DSpace Komunita:http://hdl.handle.net/11025/13772024-03-28T07:55:35Z2024-03-28T07:55:35ZApplication of selected multi-axial fatigue criteria on the results of non-proportional fatigue experimentsFojtík, FrantišekFuxa, JanPoruba, Zdeněkhttp://hdl.handle.net/11025/14142021-09-22T08:43:29Z2010-01-01T00:00:00ZNázev: Application of selected multi-axial fatigue criteria on the results of non-proportional fatigue experiments
Autoři: Fojtík, František; Fuxa, Jan; Poruba, Zdeněk
Abstrakt: The contribution describes the experimental results obtained from the combined loading of the specimens in the
field of high-cycle fatigue. Those specimens were manufactured from common construction steel 11523.1, melt
T31052.
The following experiments were performed: The first set of the specimen was loaded by the alternating bending
amplitude. The second set was loaded by the amplitude of the bending in combination with constant inner
overpressure. The results were evaluated by the conjugated strength criterion and another generally used multiaxial
fatigue criteria. The stress-strain analysis of the specimens by FEM was performed to determine parameters
(constants) of particular strength criteria.2010-01-01T00:00:00ZFojtík, FrantišekFuxa, JanPoruba, ZdeněkVibration analysis of tapered rotating composite beams using the hierarchical finite elementGhayour, RasoulGhayour, MostafaZiaei-Rad, Saeedhttp://hdl.handle.net/11025/14132021-09-22T08:43:29Z2010-01-01T00:00:00ZNázev: Vibration analysis of tapered rotating composite beams using the hierarchical finite element
Autoři: Ghayour, Rasoul; Ghayour, Mostafa; Ziaei-Rad, Saeed
Abstrakt: A hierarchical finite element model is presented for the flapwise bending vibration analysis of a tapered rotating
multi-layered composite beam. The shear and rotary inertia effects are considered based on the higher shear deformation
theory to derive the stiffness and mass matrices of a tapered-twisted rotating and composite beam element.
Certain non-composite beams for which comparative results are available in the literature are used to illustrate the
application of the proposed technique. Dimensionless parameters are identified from the equations of motion and
the combined effects of the dimensionless parameters on the modal characteristics of the rotating composite beams
are investigated through numerical studies. The results indicate that, comparedwith the conventional finite element
method, the hierarchical finite element has the advantage of using fewer elements to obtain a better accuracy in the
calculation of the vibration characteristics of rotating beams such as natural frequencies and mode shapes.2010-01-01T00:00:00ZGhayour, RasoulGhayour, MostafaZiaei-Rad, SaeedValidation of the adjusted strength criterion LaRC04 for uni-directional composite under combination of tension and pressureKrystek, JanKottner, RadekBek, LukášLaš, Vladislavhttp://hdl.handle.net/11025/14122021-09-22T08:43:29Z2010-01-01T00:00:00ZNázev: Validation of the adjusted strength criterion LaRC04 for uni-directional composite under combination of tension and pressure
Autoři: Krystek, Jan; Kottner, Radek; Bek, Lukáš; Laš, Vladislav
Abstrakt: Strength of unidirectional composite materials for some combinations of state of stress cannot be successsfully
predicted even with modern failure criteria. In case of the combination of compression in the transverse direction
and tension in the fiber direction, the criterion LaRC04 was adjusted in previous work. The predicted strengths
in this case reach significantly larger values compared to the ultimate strengths of the material in the respective
directions. The adjusted criterion is able to predict the failure of unidirectional composite in case of the mentioned
combination of loading. The validation of the adjusted criterion is carried out by means of the comparison of
experimental results and numerical analysis performed in finite element system MSC.Marc.2010-01-01T00:00:00ZKrystek, JanKottner, RadekBek, LukášLaš, VladislavShape optimization of a Timoshenko beam together with an elastic foundationNetuka, HorymírMachalová, JitkaŠimeček, Romanhttp://hdl.handle.net/11025/14112021-09-22T08:43:29Z2010-01-01T00:00:00ZNázev: Shape optimization of a Timoshenko beam together with an elastic foundation
Autoři: Netuka, Horymír; Machalová, Jitka; Šimeček, Roman
Abstrakt: In this article we are going first to aim at the variational formulation of the bending problem for the Timoshenko
beam model. Afterwards we will extend this problem to the Timoshenko beam resting on the Winkler foundation,
which is firmly connected with the beam. Hereafter a shape optimization for the aforementioned problems is
presented. The state problem is here represented by the system of two ordinary differential equations of the second
order. The optimization problem is given as a minimization of the so-called compliance functional on the set of
all admissible design variables. For our purpose as the design variable we will select the beam thickness. Shape
optimization problems have attracted the interest of many applied mathematicians and engineers. The objective of
this article is to present a solution method for one of these problems and its demonstration by examples.2010-01-01T00:00:00ZNetuka, HorymírMachalová, JitkaŠimeček, Roman