Wyniki wyszukiwania - Biblioteka Nauki

1

Wybrane problemy w modelowaniu szybkozmiennych zagadnień dynamicznych

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Dacko , Toczyski J.

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tom R. 51, nr 3

123-126

PL

Artykuł przedstawia szereg problemów związanych z dobraniem odpowiednich parametrów analizy numerycznej podczas fetowania szybkozmiennych zagadnień dynamicznych. W artykule poruszono m. in. kwestię wyboru sformułowań elementów i ich wpływu na końcową postać deformacji obciążanej struktury. Zbadano również wrażliwość wyników na przyjęte uproszczenia w modelowaniu sprzężenia płyn/struktura w zadaniu, w którym sprzężenie to odgrywa kluczową rolę. Potwierdzono bardzo silne wskazania na korelację wyników obliczeń z badaniami eksperymentalnymi. Bez takich korelacji często trudno jest mówić o prawidłowych wynikach otrzymanych z programów typu „explicit".

EN

Paper presents a number of problems in choosing the appropriate parameters of the numerical FE (explicit) models of dynamic fast-changing phenomena. The paper addresses the issue of choice of shell elements formulations and their influence on faul deformation of analyzed structure. In the paper the sensitivity of results to the choices in modeling of fluid-structure interaction was also examined. Studies confirm very strong necessity of the correlation of analysis results with experimental data. Without such a correlation it is difficult to "define" the correetness ofthe results obtained from the "explicit" codes.

2

Vulnerability analysis of aircraft fuselage subjected to internal explosion

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Dacko A. , Toczyski J.

Archive of Mechanical Engineering

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2011

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tom Vol. LVIII, nr 4

393-406

EN

The most important task in tests of resistance of aircraft structures to the terorist threats is to determine the vulnerability of thin-walled structures to the blast wave load. For obvious reasons, full-scale experimental investigations are carried out exceptionally. In such cases, numerical simulations are very important. They make it possible to tune model parameters, yielding proper correlation with experimental data. Basing on preliminary numerical analyses - experiment can be planned properly. The paper presents some results of dynamic simulations of finite element (FE) models of a medium-size aircraft fuselage. Modeling of C4 detonation is also discussed. Characteristics of the materials used in FE calculations were obtained experimentally. The paper describes also the investigation of sensitivity of results of an explicit dynamic study to FE model parameters in a typical fluid-structure interaction (FSI) problem (detonation of a C4 explosive charge). Three cases of extent of the Eulerian mesh (the domain which contains air and a charge) were examined. Studies have shown very strong sensitivity of the results to chosen numerical models of materials, formulations of elements, assumed parameters etc. Studies confirm very strong necessity of the correlation of analysis results with experimental data. Without such a correlation, it is difficult to talk about the validation of results obtained from "explicit" codes.

PL

W pracy przedstawiono wybrane aspekty modelowania i symulacji numerycznych odporności struktury cienkościennego kadłuba lotniczego na obciążenia wywołane falą uderzeniową, generowaną przez wewnętrzną detonację ładunku wybuchowego o masie m0. Charakterystyki mechaniczne materiałów przyjęto z pomiarów eksperymentalnych. Zastosowano technikę sprzężenia oddziaływań między strukturą a płynem, Arbitrary Lagrangian-Eulerian, z opcją erozji zniszczonych elementów. Przeanalizowano mechanizmy zniszczenia struktury w zależności od lokalizacji ładunku wybuchowego. Rozpatrzono wpływ różnych parametrów modelu obliczeniowego na wyniki analiz. Zbadano również wpływ wymiarów przestrzeni eulerowskiej na wyniki. Wykazano bardzo silną wrażliwość analizy na przyjęte parametry, wybrane sformułowania elementów (opcje), modele materiałów. Wskazuje to na konieczność korelacji symulacji numerycznych z wynikami eksperymentalnymi. Bez możliwości takich porównań trudno mówić o walidacji modelu obliczeniowego.

3

Structural response of a blast loaded fuselage

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Dacko A. , Toczyski J.

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tom Vol. 17, No. 1

101-109

EN

The most important task in tests of resistance of aircraft structures to the terrorist threats is to determine the sensitivity of thin-walled structures to the blast wave load. For obvious reasons, full-scale experimental investigations are carried out exceptionally. In such cases numerical analyses are very important. They allow tuning modelparameters for proper correlation with experimental data. With this preliminary analysis experiment can be planned properly. The paper presents a summary of the results of numerical analysis of model of medium sizefuselage. Various manufacturing techniques are considered - the skin made of aluminum alloy (2024-T3) and the skins made of modern layered materials (GLARE) were compared. Characteristics of the materials used in FE simulations were obtained experimentally. Modelling of C4 detonation was also discussed. Studies have shown very strong sensitivity of the results to chosen numerical models of materials, formulations of elements, assumed parameters etc. Studies confirm also very strong necessity of the correlation of analysis results with experimental data. Without such a correlation it is difficult to talk about the validation of the results obtained from the "explicit" codes.

4

Seat as an element improving physical protection of soldiers during explosion of mines under the armoured military vehicles

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Sosnowicz R. , Wachowiak P. , Dorczuk M. , Rzymkowski C. , Dacko A. , Dziewoński T. , Toczyski J.

Journal of KONES

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2011

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tom Vol. 18, No. 1

595-602

EN

This study presents possibilities to apply the numerical simulation of dynamic response for explosive (impulse) loads, caused by detonation of mine under the military armoured vehicle, acting on a crew member seating in chair, in order to determine methods to minimize the results of impact of vehicle body structure on the crew, mainly caused by it accelerations and overloads. Furthermore, this article presents factors, which have impact on numerical model and detonation phases necessary to conduct the mentioned above simulation. Information on physical values acting on the soldier and injuries resulting from such actions are important to understand how important element, improving physical protection of soldiers during mine detonation below the armoured military vehicle, is a chair. According to the dissertation "Development Of Lower Extremity Injury Criteria And Biomechanical Surrogate To Evaluate Military Vehicle Occupant Injury During An Explosive Blast Even" the most common injuries occurring during mine explosion under the military vehicles, eliminating soldiers from further service, include: sprain of vertebras, fracture of vertebra, light fracture of skull, brain shaking, brain concussion, fracture of tibia, damage to ilia, fracture of fibula bones. These injuries occur most often at the first two stages of explosion, called local and global effect.