Wyniki wyszukiwania - BazTech

1

Correction Procedure of Wave Signals for a Viscoelastic Split Hopkinson Pressure Bar

Janiszewski J., Bużantowicz W., Baranowski P.

Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa

|

2016

|

Vol. 7, Nr 1 (23)

17--30

EN

A polymeric split Hopkinson pressure bar technique (SHPB) is preferred for testing materials with low mechanical impedance. However, the use of polymeric bars requires additional analysis for data reduction, temperature complications and additional restrictions compared with traditional metallic pressure bars. A viscoelastic material, such as PMMA, exhibits both wave attenuation and wave dispersion. When a wave travels through a polymer bar, the wave amplitude decreases due to attenuation and the wave shape becomes distorted. Therefore, signals measured at given positions on a viscoelastic bar do not represent the pulse at another position along the pressure bar without complex corrections. This paper is concerned with the problem of correction of dispersion and attenuation of waves in the viscoelastic SHPB. It has been demonstrated that the Fast Fourier Transform (FFT) spectral analysis method used to reconstruct wave profiles on the measured signals which are being distorted by wave attenuation and dispersion effects is valid and allows for obtaining satisfactory results for tire rubber.

2

The Perzyna viscoplastic model in dynamic behaviour of magnetorheological fluid under high strain rates

Frąś L.

Engineering Transactions

|

2015

|

Vol. 63, iss. 2

233--243

EN

The extension of viscoplastic model of Perzyna for the field of magnetorheological materials is proposed. Perzyna’s approach is adopted to identify the mechanisms of microscopic rearrangement of ferroelements producing visible increase of material stiffness, in particular increase of shear modulus. The project of laboratory test stand is presented. It is based on Split-Hopkinson pressure bar set-up equipped with container for magnetorheological fluid and coil to control it.

3

Dynamiczne badania wytrzymałościowe drewna w obniżonych i podwyższonych temperaturach

Kruszka L.

Biuletyn Wojskowej Akademii Technicznej

|

2004

|

Vol. 53,nr 11-12

87-96

PL

W pracy przedyskutowano wyniki dynamicznych badań wytrzymałościowych trzech rodzajów drewna konstrukcyjnego: brzozy, sosny i osiki podczas monotonicznego i cyklicznego ściskania w temperaturach: pokojowej, podwyższonej i w obniżonej. Wycięte walcowe próbki były obciążane wzdłuż i w poprzek włókien oraz pod różnymi kątami do tych włókien. Drewniane próbki były badane bez i z obejmą stalową, tj. w jednoosiowym stanie naprężenia lub odkształcenia. Dodatkowo, drewniane płyty-próbki były umieszczone pomiędzy prętami pomiarowymi SPHB w celu uzyskania zależności naprężenie-odkształcenie w realnych warunkach ograniczenia poprzecznych deformacji masą materiału. Badania dynamiczne zostały zrealizowane z wykorzystaniem metody dzielonego pręta Hopkinsona na ściskanie (SPHB) przy szybkości odkształcenia 10³ s⁻¹.

EN

The dynamic strength testing results of three kinds of the structural woods, i.e. birch, pine and aspen in a monotonic and cyclic compression at room temperature as well as in lowered and elevated temperatures are discussed in this paper. The cut out cylindrical specimens were loaded along and across the fibers of the woods as well as at the other angles of cutting out from the wooden materiaIs. The wooden disk specimens were tested with and without a steel rigid jacket, i.e. in the both the unaxial strain and the stress states. Additionally, the wooden plate-specimens were placed between measuring the bars of SPHB in order to obtain the stress-strain dependence in the real confined condition of lateral deformation by the material mass. Dynamic examinations are realized using the split Hopkinson pressure bars (SPHB) method at the strain rates about 10³ s⁻¹.