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Experimentální vyšetřování závislosti mezi mechanickými vlastnostmi spongiózní kosti a její relativní hustotou
Jiroušek, Ondřej ; Jírová, Jitka ; Jíra, J.
Finite element models of parts of human skeletal system are nowadays constructed on basis of data obtained from Computed Tomography or Magnetic Resonance images. Material properties of cancellous bone have been found to be strongly dependent on apparent density of the tissue. Experimental procedures used for evaluation of mechanical properties of cancellous bone using small samples of cylindrical shape will be described and relationship between the apparent density and Young's modulus of elasticity as well as ultimate strength are proposed. Compressive and tensile specimens are used while for the strains are measured using an optical method utilizing CCD camera of high resolution
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Časově závislé mechanické vlastnosti jedné epoxidové komposice
Minster, Jiří ; Hristova, Ju.
The paper presents results of experimental investigation of time-dependent mechanical characteristics of a homogeneous isotropic epoxy composition used either as a construction material or a s the matrix of a particulate or fibre composite. The experimental programme involved short- medium- and long-term creep and relaxation investigations of samples loaded by quasi-static pressure.The Young modulus, relaxation modulus and viscoelastic compliance were defined within active pressure and also delayed recovery. The results can serve to assess influences of some important mechanical and non-mechanical loads (mechanical loading, temperature, physical aging, climate effects)
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Vibratin of bridges under high speed trains
Frýba, Ladislav
The theoretical model explains the dynamic behaviour of railway bridges subjected to high speed trains. The method of integral transformations gives the deflections, stresses and vertical accelerations of the beam in a compact form. The numerical study presents a survey on the effect of several parameters.
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DELIVERABLE D9.6 Small sample testing
Cikrle, P. ; Drdácký, Miloš ; Lesák, Jaroslav ; Slížková, Zuzana ; Válek, Jan ; Vavřík, Daniel ; Zíma, Pavel
A number of in-situ tests for mechanical material properties is readily available but there were developed improved methodologies which met the requirements and specifics of this project. It the case of historic masonry there was necessary to deal with a common additional problem, which is the testing of non-standards samples. This was for example a problem of testing of historic bedding mortars or renders, where a typical width of sample is around 10 mm. It comes along with the general need for small ů micro samples with regards to the protection of historic masonry where a minimum intervention is always required. Mechanical properties in bending were tested on non-standard mortar samples which were supplemented symmetrically on both ends with two 'prostheses'. According to the results of the tests comparing the flexural strength of pure mortar beams with the strength ascertained on prosthesized identical material the influence of prosthesization is negligible. Testing of stone samples involved comparison of the compressive and split tensile strength of specimens of standard dimensions and specimens of smaller dimensions
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DELIVERABLE D9.5 Damaged Masonry
Drdácký, Miloš ; Lesák, Jaroslav ; Urushadze, Shota ; Válek, Jan
Several masonry trial wallets were prepared for the testing. The specimens were mounted into a special testing rig which enabled simultaneous uniform compression and cyclic horizontal loading on the top of the tested specimen. There were four hydraulic jacks generating the vertical load which was transmitted to the wall by eight ties and a steel 'hatö on the top of the wall. Horizontal displacement (force) on the top of the wall was introduced from servo-hydraulic MTS actuator of 250 kN capacity. Experimental part involved testing of brick walls for determination of crack pattern development under various combined loadings and testing of brick, sandstone and marly lime stone walls for crack and damage determination by application of NDT methods. Four approaches have been studied and evaluated: i) sonic wave propagation, ii) stress wave propagation, iii) crack pattern development, iv) modal analysis in which also a case study has been accompanied with a related pilot shaking table test of a one leaf masonry model.
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