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Vulnerability analysis of aircraft fuselage subjected to internal explosion

Dacko A., Toczyski J.

Archive of Mechanical Engineering

2011

Vol. LVIII, nr 4

393-406

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.

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.

Structural response of a blast loaded fuselage

Dacko A., Toczyski J.

Journal of KONES

2010

Vol. 17, No. 1

101-109

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.