Autor: Morka, A. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: On the modelling of penetration/perforation problems
Autorzy:: Morka, A.
Powiązania:: https://bibliotekanauki.pl/articles/246015.pdf
Data publikacji:: 2010
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
impact problem
armour perforation
penetration
ballistic resistance
Opis:: The aim of this paper was to present the main aspects of the numerical modelling within the scope of penetration/perforation problems. The most important stages of the computer model development were discussed in detail. They include the study of the hypervelocity impact physics, selection of the numerical solution method, problem discretization in time (time step) and space (mesh/grid), constitutive models consideration, Initial Boundary Conditions (IBC) and finally choice of the results form for analysis and discussion. The Computer simulations were performed with the Element Free Galerkin Method (EFG) implemented in LS-DYNA code. An impact of the 12. 7x108 mm B32 armour piercing projectile on the selected targets was analyzed. Full SD models of the projectile and targets were developed with strain rate and temperature dependent material constitutive relations. The models of the projectile, ceramic and aluminium alloy targets were validated with utilization of the experimental infield tests and data found in literature. The obtained results confirm that EFG method can be considered for numerical solving of the penetration/perforation problems. The errors in Depth of Penetration have not exceeded 20% as compared numerical and experimental results. The conclusions presented in this paper can be applied to develop modern impact protection panels where the appropriate balance between the mass and protection level must be accomplished.
Źródło:: Journal of KONES; 2010, 17, 1; 291-297
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Znaczenie dyskretyzacji przestrzennej na przykładzie numerycznej analizy problemu perforacji płyt
Importance of spatial discretization on an example of numerical analysis of plate perforation problem
Autorzy:: Morka, A.
Powiązania:: https://bibliotekanauki.pl/articles/209770.pdf
Data publikacji:: 2012
Wydawca:: Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:: mechanika komputerowa
MES (metoda elementów skończonych)
zbieżność rozwiązania
siatka numeryczna
perforacja/penetracja
computational mechanics
FEM
convergent solution
numerical mesh
perforation/penetration
Opis:: Wiele zagadnień mechaniki analizowanych metodami numerycznymi, szczególnie z obszaru procesów szybkozmiennych, wykazuje dużą wrażliwość na gęstość dyskretyzacji przestrzennej. Fakt ten związany jest z występowaniem szeregu złożonych zjawisk fizycznych oraz czynników o charakterze numerycznym, jak np. erozja, czyli usuwanie z obliczeń zniszczonych elementów. Prezentowana praca, posługując się przykładem numerycznej analizy zagadnienia perforacji płyty przez wybrany pocisk, dostarcza narzędzia (metodyki) do oceny zbieżności rozwiązania numerycznego ze względu na zmiany dyskretyzacji przestrzennej problemu. Zadanie to zostało zrealizowane poprzez adaptację metody stosowanej przez NASA w analizach CFD (ang. Computational Fluid Dynamics) do problemu z zakresu mechaniki ciała stałego. W rezultacie możliwe jest uzyskanie ilościowego wyniku obarczonego określonym błędem niezależnego od siatki numerycznej. Ponadto dostępna jest informacja określająca rząd zbieżności rozwiązania, który może stanowić dodatkowy wskaźnik poprawności rezultatu.
Many of mechanic issues analyzed by numerical methods, especially in the area of fast-changing processes, are highly sensitive to the density of spatial discretization. This fact is related to the presence of a number of complex physical phenomena and factors such as numerical erosion that is removal of damaged parts of material from the calculation. The present work using the example of a numerical analysis of the plate perforation by the selected projectile provides the tools (methodology) to assess the convergence of numerical solution due to changes in the spatial discretization of the problem. This task was carried out by adapting the method used by NASA in the CFD (Computational Fluid Dynamics) analysis to the problem of solid mechanics. Consequently, it is possible to obtain a quantitative mesh size independent result carrying the particular error. In addition, there is information indicating the convergence order of solutions, which can be an additional indicator of the result correctness.
Źródło:: Biuletyn Wojskowej Akademii Technicznej; 2012, 61, 4; 123-131
1234-5865
Pojawia się w:: Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Numerical study of the projectile trajectory disturbing during the oblique impacts
Autorzy:: Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/244096.pdf
Data publikacji:: 2010
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
impact problem
armour perforation
ballistic resistance
oblique impact
Opis:: The numerical investigations have been performed to determine the effect of the projectile trajectory disturbing during oblique impacts. An impact of the 14.5x118 mm B32 armour piercing projectile on the A12O3 different shape elements backed by 7017 aluminum alloy plate was analyzed. The oblique impact was realized by different shapes of the frontal ceramic elements, including hemispheres and pyramids, with respect to standard flat tiles. The influence of the impact point location was also under considerations. The Computer simulations were performed with the Element Free Galerkin Method (EFG) implemented in LS-DYNA code. full 3D models of the projectile and targets were developed with strain rate and temperature dependent material constitutive relations. The Johson-Cook model was applied to describe the metallic parts, while the ceramic was modelled by Johnson-Holmquist constitutive relations. The models of the projectile, ceramic and aluminium alloy targets were validated with utilization of the experimental datafound in literature. The obtained results confirmed that the projectile trajectory undergoes essential deviation because of the projectile angular velocity. The conditions for maximizing the value of this angular velocity were studied and it is possible to reach several radians per millisecond. The conclusions presented in this paper can be applied to develop modern impact protection panels where the appropriate balance between the mass and protection level must be accomplished.
Źródło:: Journal of KONES; 2010, 17, 3; 307-312
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Numerical analyses of ceramic/metal ballistic panels subjected to projectile impact
Autorzy:: Morka, A.
Nowak, J.
Powiązania:: https://bibliotekanauki.pl/articles/242960.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
impact problem
armour perforation
ballistic resistance
ceramic armour
Opis:: The paper concerns research and development on modern, ceramic-based, protective layers used in the armour of tanks, combat vehicles and aeroplanes. A task of ceramic panels is reduction and dispersion of localized kinetic energy before a projectile or its fragment approaches the interior of protected object. The numerical investigations have been performed to determine the ballistic resistance of ceramic/metal panels subjected to projectile impact. The impact of the 7.62mm armour-piercing projectile on the ceramic elements backed by a metal plate was analyzed. The tested panels were composed of a ceramic layer (Al2O3, SiC or B4C) and a metal layer (7017 aluminium alloy, Armox 500T steel or Ti6Al-4 titanium alloy). Different shapes of ceramic elements were analyzed, including hemispheres and pyramids, with respect to standard flat tiles. The influence of the impact point location was also taken into considerations. The computer simulations were performed with the Finite Element Method implemented in LS-DYNA code. Full 3D models of the projectile and targets were developed with strain rate and temperature dependent material constitutive relations. The conclusions presented in the paper can be applied to develop modern impact protection panels in which the appropriate balance between the mass and protection level must be accomplished.
Źródło:: Journal of KONES; 2012, 19, 4; 465-472
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Numerical study of the shape effect in the ceramic based ballistic panels
Autorzy:: Morka, A.
Jackowska, B.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/245901.pdf
Data publikacji:: 2009
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
impact problem
armour perforation
ballistic resistance
ceramic armour
Opis:: The numerical investigations have been performed to determine the front surface shape effect in the cer based armour systems. Different shapes of ceramic elements were analyzed, including hemispheres and pyramids with respect to standard flat tiles. The influence of the impact point location was also under considerations. The Computer simulations were performed with the Element Free Galerkin Method (EFG) implemented in LS-D code. An impact of the 14.5xll8mm B32 armour piercing projectile on the A12O3 different shape elements backe 7017 aluminium alloy plate was analyzed. Full 3D models of the projectile and targets were developed with strain, rate and temperature dependent material constitutive relations. The models of the projectile, ceramic and aluminium alloy targets were validated with utilization of the experimental data found in literature. The obtained results confirm, the preliminary presumptions, that the shape of the front surface can significant role in the overall ballistic resistance of the panel. Particularly projectile-target initial contact area st to be important factor as showed by impact point location analysis. The conclusions presented in this paper can be applied to develop modern impact protection panels where the appropriate balance between the mass and protection level must be accomplished.
Źródło:: Journal of KONES; 2009, 16, 4; 539-548
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Numerical modeling of auxetics in structure strength
Autorzy:: Stanisławek, S.
Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/241667.pdf
Data publikacji:: 2010
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
auxetics
negative Poisson's ratio
material engineering
Opis:: The paper deals with computer simulations of mechanical behaviour of a no-void ideal auxetic isotropic material. Current literature offers wide range of models which resemble the manufactured or natural structures. However, it does not answer the question how a change into auxetic no-void state would affect the continuum effective mechanical properties. Auxetic with the Poisson ratio -0.3 has been compared through typical tests to a classic steel elastic material. Most of the engineering software cannot precede Poisson ratio helow zero. Therefore a unique technique was applied using equation of state to overcome this obstacle. All simulations have been done in elastic regime. For the tensile compression tests a 10 mm edge cube was modelled, the bending test used a 5x5x250 mm bar. The loading for initial tests was realized as a kinematic displacement of particular nodes. For bar bending a force was applied in the middle of the beam. The finite element method has been used with explicit time integration algorithm implemented in commercial software with one integration point brick elements. Specific properties have been observed for each test, for tensile test auxetic showed higher strength while for compression material was weaker. Logically the bending test showed no clear influence of negative Poisson to material strength. Further simulations as a shear or impact tests are planned.
Źródło:: Journal of KONES; 2010, 17, 4; 459-462
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Numerical analysis of a multi - component ballistic panel
Autorzy:: Stanisławek, S.
Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/243005.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
ballistic protection
composite armour
ceramics
Opis:: The paper presents a numerical study of a two layer composite panel impacted by an AP (Armour Piercing) 14.5x118mm B32 projectile. The panel consists of a number of pyramid ceramic components supported by an aluminium plate. The studied model is compared with a reference structure in which ceramic layer is in a form of a plate. The problem has been solved with the usage of modelling and simulation methods as well as a finite elements method implemented in LS-DYNA software. Space discretization for each option was built with three dimension elements guaranteeing satisfying accuracy of the calculations. For material behaviour simulation, specific models including the influence of the strain rate and temperature changes were considered. A steel projectile and aluminium plate material were described by Johnson-Cook model and a ceramic target by Johnson-Holmquist model. In the studied panels, the area surrounding back edges was supported by a rigid wall. The obtained results show interesting properties of the examined structures considering their ballistic resistance. All tests have given clear results about ballistic protection panel response under AP projectile impact. Panels consisting of sets of pyramids are slightly easier to penetrate. Despite this fact, a ceramic layer is much less susceptible to overall destruction what makes it more applicable for the armour usage. Furthermore, a little influence of the projectile impact point and consequently a part of the pyramid, which is first destroyed, is proved.
Źródło:: Journal of KONES; 2012, 19, 4; 585-588
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Wpływ uproszczeń w badaniach symulacyjnych zderzeń pocisków z tarczą na dokładność wyników
Influence of simulation simplifications on results accuracy
Autorzy:: Stanisławek, S.
Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/209401.pdf
Data publikacji:: 2013
Wydawca:: Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:: mechanika komputerowa
symulacja
computational mechanics
simulation
Opis:: Artykuł omawia zagadnienie możliwości stosowania określonych uproszczeń w symulacji komputerowej. Stanowi on niezbędny warsztat dla każdego badacza stosującego opisane sposoby modelowania. Weryfikacja uproszczeń numerycznych polegała na przeprowadzeniu trzech testów zderzeniowych dla rdzenia pocisku 7,62 × 51 WC oraz czwartej symulacji polegającej na porównaniu efektów uderzenia pełnego modelu pocisku oraz jedynie jego rdzenia. Opracowane modele tarczy symulowały materiał stalowy z wprowadzonymi typowymi parametrami, natomiast pocisk był opisany modelem Johnsona-Cooka. Prędkość początkowa pocisku wynosiła 854 m/s, zaś tarcza pozostawała nieruchoma i zamocowana w płaszczyźnie prostopadłej do kierunku lotu. Opisane badania potwierdzają możliwość stosowania modelu materiału nieodkształcalnego oraz sprężystego do uproszczonego opisu ciał materialnych. Pozwala to na uproszczenie i przyspieszenie obliczeń numerycznych w sytuacjach, gdzie materiały zderzających się ciał mają znacznie różne właściwości mechaniczne. Z dużą ostrożnością powinno się odnosić do odczytywania sił rejestrowanych na ściance nieodkształcalnej. Analiza sił oraz energii pokazuje natomiast, że sabot i płaszcz pocisku nie odgrywają zasadniczej roli przy uderzeniu w nieruchomą tarczę. Doznaje ona większego popędu, jednak nie jest to różnica zasadnicza.
The paper presents the possibility of applying certain simplifications for computer simulations. It is the essential knowledge for each scientist employing the described methods of modelling. Verification of numerical simplifications consisted in conducting three impact tests for a 7.62 × 51 WC projectile core and a forth one which referred to a comparison of a full model of the penetrator with its core only. The target was described with a simple steel material while the projectile with an advanced Johnson-Cook model. Projectile initial speed was 854 m/s while a target remained motionless and fixed in a plane perpendicular to the motion direction. The performed tests confirm the possibility of using rigid and elastic materials for a simplified material body description. It allows simplification and shortening of computational time when materials are characterized by very different strength. However, a user should be very careful when analyzing the forces recorded on a rigid wall. Furthermore, analysis of the forces and energies shows that both a sabot and a jacket do not play a significant role during the impact into a motionless target. It register a bigger force impulse but it is not a substantial difference.
Źródło:: Biuletyn Wojskowej Akademii Technicznej; 2013, 62, 3; 137-143
1234-5865
Pojawia się w:: Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Numerical analysis of an influence of ceramic plate surrounding by metal components in a ballistic panel
Autorzy:: Stanisławek, S.
Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/247100.pdf
Data publikacji:: 2011
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational mechanics
ballistic protection
composite armour
ceramics
Opis:: The paper presents a numerical study of the three layer composite panels impacted by an AP (Armor Piercing) 7.62x51mm projectile. The standard panel is built with aluminum and Al2O3 ceramic plate. The studied model, however, consists of the same aluminum plate but the ceramic one is surrounded by a steel packet. The problem has been solved with the usage of the modelling and simulation methods as well as finite elements method implemented in LS-DYNA software. Space discretization for each option was built with three dimension elements guaranteeing satisfying accuracy of the calculations. For material behaviour simulation, specific models including the influence of the strain rate and temperature changes were considered. Steel projectile and aluminum plate material were described by Johnson-Cook model and ceramic target by Johnson-Holmquist model. In the studied panels, the area surrounding back edges was supported by a rigid wall. The obtained results show interesting properties of the new structures considering their ballistic resistance. The ballistic protection of a three layer panel under the WC projectile impact is indentified. Panels containing the ceramic plate surrounded at each side by a steel packet plate are stronger. However, this difference reaches only the level of 2.4% regardless erosion parameters. Definitely technological complication and an area density mass increase cannot balance a small improvement of ballistic protection. However, this kind of panel is not suggested as a useful solution. Further investigations are suggested in order to analyze an influence of initial ceramic compression. The results of those numerical simulations can be used for designing of modern armour protection systems against hard kinetic projectiles.
Źródło:: Journal of KONES; 2011, 18, 4; 471-474
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Pyramidal ceramic armor ability to defeat projectile threat by changing its trajectory
Autorzy:: Stanislawek, S.
Morka, A.
Niezgoda, T.
Powiązania:: https://bibliotekanauki.pl/articles/202070.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: computational mechanics
ballistic protection
composite armor
ceramics
mechanika obliczeniowa
ochrona balistyczna
kompozytowy pancerz
ceramika
Opis:: This paper presents a numerical study of a multilayer composite panel impacted by an AP (Armor Piercing) 14.5×114 mm B32 projectile. The composite consists of alternating layers of hard ceramic and a ductile aluminum alloy. While the alloy layer consists of typical plate, ceramics confront projectiles in the form of ceramic pyramids. The studied models are compared with a reference structure, which is a standard double layer panel. The problem has been solved with the usage of modeling and simulation methods as well as a finite elements method implemented in LS-DYNA software. Space discretization for each option was built with three dimensional elements ensuring satisfying accuracy of the calculations. For material behavior simulation, specific models including the influence of the strain rate and temperature changes were considered. A steel projectile and aluminum plate material were described by the Johnson-Cook model and a ceramic target by the Johnson-Holmquist model. The obtained results indicate that examined structures can be utilized as a lightweight ballistic armor in certain conditions. However, panels consisting of sets of ceramic prisms are a little easier to penetrate. Despite this fact, a ceramic layer is much less susceptible to overall destruction, making it more applicable for the armor usage. What is most important in this study is that significant projectile trajectory deviation is detected, depending on the impact point. Such an effect may be utilized in solutions, where a target is situated relatively far from an armor.
Źródło:: Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 4; 843-849
0239-7528
Pojawia się w:: Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:: Biblioteka Nauki

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