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    Wyświetlanie 1-5 z 5
    Tytuł:
    Composite-polymer materials for energy-absorbing structures
    Autorzy:
    Barnat, W.
    Niezgoda, T.
    Ochelski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/246205.pdf
    Data publikacji:
    2009
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    energy absorption structures
    safety
    composites
    numerical simulation
    energy absorption investigations
    Opis:
    On the basis of the results obtained from our own experimental investigations of energy- absorbing elements, the influence of the given factors on absorbed energy (WEA) was determined. The objects of the research were the samples made of epoxy composites reinforced with glass fibres formed in roving, roving stripes and glass mat as well as with carbon fibres formed in roving and carbon roving stripes. To investigate the capability of hitting energy absorption of the samples in the shape of tubes, the truncate cones and in the shape of a thin cuboid were taken under consideration. The sample in the shape of tubes, wavy coats and thin cuboids with angle 45° (on one edge), play the role of the initiator of progressive destruction process. The composites matrix was taken into account during investigations: epoxy, the vinyl-esters, polyetheretherketones, reinforced with carbon and glass fibres with different structures of the samples. The influence of the sample geometry and the orientation of the layers in carbon / epoxide and the ar amid / the epoxide composites on the WEA absorption value were presented in the papers. The comparison of the structures made f rom single elements with relevant structures of four elements shows that absorbed energy is accumulating. In this case the relative absorbed energy remains at the similar level.
    Źródło:
    Journal of KONES; 2009, 16, 1; 21-34
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical and experimental study of armour system consisted of ceramic and ceramic- elastomer composites
    Autorzy:
    Chabera, P.
    Boczkowska, A.
    Morka, A.
    Niezgoda, T.
    Oziębło, A.
    Witek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/200348.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ballistic performance
    numerical simulation
    ceramic
    wydajność balistyczna
    symulacja numeryczna
    ceramiczny
    Opis:
    The paper presents numerical and experimental results in the study of composite armour systems for ballistic protection. The modelling of protective structures and simulation methods of experiment as well as the finite elements method were implemented in LS DYNA software. Three armour systems with different thickness of layers were analyzed. Discretization for each option was built with three dimensional elements guaranteeing satisfactory accuracy of the calculations. Two selected armour configurations have been ballistically tested using the armour piercing (AP) 7.62 mm calibre. The composite armour systems were made of Al2O3 ceramics placed on the strike face and high strength steel as a backing material. In case of one ballistic structure system an intermediate ceramic- elastomer layer was applied. Ceramic- elastomer composites were obtained from porous ceramics with porosity gradient using pressure infiltration of porous ceramics by elastomer. The urea-urethane elastomer, as a reactive liquid was introduced into pores. As a result composites, in which two phases were interconnecting three-dimensionally and topologically throughout the microstructure, were obtained. Upon ballistic impact, kinetic energy was dissipated by ceramic body The residual energy was absorbed by intermediate composite layer. Effect of the composite shell application on crack propagation of ceramic body was observed.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 4; 853-859
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of numerical and experimental study of armour system based on alumina and silicon carbide ceramics
    Autorzy:
    Chabera, P.
    Boczkowska, A.
    Morka, A.
    Kędzierski, P.
    Niezgoda, T.
    Oziębło, A.
    Witek, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/202054.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ballistic performance
    numerical simulation
    armour
    alumina ceramic
    silicon carbide ceramic
    ceramic-elastomer composites
    wydajność balistyczna
    symulacja numeryczna
    zbroja
    kompozyt ceramika-elastomer
    Opis:
    The main goal of this numerical and experimental study of composite armour systems was to investigate their ballistic behaviour. Numerical simulations were employed to determine the initial dimensions of panel layers before the actual ballistic test. In order to achieve this aim, multivariate computations with different thicknesses of panel layers were conducted. Numerical calculations were performed with the finite element method in the LS-DYNA software, which is a commonly used tool for solving problems associated with shock wave propagation, blasts and impacts. An axisymmetric model was built in order to ensure sufficient discretization. Results of a simulation study allowed thicknesses of layers ensuring assumed level of protection to be determined. According to the simulation results two armour configurations with different ceramics have been fabricated. The composite armour systems consisted of the front layer made of Al2O3 or SiC ceramic and high strength steel as the backing material. The ballistic performance of the proposed protective structures were tested with the use of 7.62 mm Armour Piercing (AP) projectile. A comparison of impact resistance of two defence systems with different ceramic has been carried out. Application of silicon carbide ceramic improved ballistic performance, as evidenced by smaller deformations of the second layer. In addition, one of armour systems was complemented with an intermediate ceramic-elastomer layer. A ceramic-elastomer component was obtained using pressure infiltration of gradient porous ceramic by elastomer. Upon ballistic impact, the ceramic body dissipated kinetic energy of the projectile. The residual energy was absorbed by the intermediate composite layer. It was found, that application of composite plates as a support of a ceramic body provided a decrease of the bullet penetration depth.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 2; 363-367
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelowanie i symulacja numeryczna drgań młota udarowego RG-1
    Modelling and numerical simulation of RG-1 spring stroke hammer
    Autorzy:
    Klasztorny, M.
    Niezgoda, T.
    Gieleta, R.
    Talarek, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/211218.pdf
    Data publikacji:
    2010
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    dynamika maszyn
    młot udarowy
    elementy energochłonne
    wibroizolacja
    modelowanie
    symulacja numeryczna
    dynamics of machines
    stroke hammer
    energy absorbing elements
    vibroisolation
    modelling
    numerical simulation
    Opis:
    Przedmiotem modelowania i symulacji jest oryginalny młot udarowy sprężynowy o nazwie RG -1, zaprojektowany i wykonany w Katedrze Mechaniki i Informatyki Stosowanej Wydziału Mechanicznego Wojskowej Akademii Technicznej w Warszawie [1]. Opracowano nieliniowy dyskretny model dynamiczny układu młot-badany element energochłonny-wibroizolacja-fundament-podłoże i wyznaczono wartości parametrów tego modelu. Sformułowano nieliniowe równania ruchu układu w niejawnej postaci i opracowano algorytm numerycznego całkowania tych równań. Opracowano program komputerowy KESHA v2 do symulacji numerycznej drgań układu. Przeprowadzono wstępne badania numeryczne energochłonności elementów kompozytowych cylindrycznych. W celu redukcji drgań wywołanych pracą młota, urządzenie posadowiono na żelbetowym fundamencie blokowym za pośrednictwem wibroizolacji GERB, którą stanowi układ czterech wibroizolatorów sprężynowych z tłumikami wiskotycznymi, typu KV-452-247 03. Badany młot udarowy należy do klasy młotów o średnich prędkościach uderzenia i średniej energii uderzenia (vu = 2,5-11 m/s; Eu = 0,1-6,0 kJ).
    The study presents modelling and numerical simulation of the RG -1 spring stroke hammer, using the multi-body dynamics approach. The device has been designed and erected at the Laboratory of Strength of Materials of the Department of Mechanics and Applied Computer Science of Military University of Technology, Poland. The study develops a nonlinear discrete dynamic model of the hammer-examined specimen-vibroisolation-foundation-subsoil system as well as determines the values of the system parameters. A nonlinear matrix equation of motion of the system has been formulated partly in the implicit form, taking into consideration subsequent/simultaneous stages of the dynamic process, i.e., rapid release of the ram catch, expansion of the mainsprings, impact of the ram onto the examined specimen, shock absorption by the elastomeric pads, reduction of the forced vibrations by GERB vibroisolators, propagation of the vibrations in the subsoil, free damped vibrations of the system. An implicit algorithm for numerical integration of equations of motion, based on Newmark's average acceleration method, has been formulated. The problem has been reflected by a computer programme written in Pascal. The study presents numerical simulations reflecting dynamic tests of energy-absorbing composite cylindrical specimens. The ram fixed to the moving traverse is able to induce progressive failure up to the specimen length minus 15 mm. A distance of 15 mm is reserved for gathering the material of the destroyed part of the specimen. If this distance is achieved, the moving traverse strikes onto the elastomeric pads fixed to the cantilevers. All possible breakings away are taken into consideration in the matrix equation of motion. In order to reduce vibrations, induced by rapid releasing of the ram catch and by the main impact, the device has been connected to RC block foundation with four viscoelastic KV-452-247 03 GERB vibroisolation units. The fundamental natural frequency of the system is close to f1 = 3.4 Hz. The exemplary time histories of vibrations of select subsystems, corresponding to the initial shortening of the mainsprings equal to s = 75 mm and 150 mm, number of bobs n = 0, and the carbon/epoxy specimen CE-1, are shown in Figs. 10 and 11. The multi-body dynamic model of the device, the dynamic equation of motion, the computer algorithms and the computer programme constitute an effective tool for predicting energy absorption of composite specimens and for assessment of vibration isolation effectiveness. The GERB vibroisolation has appeared to be very effective. The investigated device belongs to the hammers class of the medium impact velocities (vu = 2.5-11 m/s) and the medium impact energy (Eu = 0.1-6.0 kJ).
    Źródło:
    Biuletyn Wojskowej Akademii Technicznej; 2010, 59, 4; 313-334
    1234-5865
    Pojawia się w:
    Biuletyn Wojskowej Akademii Technicznej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelowanie i symulacja numeryczna wężykowania szybkobieżnego pojazdu szynowego Shinkansen na torze prostoliniowym
    Modelling and numerical simulation of snaking of a high-speed Shinkansen rail-vehicle moving on a rectilinear track
    Autorzy:
    Klasztorny, M.
    Niezgoda, T.
    Dziewulski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/208662.pdf
    Data publikacji:
    2011
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    dynamika pojazdów
    pojazd szynowy Shinkansen
    tor prostoliniowy
    wężykowanie
    modelowanie
    symulacja numeryczna
    dynamics of vehicles
    Shinkansen rail-vehicle
    rectilinear track
    snaking
    modelling
    numerical simulation
    Opis:
    W pracy opracowano model dynamiczny 3D (fizyczny, geometryczny i numeryczny) japońskiego szybkobieżnego pojazdu szynowego SHINKANSEN poruszającego się po torze prostoliniowym niepodatnym, o stożkowatości szyn 1:20. Opracowano metodykę modelowania układu pojazd ruchomy-szyny (MV-R) oraz modelowania wężykowania z możliwością uderzeń bocznych obrzeży kół o główki szyn. Zastosowano licencjonowane oprogramowanie CATIA V5R15, HYPERMESH v10, LS-DYNA v971. Przeprowadzono badania symulacyjne wężykowania pojazdu SHINKANSEN w zakresie prędkości 100-300 km/h. Większość podukładów układu pojazd ruchomy-szyny (MV-R) zamodelowano jako bryły idealnie sztywne. Stalowe obręcze kół pojazdu oraz górne części stalowych główek szyn zamodelowano jako odkształcalne i wykonane z materiału izotropowego liniowo-sprężystego. Łożyska osi zestawów kołowych pojazdu SHINKANSEN zamodelowano za pomocą więzów CONSTRAINED_JOINT_REVOLUTE. Uwzględniono kontakt pomiędzy obręczami kół i główkami szyn typu AUTOMATIC_SINGLE_SURFACE, z zastosowaniem funkcji kary. Uwzględniono tarcie kinetyczne Coulomba na styku powierzchni tocznych i obrzeży obręczy kół i główek szyn. Analizowano przyspieszenia poziome poprzeczne reprezentatywnych punktów nadwozia oraz przemieszczenia poziome poprzeczne środków ciężkości zestawów kołowych.
    The study develops the 3D dynamic model (physical, geometrical, and numerical) of a high-speed Shinkansen rail-vehicle moving on a rectilinear track of 1:20 rail-head conicity. A new methodology has been developed for modelling the moving vehicle-rails system (MV-R) as well as for modelling lateral vibrations of the vehicle, induced by snaking and possible impacts of wheel flanges onto rail heads. Advanced licensed CAE software has been applied, i.e., CATIA V5R15, HYPERMESH v10, and LS-DYNA v971. Numerical simulations have been performed for service velocities of a Shinkansen rail-vehicle ranged from 150 to 300 km/h. The partial geometric model of the MV-R system has been created with CATIA V5R15 software, using the Assembly Design, Part Design, Generative Shape Design modules. The geometric model in the universal form (the STEP file) has been carried into HYPERMESH v10 system in order to build the complete equivalent geometric model, to make FEM meshing, and to declare the initial and boundary conditions. Most subsystems have been modelled in LS-DYNA v971 as rigid bodies (MAT_020). Tyres and the rail heads are deformable and made of linear-elastic isotropic steel (MAT_001). Radial bearings of wheel-set axles have been modelled with CONSTRAINED_JOINT_REVOLUTE, as shown in Figure 1. The 1st and 2nd stage 3D linearly-viscoelastic suspensions (MAT_066) have been reflected with the zero-length elements of properties SECTION_BEAM, in Discrete Beam formulation. In order to activate gravity forces, the FE locations have been removed to the predicted final static state, and then the gravity forces reflecting the total weight of the vehicle have been put onto the wheel-set axle-bearing cases. After the dynamic relaxation process, all elements of the body and bogie frames had got the initial velocity in the longitudinal direction (coinciding the track axis), whereas the rotating parts (wheels and axles) had got the angular velocity about respective axle axes. In order to keep the constant service velocity, all wheel sets had got a constant angular velocity. In order to unbalance the rail-vehicle, the body has been loaded by lateral moment impact of rectangular shape and of 22 kNms value. The tyre-rail head contact of AUTOMATIC_SINGLE_SURFACE type has been used taking into account the penalty function. The kinetic dry friction coefficient is equal to 0.10. The average time step was equal to dt = 1.23 μs. The calculations in the LS-DYNA system have been performed using double precision. The real process lasting 7.2 seconds was simulated numerically for 104 hours, using 8 processors of the cluster. The final results constitute: lateral displacements and accelerations of the representative points of the body and the lateral displacements of the gravity centres of the wheel sets. Exemplary time histories are presented in the study. The main conclusions resulting from numerical simulations are as follows. The CAE software used in the study is a very effective tool for 3D numerical simulations of the MV-R system taking into consideration a curvilinear cross-section of the rail heads, the one-side contact of wheels and rails and the Coulomb friction. The simulations show that anti-symmetric unbalance rapidly tends to stable symmetric lateral vibrations of the bogies of frequency depended on the service velocity. The lateral vibration frequencies belong to the interval 1.7-4.2 Hz.
    Źródło:
    Biuletyn Wojskowej Akademii Technicznej; 2011, 60, 1; 309-324
    1234-5865
    Pojawia się w:
    Biuletyn Wojskowej Akademii Technicznej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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