Temat: experimental measurement

Skocz do pozycji: 1.

Tytuł:: Diagnostics the natural frequencies of the automobile disc and their analysis
Autorzy:: Vavro, J.
Kopecky, M.
Saga, M.
Tematy:: diagnostics
frequency
experimental measurement
shape of disc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Powiązania:: https://bibliotekanauki.pl/articles/327416.pdf Link otwiera się w nowym oknie
Opis:: The article deals with the analysis of the natural discs frequencies realized by the means of mathematic simulation by the finite elements method, by which the programs AutoCAD and Cosmos M were used. First fifty natural frequencies are presented for the listed type of the steel disc. The experimental measurement for the listed disc type was made by the Doppler vibrometer. The results of the measurement are presented in a graphic form and the measurement was performed in radial and axial direction.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Changes in aerodynamic parameters for 5-stage steam turbine during warming and gradual start-up to nominal operating parameters
Autorzy:: Hoznedl, M.
Bednář, L.
Tajč, L.
Tematy:: steam turbine
experimental measurement
warming
start-up
eﬃciency; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/175267.pdf Link otwiera się w nowym oknie
Opis:: The results of experiments on the 5-stage steam turbine are presented. The parameters of individual stages as well as the whole turbine are observed during the gradual start-up to nominal operating parameters. The pressures and temperatures are shown at stages in idling, heating up the experimental turbine and during the transition to operating speed. A greater attention is devoted to three selected operational conditions with diﬀerent processed enthalpy drops. Problems with eﬃciency and enthalpy drops measurement during warming are described. The attempts to measure ﬂow parameters quickly and without time for heating of turbine casings and other parts are often in the experimental research caused byprice of the survey. This contributionÞs task is to inform about these situations and to avoid confused and untrue results obtained by somewhat hasty measurements due to reduction and optimisation of costs.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Influence of a Directional Dependenceon Mechanical Properties of Composites Reinforced with Chopped Carbon Fibre Produced by Additive Manufacturing
Autorzy:: Majko, Jaroslav
Handrik, Marian
Vaško, Milan
Sága, Milan
Kopas, Peter
Dorčiak, Filip
Sapietová, Alžbeta
Tematy:: experimental measurement
physical properties
3D printing
composite
fibre reinforcement
MATLAB; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/27313864.pdf Link otwiera się w nowym oknie
Opis:: Progress in the industry is accompanied by the development of new materials and more efficient technological production processes. At present, additive production is becoming very attractive in all industries (research, development, production), which brings a number of advantages compared to subtractive methods (customization, production speed, control of material properties by users, etc.). The main advantage of 3D printing is the controlled deposition of material in defined places. Instead of demanding manual labour, fully automated production via computers leads to the manufacturing of complex components from materials whose production in conventional ways would be problematic or even impossible. Because these are new technologies, the main direction of research at present is to identify the basic physical properties of these materials under different types of loading. The main goal of this article is to observe the dependence of the behaviour of the extruded material (thermoplastic reinforced with chopped carbon fibre) on the printing parameters (thickness of the lamina, the orientation of the fibres of the printed material, etc.). Based on published scientific works, it appears that these settings have a significant impact on the achieved physical properties. This is the reason why the authors decided to analyze the influence of these parameters on the basis of processed data from experimental measurements of mechanical properties in the MATLAB program. As this is FFF printing, an essential condition is to identify and specify the directional dependence of the behavior of the printed material. This physical phenomenon is a necessary condition for gradual knowledge for the purposes of a subsequent mathematical description of the material properties. According to the authors, for the purposes of modeling these materials in FEM-based programs, it is essential to define the directional dependence in the plane of the lamina.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Data-based method for the determination of temperature dependence of heat capacity of highly dispersed powders
Autorzy:: Karnina, A.
Gyrenko, A.
Klymenko, A.
Mysov, O.
Tematy:: highly dispersed powder
heat capacity
equations
experimental measurement
uncertainty of measurements; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Oddział w Lublinie PAN
Powiązania:: https://bibliotekanauki.pl/articles/411297.pdf Link otwiera się w nowym oknie
Opis:: Accuracy of engineering and economic calculations in different areas requires the use of accurate and prompt values of heat capacity for new or modified materials. A number of existing methods have an error in measuring the heat capacity of powder materials, and use non-standard devices and electric heaters which are not produced industrially. This work is aimed at developing the method for determining the heat capacity of the powder, accuracy evaluation of this method and mathematical processing of experimental data to determine the temperature dependence of the molar heat capacity. To solve the problem the method based on the DTA technique was developed. The measuring apparatus for determining the temperature dependence of the heat capacity includes two standard cups for DTA analysis with investigated material and MgO, heat-variable resistor of film type Pt100, multichannel recorder. The apparatus is placed in a drying oven. From the theory of heat transfer and the assumption about steady-flow heat transfer the equation for molar heat capacity was obtained. The method requires the measuring of temperature of the investigated material and MgO during the linear heat of the drying oven as well as air temperature in the oven. Empirical values of heat capacity of standard substances calculated by the equation for each temperature were compared with the values from reference data. The uncertainty of finding the heat capacity did not exceed 0,5%.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Hydraulic transients analysis in pipe networks by the method of characteristics (MOC)
Autorzy:: Wichowski, R.
Tematy:: hydraulic transients
method of characteristics
single pipe
experimental measurement
pipe networks
numerical simulations; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Powiązania:: https://bibliotekanauki.pl/articles/240954.pdf Link otwiera się w nowym oknie
Opis:: The paper presents results of an experimental and theoretical study of the hydraulic transients in straight pipes and numerical simulations of unsteady flow in pipe networks. A mathematical model consists of a set of partial differential equations of hyperbolic type, which have been transformed by the method of characteristics into ordinary differential equations which are solved by the predictor-corrector method. Experimental tests have been performed, in order to examine the hydraulic transients phenomenon, in a single straight steel pipe. The experiments were carried out in the hydraulic laboratory of the Institute of Water Supply and Water Engineering, Environmental Engineering Faculty, Warsaw University of Technology. The numerical results show that the presented one dimensional model for a single pipe correctly describes the phenomenon since there is a good agreement with experimental maximum and minimum oscillations. In the paper, selected exemplary equations in a difference form for the pipe networks are also presented. One calculation example is given relating to the complex water-pipe network consisting of 17 loops, 48 pipelines and 33 nodes, supplied by two independent sources. Water-hammer throughout the whole pipeline network was caused by closing the gate valve at mid-point of one selected pipe. The results of the numerical calculations are presented in graphic form with respect to the final cross-sections of pipes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Axial stiffness for large-scale ball slewing rings with four-point contact
Autorzy:: Hrcek, Slavomir
Kohar, Robert
Steininger, Jan
Tematy:: stiffness
experimental measurement
slewing ring
deformation constant
sztywność
pomiar eksperymentalny
pierścień obrotowy
stała deformacji; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2090718.pdf Link otwiera się w nowym oknie
Opis:: This article deals with the design of slewing rings (slewing bearings). A fully parametric, 3D virtual model of a ball slewing ring with four-point contact was created in the PTC/Creo Parametric CAD system. This model was subsequently used for finite-element analysis using Ansys/Workbench CAE software. The purpose of the FEM analysis was to determine the axial stiffness characteristics. Results of FEM analysis were experimentally verified using a test bench. At the end of the article, we present the nomograms of the deformation constant for different pitch diameters, rolling element diameters and contact angles.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Axial stiffness for large-scale ball slewing rings with four-point contact
Autorzy:: Hrcek, Slavomir
Kohar, Robert
Steininger, Jan
Tematy:: stiffness
experimental measurement
slewing ring
deformation constant
sztywność
pomiar eksperymentalny
pierścień obrotowy
stała deformacji; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2173594.pdf Link otwiera się w nowym oknie
Opis:: This article deals with the design of slewing rings (slewing bearings). A fully parametric, 3D virtual model of a ball slewing ring with four-point contact was created in the PTC/Creo Parametric CAD system. This model was subsequently used for finite-element analysis using Ansys/Workbench CAE software. The purpose of the FEM analysis was to determine the axial stiffness characteristics. Results of FEM analysis were experimentally verified using a test bench. At the end of the article, we present the nomograms of the deformation constant for different pitch diameters, rolling element diameters and contact angles.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: On the transformation of long gravity waves on a sloping beach
Autorzy:: Szmidt, J.K.
Hedzielski, B.
Tematy:: long wave
gravity wave
transformation
wave transformation
sloping beach
wave gauge
propagation
investigation
experimental measurement; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:: https://bibliotekanauki.pl/articles/49151.pdf Link otwiera się w nowym oknie
Opis:: The transformation of long water waves arriving at a sloping beach is investigated. An approximate theory is presented for plane periodic waves propagating in water of non-uniform depth. The theoretical description of the phenomenon, based on certain kinematic assumptions, is formulated in the material variables, and the solution is constructed by applying the Hamilton variational principle. In order to assess the accuracy of the formulation and to learn more about long wave transformation, experimental measurements were carried out in a laboratory flume. In the experiments, a water wave, generated by a piston-type wave maker placed at one end of the flume, propagated towards a rigid inclined ramp installed at the other end of the flume. The wave transformation along the direction of its propagation was recorded by a set of wave gauges installed along the flume. The wave run- up on the sloping beach was measured with a special conductivity gauge placed alongside the ramp. Comparison of the theoretical results with experimental data indicates that the proposed theoretical formulation provides a good description of the main features of wave transformation behaviour over a sloping beach, except in the vicinity of the shore point, where some discrepancies occur.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: The process of aluminium moduls warming in the car industry
Autorzy:: Mlýnek, J.
Srb, R.
Tematy:: intensity of heat radiation
experimental measurement of radiation intensity
interpolation in multidimensional space
software implementation; Pokaż więcej
Wydawca:: Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Powiązania:: https://bibliotekanauki.pl/articles/384339.pdf Link otwiera się w nowym oknie
Opis:: This paper concerns the heating of aluminium moulds in the car industry. The moulds are intended for the production of artificial leathers. The mould is sprinkled with a special powder and is subsequently warmed by infra heaters located above the mould. It is necessary to ensure approximately the same heat intensity radiation on the surface mould, and in this way, the same material structure and colour of the artificial leather. The mould surface is described by its elementary surfaces. A producer uses moulds of different sizes and they are often very rugged. We must keep track of possible collisions of heater locations. We have used a genetic algorithm to optimize heater locations for a given mould. In this article, we will focus on the calculation procedure of thermal radiation intensity on the mould surface and on the determination of the average aberration of radiation intensity for particular heater locations, which is an important part of our genetic algorithm.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Influence of nearby structure on the wind flow around the cube structure
Autorzy:: Olekšáková, I.
Hubová, O.
Konečná, L.
Tematy:: wind tunnel
turbulent wind flow
cube structure
pressure coefficient
experimental measurement
tunel aerodynamiczny
turbulentny przepływ wiatru
współczynnik ciśnienia
pomiar eksperymentalny; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Komisja Inżynierii Budowlanej PAN Oddział w Katowicach
Powiązania:: https://bibliotekanauki.pl/articles/131473.pdf Link otwiera się w nowym oknie
Opis:: The influence of a nearby structure on the turbulent wind flow around the cube structure was investigated in this paper. This problem was solved by two different methods. The first one was the numerical solution by CFD simulations. Obtained results were compared with the results from tests made in the wind tunnel. Description of the problem, theory and basic equations, specification of the 3D simulations and experimental measurements were mentioned. From the evaluation of the results, pressure coefficients for this type of structure and for three solved cases, were determined. Pressure coefficients determined by the Eurocode were larger than the values determined by the tests and CFD simulations. In the case of self-standing cube, pressure coefficients were following: Cp=-2.35 (CFD), Cp=-2.404 (test). Deviations were relatively small. Hence, used k-ε model is suitable for determination of the maximum values of pressure coefficients Cp in the investigated case.
Dostawca treści:: Biblioteka Nauki

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