Temat: GaP - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Validation of selected presented method measured of length fatigue gap on compressor blades forming during resonant tests
Autorzy:: Kuźniar, M.
Bednarz, A.
Lichoń, D.
Witek, L.
Powiązania:: https://bibliotekanauki.pl/articles/243027.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: crack propagation
gap
thermovision
turbine engine
blades
Opis:: In this work, the validation of selected presented method measured of length fatigue gap was shown. The article describes three methods of determining fatigue gaps. The object of the study was the first stage compressor blade from aircraft engine. Blades have defects on the leading edge. This defect on the blade (as a result of the resonance vibration) was the origin point of the fatigue gap. Two of the methods, fluorescent and thermovision, were optical. The fluorescent method was a direct measurement, whereas direct-indirect thermography. The last of the presented methods was an analytical method, showing an algorithm based on amplitude-frequency characteristics. The advantages and disadvantages of these methods were compared. As a result of the analysis performed by the algorithm, there were specified patterns defining the dependence of change in crack length depending on the asymmetry of AF characteristics. The accuracy of the following methods and the results obtained for chord length were determined. Thanks to such use, these results have a utilitarian meaning. Such a compilation allowed us to evaluate the usefulness of particular measurement methods. Proposed methods of measuring the length of fatigue crack are used in experimental studies. It is also possible to implement them for research conducted during the operation of an aircraft engine.
Źródło:: Journal of KONES; 2017, 24, 3; 151-158
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 2.

Tytuł:: Scientific achievements obtained in the project MTKD-CT-2004-517226 in years 2005-2008
Autorzy:: Wierzcholski, K.
Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/243524.pdf
Data publikacji:: 2008
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: hydrodynamic pressure
hyperelastic human joints
deformable gap
Opis:: The synovial joint has two main components: solid one represented by the cartilage, and bio-fluid by the synovial fluid. The cartilage is a soft anisotropic solid containing pores filled with a fluid. In this paper is determined the pressure distributions in a thin layer of non-Newtonian, lubricant inside the deformable gap of spherical human hip joint. The load carrying capacities in human joints with cartilage deformations are much smaller than that obtained for not deformable cartilage surface. The changes of the joint gap height during the lubrication process are caused by the deformation of two cooperating spherical joint surfaces covered by the soft cartilage superficial layer. Hypo-elastic deformations of cartilage are taken into account. In the general case the cartilage can be subjected to large deformations. The main results described in this paper are as follows: 1.Numerical calculated values of pressure distributions for the elbow cylindrical human joints performed in this paper by virtue of analytical models taking into account the effects of congenial and growth influences on the lubrication process are compared with initial measured hydrodynamic pressure values performed by means of AFM. Measured pressure values obtained by the S. Chizhik et al. 2006 in experimental way, are different about 7 percent from the numerical values obtained in presented paper using the analytical solutions. 2.In presented paper is derived the modified Reynolds equation containing the terms describing the influences of congenial and genetic properties of the lubricant and micro-bearing materials on the pressure and load carrying capacity of bio-joints and micro-bearing. The comparisons presented in this project between human bio-joints and micro-bearings are indicated that the biobearing theory of lubrication is very helpful in MEMS and NEMS devices. The research presented in the project provides an important impact for developing the new scientific domain such as cyto-tribology, histo-tribology or tribology of cells, and tissue and of micro-surfaces occurring in mechanical micro-bearings. According to the participants knowledge such scientific domains are completely new and have been not so far initiated by any scientific centre and in any area of tribology and tissue engineering.
Źródło:: Journal of KONES; 2008, 15, 3; 543-549
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 3.

Tytuł:: Geometrical structure for endoprosthesis surface lubrication and wear prognosis
Autorzy:: Wierzcholski, K.
Powiązania:: https://bibliotekanauki.pl/articles/242452.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: endoprosthesis
surface
measurements
gap height
wear
random prognosis
Opis:: It can be stated that over the last ten years in the European Union, the number of bone fractures caused by osteoarthritis has increased twofold. More than 100,000 hip or knee joints in total were implanted in Germany during one year. Within ten years, 5% of them have failed by aseptic loosening. The non-invasive determination of friction forces and control of their values during lubrication of cartilage cells on the superficial layer of human joint surfaces before implantation has a significant but not sufficient impact on the observation of the early abrasive wear of the cartilage joint and development of osteoporosis. From this fact was drawn the inspiration for the performed investigations related to the endoprosthesis surface parameters because knowledge of the roughness of prosthesis surfaces and friction forces and their control methods permits provision of a necessary standard deviation of the gap height and finally information about the implantation possibility. This article has been prepared based on the objective of European Project UE Grant IRSES,612593, 2013-2016 to represent the methodology and goal of the idea described in and make a wider discussion possible on this subject for further developments during the realization. To the research methods and materials used in this article realization belong: Rank Taylor Hobson-Talyscan 150 Apparatus implemented by Talymap Expert and Microsoft Excel Computer Program connected with the Mathcad 15 Professional Program and a new semi-analytical methods of probabilistic and statistic prognosis applied for theory of hydrodynamic lubrication of the curvilinear orthogonal surface and coordinates extended to the friction and wear problems of the endoprosthesis surfaces during the exploitation.
Źródło:: Journal of KONES; 2017, 24, 4; 335-341
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 4.

Tytuł:: Aerodynamics of articulated multilink trucks
Autorzy:: Andreihyk, A.
Kharytonchyk, S.
Kochetov, S.
Shmelev, A.
Powiązania:: https://bibliotekanauki.pl/articles/247722.pdf
Data publikacji:: 2018
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: truck
aerodynamic resistance
articulated truck
trailer-trailer gap
modelling
Opis:: Development of new generations of supersize heavy-duty highway trucks for cargoes transportation on long and super long distances between Europe, Asia and Far East is actual now. New trucks shall reduce amount of transport on roads and quantity of drivers, involved in the transportation, will raise economic efficiency and safety of transportations and reduce fuel consumption, CO2, and harmful emissions. Multilink trucks (number of trailed links is three and more and the total truck length is above 40 m) are to achieve designated purposes and thus are under the scope in the article. The advantages of multilink trucks are formed mainly by reducing the cost of power to overcome the aerodynamic resistance of each co-trailer unit in comparison with the head element. However, the airflow in every trailer-trailer gap has been not studied for articulated vehicles such as multilink highway trucks. This zone of the truck is characterized by a rather large length and height, and the condition of the air mass is influenced by airflow from the roof, side panels and area under the bottom of a truck links. A study of this task will help us to analyse aerodynamic losses mechanics in the trailer-trailer gap and to come to new effective and substantiated decision allowing power loss and thus fuel consumption reduction. The study lists the general calculation method evaluating the aerodynamic characteristics of the multilink truck on the base of numerical simulation of fluid dynamics using Flow Vision software. During calculation, there were determined speed distribution and power lines along the truck, the distribution of pressure on the truck surface, power and full drag coefficient. The results obtained allowed numerically evaluate the effect of the distance between the links on fuel consumption for multilink trucks and define the desired changes in their design.
Źródło:: Journal of KONES; 2018, 25, 3; 25-32
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 5.

Tytuł:: A new problem of hydrodynamic lubrication with temperature and viscosity variations in gap height direction
Autorzy:: Wierzcholski, K.
Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/245652.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: liquid viscosity changes in thin gap height direction
temperature
adhesion or capillary forces variations in thin gap height direction new analytical solutions
Opis:: Numerous Authors of scientific papers occurring in hydrodynamic theory of slide bearing lubrication, up to now almost always had neglected the oil dynamic viscosity variations caused by temperature, adhesion forces, capillary forces, or hydrogen ion concentration across the film thickness by virtue of the statement of the constant temperature as well constant adhesion as capillary forces in the thin bearing gap height direction. In addition, simultaneously by virtue of boundary layer simplifications for energy equation and by virtue of new measurements performed in micro and nano- level follows that oil temperature gradients and its values differences and adhesion or capillary gradients of forces in bearing gap height directions are not negligible small. The contemporary hydrodynamic theory of lubrication for non-isothermal lubricant flow is unfortunately based on the assumption of constant viscosity values across the film thickness, despite abovementioned self-evident contradiction between the fact of constant viscosity and simultaneously temperature variations in gap height direction. Such problem was up to now not sufficient critical examined and explained in practical and theoretical sense. After Authors, knowledge by virtue of above problem the most scientific papers in the domain of non-isothermal and lamellar hydrodynamic slide bearing or biobearing lubrication were up to now not sufficient correctly solved. It denotes that the main hydrodynamic lubrication solutions presenting for example hydrodynamic pressure by the modified Reynolds equation and temperature by the energy conservation equation are not sufficiently correctly obtained and next not correctly solved. Therefore are assumed simultaneously the temperature T and oil dynamic viscosity variations in length, width and bearing gap- height directions. From this assumption follows, that the energy equation must be solved simultaneously with the equations of motion i.e. consequently with pressure equation where viscosity depends on temperature and temperature depends on the coordinate in gap height direction.
Źródło:: Journal of KONES; 2016, 23, 2; 423-430
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 6.

Tytuł:: 3D hydrodynamic pressure in gap height direction for cylindrical bearing viscoelastic lubrication
Autorzy:: Wierzcholski, K.
Powiązania:: https://bibliotekanauki.pl/articles/246411.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: pressure changes in gap height direction
HDD micro-bearings
viscoelastic lubrication
Źródło:: Journal of KONES; 2013, 20, 1; 367-374
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 7.

Tytuł:: Recurrent nets for tribology solutions
Autorzy:: Wierzcholski, K.
Powiązania:: https://bibliotekanauki.pl/articles/244153.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: pressure changes in gap height direction
HDD micro-bearings
viscoelastic lubrication
Opis:: The contemporary problems of numerical calculations ocurring in powertrain tribology and transport problems demand the more and more exactness for obtained results.Moreover in performed calculations very important is the convergence, stability and reliability of the gained numerical values. The main scientific topic of the presented paper concerns the method of the determination of the optimum net for numerical calculations of partial difference and recurrence equations. The abovementioned optimum difference and recurrence method is referring to the stability of obtained particular and general numerical solutions and assures the convergence process of obtained calculation values. The Unit Net Region (UNR) was assumed at first for Laplace Operator. The optimum of the nod geometry localization was examined at first for UNR. The optimization index is defined and derived for UNR to determine the most useful net among the various geometries of the nods localization during the difference methods performances of partial recurrence numerical calculations. In the next considerations had been proved the corollary, where taking into account the optimum UNR, we can create optimum nets for other numerous partial difference and recurrence equations in discrete spaces. For example the numerous calculation results of presented optimum net for recurrent calculations are applied for numerical solutions of a Reynolds partial recurrence equation with variable coefficients in curvilinear orthogonal coordinates for curvilinear boundary conditions, and for other numerical problems occurring in applied and hydrodynamics.
Źródło:: Journal of KONES; 2013, 20, 2; 401-408
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 8.

Tytuł:: Operating parameters of slide micro – bearings with consideration of oil temperature changes and micro - grooves on sleeve surface
Autorzy:: Miszczak, A.
Powiązania:: https://bibliotekanauki.pl/articles/247490.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: HDD micro-bearings
micro-grooved surfaces
oil viscosity changes in gap height
hydrodynamic pressure
friction forces
load carrying capacity
Opis:: In this paper author presents results of numerical calculations of hydrodynamic pressure distribution in bearing gap, load-carrying capacity, friction force and friction coefficient of slide micro-bearing considering the influence of lubricating oil temperature changes and also taking into account the influence of micro-grooves, which occur on sleeve internal surface. The micro-grooves on that surface are in longitudinal direction. The equation, which describes a bearing gap with micro-grooves on sleeve surface, was adopted from prof. K Wierzcholski's investigations. In very thin gap height of cylindrical micro-bearings, large gradients of temperature can be observed. This causes significant changes of oil dynamic viscosity in the gap height direction. According to this, oil flow velocity, friction forces, and a hydrodynamic pressure during the micro-bearing operation are changing. Up to now the influence of temperature on oil viscosity changes and due to this, on hydrodynamic pressure and on load carrying capacity in cylindrical micro-bearing gap in numerical way were not considered yet. The numerical calculations were performed with the use of Mathcad 14. The finite differences method and own computational procedures were implemented. The calculations were begun by solving the Reynolds' equation, assuming, that the dynamic viscosity is constant. After calculating the hydrodynamic pressure distribution, the temperature distribution in lubricating oil was determined. The obtained function of temperature was used to describe the viscosity changes with temperature. Next step involved determining the hydrodynamic pressure distribution taking into account the viscosity dependence on temperature, and then new distribution of temperature and again new values of viscosity were calculated. Calculations were repeated until assumed convergence and accuracy were reached. The friction force depends on pressure gradient and rotational motion of bearing journal. Part of friction force, which resulting from the pressure gradient, is determined for the area, where the oil film occurs, i.e. from omega p to omega k. Part of friction force, which is related to journal motion, is determined for full wrap angle, i.e. from 0 to 2 pi. The results were presented in the form of graphs, for eccentricity ratio gamma from 0.1 to 0.9, for dimensionless length of the bearing L1=1/4. In numerical calculations were used the theoretical considerations and solutions presented in papers of K. Wierzcholski and A. Miszczak.
Źródło:: Journal of KONES; 2012, 19, 2; 329-336
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Skocz do pozycji: 9.

Tytuł:: Estimation of random friction forces on the microbearing cooperating surfaces
Autorzy:: Wierzcholski, Krzysztof
Miszczak, Andrzej
Powiązania:: https://bibliotekanauki.pl/articles/244986.pdf
Data publikacji:: 2019
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: microbearings
computer fan
hard disc driver bearings
hydrodynamic lubrication
analytical stochastic principles
analytical solutions
apparent viscosity depended on the gap height variations
Opis:: Presented paper concerns a new mathematical form of stochastic theory of hydrodynamic friction forces occurring on the real cooperating surfaces in computer micro bearing fan and computer microbearing in hard disc driver HDD. This paper presents particularly a new-review of stochastic analytical considerations realized by the authors for friction forces estimation during hydrodynamic lubrication performed on the ground of the measurements of the gap height between two roughness surfaces. After numerous experimental measurements directly follows that the random unsymmetrical increments and decrements of the gap height of computer microbearings have important influence on the load carrying capacities and finally on the friction forces and wear of cooperating surfaces. The main topic demonstrates the influence of the variations of expectancy values and standard deviation of the computer microbearing gap height on the friction forces occurring in the HDD and microbearing fan. Moreover, it is observed the evident connection between the apparent dynamic viscosity and the features of the microbearing superficial surface. Hence after abovementioned remarks follows the corollary that the influence of the microbearing gap height stochastic variations connected with the surface roughness tend moreover indirect from the apparent viscosity into the friction forces variations. The synthetic, complex elaboration of obtained results indicates finally the influence of the random roughness in micro and nano level of microbearing surfaces on the friction forces distribution. A new results contained in this paper are obtained taking into account 3D variations of dynamic viscosity of the non-Newtonian lubricant, particularly variations crosswise the film thickness and influences of surface superficial layer features on the lubricant apparent viscosity.
Źródło:: Journal of KONES; 2019, 26, 2; 167-174
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

Artykuł

Zmień widok

na półce

Informacja

Wyszukujesz frazę "GaP" wg kryterium: Temat

Źródło danych

Dostawca treści

Kolekcja

Rok wydania

Wydawca

Temat

Autor

Typ dokumentu

Język