Wszystkie pola: structural method - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Outline of the method for prediction of lifetime achieved by ayionic hydraulic drives operated under real field conditions
Autorzy:: Ułanowicz, L.
Powiązania:: https://bibliotekanauki.pl/articles/242145.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: lifetime
probability density function
hydraulic drive
pump delivery
structural parameter
deterioration rate
wear and tear
Opis:: The presented approach to predict lifetime of avionic hydraulic drives belongs to a priori (accelerated) methods as by its nature it does not reeuire to continue tests until a hydraulic subassembly or drive reaches its boundary value of a structural parameter. The method uses distributions of a random variable with time-dependent variance as models for lifetime prediction. Variations of structural parameters over a discretional period of time are described with use of the Gaussian distribution with the assumption that the course of the process when the structural parameters are subject to deterioration comprises the entire probabilistic characteristic that defines resistance of the hydraulic drive to a wear and tear process. In that context distributions of characteristics for variations of structural parameters were determined for a selected period of time and it served as a basis to find out parameters for the distribution of the defect-free operation time. The completed functional and design decomposition of an example avionic hydraulic drive made it possible to obtain a hierarchical description of the hydraulic drive, to identify its structural parameters that are available during the drive operation as well as to define a set of measurable out put parameters of a system, a module (a hydraulic system) and a block (a hydraulic subassembly). The set of measurable output parameters attributable to the hydraulic system in question is described with use of mathematic equations that result from fundamental equations for hydraulic systems dynamics, i.e. the mass conservation law, the principle of momentum and angular momentum conservation as well as the energy conservation law.
Źródło:: Journal of KONES; 2009, 16, 2; 473-484
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Application of uncertainty analysis in structural dynamics
Autorzy:: Martowicz, A.
Pieczonka, Ł.
Uhl, T.
Powiązania:: https://bibliotekanauki.pl/articles/243305.pdf
Data publikacji:: 2008
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: structural dynamics
uncertainty analysis
eigen problem
finite element method
genetic algorithms
Opis:: The paper deals with the application of uncertainty analysis in structural dynamics. The usage of soft computing method, namely Genetic Algorithms (GA), is presented to show effective computational technique that allows for assessing the propagation of defmed uncertainties in modelled mechanical structure. Tested method is capable of finding variation of eigenfrequencies of Finite Element models and is based on scanning of interval global system matrices. During this process combination of values of input design parameters are found for which extremes of frequencies of vibration appear. FE model of windscreen, made available by Renault Technocentre, has been anafysed. Assumed uncertainties have taken. into account variability of material properties, geometrical characteristics and environmental conditions. Fuzzy theory together with alpha-cut strategy has been applied for modelling uncertain parameters. Sensitivity analysis has been performed to investigate the contribution effect introduced by each assumed input parameter to studied frequency of vibration. Obtained results have been presented and discussed within the context of referential results yielded from Monte Carlo simulation and GA used directly for the search of frequency extremes. Finally, observed time savings have been mentioned to justify the usage of tested computational method.
Źródło:: Journal of KONES; 2008, 15, 1; 153-167
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Method of determining the structural parameters of wood-polymer composite
Autorzy:: Kyzioł, L.
Murawski, L.
Powiązania:: https://bibliotekanauki.pl/articles/242880.pdf
Data publikacji:: 2014
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: modified wood
wood-polymer composite
methyl methacrylate
material constants
soft layers, hard layers
Opis:: A composite material consisting of woody skeleton and polymerized methacrylate has been developed and characterized. This paper presents an experimental program and the results concerning mechanical properties and strength of wood modified with polymerized methacrylate. In the article, there are examples of structural elements made of natural wood. Wood is a composite consisting of the layers of soft and hard wood. Wood is a composite and porous material. The porosity, which is a serious defect of wood, may be simultaneously its advantage. Wood saturation with different impregnates to minimize its disadvantages. If the wood pores will fill the monomer there is obtained the wood polymer composite. This composite is classified as of fiber composites. Such composite is effectively protected against degradation; it is durable in use, and show an improvement in mechanical properties. Design constructions of surface modified wood require the determination of fundamental material constants. Therefore, for the determination of these parameters is very important obtaining the appropriate research material. The surface impregnation of wood allows obtaining strength characteristics in a function of polymer content. This allows to model it's, and then design and perform specific ship structures. In the wood, there are three directions in relation to the annual rings. Wood properties, especially mechanical properties, are different in the selected directions. For the computation takes the orthogonal anisotropy in which there are three mutually orthogonal planes of symmetry, for which there is symmetry properties of the wood.
Źródło:: Journal of KONES; 2014, 21, 2; 177-184
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Analytical and numerical identification of lamb waves modes for hybrid composites
Autorzy:: Barski, M.
Pająk, P.
Powiązania:: https://bibliotekanauki.pl/articles/245066.pdf
Data publikacji:: 2017
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: structural health monitoring
elastic waves
dispersion curve
stiffness matrix method
numerical simulations
finite element method
group velocity
fale sprężyste
krzywa dyspersji
symulacje numeryczne
metoda elementów skończonych
prędkość grupowa
Opis:: The current work is devoted to the problem of analytical and numerical identification of fundamental elastic waves' modes, namely symmetric mode S0 and antisymmetric mode A0, in the case of hybrid composite. The investigated material consists of one layer made of aluminum alloy Pa38 and six layers made of glass fabric/epoxy resin. At the very beginning, the dispersion curves are determined with the use of stiffness matrix method. The calculated values of phase velocities are verified by numerical simulation. The semi – analytical finite element method is applied. Next, the numerical simulations of elastic waves propagation are performed. In the studied model, the plane state of strain is assumed. These simulations are carried out with the use of finite element method. The excitation signal is a sine wave modulated by Hanning window. The simulation is repeated for different excitation frequency. The group velocities of wave modes S0 and A0 are estimated and compared with the analytical results. The evaluation of the group velocities is based on the analysis of the appropriate components of displacement. The two different method are employed, namely: cross – correlation method and envelope extraction by Hilbert transform. Generally, the obtained results are in a good agreement. However, the method based on envelope extraction by Hilbert transform provides better correlation between analytical and numerical results. The significant discrepancy is observed in the case of symmetric mode S0 for relatively high values of frequency. It is caused by the dispersion phenomena. The analytical calculations are performed with the use of SCILAB 5.5.2 free software and the numerical simulations are carried out with the use of finite element system ANSYS 13.0.
Źródło:: Journal of KONES; 2017, 24, 1; 31-38
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The analysis of chosen technological parameters in the process of manufacturing components of landing gear of structural post aircraft
Autorzy:: Boś, P.
Hakim, M.
Budzik, G.
Rybak, M.
Powiązania:: https://bibliotekanauki.pl/articles/950100.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: transport
aviation
landing gear
measuring method
engineering
Opis:: High quality of components used in constructions of Landing Gears forces the manufacturers to choose appropriate technologies in order to manufacture and control dimensions of particular details. It is especially difficult to predict how the elements of huge dimensions will act during heat treat and chemical processing. The changes in size and. shape of the elements of suspension of STRUCTURAL POST aircraft are connected with hardening stresses. This requires accurate determining of allowance of final machining. The analysis of processing parameters and manufacturing of a precise component is possible with the use of high-tech coordinate measuring techniques based on touch and untouched measurements . The highest quality of machines used in manufacturing and measuring as well as innovative technologies used during the process of manufacturing STRUCTURAL POST components result in effects assumed by the designing engineer. The aim of this article is to present issues connected with technological process of manufacturing STRUCTURAL POST components as well as the analysis of particular parameters of manufacturing process which have an impact on the accuracy of dimensions and shape of the final product. These parameters are also responsible for functionality, operational reliability and safety of the Landing Gear.
Źródło:: Journal of KONES; 2013, 20, 1; 23-28
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: A probabilistic method of determining fatigue life of a structural component using the paris formuła and the probability density function of time of exceeding the boundary condition - an outline
Autorzy:: Tomaszek, H.
Klimaszewski, S.
Zieja, M.
Powiązania:: https://bibliotekanauki.pl/articles/245569.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: fatigue life
density function
fatigue cracking
Opis:: An attempt has been made to present a probabilistic method to determine fatigue life of an aeronautical structure's component by means of a density function of time a growing crack needs to reach the boundary condition. It has been assumed that in a component of a structure given consideration there is a small crack that grows due to fatigue load affecting it. After having reached the boundary value the component in question loses its usability. Time of the crack growth up to the boundary value is termed a fatigue life of the component. From the aspect of physics, the propagation of a crack within the component, if approached in a deterministic way, is described with the Paris 's relationship for m = 2. To model the fatigue crack growth a difference equation has been applied, from which the Fokker-Planck equation has been derived to be then followed with a density Junction of the growing crack. The in this way found density function of the crack length has been applied to find density Junction of time of reaching the boundary condition. This function has been used in the present paper to determine the randomly approached fatigue life of a component of a structure. The present paper has been prepared for the case there is coefficient m = 2 in the Paris formula. With the in the paper presented scheme, one can find fatigue life of the structure's component for the case m not equal to 2.
Źródło:: Journal of KONES; 2009, 16, 3; 431-438
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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