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1

Mechanical properties of chromium steel drills in the context of durability and safety of use

Bałaga Zbigniew, Opydo Michał, Dudek Agata, Lisiecka Barbara

System Safety : Human - Technical Facility - Environment

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2024

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Vol. 6, iss. 1

311--319

EN

This article presents the research results on the influence of heat treatment of chromium steel, used in the production of drill bits, on their mechanical properties and operational safety. The analyses revealed that the steel used in manufacturing the studied drill bit underwent hardening and tempering processes, which affected its structure and hardness. The presence of tempered martensite and manganese sulfides was observed, which, although not having a destructive impact on the steel's properties, may limit the formation of undesirable iron sulfides. Additionally, a layer with reduced hardness was identified on the working surface of the drill bit, suggesting the possibility of tool overheating during operation. During the tool's use, complex mechanical stresses, such as torsional, compressive, and bending stresses, may accumulate in areas prone to damage, especially at the interface between the tooth and the drill bit shank. The article emphasizes the importance of proper tool usage, including adjusting pressure and drilling angle and maintaining optimal operational conditions to ensure safety and durability. The research findings aim to enhance workplace safety and improve the performance of cutting tools in materials engineering.

2

Analysis of the tensile process energy consumption of coniferous wood exposed to seawater

Roman Kamil

Inżynieria Materiałowa

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2024

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Vol. 45, nr 1

12--22

EN

The woodworking industry is notorious for its use of wood, despite the availability of laminates and other sub-materials. In the marine industry, it is used in the construction of boats, yachts, and other marine structures. In this study, tensile properties of coniferous species were examined as a function of salty water exposure for different periods of time. In coniferous woods such as pine, larch, and spruce, wood strength is determined by its ability to undergo tension and compression over time. Different mechanical strengths of wood soaked in water with a salinity of 7‰ were determined. According to the data, the salinity value corresponds to the average salinity on the Polish Baltic coast. As a result of the experiments, it can be concluded that the applied medium directly affects the species and structure of the wood. The parameters of wood are affected differently by soaking depending on its species. The tensile strength of pine was enhanced after incubation in seawater. By soaking other specimens in saltwater for a certain period of time, the study demonstrated different strength parameters. Wood exposed to salty water was compared to native wood in this study to determine its tensile properties. In conclusion, soaking wood in a certain medium significantly alters its mechanical properties. Analysis showed that all samples had an average strength between 5.4MPa and 102.04MPa. There was a slight difference in strength results for each wood species over time despite subsequent treatment cycles.

PL

Zbadano właściwości rozciągające gatunków drzew iglastych w funkcji ekspozycji na słoną wodę przez różne okresy czasu. Określono różne wytrzymałości mechaniczne drewna nasączonego wodą o zasoleniu 7‰, które odpowiadało średniemu zasoleniu na polskim wybrzeżu Bałtyku. Stwierdzono, że zastosowane medium wpływa bezpośrednio na gatunek i strukturę drewna. Nasączanie wpływa w różny sposób na parametry drewna w zależności od jego gatunku. Wytrzymałość na rozciąganie sosny została zwiększona po inkubacji w wodzie morskiej. W badaniach wykazano odmienne parametry wytrzymałościowe, mocząc różne próbki w słonej wodzie przez pewien czas. Drewno wystawione na działanie słonej wody porównano z drewnem naturalnym, aby określić jego właściwości rozciągające. Namoczenie drewna w określonym medium znacząco zmienia jego właściwości mechaniczne. Analiza wykazała, że wszystkie próbki miały średnią wytrzymałość 5,4–102,04 MPa. Zaobserwowano niewielką różnicę w wynikach wytrzymałości dla każdego gatunku drewna w czasie, pomimo kolejnych cykli obróbki.

3

Thermal stresses associated with a thermosensitive multilayered disc analysed due to point heating

Srinivas V. B., Manthena V. R., Warbhe S. D., Kedar G. D., Lamba Navneet Kumar

International Journal of Applied Mechanics and Engineering

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2024

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Vol. 29, no. 2

118--137

EN

In this paper, analytical solutions are presented for temperature and thermal behavior of a thermosensitive multilayered annular disc due to point heat source. Convective heating is applied to both the innermost and outermost layers. The nonlinearity of the thermal diffusivity equation is dealt using Kirchhoff’s transformation technique. A finite integral transform in the form of Bessel’s function is used to deal with the radial variable r. Fourier transform and angular eigen functions are also used to solve the thermal diffusivity equation. Deflection, resultant forces, shearing forces, resultant moments and thermal stresses are obtained. A mathematical representation is formulated for a 3-layered disc, with the inner, middle and outer layers composed of copper, zinc and aluminum respectively. The results are depicted graphically.

4

Dependance of Membrane Stress on the Supports Geometry of the Barrel-Vault Shaped Tensile Membrane Structures

Milošević Vuk, Marchwiński Janusz, Kopyłow Ołeksij

Builder

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2024

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R.28, nr 5

46--49

EN

Membrane stress under load depends on several factors in tensile membrane structures. This research aims to find out how geometry of the supports affects the membrane stress in barrel-vault shaped membranes. A numerical experiment is conducted and the parameters of the support geometry are varied in order to understand their influence on the maximal membrane stress under load. Three load types are applied to numerical models and maximal stresses are monitored. The results show how change of the size of the base of the structure and the change of the height of the supporting arches influence the stress. The results can be used in design of tensile membrane structures, but also in assessing the possibilities for integration with other systems, such as photovoltaics.

PL

Naprężenia membranowe w rozciągliwych konstrukcjach membranowych powstające pod wpływem obciążenia zależą od kilku czynników. Celem badań jest sprawdzenie, jak geometria podpór wpływa na naprężenia membranowe w membranach kolebkowych. Aby poznać wpływ obciążeń na maksymalne naprężenie membrany, przeprowadzono eksperyment numeryczny, zmieniając parametry geometrii podpory. Do modeli numerycznych stosowane są trzy typy obciążeń i monitorowane są maksymalne naprężenia. Wyniki pokazują, jak zmiana wielkości podstawy konstrukcji i zmiana wysokości łuków nośnych wpływają na naprężenia. Wyniki można wykorzystać przy projektowaniu rozciągliwych konstrukcji membranowych, ale także przy ocenie możliwości integracji z innymi systemami, takimi jak fotowoltaika.

5

Analysis of Friction Forces in the Process of Forming Moulding Mass

Szewczyk Marek, Szwajka Krzysztof

Tribologia

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2023

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nr 1

65--75

EN

Accelerated wear of the moulds' inner surface used in forming loose masses contributes to its frequent replacement or regeneration. This wear is indirectly influenced by the high pressure accompanying the compaction process, but the main cause of accelerated wear is the friction that occurs between the die and the compacted medium. Knowing that the value of the internal pressure in the moulded medium changes with the change of the distance from the punch, in order to properly understand the phenomena accompanying the friction that occurs in the mould during the pressing process, its characteristics must be determined. The paper analyses the distribution of forming pressure inside the mould during the compaction of high-silica sand. The deformation on the die surface was measured using strain gauges, and x-ray tomography was used to visualise the compaction of high-silica sand during the compaction process. The usefulness of an indirect method for measuring the friction coefficient based on the analysis of die deformation has been demonstrated.

PL

Przyśpieszone zużycie powierzchni wewnętrznej form, stosowanych w procesach formowania mas sypkich, przyczynia się do częstej jej wymiany lub regeneracji. Na zużycie to pośrednio wpływa wysokie ciśnienie towarzyszące procesowi zagęszczania, ale główną przyczyną mającą wpływ na przyspieszone zużycie jest tarcie, które występuje pomiędzy matrycą a medium zagęszczanym. Wiedząc, że wartość ciśnienia wewnętrznego w medium formowanym zmienia się wraz ze zmianą odległości od stempla, dla prawidłowego zrozumienia zjawisk towarzyszących tarciu, które zachodzi w formie podczas procesu prasowania, należy więc określić jego charakterystykę. W pracy przeanalizowano rozkład ciśnienia formującego wewnątrz formy podczas zagęszczania piasku wysokokrzemionkowego. Odkształcenie na powierzchni matrycy mierzono za pomocą tensometrów. W celu zobrazowania zagęszczania piasku wysokokrzemionkowego podczas procesu zagęszczania zastosowano tomografię rentgenowską. Wykazano przydatność zastosowania pośredniej metody do pomiaru współczynnika tarcia opartej na analizie odkształceń matrycy.

6

Strength of a bent sandwich beam with clamped ends

Kustosz Joanna, Magnucki Krzysztof, Goliwąs Damian

Pojazdy Szynowe

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2023

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Nr 1-2

3--7

EN

The subject of the work is a symmetrical sandwich beam with clamped ends under uniformly distributed load. The system of two equilibrium equations, formulated taking into account the literature, was solved analytically. The function of the shear effect and the maximum deflection of the beam were determined. The stress state at the clamped end of the beam is described in detail. The significant influence of the shear effect on the normal stresses in the outer layers of the beam near the clamped end was indicated. Exemplary calculations were made for the adopted family of beams. Moreover, the numerical FEM model of the beam was developed and calculations were made for this adopted family of beams. A comparative analysis of the obtained results was carried out.

7

Destruction of high pressure vessels in pipeline structures

Rahimova Mahluqa S., Abbasov Sakit H., Ahmadov Alihikmat A.

Nafta-Gaz

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2023

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R. 79, nr 5

360--364

EN

The article indicates that engineering design criteria do not provide measures to prevent failures; this is evidenced by the occurrence of many accidents. Fracture prevention criteria should be derived from the principles of fracture mechanics, what should be developed further. However, the current concepts of fracture mechanics, when properly applied, provide an opportunity to ensure the reliability of the structure or organise the supervision of expensive structures to ensure their safe operation. These methods of preventing damage can be divided into two large groups: 1) checking for the formation of cracks and 2) monitoring their development. Both methods are based on similar principles; it would be easier to explain them with examples. To ensure the safe operation of the pressure vessel used in the reactor, the maximum allowable initial crack size should be known. The size of this crack should not expand to a critical point during the entire operation of the reactor. Knowing how the process of crack propagation proceeds and how the structure behaves during failure, it is possible to calculate the critical size of the defect and, based on this, calculate the maximum allowable size of the crack at the beginning of operation. Proper inspection of the new vessel will eliminate the possibility of shells that are larger than the original size. Checking for the presence of cracks, and determining their rate of growth during operation, presents significant difficulties. Therefore, checks should be avoided during operation. If the fracture and crack growth calculations, as well as the initial checks, are carried out correctly, then checks made during operation are an optional extra. However, in practice, such checks should still be performed. For vessels used in reactors, remote observation of crack growth using ultrasonic waves is a particularly useful method. If a crack is found, measures must be taken to either repair or replace the partially destroyed element.

PL

W artykule wskazano, że kryteria na etapie tworzenia projektu technicznego często nie uwzględniają środków zapobiegających awariom, o czym świadczą liczne wypadki przy pracy. Kryteria zapobiegania powstawaniu pęknięć powinny być wyprowadzane z zasad mechaniki powstawania pęknięć, co wymaga dalszego rozwoju. Jednak obecne koncepcje mechaniki powstawania pęknięć, przy ich właściwym stosowaniu, dają możliwość zapewnienia niezawodności konstrukcji lub zorganizowania nadzoru nad kosztownymi konstrukcjami, aby zapewnić ich bezpieczną eksploatację. Te metody zapobiegania uszkodzeniom można podzielić na dwie duże grupy: 1) kontrola pod kątem powstawania pęknięć, 2) monitorowanie ich wzrostu. Obie metody opierają się na podobnych zasadach i lepiej wyjaśnić je na przykładach. W celu zapewnienia bezpiecznej eksploatacji zbiornika ciśnieniowego używanego w reaktorze należy znać maksymalną dopuszczalną początkową wielkość pęknięcia. Wielkość takiego pęknięcia nie powinna wzrosnąć do wartości krytycznej przez cały czas pracy reaktora. Wiedząc, jak przebiega proces propagacji pęknięć i jak zachowuje się konstrukcja podczas uszkodzenia, można obliczyć krytyczną wielkość uszkodzenia i na tej podstawie obliczyć maksymalną dopuszczalną wielkość pęknięcia na początku eksploatacji. Prawidłowa kontrola nowego zbiornika wyeliminuje możliwość wystąpienia pęknięć większych niż o pierwotnym rozmiarze. Kontrole pod kątem obecności pęknięć i określenie tempa ich wzrostu podczas pracy wiążą się z dużymi trudnościami. Dlatego należy unikać wykonywania kontroli podczas pracy. Jeżeli obliczenia dotyczące pęknięć i ich wzrostu, jak również kontrole wstępne, zostały przeprowadzone prawidłowo, to kontrole podczas eksploatacji byłyby opcjonalnym dodatkiem. Jednak w praktyce takie kontrole i tak są przeprowadzane. W przypadku zbiorników używanych w reaktorach szczególnie przydatną metodą jest zdalna obserwacja wzrostu pęknięć za pomocą fal ultradźwiękowych. W przypadku stwierdzenia pęknięcia należy podjąć działania w celu naprawy lub wymiany częściowo zniszczonego elementu.

8

Numerical Analysis of the Strength Properties of the Movable Connection

Dziwis Amadeusz, Tański Tomasz, Sroka Marek, Śliwa Agata, Dziwis Rafał

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 4

1585--1590

EN

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised.

9

Jak zakres ugięcia sprężyn krążkowych wpływa na ich wydajność

Leckfor John

Napędy i Sterowanie

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2022

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R. 24, nr 4

24--25

PL

Sprężyny krążkowe są podkładkami w kształcie stożka zaprojektowanymi tak, aby działały w przewidywalny i powtarzalny sposób. Można stosować je do przykładania obciążenia statycznego, gdy jest ono niemal stałe, lub w sytuacjach dynamicznych, gdy jest do nich wielokrotnie przykładane i usuwane. Zrozumienie, w jaki sposób charakterystyka obciążenia wpływa na ich działanie, jest kluczowe dla prawidłowego zaprojektowania systemu wykorzystującego sprężyny krążkowe.

10

Research of stress concentration at closely placed holes in wing bearing area in anisotropic plater

Maksymovych Marta, Lazorko Aleksandr, Maksymovych Olesia, Dmitriiev Oleh

Diagnostyka

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2022

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Vol. 23, No. 4

art. no. 2022302

EN

In this article effective approach of the study of high-stress concentration at closely placed holes in wing bearing area (in anisotropic plates) is proposed. It is based on the boundary integral equation method with the additional use of the asymptotic method. The simplicity, precision of the approach and the stability of the solution are illustrated in the calculation of stresses in the plate with a circular hole, an elliptical hole, elongated holes, a plate with two closely spaced elliptical holes.

11

Numerical analysis of interfacial debonding of metal/ceramic bimaterial using FEM

Ramdoum Sara, Serier Boualem, Feo Luciano

Composites Theory and Practice

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2022

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R. 22, nr 3

130--134

EN

The bimaterials applied in various fields of industry consist mainly of ceramics and metal. Their damage is mainly due to the presence of residual stresses generated during their manufacture. The damaged area is closely related to the high production temperature. The aim of this study is to analyze the effect of these factors on the behavior of an interfacial and subinterfacial crack in the volume of alumina material. This behavior is studied in terms of variation of the stress intensity factor (SIF) in Modes I, II and III. A study by means of the finite element method (FEM) was carried out. This work demonstrates that the risk of sudden propagation of these cracks is all the more probable when the bimaterial is produced at high temperatures. The elastoplastic behavior of the metal considerably minimizes this risk by plasticizing the metal, which allows strong relaxation of the residual stresses.

12

Zasady prawidłowego doboru ogranicznika naprężeń do gwintowanego insertu w złożeniu elementów z tworzywa sztucznego

Jones Christie L.

Napędy i Sterowanie

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2021

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R. 23, nr 6

44--45

PL

W zastosowaniach, w których element współpracujący jest również wykonany z tworzywa sztucznego, ogranicznik naprężeń jest niezbędny, aby uniknąć pełzania materiału lub osłabienia naprężeń w elemencie współpracującym w wyniku zmniejszenia sił tarcia w połączeniu gwintowanym.

13

Tests on the Mechanical Properties of Polymers in the Aspect of an Attempt to Determine the Parameters of the Mooney-Rivlin Hyperelastic Model

Śliwa-Wieczorek Klaudia, Zając Bogusław, Kozik Tomasz

Civil and Environmental Engineering Reports

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2020

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Vol. 30, no. 2

1--14

EN

The article presents testing of the mechanical properties of SIKA® polymer adhesives of the type PBM, PMM, PM, and PSM in the aspect of an attempt to determine the parameters of the Mooney-Rivlin hyperelastic model. The article contains a literature review on developed models for hyperelastic materials as well as a description of the author’s own results obtained in monaxial tensile and monaxial compression tests conducted on oars and cylindrical samples, respectively. Furthermore, the results of modeling of Mooney-Rivlin hyperelastic model parameters are shown in relation to the value of average parameters for polymers after both a week and a month-and-a-half of ripening.

14

Assessment of the early-age strains and stresses in 2D restrained self-stressed members

Tur Viktar V., Sannikava Volha H.

Budownictwo i Architektura

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2020

|

Vol. 19, no 4

85--94

EN

The paper presents the implementation of the modified strains development model (MSDM) for the two-way restrained self-stressed members such as expansive concrete-filled steel tubes and expansive concrete plane elements with arbitrary orthogonal reinforcement. The analytical approach allows defining the restrained strains and stresses in any 2D restraint conditions by following the iterative procedures and accounting for the elastic-plastic behaviour of expansive concrete at an early age. The consistency of the proposed method was confirmed by assessing the experimental results of the two series of the expansive concrete-filled steel tubes and three series of the expansive concrete plane members with mesh reinforcement in the centre of gravity.

15

Effect of Steel Cord Tension During the Lapping on Steel Cord Straightness After Lapping

Knapiński Marcin, Bobarikin Yuri L., Martyanov Yuri. V.

New Trends in Production Engineering

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2019

|

Vol. 2, Iss. 2

36-45

EN

One of the variable parameters in steel cord twisting technologies is the steel cord tension before final reel. Changing this parameter is used to produce steel cord with high quality of straightness. Steel cord straightness is the most important technological parameter after tensile strength. It is simple to change the value of steel cord tension with special mechanisms or devices in composition of cable machines and twisting machines. It is very important to know the measures of tension setting. Low tension causes bad quality of steel cord and defects. High tension may brake steel cord during the twisting and lapping. Also high tension may change the mechanical properties of steel wire in the steel cord construction. The influence of steel cord tension in the range from 9 N to 30 N on active equivalent stresses in wire cross section and macro displacements of wire contact points in steel cord construction was shown. Effect of steel cord tension during the lapping on steel cord straightness after lapping was shown. In this research the optimal tension for producing steel cord 2x0.30HT was defined with numerical simulation, finite element analysis and criteria method. The optimal value of tension for other steel cord constructions will change, because of number of wires and its hardness.

16

Experimental studies of the prototype device for soil application of dehydrated digestate

Talarczyk Włodzimirz, Łowiński Łukasz, Mac Jarosław, Wojciechowski Jacek

Journal of Research and Applications in Agricultural Engineering

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2019

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Vol. 64, nr 1

44--49

EN

The experimental results of the prototype device for soil application of dewatered digestate, consisting of a modernized manure spreader and aggregated disc harrow, are presented. The main purpose of the tests were stress measurements in the harrow's frame structure and the hitch attached to the manure spreader's chassis. The results of measurements were found to be very consistent in real conditions with the results of strength analyzes carried out on the computational model. The work was carried out at the Industrial Institute of Agricultural Engineering in Poznań as part of the BIOSTRATEG 1/269056/NCBR/2015 project co-financed by the National Center for Research and Development under the Biostrateg program.

PL

Przedstawiono wyniki badań eksperymentalnych prototypu urządzenia do doglebowej aplikacji odwodnionego pofermentu, składającego się ze zmodernizowanego rozrzutnika obornika i zagregowanej z nim brony talerzowej. Głównym celem badań były pomiary naprężeń w konstrukcji nośnej brony i zaczepie zamocowanym do podwozia rozrzutnika. Stwierdzono dużą zgodność wyników pomiarów w warunkach rzeczywistych z wynikami analiz wytrzymałościowych przeprowadzonych na modelu obliczeniowym. Prace przeprowadzono w Przemysłowym Instytucie Maszyn Rolniczych w Poznaniu w ramach projektu BIOSTRATEG 1/269056/NCBR/2015 dofinansowanego przez NCBR w ramach programu Biostrateg.

17

Numerical Analysis of Thermo-Mechanical Phenomena of the Progressive Hardening Elements Made of Tool Steel for Cold Work

Domański T.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

329--338

EN

The numerical algorithm of thermal phenomena is based on the solution of the heat conduction equations in Petrov-Galerkin’s formula using the finite element method. In the modeling of phase transformation in the solid state, the models based on the diagrams of continuous heating and continuous cooling (CHT and CCT). In the modeling of mechanical phenomena, equations of equilibrium and constitutive relationships were adopted in the rate form. It was assumed that the hardened material is elastic-plastic, and the plasticizing can be characterized by isotropic, kinematic or mixed strengthening. In the model of mechanical phenomena besides thermal, plastic and structural strains, the transformations plasticity was taken into account. Thermo-physical size occurring in the constitutive relationship, such as Young’s modulus and tangential modulus, while yield point depend on temperature and phase composition of the material. The modified Leblond model was used to determine transformation plasticity. This model was supplemented by an algorithm of modified plane strain state, advantageous in application to the modeling of mechanical phenomena in slender objects. The problem of thermoelasticity and plasticity was solved by the FEM. In order to evaluate the quality and usefulness of the presented numerical models, numerical analysis of temperature fields, phase fractions, stresses and strains was performed, i.e. the basic phenomena accompanying surface layer of progressive-hardening with a movable heat source of slender elements made of tool steel for cold work.

18

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

Czarniawski T.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

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2018

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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.

19

Konstrukcja, diagnostyka i utrzymanie toru bezstykowego - zagrożenia w okresie niskich temperatur

Makowski J.

Prace Naukowe Politechniki Warszawskiej. Transport

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2018

|

z. 122

63--80

PL

W artykule scharakteryzowano konstrukcję toru bezstykowego oraz wyjaśniono zjawisko powstawania naprężeń termicznych. Pękanie szyn kolejowych w okresach niskich temperatur, związane również z występowaniem defektów szyn, stanowi zagrożenie dla bezpieczeństwa ruchu i wymaga prawidłowej diagnostyki stanu toru, oraz stosowania właściwej technologii napraw pękniętych szyn.

EN

The article characterizes the construction of a contactless track and explains the phenomenon of thermal stress formation. The breakage of railway rails during periods of low temperatures, also related to the occurrence of rail defects, poses a threat to traffic safety and requires proper diagnostics of the track condition, as well as the use of correct repair technology for broken rails.

20

Parametric optimization of dental implants

Bensmain W., Benlebna M., Serier B., Abbes B., Bouiadjra B.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 4

1061--1076

EN

Osseointegration is a fundamental phenomenon of dental implantology. It ensures the stability, the safety and the durability of dental implants and predictable clinical success in long-term. The geometric form of the implant is a defining parameter of osseointegration and implant-bone charge transfer. This is the essential constitutes of this study. In fact, we demonstrate using the finite elements method with tridimensional numerical computations, that the geometrical parameters of the implant conditionate the level and the repartition of the stresses, induced in the cortical bone and the spongy bone during the masticatory process, simulated here by dynamic charging. The effect of several parameters [size and conicity of the implant neck, size and radius of curvature of the implant apex] and the shape of the implant corps on the biomechanical behavior of the bone. The latest was analyzed in terms of variation of the equivalent stress induced in the bone. The purpose of this analysis was the developing of an implant form allowing stress relaxation, during the mastication process, in the living tissue.