Wyniki wyszukiwania - BazTech

1

Numerical comparison of blast waves generatedby cylindrical explosive charges with varying shapes and materials

Panowicz R., Trypolin M., Konarzewski M.

Computer Assisted Methods in Engineering and Science

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2016

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Vol. 23, no. 4

206--212

EN

A significant influence of explosive charge geometry is frequently observed during experimental testing.In this paper, the effect of explosive charge shape, along with its material properties, on the generatedblast waves is studied. The FEM analysis was conducted for six different explosive materials and threedifferent cylindrical shapes, with geometrical proportions of length L to diameter D varying between 2, 1and 0.25 and constant charge mass. We found that the blast wave generated by detonation is susceptibleto shape changes. However, the different explosive materials were influenced by the charge shape in almostthe same way, with only insignificant differences resulting from the material properties.

2

Numerical and experimental study on soil penetration with the use of vibrating head

Małek E., Miedzińska D., Bogusz P.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 72, nr 1

23--31

EN

Purpose: The aim of the paper is to present the numerical modeling of soil penetration with the steel cylinder and experimental research of deflection of elastomer pillows in vibrating head. Design/methodology/approach: Simulations were performed using LS-DYNA package with two different methods to represent soil: a hybrid approach combining typical Lagrangian elements with Smoothed Particle Hydrodynamics (SPH) particles and Arbitrary Lagrangian-Eulerian (ALE) formulation. The experimental study was performed during work of the vibrating head using optical measuring methods. Two black and white cameras of high definition (1280x800) Vision Research Phantom V12 were used. Findings: As a result of conducted numerical simulations the behavior of the soil under condition of dynamic interaction of the steel element was reflected on the base of experimental research the maximum deflection of pillows was determined. Research limitations/implications: The modeling will be used to study the coupling of steel cylinder – soil for different soil properties and different speeds of load and its correctness was prooved. The presented results of experimental studies will be used for developing a construction of MRE regulator for vibrator resonance control. Practical implications: Presented investigations are the part of a new vibrator construction development in which the modeling of soil and its interaction with the steel-like elements will be crucial for obtaining satisfactory results as well as a presented experiment. Originality/value: New solutions to enhancing effectiveness for coupled mechanical systems can be achieved by using so called “smart” materials that have one or more properties that can be significantly changed in a controlled way by external stimulation.

3

Vulnerability analysis of aircraft fuselage subjected to internal explosion

Dacko A., Toczyski J.

Archive of Mechanical Engineering

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2011

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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.

4

ALE method in the fluid-structure interactions

Křen J., Žán J.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2002

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z. 19

101-104

EN

The paper deals with an approach to the solution of the coupled fluid-structure interaction problem, where a viscous incompressible fluid and a rigid body-spring system interact with each other. In order to incorporate the effect of the moving surface of the rigid body, the arbitrary Lagrangian-Eulerian formulation is employed as the basis of the finite element spatial discretization. The semi-coupled numerical method is then used for the time integration of the equations of the motion.