to analyse the wear behaviour of the researched materials. Optical microscopic observations of worn surfaces were carried out to study wear mechanisms.

12

The identification and quantification of factors determining soil compaction caused by single agricultural tyres on a field

58%

Błaszkiewicz Z.

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tom Vol. 63, nr 4

24--30

EN

In field research, the influence of factors determining soil compaction in an arable layer caused by agricultural tyres during the first pass was determined. The factors were the following: a normal load of tyres resulting from a static load of a tractor axle, dimensions of tyres: diameter, and width as well as pressure determined by a simplified method. The research was conducted on soil cultivated with ploughing – Luvisol loamy sand. It was generally shown that tyre load was the main determinant of soil compressing. A bigger tyre load leads to higher soil density only in a deeper arable layer. Higher soil density caused by bigger tyres is the result of their higher load rather than their higher external diameter. Wider driving tyres of a similar diameter caused only slightly lower soil density mainly at a greater depth in an arable layer. Pressure determined by a simplified method is not correlated with soil density changed by tyres. A soil density increment caused by the investigated tyres was from approx. 30% to approx. 65% of the whole growth potential.

PL

W badaniach polowych określono wpływ czynników determinujących zgęszczanie gleby powodowane w warstwie ornej oponami rolniczymi podczas pierwszego przejazdu. Czynnikami były: obciążenie normalne opon wynikające ze statycznych obciążeń osi ciągników, wymiary opon: średnica i szerokość oraz nacisk wyznaczony metodą uproszczoną. Badania dokonano na glebie Luvisol spulchnionej orką – piasek gliniasty. Wykazano ogólnie, że obciążenie opon jest głównym determinantem zgęszczania gleby. Wyższe obciążenia opon powodują większe gęstości gleby tylko na większej głębokości warstwy uprawnej. Większe gęstości gleby powodowane oponami większymi są rezultatem bardziej ich większego obciążenia niż większej średnicy zewnętrznej. Szersze opony napędowe o podobnej średnicy powodują tylko nieco mniejsze gęstości gleby głównie na większej głębokości warstwy uprawnej. Nacisk wyznaczany metodą uproszczoną nie jest skorelowany z gęstością gleby zmienianą oponami. Spowodowany przyrost gęstości gleby badanymi oponami wynosi od około 30 do około 65% całego potencjału wzrostu.