DSpace Kolekce:
http://hdl.handle.net/11025/6190
2019-12-09T05:28:52ZA numerical study of wave dispersion curves in cylindrical rods with circular cross-section
http://hdl.handle.net/11025/6199
Název: A numerical study of wave dispersion curves in cylindrical rods with circular cross-section
Autoři: Valsamos, Georgios; Casadei, Folco; Solomos, George
Abstrakt: This work presents a finite element approach for modeling longitudinal wave propagation in thick cylindrical
rods with circular cross-section. The formulation is based on simple time domain response of the structure to a
properly chosen excitation, and is calculated with an explicit finite element solver. The proposed post-treatment
procedure identifies the wavenumber for each mode of wa
ve propagation at the desired frequency. The procedure
is implemented and integrated in an efficient way in the explicit finite element code Europlexus. The numerical
results are compared to the analytical ones obtaine
d from the solution of the Pochhammer — Chree equation,
which provides the dispersion curves for wavetrains in solid cylinders of infinite length.2013-01-01T00:00:00ZValsamos, GeorgiosCasadei, FolcoSolomos, GeorgeThree-body segment musculoskeletal model of the upper limb
http://hdl.handle.net/11025/6198
Název: Three-body segment musculoskeletal model of the upper limb
Autoři: Valdmanová, Linda; Čechová, Hana
Abstrakt: The main aim is to create a computational three-body segment model of an upper limb of a human body for
determination of muscle forces generated to keep a giv
en loaded upper limb position. The model consists of three
segments representing arm, forearm, hand and of all majo
r muscles connected to the segments. Muscle origins and
insertions determination corresponds to a real anatom
y. Muscle behaviour is defined according to the Hill-type
muscle model consisting of contractile
and viscoelastic element. The upper
limb is presented by a system of three
rigid bars connected by rotational joints. The whole limb is fixed to the frame in the shoulder joint. A static balance
problem is solved by principle of virtual work. The system of equation describing the musculoskeletal system is
overdetermined because more muscles than necessary cont
ribute to get the concrete upper limb position. Hence the
mathematical problem is solved by an optimization method s
earching the least energetically-consuming solution.
The upper limb computational model is verified by electromyography of the biceps brachii muscle.2013-01-01T00:00:00ZValdmanová, LindaČechová, HanaSemi-analytic solution to planar Helmholtz equation
http://hdl.handle.net/11025/6197
Název: Semi-analytic solution to planar Helmholtz equation
Autoři: Tukač, Martin; Vampola, Tomáš
Abstrakt: Acoustic solution of interior domains is of great interest. Solving acoustic pressure fields faster with lower computational requirements is demanded. A novel solution technique based on the analytic solution to the Helmholtz
equation in rectangular domain is presented. This semi-analytic solution is compared with the finite element
method, which is taken as the reference. Results show that presented method is as precise as the finite element
method. As the semi-analytic method doesn’t require spatial discretization, it can be used for small and very large
acoustic problems with the same computational costs2013-01-01T00:00:00ZTukač, MartinVampola, TomášApplication of patch test in meshless analysis of continuously non-homogeneous piezoelectric circular plate
http://hdl.handle.net/11025/6196
Název: Application of patch test in meshless analysis of continuously non-homogeneous piezoelectric circular plate
Autoři: Staňák, Peter; Sládek, Vladimír; Sládek, Ján; Krahulec, Slavomír; Sátor, Ladislav
Abstrakt: Proposed paper presents application of the patch test for meshless analysis of piezoelectric circular plate with functionally graded material properties. Functionally graded materials (FGM) are the special class of composite materials with continuous variation of volume fraction of constituents in predominant direction. Patch test analysis is an important tool in numerical methods for addressing the convergence. Meshless local Petrov-Galerkin (MLPG) method together with moving least-squares (MLS) approximation scheme is applied in the analysis. No finite elements are required for approximation or integration of unknown quantities. Circular plate is considered as a 3-D axisymmetric piezoelectric solid. Considering the axial symmetry, the problem is reduced to a 2-dimensinal one. Displacement and electric potential fields are prescribed on the outer boundaries in order to reach the state of constant stress field inside the considered plate as required by the patch test and the governing equations. Values of prescribed mechanical and electrical fields must be determined in order to comply with applied FGM gradation rule. Convergence study is performed to assess the considered meshless approach and several conclusions are finally presented.2013-01-01T00:00:00ZStaňák, PeterSládek, VladimírSládek, JánKrahulec, SlavomírSátor, Ladislav