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Influence of vertical compresive force on level of constraint in cubical specimen for wedge splitting test
Seitl, Stanislav ; Klusák, Jan ; Dymáček, Petr ; Řoutil, L. ; Veselý, V.
The subject of the contribution is to gain new aspects of knowledge about the fracture behaviour of cementitious building materials by the wedge splitting test (WST). The particularly, the paper investigates the influence of the vertical compressive force Pv, that represents a reaction of the bottom support of the specimen, on the fracture parameters via tools of the two-parameter fracture mechanics. The effects of the vertical compressive force, Pv, on the plastic and fracture process zones are examined.
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Transition from the saltation mode of bed load transport to the rolling mode
Lukerchenko, Nikolay ; Ivanova, Irina ; Chára, Zdeněk ; Vlasák, Pavel
The paper deals with the sediment transport of sand particles conveyed by water in an open channel. A 3D numerical model developed by the authors was used for simulation of the sand particles movement in the channel with rough bed. Similarly to Shields theory of sediment transport incipient motion of the bed load particles the shear stress for the transition process from saltation mode to rolling mode can be defined. The shear stress value can be determined as a function of two dimensionless parameters, particle parameter and equivalent bed roughness. The particle parameter is a function of the particle size and density, and the carrier liquid density and viscosity. The presented numerical solution reveals that the shear stress for the transition process from saltation mode to rolling mode is less than the shear stress for the incipient sediment motion and depends on channel bed roughness.
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Creation of the helmet model from the 3D scanning
Micka, Michal ; Vyčichl, J.
Contribution deals with the preparation of the numerical model of the cycling protective helmet for calculation with the computer programme ANSYS. The helmet was scanning by the hand scanner. After evaluation of the pictures of the helmet surface are at disposal the graphic output files in the format IGES and STL . To unloaded them and for the creation of the numerical geometrical model in ANSYS the modification of the model was performed in two ways. First the input file is edited from the format IGES and second it is the creation of the helmet outside surface from triangles inscribed into the surface of the model in format STL.
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Remodelace živé kosti indukované dynamickým zatížením a dodáním léčiv – Numerické modelování a klinická terapie
Maršík, František ; Klika, V. ; Chlup, H.
The bone remodelling process is described by five ordinary differential equations for the concentrations of five relevant chemical components - mononuclear cells, old bone, osteoblast activators, osteoid and new bone. Driving force of bone remodelling process is a dynamic loading which strongly influences the rate of chemical reactions. The evolution from the homogeneous density distribution to the cancellous bone formation is shown. An influence of a dynamic mechanical loading and osteoprotegerin concentration is demonstrated. Bone deformations were calculated by commercial code ANSYS.
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