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Nestacionární pohyb tenké ortotropní desky zatížené impulsní silou
Valeš, František ; Červ, Jan ; Volek, J.
Analytical solutions based on Flügge and Mindlin approximations of a thin elastic orthotropic plate under transverse impulse loading are discussed in the paper. The results in the form of displacements and velocities are compared with those obtained by 3D finite element solutions. Dispersion behaviour of the Mindlin approximation is studied as well. It was found out that there are always three different dispersion curves for any arbitrary direction of propagation.
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Vliv volby konstitutivního vztahu na modelování šíření vln v předepjatém prostředí
Kruisová, Alena ; Plešek, Jiří ; Červ, Jan
The most common constitutive relation in acoustoelasticity is the second-order constitutive relation expressed in terms of the Green-Lagrange strain tensor. This material model is characterized by the high sensitivity of material parameters to the small measurement errors. This rather bad property leads to the proposal of another material model with the second-order constitutive relation expressed in terms of the logarithmic strain tensor. For this material model the acoustic wave velocities were derived for three different types of homogeneous pre-stress.
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Modeling of the impact of railway wheel on a rail
Valeš, František ; Červ, Jan ; Tikal, B. ; Adámek, V.
This contribution concerns the simulation of wave phenomena originating by impacts of a railway wheel on a rail. With respect to the character of these phenomena running in time of microsecond order, it is not possible to model contacting bodies in true dimensions. Hence the model research has to be used and dimensions of bodies are chosen in such way so that the numerical solution (FEM) is feasible.The influence of material models (elastic and plastic) are studied in this work.Furthermore, the influence of plastic layer generated during wheel service on wave phenomena in the wheel is investigated.
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Wave propagation in 3D anisotropic media with cubic symmetry
Červ, Jan
Harmonic wave propagation in an anisotropic medium with cubic symmetry is studied in the paper. First of all, the general relation for phase velocities and polarizations vectors of qL and qT waves having wave vectors in planes {1 0 0} have been derived. For a general direction of wave vector in turns out that the best way to get the solution is numerical solution based on Matlab.
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R-waves in an orthotropic elastic half-plane
Červ, Jan
The properties of Rayleigh waves in an orthotropic elastic half-plane are studied in the paper. It is supposed that body axes x, y and principal materials axes 1,2 coincide. the laminate Aramid is then considered as an examle of typical orthotropic material it has been proven that R-waves propagate in principal directions nondispersively.
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