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Abstract

The problem of the optimal driving technique during the fuel economy competition is reconsidered. The vehicle is regarded as a particle moving on a trace with a variable slope angle. The fuel consumption is minimized as the vehicle covers the given distance in a given time. It is assumed that the run consists of two recurrent phases: acceleration with a full available engine power and coasting down with the engine turned off. The most fuel-efficient technique for shifting gears during acceleration is found. The decision variables are: the vehicle velocities at which the gears should be shifted, on the one hand, and the vehicle velocities when the engine should be turned on and off, on the other hand. For the data of students’ vehicle representing the Faculty of Power and Aeronautical Engineering it has been found that such driving strategy is more effective in comparison with a constant speed strategy with the engine partly throttled, as well as a strategy resulting from optimal control theory when the engine is still active.

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Authors and Affiliations

Paweł Sulikowski
Ryszard Maroński
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Abstract

Unlike in conventional bridges, the backfill and the roadway pavement have a major bearing on the load capacity of buried corrugated metal structures. In the soil-steel structure model one can distinguish two structural subsystems: the shell made of corrugated steel plates and the soil backfill with the road pavement. The interaction between them is modelled as a contact (interfacial) interaction, i.e. forces normal and tangent to the surface of the shell. The normal interactions are variable during both construction and service life. Two algorithms are presented. In the first algorithm on the basis of unit strains the internal forces in the shell are determined and consequently the contact interactions are calculated. A large number of measuring points distributed on the circumferential section of the shell is needed for the calculations. In the second algorithm the collocation condition, according to which the result obtained from the shell geometry model must agree with the measured displacement of the structure’s collocation point, is used. When there are more such points, the estimated result is more precise. The advantage of both algorithms is that they take into account the physical characteristics of the soil in the backfill layers, but above all the backfill laying and compacting technology. The results of such analyses can be the basis for comparing the effectiveness of conventional geotechnical models.
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Authors and Affiliations

Czesław Machelski
1
ORCID: ORCID
Leszek Korusiewicz
2

  1. Wrocław University of Science and Technology, Faculty of Civil Engineering, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
  2. Wrocław University of Science and Technology, Faculty of Mechanical Engineering, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Abstract

The approach to numerical analyses was changed by the introduction of Eurocodes . The EN 1993-1-6 standard allows taking into account imperfections on the shape of a buckling form from a linear elastic bifurcation analysis. The article analyses the first ten forms of imperfection from a linear elastic bifurcation analysis on the reduction of the capacity of a cylindrical shell. Calculations were made using finite element methods.

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Authors and Affiliations

K. Schabowicz
Ł. Zawiślak
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Abstract

This investigation is carried out to evaluate the repair and strengthening the techniques of elliptical paraboloid reinforced concrete shells with openings. An experimental program of several different techniques in repair and strengthening is executed. The materials, which are considered for strengthening, are; Glass fiber reinforced polymers GFRP at different position of the shell bottom surface, steel strip and external tie. They loaded by four concentrated loads affected on the corners of the opening. The initial and failure loads as well as the crack propagation for the tested shells at different loading stages, defl ections and failure load for repaired and shells are recorded. A non-linear computer program based on finite element techniques is used to study the behavior of these types of shells. Geometric and materials nonlinearities are considered in the analysis. The efficiency and accuracy of computer program are verified by comparing the program results with those obtained experimentally for the control shell with opening and strengthened shells.

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Authors and Affiliations

N.N. Meleka
M.A. Safan
A.A. Bashandy
A.S. Abd-Elrazek
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Abstract

The paper considers method of determination of solar radiation amount falling on arbitrarily oriented surface of a structure. Provided method allows calculation of influence of structure’s geographical coordinates, spatial orientation of structure’s surface, day of year and time of day on received amount of solar radiation. The method is intended for determination of thermal stresses and deformations of sheet steel structures caused by action of direct solar radiation. Examples show usage of provided method.

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Authors and Affiliations

O.I. Kordun
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Abstract

Work was done as a part of the project " New generation haulage system of highly productive longwall systems" aiming to develop and implement a new longwall shearer system called KOMTRACK. The widely used EICOTRACK feed system developed forty years ago is not adapted to modern longwall shearers' power. Within the project, an innovative, flexible feed system with a modular structure was created with the possibility of continuous adjustment to the carbon wall's unevenness. Newly-developed three cast steels variants have been initially selected to fabricate this system's elements. The material's final selection was realized based on the tensile tests, Charpy impact tests, Brinell hardness surveys, and wear resistance measurements. Results analysis allowed to select cast steel marked as "2", which fulfilled all requirements and was used in further casting trials.
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Bibliography

[1] Pirowski Z. (2020). A new generation feed system for high-performance longwall shearers. Stage 4; Kraków: Report 2019 – Łukasiewicz Research Network – Foundry Research Institute, 64-69.
[2] Pieczora, E., Zachura, A., Pirowski, Z., Pysz, S., Kurdziel, P., Żyła, P., Kotulski, W. (2015). Flextrack - innovative longwall shearer feed system. Part 1, Modern methods of coal and hard rock mining. Kraków: AGH University of Science and Technology. 185-194. ISBN 978-83-930353-5-9.
[3] Zachura, A., Pieczora, E., Pysz, S., Żuczek, R., Pirowski, Z., Kurdziel, P., Żyła, P., Kotulski, W. (2015). Flextrack - innovative longwall shearer feed system. Part 1, Modern methods of coal and hard rock mining. Kraków: AGH University of Science and Technology, 195-203. ISBN 978-83-930353-5-9.
[4] Pirowski, Z., Uhl, W., Jaśkowiec, K., Pysz, S., Gazda, A., Kotulski, W., Kurdziel, P., Zachura, A. (2015). Innovative FLEXTRACK feed system - selection of materials (casting al-loys), in: A. Klich, A. Kozieł: Innovative techniques and technologies for mining. Safety - Efficiency - Reliability - KOMTECH 2015, KOMAG Institute of Mining Technology, 223-236. ISBN 978-83-60708-90-3.
[5] Pysz, P., Żuczek, R., Pirowski, Z., Uhl, W., Kotulski, W., Żyła, P., Kurdziel, P., Zachura, A. (2015). Innovative FLEXTRACK feed system - development of the technology of making cast segments of the toothed elements and the guider, in: A. Klich, A. Kozieł: Innovative techniques and technologies for mining. Safety - Efficiency - Reliability - KOMTECH 2015, KOMAG Institute of Mining Technology, 237-249. ISBN 978-83-60708-90-3.
[6] Pirowski, Z., Uhl, W., Jaśkowiec, K., Krzak, I., Wójcicki, M., Gil, A., Kotulski, W., Kurdziel, P., Pieczora, E., Zachura, A. (2015). Innovative FLEXTRACK feed system - quality assessment of the manufactured prototype castings, in: A. Klich, A. Kozieł: Innovative techniques and technologies for mining. Safety - Efficiency - Reliability - KOM-TECH 2015, KOMAG Institute of Mining Technology, 250. ISBN 978-83-60708-90-3.
[7] Kalita, M. (2019). Designing process of a toothed segment of the KOMTRACK haulage system. New Trends in Production Engineering. 2(1), 121-129. https://doi.org/10.2478/ntpe-2019-0013.
[8] Nieśpiałowski, K., Kalita, M., Rawicki, N, (2019). System for tensioning the toothed path of the longwall shearer's feed system, Scientific and Technical Conference: KOMTECH Innovative Mining Technologies – IMTech. [9] Pirowski, Z. (2015). Thermal Analysis in the Technological “Step” Test of H282 Nickel Alloy. Archives of Foundry Engineering. 15(1), 87-92. DOI: 10.1515/afe-2015-0016.
[10] Pirowski, Z., Warmuzek, M., Radzikowska, J. (2012). Test casting Inconel 740 alloy, 70th World Foundry Congress, 560-565.
[11] Rakoczy, Ł., Grudzień, M., Cygan, R. & Zielińska-Lipiec, A. (2018). Effect of cobalt aluminate content and pouring temperature on macrostructure, tensile strengh and creep rupture of Inconel 713C castings. Archives of Metallurgy and Meterials. 63(3), 1537-1545. https://doi.org/10.24425/123845.
[12] Pirowski, Z., Jaśkowiec, K., Tchórz, A., Krzak, I., Sobczak, J., Purgert, R. (2016). Technological conversion applicable for manufacturing elements from Nickel superalloy H282, 72nd World Foundry Congress, 223-224.
[13] Grudzień-Rakoczy, M., Rakoczy, Ł., Cygan, R., Kromka, F., Pirowski, Z. & Milkovic, O. (2020). Fabrication and characterization of the newly developed superalloys based on Inconel 740. Materials. 13, 2362. https://dx.doi.org/10.3390%2Fma13102362.
[14] Rakoczy, Ł., Grudzień-Rakoczy, M. & Cygan, R. (2019). The influence of shell mold composition on the as-cast macro-and micro-structure of thin-walled IN713C superalloy castings. Journal of Materials Engineering and Performance. 28(7), 3974-3985. https://doi.org/10.1007/s11665-019-04098-9.
[15] Grudzień, M., Cygan, R., Pirowski, Z. & Rakoczy, Ł. (2018). Transactions of the Foundry Research Institute. 58, 39-45. https://dx.doi.org/10.7356/iod.2018.04.
[16] Pirowski, Z. & Gościański, (2013). Casting Alloys for Agricultural Tools Operating under the Harsh Conditions of Abrasive Wear. TEKA Commission of Motorization and Energetics in Agriculture. 13(1), 119-126 ISSN 1641-773.
[17] Pirowski, Z., Gwiżdż, A. & Kranc, M. (2012). Cast Agricultural Tools Operating in Soil. Tekhnika ta energetika APK. 170(1), 378-385. ISSN 2222-8618.
[18] Gościański, M. & Pirowski, Z. (2009). Construction and Technology of Production of Casted Shares for Rotating and Field Ploughs, TEKA Commission of Motorization and Energetics in Agriculture. - O.L. PAN, 9(9), 231-239. ISSN 1641-7739.
[19] Pirowski, Z., Olszyński, J., Turzyński, J. & Gościański, M. (2006). Elements of agricultural ma-chinery working in soil made of modern casting materials. Motrol. 8, 169-180. (in Polish).
[20] Pirowski, Z. (2014). Evaluation of High-temperature Physico-chemical Interactions Between the H282Alloy Melt and Ceramic Material of the Crucible. Archive of Foundry Engineering. 14(4), 83-90. https://doi.org/10.2478/afe-2014-0091.
[21] Wang, Z., Huang, B., Chen, H., Wang, CH. & Zhao, X. (2020). The Effect of Quenching and Partitioning Heat Treatmenton the Wear Resistance of Ductile Cast Iron Journal of Materials Engineering and Performance. 29, 4370-4378. https://doi.org/10.1007/s11665-020-04871-1.
[22] Srinivasu, R., Sambasiva Rao A., Madhusudhan Reddy G., K. Srinivasa Rao, K. (2015). Friction stir surfacing of cast A356 aluminiumesilicon alloy with boron carbide and molybdenum disulphide powders. Defence Technology. 11(2), 140-146.
[23] Heldin, M., Heinrichs, J., Jacobson, S. (2021). On the critical roles of initial plastic deformation and material transfer on the sliding friction between metals. Wear. 477(Spec.203853). DOI: 10.1016/j.wear.2021.203853, Published JUL 18.
[24] Grzesik, W., Zalisz, Z., Krol, S. & Nieslony, P. (2006). Investigations on friction and wear mechanisms of the PVD-TiAlN coated carbide in dry sliding against steels and cast iron. Wear. 261(11-12), 1191-1200.
[25] Holmberg, K., Matthews, A., Dowson, D. (Ed.) (1998). Coating Tribology. Properties, Techniques and Applications in Surface Engineering. Tribology Series. 28, Elsevier, Amsterdam.
[26] PN-88/H-83160; Wear-resistant cast steel - Grades. (in Polish). [27] NF A 32-058/1984: Produits de founderie aciers et fontes blanches moules resistant a l'usure par abrasion.

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Authors and Affiliations

D. Wilk-Kołodziejczyk
1 2
ORCID: ORCID
Z. Pirowski
2
ORCID: ORCID
M. Grudzień-Rakoczy
2
ORCID: ORCID
A. Bitka
2
ORCID: ORCID
K. Chrzan
2
ORCID: ORCID

  1. AGH University of Science and Technology, Al. A. Mickiewicza 30, 30-059 Krakow, Poland
  2. Łukasiewicz Research Network – Krakow Institute of Technology, 73 Zakopiańska Str., 30-418 Kraków, Poland
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Abstract

The purpose of the present work is to investigate the effect of dietary-supplemented artichoke ( Cynara scolymus L.) on the mRNA expression of calbindin 1 ( Calb1), osteopontin ( Spp1), albumin ( Alb) and CALB1 protein in the eggshell gland (ESG) of laying hens. A total of 80 ISA Brown hens (each at 40 weeks of age) were randomly divided into two groups: a control and a treated group. All poultry received 130 g/day of compound feed for laying hens but the treated hens’ diet was also supplemented with 3g/kg of dried and milled artichoke ( Cynara scolymus L.). The increase of the Ca content in blood of the treated hens was established. Significantly decrease of Spp1 mRNA transcripts was found in the eggshell gland of the treated hens, while the mRNA level of Alb was increased. The relative expression of Calb1 mRNA tended to increase in the treated group. The expression of calbindin protein in the cytoplasm of glandular cells of the shell gland was defined by immunohistochemical method. Very strong signals of calbindin were observed in the treated group. The supplementation of the laying hens’ diet with dried artichoke ( C. scolymus L.) led to a significant increase of Ca content in blood that was reflected in the changes of expression of the eggshell gland genes involved in the mineralization of eggshell.
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Authors and Affiliations

D. Abadjieva
1
D. Ankova
1
S. Grigorova
2
E. Kistanova
1

  1. Institute of Biology and Immunology of Reproduction – Bulgarian Academy of Sciences 1113 Sofia, Tzarigradsko shosse 73, Bulgaria
  2. Institute of Animal Science - AA, 2232 Kostinbrod, Bulgaria
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Abstract

Fuel tanks are designed with regard to standard loads and operating conditions. The investigations of the paper show the impact of such factors as tank corrosion and other means on variation of stress fields and deformation of the underground horizontal tank shell. Introduction of probabilistic methods allows for structural reliability assessment. While the computational time of the entire tank FEM model is high the preliminary analysis is restricted to structural part only. The analysis makes it possible to optimize the structure with regard to construction costs.
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Authors and Affiliations

Przemysław Sorn
1 2
Mateusz Sondej
1
Jarosław Górski
1
ORCID: ORCID

  1. Faculty of Civil and Environmental Engineering, Gdańsk University of Technology, Poland
  2. KB Pomorze, Gdańsk, Poland
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Abstract

Optimization plays an important role in scientific and engineering research. This paper presents the effects of using the catenoidal shape to design the structure of a chimney cooling tower. The paper compares some geometrical variations of the catenoid with the reference existing hyperboloidal structure. It also compares internal forces, deformation and stability of the catenoidal structure. The comparison shows some predominance of the catenoid over the popular hyperboloid structure of the shell. The paper attempts to find an optimal shape of the cooling tower in order to reduce the amount of material and labor. The paper utilizes engineering tools and the designing process for chimney cooling towers.
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Authors and Affiliations

Maciej Wiśniowski
1
ORCID: ORCID
Robert Walentyński
1
ORCID: ORCID
Dawid Cornik
1
ORCID: ORCID

  1. Faculty of Civil Engineering, Department of Mechanics and Bridges, ul. Akademicka 5, 44-100 Gliwice, Poland
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Abstract

In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.

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Authors and Affiliations

Jarosław Bartoszewicz
Leon Bogusławski
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Abstract

The article presents a novel method that allows measurement of thermal conductivity that is based on Stefan-Boltzmann law. The developed method can be used to determine thermal conductivity of ceramic investment casting molds. The methodology for conducting thermal conductivity tests of ceramic material samples is presented. Knowledge of the value of thermal capacity and thermal conductivity as a function of temperature enables computer simulations of the process of cooling and solidification of liquid metal in a mold.

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Authors and Affiliations

W. Leśniewski
E. Czekaj
P. Wieliczko
M. Wawrylak
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Abstract

The paper presents the methodology that makes it possible to evaluate computational model and introduce current corrections to it. The methodology ensures proper interpretation of nonlinear results of numerical analyses of thin-walled structures. The suggested methodology is based on carrying out, in parallel to nonlinear numerical analysis, experimental research on some selected crucial zones of loadcarrying structures. Attention is drawn to the determinants concerning the performance of an adequate experiment. The author points out on indicating the role of model tests as a fast and economically justified research instruments practicable when designing thin-walled load-carrying structures.

The presented considerations are illustrated by an example of a structure whose geometrical complexity and ranges of deformation are characteristic for modern solutions applied in the load-carrying structures of airframes. As the representative example, one selected the area of the load-carrying structure that contains an extensive cut-out, in which the highest levels and stress gradients occur in the conditions of torsion evoking the post-buckling states within the permissible loads. The stress distributions within these ranges of deformations were used as the basis for determining the fatigue life of the structure.

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Authors and Affiliations

Tomasz Kopecki
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Abstract

In this paper, the authors investigate a cylindrical shell reinforced by carbon nanotubes. The critical buckling load is calculated using analytical method when it is subjected to compressive axial load. The Mori-Tanaka method is firstly utilized to estimate the effective elastic modulus of composites having aligned oriented straight CNTs. The eigenvalues of the problem are obtained by means of an analytical approach based on the optimized Rayleigh-Ritz method. There is presented a study on the effects of CNTs volume fraction, thickness and aspect ratio of the shell, CNTs orientation angle, and the type of supports on the buckling load of cylindrical shells. Furthermore the effect of CNTs agglomeration is investigated when CNTs are dispersed none uniformly in the polymer matrix. It is shown that when the CNTs are arranged in 90 degrees direction, the highest critical buckling load appears. Also, the results are plotted for different longitudinal and circumferential mode numbers. There is a specific value for aspect ratio of the cylinder that minimizes the buckling load. The results reveal that for very low CNTs volume fractions, the volume fraction of inclusions has no important effect on the critical buckling load.

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Authors and Affiliations

Jafar Eskandari Jam
Esmail Asadi
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Abstract

The problem of optimal driving techniques during fuel economy competition is considered. The kinetic model of the record wheeled vehicle is proposed. It is regarded as a particle moving on a trace with variable slope angle. Engine characteristics are taken into account. The fuel consumption is minimized as the vehicle goes over a given distance. The problem is formulated in optimal control. The direct pseudospectral Chebyshev’s method is employed. The motion of student’s vehicle representing the Faculty of Power and Aeronautical Engineering during Shell Eco-marathon in Nogaro, France, in 2006, is used as an example.

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Authors and Affiliations

Krzysztof Rogowski
Ryszard Maroński
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Abstract

In the present work, a tire model is derived based on geometrically exact shells. The discretization is done with the help of isoparametric quadrilateral finite elements. The interpolation is performed with bilinear Lagrangian polynomials for the midsurface as well as for the director field. As time stepping method for the resulting differential algebraic equation a backward differentiation formula is chosen. A multilayer material model for geometrically exact shells is introduced, to describe the anisotropic behavior of the tire material. To handle the interaction with a rigid road surface, a unilateral frictional contact formulation is introduced. Therein a special surface to surface contact element is developed, which rebuilds the shape of the tire.

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Authors and Affiliations

Michael Roller
Peter Betsch
Axel Gallrein
Joachim Linn
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Abstract

The economic envelopes obtained by optimization techniques in open pit mining are transformed into operational phases that are suitable for extraction through ramp designs. This process is performed with the aid of specialized design software, which is still very manual, time consuming and highly dependent on the expertise of the planner. In this paper, we introduce a new methodology based on a mathematical model to automatically propose the design of ramps from the economic envelope of a pushback, with the resulting envelope having the maximum value. The developed model was tested against a real case scenario showing reasonable and useable solutions for the planner. Using this approach, a planner can evaluate several alternatives in a reasonable time before selecting the final design.

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Authors and Affiliations

Pierre Nancel-Penard
Andrés Parra
Nelson Morales
Cristopher Díaz
Eleonora Widzyk-Capehart
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Abstract

Shell and tube heat exchangers are commonly used in a wide range of practical engineering. The key issue in such a system is the heat exchange between the hot and cold working media. An increased cost of production of these devices has forced all manufacturing companies to reduce the total amount of used materials by better optimizing their construction. Numerous studies on the heat exchanger design codes have been carried out, basically focusing on the use of fully time-dependent partial differential equations for mass, momentum, and energy balance. They are very complex and time-consuming, especially when the designers want to have full information in a full 3D system. The paper presents the 1D mathematical model for analysis of the thermal performance of the counter-current heat exchanger comprised of mixed time-dependent and time-independent equations, solved by the upwind numerical solution method, which allows for a reduction in the CPU time for obtaining the proper solution. The comparison of numerical results obtained from an in-house program called Upwind Heat Exchanger Solver written in a Fortran code, with those derived using commercial software package ASPEN, and those obtained experimentally, shows very good agreement in terms of the temperature and pressure distribution predictions. The proposed method for fast designing calculations appears beneficial for other tube shapes and types of heat exchangers.
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Authors and Affiliations

Dariusz Kardaś
1
Izabela Wardach-Święcicka
1
Artur Grajewski
2

  1. The Szewalski Institute of Fluid Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdansk, Poland
  2. HEXONIC Sp. z o.o., Warszawska 50, 82-100 Nowy Dwór Gdanski, Poland
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Abstract

For the manufacture of near net shape complex titanium products, it is necessary to use investment casting process. Melting of titanium is promising to carry out by electron beam casting technology, which allows for specific processing of the melt, and accordingly control the structure and properties of castings of titanium alloys. However, the casting of titanium in ceramic molds is usually accompanied by a reaction of the melt with the mold. In this regard, the aim of the work was to study the interaction of titanium melt with ceramics of shell molds in the conditions of electron beam casting technology. Ceramic molds were made by using the following refractory materials – fused corundum Al2O3, zircon ZrSiO4 and yttria-stabilized zirconium oxide ZrO2, and ethyl silicate as a binder. Melting and casting of CP titanium was performed in an electron beam foundry. Samples were made from the obtained castings and electron microscopic metallography was performed. The presence and morphology of the altered structure, on the sample surface, were evaluated and the degree and nature of their interaction were determined. It was found that the molds with face layers of zirconium oxide (Z1) and zircon (ZS1) and backup layers of corundum showed the smallest interaction with the titanium melt. Corundum interacts with titanium to form a non-continuous reaction layer with thickness of 400-500 μm. For shell molds with face and backup layers of zircon on the surface of the castings, a reaction layer with thickness of 500-600 μm is formed. In addition, zirconium-silicon eutectic was detected in these layers.
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Bibliography

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Authors and Affiliations

Pavlo Kaliuzhnyi
M. Voron
1
O. Mykhnian
1
A. Tymoshenko
1
O. Neima
1
O. Iangol
1

  1. Physico-Technological Institute of Metals and Alloys of the National Academy of Sciences of Ukraine, Ukraine
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Abstract

We document an upper upper Albian ( Mortoniceras rostratum Zone) cephalopod assemblage from Clansayes (Drôme, south-eastern France). Although fossils are rare in local exposures and in the single sampled level, a decade of intensive fossil collecting yielded 290 ammonite and 5 nautilid specimens. In total, we describe 1 species of nautilid and 24 species (within 17 genera) of ammonites, including 13 heteromorphs. Only two of these ammonite taxa were previously recorded from the upper upper Albian at Clansayes, which demonstrates the value of this fauna with regard to taxonomy, palaeobiology and palaeobiogeography. Based on morphological and biometric analyses performed on an extensive material (104 specimens), we discriminate two species for the heteromorphic ammonite genus Mariella Nowak, 1916 within the Mortoniceras rostratum Zone. In addition, we investigate shell chirality patterns in Mariella from the late Albian of southern France. Upon comparison of the Clansayes material with older material from the immediately underlying upper Albian Mortoniceras fallax Zone at the neighbouring Salazac locality, we identify an increase in the proportion of sinistral specimens. This observed increase in the frequency of sinistral Mariella specimens may hypothetically be part of a global evolutionary pattern, considering that nearly all documented younger Cenomanian Mariella (and more generally Cenomanian turrilitids) are sinistral.
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Authors and Affiliations

Romain Jattiot
1
Jens Lehmann
1
Benjamin Latutrie
2
Amane Tajika
3 4
Emmanuelle Vennin
5
Pauline Vuarin
6
Arnaud Brayard
5
Emmanuel Fara
5
Vincent Trincal
7

  1. Fachbereich 5 Geowissenschaften, Universität Bremen, Klagenfurter Strasse 4, 28357, Bremen, Germany
  2. La Grange, 9003 En Cros, route de Garrigues, 81500, Lavaur, France
  3. Division of Paleontology (Invertebrates), American Museum of Natural History, Central Park West 79th Street, New York, NY, 10024, USA
  4. University Museum, University of Tokyo, Hongo 7‐3‐1, Bunkyo‐ku, Tokyo, 113‐0033, Japan
  5. UMR CNRS 6282 Biogéosciences, Université Bourgogne Franche-Comté, 6 Boulevard Gabriel, F-21000 Dijon, France
  6. Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR 5558, F-69622 Villeurbanne, France
  7. LMDC, INSAT/UPS Génie Civil, 135 Avenue de Rangueil, 31077 Toulouse cedex 04, France
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Abstract

In this study, a molybdenum alloy with dispersed high-entropy particles was fabricated using the powder metallurgy method. The high-entropy powder, composed of Nb, Ta, V, W, and Zr elements with a same atomic fraction, was prepared via high-energy ball milling. Using this powder, an ideal core-shell powder, composed of high-entropy powder as core and Mo powder as shell, was synthesized via the milling and reduction processes. These processes enabled the realization of an ideal microstructure with the high-entropy phase uniformly dispersed in the Mo matrix. The sintered body was successfully fabricated via uniaxial compaction followed by pressureless sintering. The sintered body was analyzed by X-ray diffraction and scanning electron microscope, and the high-entropy phase is uniformly dispersed in the Mo matrix.

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Authors and Affiliations

Won June Choi
CheonWoong Park
Jongmin Byun
ORCID: ORCID
Young Do Kim
ORCID: ORCID
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Abstract

The work is devoted to a horizontal tank composed of cylindrical shell closed with ellipsoidal heads and supported at the ends. The tank is loaded with internal or external pressure. For the first load case, a strength condition was formulated, for the other one -the condition of stability of the structure. An optimization model was formulated, in which the mass of the tank subject to the strength and stability conditions was assumed as an objective function. Optimal proportions of geometric dimensions for a family of the tanks of various capacities provided with heads of various convexities were determined. The results were presented in the form of plots. A function was proposed that approximated the solution and could be useful for purposes of designing of the tanks.
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Authors and Affiliations

Krzysztof Magnucki
ORCID: ORCID
Jerzy Lewiński
Piotr Stasiewicz
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Abstract

One of the shortcomings of the analysis of subfossil Cladocera (water flee) remains is that preservation of remains is selective. Of Daphnia spp. which are very common in zooplankton assemblages of lakes, usually only postabdominal claws and ephippia are found. In the present paper I describe Daphnia shell margins and some tail spines from the Holocene sediments of a lake in southern Finland where the margins were much more abundant than the postabdominal claws, indicating that postabdominal claws may be underrepresented. Daphnia claws, shell margins and tail spines were found also in surface samples of 17 Finnish lakes and thus the abundance of tail spines could be compared with that of postabdominal claws. The results showed that in most cases the tail spines are more abundant than postabdominal claws and may give a closer estimate of the true abundance of Daphnia. However, in some lakes claws were clearly more frequent than tail spines. Apparently, there are differences in preservation of different types of Daphnia remains between lakes, possibly connected with water chemistry. Overall, the results indicate that probably Daphnia remains are always underrepresented in lake sediments.
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Authors and Affiliations

Kaarina Sarmaja- Korjonen
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Abstract

This paper investigates the effect of friction on the buckling behavior of a thin, shallow, elastic spherical shell under uniform external pressure based on an axisymmetric model of the finite element method. The study examines a combination of different geometric parameters with three different types of boundary conditions: clamped, hinged, and frictional ends with a wide range of friction coefficients. Friction has a significant influence on the buckling response of the spherical shell for all geometric parameters. In general, the critical pressure decreases as the friction coefficient or geometric parameter decreases. The buckling behavior of the frictional end with small friction coefficients presents an obvious difference compared to the results of high coefficients. For certain geometric parameters, the buckling mode of the spherical shell is transited because of changing the friction coefficient. A buckling map that describes the dependence of critical pressure on both friction coefficient and geometric parameter combined with buckling mode is generated. This map can be applied to the design of the spherical shell against buckling.
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Authors and Affiliations

XuanCuong Nguyen
1 2
ORCID: ORCID
Yoshio Arai
1
Wakako Araki
3

  1. Saitama University, Saitama, Japan
  2. Hanoi University of Civil Engineering, Hanoi, Vietnam
  3. Tokyo Institute of Technology, Tokyo, Japan
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Abstract

The scattering of plane steady-state sound waves from a viscous fluid-filled thin cylindrical shell weak- ened by a long linear slit and submerged in an ideal fluid is studied. For the description of vibrations of elastic objects the Kirchhoff-Love shell-theory approximation is used. An exact solution of this problem is obtained in the form of series with cylindrical harmonics. The numerical analysis is carried out for a steel shell filled with oil and immersed in seawater. The modules and phases of the scattering amplitudes versus the dimensionless wavenumber of the incident sound wave as well as directivity patterns of the scattered field are investigated taking into consideration the orientation of the slit on the elastic shell surface. The plots obtained show a considerable influence of the slit and viscous fluid filler on the diffraction process.
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Authors and Affiliations

Olexa Piddubniak
Nadia Piddubniak

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