Volume 6, number 2 (2012)

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http://hdl.handle.net/11025/30254

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Showing 1 - 8 out of 8 results

Dynamic response of nuclear fuel assembly excited by pressure pulsations
(University of West Bohemia, 2012) Zeman, Vladimír; Hlaváč, Zdeněk
The paper deals with dynamic load calculation of the hexagonal type nuclear fuel assembly caused by spatial motion of the support plates in the reactor core. The support plate motion is excited by pressure pulsations generated by main circulation pumps in the coolant loops of the primary circuit of the nuclear power plant. Slightly different pumps revolutions generate the beat vibrations which causes an amplification of fuel assembly component dynamic deformations and fuel rods coating abrasion. The cyclic and central symmetry of the fuel assembly makes it possible the system decomposition into six identical revolved fuel rod segments which are linked with central tube and skeleton by several spacer grids in horizontal planes. The modal synthesis method with condensation of the fuel rod segments is used for calculation of the normal and friction forces transmitted between fuel rods and spacer grids cells.
Self-contained gas turbine unite with turbine expander drive of the compressor for the gas distribution station
(University of West Bohemia, 2012) Zaryankin, Arkadiy; Arianov, Sergey; Storoguk, Sergey; Rogalev, Andrey
This paper deals with the gas turbine installation with turbine expander drive of the compressor. It is shown that the offered installation has greater power capacity in comparison with the existent power turbo expanders and this unit can work in the regardless of steam turbine mode.
Thermoelastic wave propagation in laminated composites plates
(University of West Bohemia, 2012) Verma, K. L.
The dispersion of thermoelastic waves propagation in an arbitrary direction in laminated composites plates is studied in the framework of generalized thermoelasticity in this article. Three dimensional field equations of thermoelasticity with relaxation times are considered. Characteristic equation is obtained on employing the continuity of displacements, temperature, stresses and thermal gradient at the layers’ interfaces. Some important particular cases such as of free waves on reducing plates to single layer and the surface waves when thickness tends to infinity are also discussed. Uncoupled and coupled thermoelasticity are the particular cases of the obtained results. Numerical results are also obtained and represented graphically.
Buckling analysis of thick isotropic plates by using exponential shear deformation theory
(University of West Bohemia, 2012) Sayyad, Atteshamuddin Shamshuddin; Ghugal, Yuwaraj M.
In this paper, an exponential shear deformation theory is presented for the buckling analysis of thick isotropic plates subjected to uniaxial and biaxial in-plane forces. The theory accounts for a parabolic distribution of the transverse shear strains across the thickness, and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Governing equations and associated boundary conditions of the theory are obtained using the principle of virtual work. The simply supported thick isotropic square plates are considered for the detailed numerical studies. A closed form solutions for buckling analysis of square plates are obtained. Comparison studies are performed to verify the validity of the present results. The effects of aspect ratio on the critical buckling load of isotropic plates is investigated and discussed.
Influence of crucial parameters of the system of an inverted pendulum driven by fibres on its dynamic behaviour
(University of West Bohemia, 2012) Polach, Pavel; Hajžman, Michal; Šika, Zbyněk
Fibres, cables and wires can play an important role in design of many machines. One of the most interesting applications is replacement of chosen rigid elements of a manipulator or a mechanism by fibres. The main advantage of this design is the achievement of a lower moving inertia, which leads to a higher mechanism speed, and lower production costs. An inverted pendulum attached and driven by two fibres serves as a typical testing system for the investigation of the fibres properties influence on the system dynamic response. The motion of the pendulum of this nonlinear system is investigated using the alaska simulation tool. The influence of some parameters of the system of inverted pendulum driven by fibres has been investigated. The evaluation of influence of these crucial parameters of the system of inverted pendulum driven by fibres on its dynamic behaviour is given in this article.
Flexural analysis of deep beam subjected to parabolic load using refined shear deformation theory
(University of West Bohemia, 2012) Ghugal, Yuwaraj M.; Dahake, Ajay G.
A trigonometric shear deformation theory for flexure of thick or deep beams, taking into account transverse shear deformation effects, is developed. The number of variables in the present theory is same as that in the first order shear deformation theory. The sinusoidal function is used in displacement field in terms of thickness coordinate to represent the shear deformation effects. The noteworthy feature of this theory is that the transverse shear stresses can be obtained directly from the use of constitutive relations with excellent accuracy, satisfying the shear stress free conditions on the top and bottom surfaces of the beam. Hence, the theory obviates the need of shear correction factor. Governing differential equations and boundary conditions are obtained by using the principle of virtual work. The thick isotropic beams are considered for the numerical studies to demonstrate the efficiency of the theory. It has been shown that the theory is capable of predicting the local effect of stress concentration due to fixity of support. The fixed isotropic beams subjected to parabolic loads are examined using the present theory. Results obtained are discussed critically with those of other theories.
Modeling of damage evaluation in thin composite plate loaded by pressure loading
(University of West Bohemia, 2012) Dudinský, Martin; Žmindák, Milan; Frnka, Pavol
This article presents the results of numerical analysis of elastic damage of thin laminated long fiber-reinforced composite plate consisting of unidirectional layers which is loaded by uniformly distributed pressure. The analysis has been performed by means of the finite element method (FEM). The numerical implementation uses layered plate finite elements based on the Kirchhoff plate theory. System of nonlinear equations has been solved by means of the Newton-Raphson procedure. Evolution of damage has been solved using the return-mapping algorithm based on the continuum damage mechanics (CDM). The analysis was performed using own program created in MATLAB. Problem of laminated fiber-reinforced composite plate fixed on edges for two different materials and three different laminate stacking sequences (LSS) was simulated. Evolution of stresses vs. strains and also evolution of damage variables in critical points of the structure are shown.
Complex model of the lower urinary tract
(University of West Bohemia, 2012) Brandner, Marek; Egermaier, Jiří; Kopincová, Hana; Rosenberg, Josef
The complex model of the lower part of the urinary tract is introduced. It consists of the detrusor smooth muscle cell model and the detailed 1D model of the urethra flow. The nerve control is taken into account. In future this model will allow to simulate the influence of different drugs and mechanical obstructions in the bladder neck and urethra. A general muscle model involving the calcium dynamics in the smooth muscle cell and the growth and remodelling theory will be shortly introduced. For the modelling calcium dynamics the approach of Koenigsberger published in Biophysical Journal (Koenigsberger, M., Sauser, R., Seppey, D., Beny, J.-L., Meister, J.-J., Calcium dynamics and vosomotion in arteries subject to isometric, isobaric and isotonic conditions, Biophysical Journal 95 (2008) 2 728–2 738.) was adopted. The model includes the ATP consumption calculation according to Hai et al. (Hai, C. M., Murphy, R. A., Adenosine 5’-triphosphate consumption by smooth muscle as predicted by the coupled four-state crossbridge model, Biophysical Journal 61(2) (1992) 530–541.). The main part is devoted to the development of a simple bladder model and the detrusor contraction during voiding together with the detailed model of the urethra flow.

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