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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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Když dobrá shoda nestačí
Okrouhlík, Miloslav
Paper deals with assessment of accuracy, credibility and reliability of results obtained by analytical, experimental and numerical methods within the scope of computational mechanics.
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Rudolf Brepta – his life, work and people around him
Okrouhlík, Miloslav
The paper is devoted to life of Rudolf Brepta and to his scientific achievements. A survey of his investigation deeds, dedicated to propagation of stress waves in solids, is presented as well as contributions of his colleagues and co-workers. The analytical methods he used are briefly sketched out and a few typical results are shown
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The preprocessor for system LISA
Hora, Petr ; Šiňor, M.
In this contribution we pay attention to the propagation of the stress waves in an arbitrary complex inhomogeneous media. For the system of elastodynamic wave equations we have adopted the method of solution based on the local interaction simulation approach (LISA) and the sharp interface model (SIM) introduced for 1D, 2D and 3D cases in [1-3].
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