Národní úložiště šedé literatury Nalezeno 4 záznamů.  Hledání trvalo 0.00 vteřin. 
Finite element implementation of creep constitutive model including transient effects
Gabriel, Dušan ; Masák, Jan ; Plešek, Jiří ; Kloc, Luboš ; Dymáček, Petr
A complex creep constitutive model including transient effects was implemented in the finite element code PMD (Package for Machine Design). The material model for P-91-type creep-resistant steel together with computer implementation was verified by means of uniaxial stress loadings. Testing bar was discretized by the finite element method (FEM) and loaded with uniaxial stresses and constant temperatures that were used to demonstrate the analytical solutions in original paper.
Temporal-spatial dispersion analysis of finite element method in implicit time integration
Kruisová, Alena ; Kolman, Radek ; Mračko, Michal ; Okrouhlík, Miloslav
The temporal-spatial dispersion analysis for the linear finite element method with implicit time integration is presented. The Newmark method with β = 1/2 and γ = 1/4 is used as well as the consistent\nmass matrix. The temporal-spatial dispersion relationships are derived in the closed form and analyzed due to errors in numerical wave speed of propagation of harmonic wave. Based on this temporal-spatial dispersion analysis, a suitable mesh size and time step size for allowed errors in phase speed are mentioned as well as we present the polar dispersion graphs.
Bi-penalty stabilized explicit finite element algorithm for one-dimensional contact-impact problems
Kolman, Radek ; Kopačka, Ján ; Tkachuk, A. ; Gabriel, Dušan ; Gonzáles, J.A.
In this contribution, a stabilization technique for finite element modelling of contact-impact problems based on the bipenalty method and the explicit predictor-corrector time integration is presented. The penalty method is a standard method for enforced contact constrains in dynamic problems. This method is easily implemented but the solution depends on numerical value of the stiffness penalty parameter and also the stability limit for explicit time integration is effected by a choice of this parameter. The bipenalty method is based on penalized not only stiffness term but also mass term concurrently. By this technique with a special ratio of mass and stiffness penalty parameters, the stability limit of contact-free problem is preserved. In this contribution, we also present a modification of the explicit time scheme based on predictor-corrector form. By meaning of this approach, spurious contact oscillations are eliminated and the results do not depend on numerical parameters.
On computing of pulse propagation and reflection in 2D elastic waveguide
Berezovski, Arkadi
Pulse propagation in elastic waveguides is simulated by means of finite volume methods. Results of calculations by means of the standard wave-propagation algorithm are compared with those obtained by the thermodynamically consistent excess quantities method. The main difference in these approaches is in the implementation of boundary conditions. The similarity and the distinction of the results are demonstrated.

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