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Hodnocení mechanických vlastností částicových polymerních kompozitů pomocí měření mikrotvrdosti
Minster, Jiří ; Berka, L. ; Hristova, J.
The applicability of Vickers microhardness measurements for mechanical assessment of heterogeneous polymer composites (filled polymer composites and polymer concretes) is discussed. Two types of composites based on epoxy and polyester matrices were investigated and two types of finely dispersed fillers were used with the 20% volumetric concentration of the individual fillers. The reinforcing effect of the hard filler and changes in the microhardness (i.e. in the yield strengths and moduli) in the neighbourhood of filler micrograins have been substantiated.
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Impact of the orientation and width of wood rings on the spreading of ultrasound in the wood structure
Kloiber, Michal ; Kotlínová, M.
The subject of the paper is the relationship between ultrasound wave velocity in wood, tree rings orientation and width, and wood mechanical properties (MOE in our case). For measuring, the Arborsonic Decay Detector has been chosen. Sound velocity decreased from radial to tangential direction of measurement. In groups with radial (3) and diagonal (2) position of tree ring, increasing of tree ring width has increased sound velocity. In group with tangential tree ring position no significant influence of tree ring width has been found.
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Development of testing equipment for measuring mechanical properties of cancellous bone
Jiroušek, Ondřej ; Jírová, Jitka ; Vavřík, Daniel
Development of experimental procedures used for evaluation of mechanical properties of cancellous bone using small samples of cylindrical shape. Both the compressive and tensile specimens are tested while for the strain measurement an optical method utilizing CCD camera of high resolution is used. The procedure is used to assess the relationship between the apparent density of the cancellous bone in Hounsfield units obtained from computer tomography scans and viscoelastic material properties used in finite element modeling of whole bones.
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