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    Wyświetlanie 1-5 z 5
    Tytuł:
    Experimental and numerical analysis of guided waves propagation in narrow isotropic plate with notch
    Autorzy:
    Barski, M.
    Pająk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/241897.pdf
    Data publikacji:
    2014
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    narrow plate
    aluminium alloy
    notch
    guided waves
    piezoelectric transducers
    finite element method
    Opis:
    The phenomenon of the guided waves propagation can be applied in order to detect different types of damages in real structures. The existence of flaws, like cracks, notches, or holes, causes the change of the wave propagation in the analysed structure in comparison with the intact one. However, in the vicinity of the free edges the dynamic response is very complicated due to the reflections and interference of the incident waves. Thus, the process of the damage detection and localization can be very difficult. Therefore, the current work is devoted to the experimental and numerical analysis of the guided waves propagation in the narrow, thin plates (beams). The investigated structure is made of aluminum alloy. Mainly, the influence of the notch on the waves’ propagation is studied. The waves are generated and picked up by the piezoelectric transducers. In order to carry out the numerical simulations the finite element method is applied. Moreover, the piezoelectric activators and sensors are modelled with the use of the coupled field finite solid elements and the plate with the use of the structural solid elements. Generally, three types of the waves are observed, namely the horizontal and shear wave, which move along the symmetry axis of the plate and the horizontal wave, which propagates in the perpendicular direction. The existence of the notch generally causes that the voltage amplitude of the received signal is reduced in comparison with the results obtained for the intact structure. Qualitatively, the similar effect is observed in the case of the experimental findings.
    Źródło:
    Journal of KONES; 2014, 21, 1; 23-30
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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:
    Detection of damages in hybrid composite plates with the use of elastic waves generated by PZT active sensors
    Autorzy:
    Barski, M.
    Pająk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/246873.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    elastic waves
    hybrid composite plates
    piezoelectric active sensors
    low velocity impact
    damages
    FEM
    Opis:
    The presented article is devoted to the problem of detection and localization of damages occurring in components of structures, which are made of hybrid composite materials. The subject of the work is a square plate consisting of a single layer made of aluminum alloy and several layers made of glass fibres (glass fabric) and epoxy resin. On the surface, which is made of composite, 12 piezoelectric elements are installed. These elements sequentially, one by one, generates a signal that is further recorded by the remaining piezoelectric elements. Picked up signal for the selected pair of activator – sensor is compared with the reference signal. The reference signal corresponds to the intact structure. This kind of approach is known as the pitch – catch configuration. In situations when the signal obtained for interrogated structure and reference one differs significantly, this may indicate that a damage exists between the activator and the sensor. Next, taking into account the information obtained from the other sensors, it is possible not only to detect but also to determine the approximate location of the flaw and to estimate its size. In order to visualize the obtained results, an especially dedicated software is developed according to the algorithms available in the literature – probability ellipse. Several computer simulations of wave propagation are performed using the finite element method. The proposed procedure is also tested experimentally. The presented approach makes it possible to detect both single and multiple damages.
    Źródło:
    Journal of KONES; 2017, 24, 2; 17-24
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of dispersion curves for composite materials with the use of stiffness matrix method
    Autorzy:
    Barski, M.
    Pająk, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/386825.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    structural health monitoring
    layered composite materials
    guided waves
    dispersion curves
    stiffness matrix method
    Opis:
    Elastic waves used in Structural Health Monitoring systems have strongly dispersive character. Therefore it is necessary to determine the appropriate dispersion curves in order to proper interpretation of a received dynamic response of an analyzed structure. The shape of dispersion curves as well as number of wave modes depends on mechanical properties of layers and frequency of an excited signal. In the current work, the relatively new approach is utilized, namely stiffness matrix method. In contrast to transfer matrix method or global matrix method, this algorithm is considered as numerically unconditionally stable and as effective as transfer matrix approach. However, it will be demonstrated that in the case of hybrid composites, where mechanical properties of particular layers differ significantly, obtaining results could be difficult. The theoretical relationships are presented for the composite plate of arbitrary stacking sequence and arbitrary direction of elastic waves propagation. As a numerical example, the dispersion curves are estimated for the lamina, which is made of carbon fibers and epoxy resin. It is assumed that elastic waves travel in the parallel, perpendicular and arbitrary direction to the fibers in lamina. Next, the dispersion curves are determined for the following laminate [0°, 90°, 0°, 90°, 0°, 90°, 0°, 90°] and hybrid [Al, 90°, 0°, 90°, 0°, 90°, 0°], where Al is the aluminum alloy PA38 and the rest of layers are made of carbon fibers and epoxy resin.
    Źródło:
    Acta Mechanica et Automatica; 2017, 11, 2; 121-128
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    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 1-5 z 5

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