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    Wyświetlanie 1-13 z 13
    Tytuł:
    Numerical analysis of progressive failure of composite energy absorbing structures
    Autorzy:
    Niezgoda, T.
    Barnat, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/243301.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    transport safety
    road barriers
    numerical analysis
    energy-absorbing element
    FEM
    Opis:
    The aim of the paper was to compare the influence of the applied fill on the energy absorbed by the energy ubsorbing structural elements made of composite, steel and from composite with fill foam. The experimental tests were carried out on an INSTRON universal testing machine at the speed rate of the machine's traverse equal 10 mm/min md the numerical analysis has been performed using MSC. Dytran software based on the Finite Element Method. The elements were subjected to axial kinematic loads. The higher specific absorbed energy occurs in the case of energy absorbing elements made of composites and from composite with fill foam. These elements can be applied in structures designed for the protection of people or limitation of the whole structure failure, e.g. in the case of a helicopter or car crash etc. The failure progressing in a relatively uniform manner results in the fact that the work md for failure of an energy absorbing element causes a substantial reduction of the impact load results. Application of energy absorbing elements may be a system dissipating the energy of a car impact into a crash barrier. The results of numerical simulation of stiffness plate hitting to the road barrier are presented. Experimental tests and numerical simulations were also presented for a composite sleeve subjected to progressive failure, which allowed carrying out simulation and analysis of a crash into a road barrier protected by a system of two such sleeves.
    Źródło:
    Journal of KONES; 2008, 15, 1; 169-181
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical and Experimental Comparison of Combined Multilayer Protective Panels
    Autorzy:
    Barnat, W.
    Panowicz, R.
    Niezgoda, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/387055.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    MES (metoda elementów skończonych)
    fala uderzeniowa
    interakcja struktury płynu
    elastomery
    panel energochłonny
    FEM
    blast wave
    fluid structure interaction
    elastomers
    protective panel
    Opis:
    The paper presents numerical and experimental analysis of combined multilayer protective panels. The developed structures are prospective solutions for enhancing protection of military vehicles and crucial elements of pipelines especially in places like river crossings.
    Źródło:
    Acta Mechanica et Automatica; 2012, 6, 1; 148-153
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Aspects of Penetration Simulation
    Autorzy:
    Morka, A.
    Zduniak, B.
    Niezgoda, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/403496.pdf
    Data publikacji:
    2011
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    computer simulations
    EFG
    SPH
    FEM
    penetration problem
    model validation
    Opis:
    Several numerical methods were studied as means of solution to a penetration problem. The Element Free Galerkin (EFG), Smooth Particle Hydrodynamics (SPH), Finite Element Analysis (FEA) methods were considered. The above mentioned algorithms implemented in the LS-DYNA code were applied. Additionally, the mesh density was taken into consideration. The reference case assumed an average node to node distance of 1 mm. The finer and coarser mesh densities were analysed. The full 3D models of the projectile and target were developed with a strain rate and temperature dependent material constitutive relations. An impact of 12.7x108 mm B32 armour piercing projectile on a 80 mm thick block of 7017 aluminium alloy was modelled. The results obtained by a computer simulation were validated and then verified by experimental data. The study of the erosion criteria involves defining the most efficient and reliable way of removing the failed and extremely deformed parts of the projectile and targets. Generally, EFG method applied to solve the perforation/penetration problems can be characterized as a very stable, reliable and effective method.
    Źródło:
    Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2011, 2, 3 (5); 21-30
    2081-5891
    Pojawia się w:
    Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Device supporting military vehicles buoyancy and ballistic resistance
    Autorzy:
    Derewońko, A.
    Sławiński, G.
    Niezgoda, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/244644.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    FEM
    ballistic protection
    buoyancy
    military vehicles
    panels
    elasto-plastic
    Opis:
    A deep modernization of equipment due to its assembling to the modern requirements of a battlefield and getting full compatibility to NATO structures caused that some military vehicles equipment with additional staff lose their buoyancy or are at the edge of losing it. The solution to this problem can be setting an additional device which helps to increase mass that allows to keep buoyancy of a military vehicle. The panels are fixed as the outer elements of the container which is simultaneously used for storing the elastic air cushions. Before the water crossing, the air cushions are filled with gas and additional buoyancy force is generated. The paper presents a structure and usage of a multipurpose ballistic protection which, in the passive state, is an additional armour and in the unfolded state increases buoyancy lost in the case of setting additional devices or armament. In the paper, initial simulations developed with the use of Ls-Dyna software are described. The influence of modules number of the air cushion on the buoyancy of the multi-purpose ballistic protection is considered. The advantage of the solution is possibility of the chamber volume change which causes the increase of device volume of the whole module of the chambers is dependent on the vehicle buoyancy which results from its current weight.
    Źródło:
    Journal of KONES; 2011, 18, 1; 129-134
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical analysis of a shaped rail pad under selected static load
    Autorzy:
    Szurgott, P.
    Gotowicki, P.
    Niezgoda, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/248000.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    numerical analysis
    FEM
    rail pad
    hyperelastic material
    fastening
    Opis:
    Numerical analysis of selected type of the polyurethane rail pad is presented in the paper. A shaped pad with cylindrical-shaped elements in its working section was selected as a representative for the computational simulation. Analysis reflected the experimental test according to the valid standard. The test included loading of the vertical force perpendicular to the foot of the rail. Such test allows determining the static stiffness of the pad. The Mooney - Rivlin material model was selected in the current study. Necessary experimental tests including a uniaxial compression and tension were conducted to provide material constants for the hyperelastic material model applied for the FE model. Simplified FE models of the considered rail pad and the rail were developed. Rounded corners and edges of the cylindrical-shaped elements were omitted, since their modelling required a significant density of the FE mesh. Vertical force perpendicular to the foot of the rail was declared as nodal force distributed evenly along the edges of the selected finite element models Non-linear static analysis was performed using MSC.Marc software with large displacements and deformations taken into consideration. The obtained results allowed estimating deformations and the state of stress in a highly deformed rail pad. The static stiffness of the pad was defined as secant stiffness based on the vertical force - deflection curve.
    Źródło:
    Journal of KONES; 2012, 19, 1; 407-414
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of true stress in engineering materials using optical deformation measurement methods
    Autorzy:
    Bogusz, P.
    Popławski, A.
    Morka, A.
    Niezgoda, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/241743.pdf
    Data publikacji:
    2012
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    true stress
    optical deformation measurement
    experimental studies
    FEM
    steel
    Opis:
    The aim of the paper is to evaluate a method of determining true stress in the steel sample subjected to static axial tensile on a universal testing machine. The tensile specimens were made of steel ST3, which was chosen because of its relatively high plastic deformations. Strain measurement was performed using traditional extensometers and additionally a non-contact optical deformation measuring system. Material properties were obtain by the extensometer measurements. The optical equipment registered the investigated sample through the optical system composed of two cameras and calculated a three-dimensional model of the material deformation in time. Displacement fields in axial and radial directions were determined with Digital Image Correlation method (DIC). Then the logarithmic axial strain map and radius shrinkage map in the area of the neck were obtained. Characteristic dimensions of the neck: curvature and width were also measured. It allowed determination of cross-section area changes in the real time, and in the result, calculation of actual true stress in the material during failure process. In this case Bridgman's and other scientists' formulas of stress distribution in the neck were applied. A numerical model, where material properties of finite elements were described by the Johnson-Cooke material model, was developed in LS-PrePost software. The FEM model was computed in LS-DYNA solver. The output tensile curve and neck curvature radius were compared with relevant data obtained from the optical measuring system.
    Źródło:
    Journal of KONES; 2012, 19, 4; 53-64
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical study of the influence of shape imperfections on residual stress fields in a rivet hole
    Autorzy:
    Sławiński, G.
    Niezgoda, T.
    Szymczyk, E.
    Jachimowicz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/246398.pdf
    Data publikacji:
    2010
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    FEM
    riveted joints
    imperfections
    residual stress
    Opis:
    The paper deals with the numerical analysis on residua! stress and strain fields in a rivet hole. This stage of study concerns improving of the fatigue performance of riveted joints in an airframe. Riveting, particularly in aviation, is a traditional but still commonly used method of joining sheet metal components. Aircraft structures are thin-walled ones, with coverings made of thin sheets stiffened by stringers, frames or ribs. Sheets are typically assembled by a multiple rivet or bolt joints. Rivets and bolts are also used to joint sheets and stiffeners. Therefore, fatigue resistance of the aircraft structure depends on tens of thousands or even hundreds of thousands r ivet joints, which are used to build it. The local numerical models of the joint are considered with regard to the aim introduced in the paper. Numerical FE simulations of an upsetting process are carried out using the LS-DYNA code. Three-dimensional numerical models are used to determine the resulting stress and strain fields at the mushroom rivet and around the hole. This type of problem requires the use of contact between the elements assembled and non-linear geometrie and elasto-plastic multilinear materiał models to simulate the behaviour of the rivet and sheets. The influence of shape imperfection on strain and stress states is studied.
    Źródło:
    Journal of KONES; 2010, 17, 2; 427-434
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical simulation of blast resistant steel plate strengthened with composite
    Autorzy:
    Kosiuczenko, K.
    Niezgoda, T.
    Barnat, W.
    Panowicz, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/245529.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    blast
    composite
    FEM
    ply
    simulation
    Opis:
    The paper presents the process of enhancing blast resistance of a thin steel plate by reinforcing it by a composite. The composite consisted of five differently orientated layers of high resistant S2/Glass fabric. Such system was subjected to a pressure wave generated by detonation of small TNT charge placed at a certain distance from the plate. Reinforcing the plate with composite layer improved the ballistic and blast wave protection level of the shield. Due to the usage of the composite the overall mass of the entire plate raised only slightly. Proposed solution can be used to improve the characteristics of existing armours by adding extra panels or modifying armours of transport vehicles. For the purpose of the numerical analysis, the Finite Element Method and explicit time integration were used. Calculations were done using LS-Dyna software. Numerical solutions of both steel plate and steel plate with composite are presented and evaluated. Pressure wave of the blast impulse, the physical model of the blast test, Structure of the four composite layer, deformation shape of steel-composite plate (pressure wave in Z-direction, t=1 ms), failure of plies, Huber-Mises-Hencky stress as material effort on plate are presented in the paper.
    Źródło:
    Journal of KONES; 2011, 18, 3; 155-160
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical simulation of thermal shock of FGMS disks
    Symulacja numeryczna szoku termicznego dysków gradientowych
    Autorzy:
    Niezgoda, T.
    Boniecki, M.
    Kosiuczenko, K.
    Barnat, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/246450.pdf
    Data publikacji:
    2007
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    MES (metoda elementów skończonych)
    materiały gradientowe
    szok termiczny
    naprężenia
    FEM
    FGM
    stress
    thermal shock
    Opis:
    Praca zawiera opis symulacji numerycznej szoku termicznego w cylindrycznych próbkach kompozytowych o zróżnicowanej grubości. Próbki wykonano z materiałów gradientowych na bazie aluminy Al2O3, z warstwami o zróżnicowanej zawartości cyrkonii zro2 w każdej warstwie. W celu przeprowadzenia oceny otrzymanych wyników numerycznych wykonano eksperyment. Wykorzystywane w obliczeniach parametry materiałowe obliczono w oparciu o wzory zaczerpnięte z teorii mieszanin. Symulację przeprowadzono wykorzystując metodę elementów skończonych zaimplementowaną w programie LS-Dyna. Modele numeryczne symulacji składały się z siatki elementów bryłowych 6 i 8-węzłowych z 3 stopniami swobody w każdym węźle, opisującej 5-stopniowy wycinek krążka. Odpowiedni sposób zdefiniowania warunków brzegowych umożliwił zmniejszenie wielkości zadania numerycznego poprzez wykorzystanie osiowej symetrii Otrzymane wyniki symulacji numerycznej pozwalają ocenić poziom naprężeń w materiale gradientowym poddanym szokowi termicznemu. Pozwalają na świadome kształtowanie odporności termicznej barier cieplnych, nie tylko modyfikując ich grubość, ale również skład chemiczny warstw. Zestawienie wyników symulacji numerycznej i eksperymentu pokazuje niewielkie różnice w przebiegach wykresów temperatur, co świadczy o poprawności zamodelowania zjawiska.
    The paper presents a description of the numerical simulation of the thermal shock in cylindrical composite specimens of diversified thickness. The specimens were made of graded materials (Al2O3 with various admixture of ZrO2). The material parameters used in numerical calculations were calculated on the grounds of the mixture method. The simulation was carried out using the Finite Element Method implemented in the LS-Dyna code. The results of numerical calculations were verified experimentally. The aim of the paper is theoretical modelling of the thermal shock problem in a strip made of functionally graded composite (FGMs). The distributions of thermal are analyzed respectively by thermo-mechanical finite element analysis (FEA). The propagation of stress in fgms is studied numerically by means of the LS Dyna code. The numerical simulation demonstrates the applicability of the algorithm to the modeling of FGM without any averaging procedure. The thermal shock resistance of disks (780 centigrade) was evaluated by sudden cooling with a high-velocity nitrogen jet at room temperature (20 centigrade).
    Źródło:
    Journal of KONES; 2007, 14, 3; 459-465
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Analysis of IED Detonation Effect on Steel Plate
    Autorzy:
    Barnat, W.
    Panowicz, R.
    Niezgoda, T.
    Dybcio, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/387041.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    fala uderzeniowa
    improwizowane ładunki wybuchowe
    MES (metoda elementów skończonych)
    blast wave
    IED
    improvised explosive device
    FEM
    finite element method
    Opis:
    The article presents the results of initial works on protection of vehicles crews against improvised explosive mechanisms (charges) IED. The presented coupled problem of explosion and interaction of pressure impulse coming from detonation was described in available standard documents. The presented results are the introduction to works oncomposed protective layers applied in vehicles.
    Źródło:
    Acta Mechanica et Automatica; 2012, 6, 1; 10-12
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on carbon dioxide thermodynamic behavior for the purpose of shale rock fracturing
    Autorzy:
    Niezgoda, T.
    Miedzińska, D.
    Małek, E.
    Kędzierski, P.
    Sławiński, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/201878.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    carbon dioxide
    shale gas
    storage system
    thermodynamics
    FEM
    Opis:
    The possibility of using CO2 to fracturing a shale rock has been presented in the paper. The described innovative method which allows for the efficient extraction of shale gas and carbon dioxide storage in a shale rock was developed in Department of Mechanics and Applied Computer Science at the Military University of Technology, Warsaw, Poland. Firstly, the method was verified on the base of analytical and experimental research. In the next stage of the method verification carbon dioxide thermodynamic behavior was studied. The growth in pressure of drop of CO2 heated in a closed volume was numerically tested. The research confirmed the efficiency of the use of carbon dioxide as a medium for fracturing of rocks. The usage of liquid CO2 can be alternative for hydraulic fracturing and is safe for the environment.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2013, 61, 3; 605-612
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical-Experimental Investigation of Squared-Based Metal Pyramids Loaded with A Blast Wave From A Small Explosives Charge
    Autorzy:
    Panowicz, R.
    Barnat, W.
    Niezgoda, T.
    Szymańczyk, L.
    Grzymkowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/387276.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    MES (metoda elementów skończonych)
    fala uderzeniowa
    interakcja struktury płynu
    FEM
    blast wave
    flud structure interaction
    Opis:
    The paper presents the results of computer simulation and experimental investigation of blast wave action arising from a small explosive charge on a metal pyramid with a square base. This explicit finite element has been used to perform numerical analyses. This method is included in the Ls-Dyna software for modelling the behaviour of the pyramid exposed to the action of a pressure wave arising from the detonation of an explosive charge. The detonation process was described in programming bubble structure interaction was used to describe an influence of a blast wave on the structure.
    Źródło:
    Acta Mechanica et Automatica; 2012, 6, 1; 49-52
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numeryczna symulacja dynamicznego procesu spęczania nitu grzybkowego z kompensatorem
    Numerical simulation of dynamic riveting process of a rivet with a compensator
    Autorzy:
    Sławiński, G.
    Derewońsko, A.
    Jachimowicz, J.
    Niezgoda, T.
    Szymczyk, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/208816.pdf
    Data publikacji:
    2010
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    połączenie nitowe
    naprężenia wstępne
    MES (metoda elementów skończonych)
    riveted joint
    residual stress
    FEM
    Opis:
    W trakcie spęczania nitu do łączonych blach wprowadzane są naprężenia wstępne, których wartość przekracza granicę plastyczności i które zależą od sposobu formowania zakuwek. Zjawisko to wpływa na wzrost trwałości zmęczeniowej połączenia. W artykule przedstawiono numeryczną analizę dynamicznego procesu zakuwania nitu przy zastosowaniu tzw. prostej metody nitowania. Analizy przeprowadzono przy zastosowaniu metody elementów skończonych za pomocą systemu LS-Dyna. Obejmowały one nieliniowości materiałowe oraz zjawiska kontaktowe z tarciem w trakcie procesu spęczania nitu.
    This paper deals with the numerical FE simulation of the dynamic riveting process of a mushroom rivet with a compensator. The riveting has remained a traditional and the most popular parts joining method in aircraft structures for many years. The residual stress state appears at the rivet hole after the riveting process, which improves the joint's fatigue behaviour. Numerical FE simulations of the upsetting process are carried out using the Ls-Dyna code. The contact phenomena with friction and nonlinear material model are analysed.
    Źródło:
    Biuletyn Wojskowej Akademii Technicznej; 2010, 59, 1; 61-74
    1234-5865
    Pojawia się w:
    Biuletyn Wojskowej Akademii Technicznej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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