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1

Geodezyjny monitoring deformacji i przemieszczeń zapory grawitacyjnej

Bryś Henryk

Przegląd Geodezyjny

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2024

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R. 96, nr 3

4--6

PL

Betonowa zapora wodna ulega statycznym i dynamicznym obciążeniom, których efektem jest występowanie trwałych i sprężystych odkształceń oraz przemieszczeń przestrzennych. Opisano przyczyny i skutki przemieszczeń, geometrię deformacji oraz ich wpływ na bezpieczeństwo eksploatacyjne obiektów hydrotechnicznych. Przedstawiono telemetryczną metodykę geodezyjnych pomiarów kontrolnych sekcji zapory w okresie jej wieloletniej eksploatacji oraz wybrane obrazy największych katastrof budowli piętrzących na świecie.

EN

A concrete dam is subject to static and dynamic loads, the existence of which is permanent, and elastic deformations and spatial displacements. The effects and effects of displacements, the geometry of deformations and the impact on the operational safety of hydrotechnical devices are described. Telemetric geodetic methods of monitoring the control of dam sections in the environment of its operation and selected images of the disaster occurring in the world were presented.

2

Geophysical imprint of mining-induced rock mass deformation in the area of construction disaster in Bytom (Poland)

Kotyrba Andrzej, Kortas Łukasz

Journal of Sustainable Mining

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2023

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Vol. 22. iss. 3

169--184

EN

The paper presents the analysis of the results of geophysical surveys conducted in the mining area located in Bytom - Karb (USCB, Poland) in the aspect of identifying the causes of significant damage to the complex of inhabited tenement houses which occurred in 2011. The surveys were carried out by microgravimetric and GPR methods. The construction disaster was caused by the exploitation of one of the hard coal seams at a depth of about 800 m along the mining longwall running underneath the settlement. The terrain deformation parameters exceeded the forecasted values, and in several places discontinuities took linear forms along the diagonal directions to the front lines of the longwall. In addition to the sliding movement, the rotational movement appeared in the ground. As a consequence of spatially complex ground movements, some buildings suffered significant damage. The extent of the damage turned out to be catastrophic and immediate relocation of the inhabitants and demolition of the buildings became necessary. The article is an attempt to explain the nature and the causes of excessive terrain deformations in relation to those modeled on the basis of analysis and interpretation of geophysical data from the current measurements as well as archival maps and geological and mining cartography data.

3

Influence of Defects on Deformation Behavior of High-Pressure Die-Casting Magnesium Alloys

Braszczyńska-Malik Katarzyna

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

10--14

EN

The results of investigations of defects in AME-series magnesium alloys produced by the high-pressure die-casting method are presented. The analyzed magnesium alloys contain about 5 wt% aluminum and 1-5 wt% rare earth elements introduced in the form of mischmetal. The casts were fabricated using a regular type cold-chamber high-pressure die-casting machine with a 3.2 MN locking force. The same surfaces of the casts were analyzed before and after the three-point bending test in order to determine the influence of the gas and shrinkage porosity on the deformation behavior of the alloys. The obtained results revealed that the most dangerous for the cast elements is the shrinkage porosity, especially stretched in the direction perpendicular to the that of the tensile stress action. Additionally, the influence (Mg) solid solution and its interaction on the cracking process was described [alpha]  of deformation twins arise in the dendrites of the primary.

4

Milimetry z satelity

Królikowski Jerzy

Geodeta : magazyn geoinformacyjny

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2022

|

nr 6

42--43

5

Działalność Komisji do spraw Ochrony Powierzchni przy Wyższym Urzędzie Górniczym

Białożyt Tomasz, Kowalski Andrzej, Wojtacha Piotr

Bezpieczeństwo Pracy i Ochrona Środowiska w Górnictwie

|

2022

|

nr 1

2--9

PL

W artykule przedstawiono syntetycznie działalność Komisji ds. Ochrony Powierzchni przy Wyższym Urzędzie Górniczym w okresie od 2012 do 2021 r., w tym kilku wniosków opiniowanych kilkukrotnie lub cyklicznie dotyczących: eksploatacji w filarach ochronnych dla śródmieścia Bytomia i dla Lubina oraz na terenie górniczym w Marklowicach, a także zasad stosowania Górniczej Skali Intensywności Sejsmicznej - GSIS. Szczególnym problemem dyskutowanym na posiedzeniach komisji w 2012 r. były zasady prognozowania wpływów i szkód górniczych przez przedsiębiorców górniczych. Geneza tej dyskusji miała związek z eksploatacją górniczą i szkodami, jakie wystąpiły w 2011 r. w dzielnicy Karb w Bytomiu.

EN

The activities of the Commission for Surface Protection at the State Mining Authority are regulated by an ordinance [10] and its composition by a decision [1] of the President of the State Mining Authority. The tasks of the commission include issuing opinions on the state of public safety related to mineral exploitation, and in particular on the evaluation of mining exploitation programs and issuing opinions on: mining and construction prophylaxis in mining areas, methods of mine liquidation and directions of development of post-mining areas along with evaluation of their suitability for development. In addition, the Committee initiates research on the impact of mining activities on the environment and buildings and gives its opinion on draft regulations, Polish Standards and instructions on the above issues. In the years 2012-2020, the Committee considered 24 motions, of which the most frequent were motions concerning mining operations near Bytom and Marklowice, in the protective pillar of Lubin, and those concerning the mining seismic intensity scale. A particular problem discussed at the commission's meeting was a letter on shortcomings in forecasting the impact of the planned exploitation by mining enterprises. The list of applications reviewed in 2012-2020 by the commission (Table 1) shows that their number is gradually decreasing, which is due to, among others, restructuring of the hard coal mining industry, which resulted in termination of exploitation under the center of Bytom and also Wirek district in Ruda Śląska.

6

Detection of periodic displacements of shell structures with edges using spline surfaces, meshes and point clouds

Lenda Grzegorz, Abrachamowicz Katarzyna

Reports on Geodesy and Geoinformatics

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2021

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Vol. 112

27--33

EN

This research paper tackles the problem of determining displacements of complex-shaped shell structures, measured periodically using laser scanning. Point clouds obtained during different measurement epochs can be compared with each other directly or they can be converted into continuous models in the form of a triangle mesh or smooth patches (spline functions). The accuracy of the direct comparison of point clouds depends on the scanning density, while the accuracy of comparing the point cloud to the model depends on approximation errors that are formed during its creation. Modelling using triangle meshes flattens the local structure of the object compared to the spline model. However, if the shell has edges in its structure, their exact representation by spline models is impossible due to the undulations of functions along them. Edges can also be distorted by the mesh model by their chamfering with transverse triangles. These types of surface modelling errors can lead to the generation of pseudo-deformation of the structure, which is difficult to distinguish from real deformation. In order to assess the possibility of correct determination of deformation using the above-mentioned methods, laser scanning of a complex shell structure in two epochs was performed. Then, modelling and comparison of the results of periodic measurements were carried out. As a result of the research, advantages and disadvantages of each method were identified. It was noticed that none of the methods made it possible to correctly represent all deformations while suppressing pseudo-deformation. However, the combination of their best qualities made it possible to determine the actual deformation of the structure.

7

Comparison of methods of monitoring structure deformations based on tests of a column-plate slab

Nykiel Damian

Budownictwo i Architektura

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2021

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Vol. 20, no 4

5--16

EN

This work includes a comparison of the methods of monitoring the deformations of a structure on the example of a flat plate slab test. Classic ESG (electrofusion strain gauges) and modern DFOS (distributed fiber optic sensors) were compared. During the research, both types of sensors were used on some of the reinforcing bars. The study aims to indicate the differences between the compared monitoring methods, both in terms of the obtained results and their utility values.

8

Metodyka wyznaczania odkształceń mostu suwnicowego

Bryś Henryk, Ćmielewski Kazimierz

Przegląd Geodezyjny

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2020

|

R. 92, nr 8

16--18

PL

W pracy przedstawiono zintegrowaną technologię wyznaczania geometrii odkształcenia mostu suwnicy w stanie statycznym z wykorzystaniem precyzyjnych tachimetrów elektronicznych o prospektowych parametrach technicznych S_α=0,15 mgon oraz S_D=0,5+1 ppm. Wyznaczone analitycznie parametry geometryczne (kąty i długości), pozwalają na precyzyjną interdyscyplinarną interpretację zaistniałych w czasie i przestrzeni zmian odkształceń.

EN

The paper presents the integrated technology for determining the geometry of the crane bridge deformation in a static state using precise electronic total stations with prospective technical parameters Sα = 0.15 mgon and SD = 0.5 + 1 ppm. Analytically determined geometrical parameters (angles and lengths) allow for precise interdisciplinary interpretation of deformations occurring in time and space.

9

The Main Features of Hydraulic Fill Soils and River Dnieper Alluvial Deposits in the Kyiv Region

Rashchenko Andriy, Dyptan Tatyana, Malyshev Oleg

Civil and Environmental Engineering Reports

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2020

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Vol. 30, no. 4

72--89

EN

The features of the tectonic structure together with the geological and geomorphological zoning of Kyiv city are highlighted in the article. Particular attention is paid to the floodplains of the Dnieper River, which were formed by the hydraulic fill method. As a rule, such sites were created for new constructions and were quickly built up with low rise buildings, the bases of which were made using such hydraulic soils. Completed engineering-geological investigations of sites after hydraulic filling and observation of the base deformation over time allowed setting of the basic regularity and rules for construction on such territories. The ongoing development of the city has also covered these territories, where high-rise buildings, shopping malls, and other buildings are actively being built, and the loads from these must be transferred to reliable bases.

10

The improvement of the rheological model for controlling the stress-strain state and humidity in the materials of museum pieces: zener thermodiffusion model for capillary-porous bodies

Dovhaliuk V. B., Chovnyuk Y. V., Ivanov E. A., Shyshyna M. O.

Zeszyty Naukowe. Quality. Production. Improvement

|

2019

|

No. 2 (11)

51--71

EN

The drying and humidifying processes of capillary-porous (colloid) bodies occur during the production of various materials for the consumer goods industry, building materials, storage of museum pieces, etc. It is known that the main linkage forms of the moisture and colloid capillary-porous bodies (CCPBs), namely adsorption, capillary condensation and capillary linkage of the free moisture in the cavities of the above bodies, depend on the temperature and relative humidity of drying/humidifying agent. It means that the CCPBs behave in a peculiar way depending on the temperature and humidity fields. The problems of CCPBs drying (or humidifying) process include the issue of the heat and humidity transfer both in the middle of the body and in the boundary layer on the interface of phases “body (object of drying/humidifying process) – environment”. The drying/humidifying intensity is at its maximum when the possibilities of the heat and mass transfer in the boundary layer correspond to the possibilities of moisture and heat moving inside the object of drying/humidifying process. The properties of the CCPB as material possessing specific elastic-viscous properties are described within the framework of O.Y. Ishlinskiy - O.R. Rzhanitsin generalized elastic-viscous body theory. A comparative analysis of the above mentioned CCPB’s properties from the point of view of Zener thermodiffusion theory is conducted. The mechanism of moisture transferring from the CCPBs’ central layers (as object of drying/humidifying process) up to their surfaces is developed. The theoretical researches examined the drying/humidifying phenomena for both the entire volume of the CCPB and three structural directions. It is noted that drying/humidifying of CCPBs is a complicated heat and mass transfer process accompanied by mechanisms of molecular nature determining the kinetics of their running. It is shown that the appropriate equations’ solution of molecular-molar heat and moisture transfer under the appropriate boundary (limit) conditions allows to describe the fields, i.e. the distribution of transfer potentials (the temperature and moisture content in the CCPB as object of drying/humidifying) at any time of the appropriate process. The drying/humidifying curves (“drying/humidifying rate versus CCPB humidity”) and the temperature curves (“CCPB temperatures versus CCPB humidity”) reflect the nature of the drying/humidifying processes. In the framework of the proposed generalized rheological model of CCPB, the residual deformations of bodies for various load types (the time-varying stress applied to the CCPB) is estimated.

11

Estimation of the coefficient of static friction by means of numerical analysis

Biernacki Krzysztof

Tribologia

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2019

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nr 5

19--24

EN

The friction coefficient is one of the most important tribological parameters. The value of this coefficient may be determined with the use of various methods. The friction coefficient proves to be of significance when assembling the elements of the gear pump body WPZ-80A. The bodies of these pumps consist of three elements and are manufactured in two configurations of materials. These materials are aluminium alloy AK-20 and grey iron ZL-250. Friction interaction between the elements of the pump body ensures its stable operation under load. Research so far has focused on numerical analyses for pump bodies at a set friction coefficient. This article presents a reverse analysis, i.e. an estimation of the friction coefficient value based on the WPZ-80A pump body effort. To this end, numerical analysis based on the Finite Element Method (FEM) has been used. The analysis was based on the fact that the value of friction coefficient significantly influences deformation distribution in the WPZ-80A pump body. The analysis was performed on an already constructed pump body of known geometry with no structural modifications. The value of the static friction coefficient was estimated by observing the scale of deformations in the pump body under a set load. Although the main focus was on analysing the mechanism behind the deformations, an attempt was also made at extending the application scope for FEM. Depending on the measurement method, friction coefficient values may significantly differ. Despite the differences, the values resulting from numerical analysis should not differ from the range of values obtained with other methods of analysis. The range of friction coefficient values was determined on the basis of literature studies. As a result, it was possible to verify FEM in a field different than classic effort analysis. The aim of the work presented in this article was to obtain information on tribological properties with the use of numerical analysis.

PL

Współczynnik tarcia jest jednym z najważniejszych parametrów tribologicznych. Wartość tego współczynnika jest określana na różne sposoby. Duże znaczenie ma współczynnik tarcia dla montażu elementów zespołu korpusu pompy zębatej WPZ-80A. Korpusy tych pomp są trzyczęściowe i wykonywane są w dwóch konfiguracjach materiałowych. Jako materiały użyte zostały stop Aluminium AK-20 oraz żeliwo szare ZL-250. Wzajemne tarcie pomiędzy elementami zespołu korpusu pompy gwarantuje jej stabilną pracę pod obciążeniem. Jak do tej pory prowadzono analizy numeryczne dla korpusów pomp przy zadanym współczynniku tarcia. Postanowiono wykonać analizę odwrotną, czyli oszacować wartość współczynnika tarcia na podstawie wytężenia zespołu korpusu pompy WPZ-80A. Cel ten postanowiono zrealizować za pomocą analizy numerycznej z użyciem metody elementów skończonych (MES). Analizę oparto na fakcie, że wartość współczynnika tarcia ma bardzo istotny wpływ na rozkład deformacji dla zespołu korpusu pompy WPZ-80A. Do analizy numerycznej przyjęto istniejący już zespół korpusu pompy o ustalonej geometrii, w którym nie wprowadzano zmian konstrukcyjnych. Wartość współczynnika tarcia oszacowywano na podstawie obserwacji wielkości deformacji dla zespołu korpusu pod zadanym obciążeniem. Oprócz tego, iż głównie skupiono się na analizie mechanizmu tych deformacji, to podjęto też próbę rozszerzenia zakresu użycia MES. Z literatury wynika, że w zależności od metody pomiaru uzyskane wartości współczynników tarcia często bardzo różnią się pomiędzy sobą. Pomimo tych różnic to wartości uzyskane z analizy numerycznej nie powinny odbiegać od zakresu wartości uzyskanych z innych metod badawczych. Dzięki temu sprawdzono MES na innym polu niż klasyczna analiza wytężenia. Celem pracy jest zatem uzyskanie informacji na temat właściwości tribologicznych z pomocą analizy numerycznej.

12

Investigation of the mechanism of moisture absorption in colloidal museum materials in order to improve the safety of exhibits and improve the hygiene of museum rooms

Dovhaliuk Volodymyr, Ujma Adam, Chovniuk Yurii

System Safety : Human - Technical Facility - Environment

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2019

|

Vol. 1, nr 1

805--809

EN

Moisture sorption is one of the most important destruction factors for colloidal capillary-porous exhibits in museums (painting, clothing etc.), which is dependent on microclimate in museum rooms. The analysis of moisture sorption properties, kinetics of sorption and swelling of textile museum exhibits is carried out. Isotherms of desorption of viscose and woollen yarns and fabrics of different density (and threads of them) are identical. The analysis of the isotherms of fabrics of various fibre cloths and threads of them shows that they all are similar in shape to the curves and have the form typical for leading capillary-porous bodies. The hysteresis loop for almost all tissues is observed throughout the range of relative humidity of the medium. In this work, the characteristics of the hysteresis loop (area, limited by it, length of the loop), which are of informational significance in the description of the processes of isothermal sorption-desorption of the materials mentioned above, are indicated. The research results allow optimizing of microclimate control in museum rooms for elimination of destruction of exhibits, improve the safety of storage and ensure the hygiene of the air indoor environmental.

13

Badanie wytężenia wybranych elementów słupa energetycznego SSF typu W4 ONIIz(–2)/24

Czarniawski T.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2018

|

Z. 24 (174)

42-49

PL

Celem opracowania było określenie rzeczywistych odkształceń i naprężeń w elementach słupa elektroenergetycznego SSF typu W4 ONIIz(–2)/24, poddanego badaniu niszczącemu na poligonie badawczym w Żilinie na Słowacji. Badanie było wykonane 17 IX 2009 roku. Oprogramowanie, jak również dobór i montaż mierników tensometrycznych przygotowano dla ustalonego kierunku naprężeń w badanych fragmentach słupa, co było niezgodne z rzeczywistym rozkładem naprężeń. Ze względu na niewłaściwy montaż i dobór mierników tensometrycznych wyniki uzyskane nie odpowiadały rzeczywistym odkształceniom. Analizując otrzymane wyniki, można stwierdzić, że słup został zaprojektowany poprawnie, wyczerpanie nośności nastąpiło zgodnie z przewidywaniami, wystąpiła utrata lokalnej stateczności przy podstawie słupa. Mimo zastosowania niewłaściwych mierników tensometrycznych osiągnięto częściowo założony cel badań.

EN

An intense growth of the demand for the electric energy is forcing the demand for the electric energy contractors for transmission lines into applying more and more of structural high–tech solutions. It is also regarding the structure of overhead power grids so as poles. In order to draw up determining real deformations and stresses in elements was of electrical power engineering SSF pole of the type W4 ONIIz (–2)/24 subjected to the examination destroying on the research training ground in Żilina on Slovakia. The software as well as the selection and the assembly of measuring equipment they prepared for known direction of stresses in studied fragments of the pole what was at variance with the real schedule of stresses. The examination was performed 17 IX of 2009. On account of the improper assembly and the assortment of gauges electrical resistors achieved results based on the measurement system didn't correspond to real deformations. Based on obtained data determining real stresses and deformations of the pole in chosen elements inspected was a purpose of the article. Exploiting the property applied of measures electrical resistors, and knowledge about the durability of materials they caused the transformation of had results. Analysing received results it is possible to state that the pole was designed correctly, using the carrying capacity up took place as expected, loss of the local sedateness appeared by the base of the pylon that the pole was designed correctly, using the carrying capacity up took place as expected, loss of the local sedateness appeared by the base of the pylon In spite of applying wrong gauges electrical resistors a partly established purpose of research was achieved. With fundamental lack which made the full determination impossible measuring effort in points of fixing trusses of the pole was market paucity of applied gauges, resulting from organizational mistakes at the assembly of sphygmomanometers. Achieved results are confirming the correctness of the modelling of the coating of the pole in places of fixing trusses supporting energy wires of the pole.

14

Predicting Deformations in Aluminum Overlap Joint Produced by FSW Process

Adamus K.

Archives of Metallurgy and Materials

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2018

|

Vol. 63, iss. 1

13--18

EN

The goal of the work was to develop model of Friction Stir Welding process that predicts deformations of the joined components based on the specified heat input. In the analyzed case two overlapping aluminum sheets were welded. The top sheet had the thickness of 1.0 and the bottom sheet had the thickness of 0.6 mm. The model used Finite Element Method. Thermal mechanical coupled formulation was chosen. The heat input was estimated based on the temperature measurements in the selected points along the welding line. Heat source was calibrated to match the numerically calculated and experimentally measured thermal cycles. The calculated field of displacements in direction perpendicular to the sheet surface was selected to compare the numerical results with the actual geometry of welded sheets. The model achieved the satisfying accuracy with respect to the qualitative description of the deformations.

15

Metoda oceny deformacji obudowy wyrobiska korytarzowego

Majcherczyk T., Bednarek Ł.

Przegląd Górniczy

|

2017

|

T. 73, nr 10

44--50

PL

Zwiększająca się co roku głębokość eksploatacji pokładów węgla kamiennego skutkuje wykonaniem wyrobisk na coraz większych głębokościach, przekraczających często 1000 m. Dlatego istotne jest prowadzenie badań w wyrobiskach na dużych głębokościach, aby możliwe było sformułowanie wniosków na temat zachowania się górotworu i jego współpracy z obudową. Niniejszy artykuł prezentuje identyfikację parametrów i czynników wpływających na stateczność obudowy w wyrobiskach korytarzowych oraz metodykę prognozowania obciążeń i deformacji obudowy wyrobisk korytarzowych w kopalniach węgla kamiennego. Zaproponowana prognoza obciążenia i deformacji obudowy wykorzystuje zależności dotyczące: głębokości wyrobiska względem głębokości krytycznej oraz jakości górotworu określonej na podstawie różnicy wskaźnika litologii stropu WL i współczynnika intensywności spękań n.

EN

Every year coal seams are exploited at greater depths, thus excavations need to be driven deeper and deeper, often going below 1000 m. Therefore, it is important to conduct the investigations at workings at great depths in order to formulate conclusions about the behavior of the rock mass and its interaction with the ground support. This paper presents the identification of the parameters and factors influencing the stability of ground support in the excavations and a methodology of forecasting the load strains and deformations of ground support in excavations of coal mines. The proposed forecast of the load strain and deformation of support system uses dependencies related to: the depth of the excavation in relation to the critical depth and the quality of the rock mass determined on the basis of the difference of the WL roof lithology index and the n crack intensity factor.

16

Investigation of stress-strain state of a workpiece at gauge burnishing of its holes

Václav Š., Sivtsev N. S., Senderská K.

Advances in Science and Technology. Research Journal

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2017

|

Vol. 11, no 3

211--222

EN

The application of finite-element method when investigating the stress-strain state of a workpiece exposed to the gauge burnishing under the conditions of nonzero friction is considered. The mathematical model of the workpiece surface-plastic deformation during burnishing, algorithm and computational results of stresses and deformations are given.

17

Properties of numerical solution of the deformation and stability problem in shallow conical shells under external pressure

Krasovsky V., Karasev A.

Roads and Bridges - Drogi i Mosty

|

2016

|

Vol. 15, no. 2

117--135

EN

The paper presents an analysis of a numerical solution in the ANSYS software to three problems related to determination of deformations and stability of closed shallow conical shells under external pressure: 1) linear (bifurcation) problem of determining the critical pressure; 2) geometrically non-linear problem of shell deformation and buckling to determine the limit pressure using axisymmetric finite elements (FE); 3) solution to the same problem as set out in 2, yet using 4-node shell elements. The solutions presented in the paper concern the stationary state of a simply supported and fixed shell. Shallow conical shells are applied as load bearing and protective elements of bridge structures.

PL

W pracy wykonano analizę rozwiązania numerycznego w środowisku oprogramowania ANSYS trzech zadań wyznaczenia deformacji i stateczności zamkniętych małowyniosłych powłok stożkowych, poddanych działaniu ciśnienia zewnętrznego: 1) zadania liniowego (bifurkacyjnego) określenia wartości krytycznej ciśnienia; 2) geometrycznie nieliniowego zadania deformacji i wyboczenia powłoki oraz wyznaczenia ciśnienia granicznego przy wykorzystaniu osiowo-symetrycznych elementów skończonych (ES); 3) rozwiązania zadania 2, lecz przy wykorzystaniu czterowęzłowych elementów powłokowych. Przedstawiono rozwiązania stanu stacjonarnego powłoki swobodnie podpartej i utwierdzonej. Małowyniosłe powłoki stożkowe wykorzystywane są jako elementy nośne i ochronne konstrukcji mostowych.

18

Optymalizacja kształtu wypraski poprzez analizę rozkładu temperatury na powierzchni wypraski z wykorzystaniem pomiarów termowizyjnych

Humienny R., Postawa P., Stachowiak T.

Przetwórstwo Tworzyw

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2016

|

T. 22, Nr 5 (173)

421--427

PL

Poprawnie zaprojektowany układ termostatowania jest jednym głównym czynników efektywnego ochładzania wyprasek wtryskowych w gnieździe formy a tym samym efektywności całości procesu wtryskiwania. Ponadto równomierne ochładzanie poszczególnych obszarów wypraski w formie powoduje ograniczenie do minimum naprężeń własnych i deformacji wypraski po jej wyjęciu z formy. Ze względu na funkcje wypraski nie zawsze możliwe jest zapewnienie jej równomiernej grubości ścianki co ułatwia uzyskanie równomiernego ochładzania w procesie wtryskiwania. Wypraski od których oczekiwana jest duża sztywność bardzo często są mocno użebrowane, co pozwala oszczędzić materiał i uzyskać równomierną grubość ścianki, jednak powoduje dużą kumulację ciepła a tym samym konieczność większej intensywności jego odbioru z formy.

EN

Properly designed system of temperature control is one of the guarantors of effective cooling of injection moldings in the mold cavity and thus the efficiency of the whole injection molding process. Furthermore uniform cooling of specific areas in the compact form reduces to a minimum the stresses and deformation of the molding after removal from the mold. Due to the function of the compact it is not always possible to ensure the uniform wall thickness which facilitates the uniform cooling in the injection molding process. Moldings of which is expected to be high rigidity are of ten ribbed, thus saving material and achieve a uniform wall thickness, however, results in a large accumulation of heat and needs more effective mold cooling systems.

19

Błędy wykonawcze i zniszczenia nawierzchni bitumicznych

Sochacki T.

Magazyn Autostrady

|

2016

|

Nr 4

50--55

PL

Nawierzchnie bitumiczne powinny być zaprojektowane i wykonane tak, aby wytrzymały bez większych uszkodzeń co najmniej kilkanaście lat. W praktyce jednak często zniszczenia pojawiają się już po kilku latach eksploatacji, a nawet wcześniej. W wielu przypadkach wina leży przede wszystkim po stronie wykonawców, którzy nie przykładają należytej uwagi do wszystkich etapów wbudowania warstw bitumicznych.

EN

The article discusses the selected damages in bituminous pavements, such as plastic deformations (ruts), ravelling of pavement material, cracks at the edge of the road and fatigue cracking. We also discuss the phenomenon of reflective cracking in stiff structures.

20

Closed system of coupling effects in generalized thermo-elastoplasticity

Śloderbach Z.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 2

461--483

EN

In this paper, the field equations of the generalized coupled thermoplasticity theory are derived using the postulates of classical thermodynamics of irreversible processses. Using the Legendre transformations two new thermodynamics potentials P and S depending upon internal thermodynamic forces Π are introduced. The most general form for all the thermodynamics potentials are assumed instead of the usually used additive form. Due to this assumption, it is possible to describe all the effects of thermomechanical couples and also the elastic-plastic coupling effects observed in such materials as rocks, soils, concretes and in some metalic materials. In this paper not only the usual postulate of existence of a dissipation qupotential (the Gyarmati postulate) is used to derive the velocity equation. The plastic flow constitutive equations have the character of non-associated flow laws even when the Gyarmati postulate is assumed. In general formulation, the plastic strain rate tensor is normal to the surface of the generalized function of plastic flow defined in the the space of internal thermodynamic forces Π but is not normal to the yield surface. However, in general formulation and after the use the Gyarmati postulate, the direction of the sum of the plastic strain rate tensor and the coupled elastic strain rate tensor is normal to the yield surface.