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Wyszukujesz frazę "matrix method" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
An application of stiffness matrix method to determining of dispersion curves for arbitrary composite materials
Autorzy:
Barski, M.
Pająk, P.
Powiązania:
https://bibliotekanauki.pl/articles/244021.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
SHM system
multi-layered composites
elastic waves
dispersion curves
stiffness matrix method
Opis:
Nowadays multi-layered composite material is very often applied in different kind of structures, like aircrafts, boats or vehicles. Parts of structures, which are made of these materials, are significantly lighter in comparison with traditional materials, like aluminum or steel alloys. On the other hand, the process of damage creation and evolution in the case of composites is much more complex. Moreover, the damages, which are characteristic for multi-layered materials (matrix cracking, fibre breakage, delaminations), are very difficult to detect at early stage of creation. Hence, there is a need to develop the advanced methods to detect them without destroying tested composite element. One of them is based on analysis of elastic wave propagation through the composite structure. Unfortunately, elastic waves possess strongly dispersive character. Thus, it is necessary to determine dispersion curves for investigated material before the tests in order to appropriate interpretation of received dynamic response of structure. In the case of arbitrary composite materials, it is rather challenging task. In the present article the relatively new, analytical method is applied, namely stiffness matrix method. The fundamental assumptions and the theoretical formulation of this method are discussed. Next numerical examples are presented, namely the dispersion curves are determined for the single orthotropic lamina and multi-layered 'quasi - isotropic' composite plate. The studied plates are made of glass fibres and epoxy resin. In the case of single lamina, the dispersion curves are determined in the parallel, perpendicular and arbitrary direction of waves propagation with respect to the fibre direction. In the case of multi-layered plates, the dispersion curves are computed for one arbitrary direction. Additionally, the phase and group velocities for fundamental modes and fixed excitation frequency are estimated in all directions of waves propagation.
Źródło:
Journal of KONES; 2016, 23, 1; 47-54
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
    Wyświetlanie 1-2 z 2

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