Autor: Morka, A. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

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: 2.

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: 3.

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: 4.

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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