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A Split Hopkinson Bar Method for Testing Materials with Low Characteristic Impedance
Buchar, J. ; Řídký, R. ; Drdlová, M. ; Trnka, Jan
A split Hopkinson pressure bar (SHPB) technique has been developed to study dynamic behaviour of materials having low characteristic impedance. To enable better matching of characteristic impedance with a specimen, polymethyl methacrylate (PMMA) bar is used as the output bar. The viscoelastic properties of PMMA are determined in advance through preliminary experiments. In the present SHPB method, the wave analysis of the stress pulses is executed in the frequency domain. Transmitted pulses on the PMMA output bar resulting from a SHPB test are resolved into frequency components by the Fourier transform, and are corrected to be the waveforms at the specimen-bar interfaces. The corrected waveforms have been used for the evaluation of experimental results on the stress pulse transmission and reflection at the interface between elastic (Aluminium) and viscoelastic bars.
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Component-wise partitioned finite element method in linear wave propagation problems: benchmark tests
Kolman, Radek ; Cho, S.S. ; Červ, Jan ; Park, K.C.
A novel explicit time scheme for nite element computations of wave propagation problems in solids is presented. The presented algorithm, with the component-wise partition of equations of motion to the longitudinal and shear parts, is designed to more precisely integrate wave propagation in accordance with their dierent propagation wave speeds. The suggested three-time step integrator is fully explicit with the diagonal mass matrix, of second-order accuracy, conditionally stable and it exhibits minimal sensitivity behavior on time step size satisfying the stability limit. We present two numerical tests of wave propagation phenomena to show accuracy and performance of the proposed method.
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Rudolf Brepta a jeho doba
Okrouhlík, Miloslav
Článek se věnuje životu a dílu Rudolfa Brepty. Je uveden přehled jeho prací, prací jeho kolegů a spolupracovníků. Analytické metody, jichž byl v tomto oboru zakladatelem jsou stručně naznačeny.
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Preprocesor pro systém LISA
Hora, Petr ; Šiňor, M.
V příspěvku jsme nastínili odvození a implementaci metody založené na přístupu simulace lokální interakce (LISA) a modelu ostrého přechodu (SIM) pro řešení šíření napěťových vln ve 2D a 3D prostředí.V současnosti zahrnuje implementace pouze ortotropní materiály a vnitřní geometrii lze sestavit pouze z jednoduchých útvarů (2D: obdélníky, kruhy, elipsy, atd.; 3D: kvádry, koule, válce, atd.).
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