Papers by Keyword: Eigenfrequencies

Abstract: The study of the bending vibrations of Euler-Bernoulli beams is typically performed based on pure elastic material models, which neglect the damping. However, in practice, due to the internal friction of the material, the vibrations are damped. This phenomenon can be taken into account by using a viscoelastic material model, in which supplementary strains, dependent on the strain rates, are considered. In the paper, free bending vibrations of homogeneous viscoelastic Euler-Bernoulli beams are studied by developing generalized forms of an exact and of an approximate method, respectively, used regularly in the study of pure elastic Euler-Bernoulli beams. The developed methods are applied and compared on a numerical example, highlighting their advantages and limitations.

Abstract: This paper deals with a problem of eigenfrequencies of cylindrical tank (steel water tank). For an ANSYS analysis of eigenfrequencies some numerical models of cylindrical tank are used and finally results got by these models are compared with experimental results in laboratory. In final part of the paper some crucial results are presented both in a graphical and numerical way.

Abstract: In this paper, modal characteristics of self-compacting concrete (SCC) beams were studied through experiment. 3 self-compacting concrete beams were gradually damaged and then subjected to vibration test in free-free boundary conditions after each load step. From analysis, eigenfrequencies could indicate the existence of damage but it could not represent the damage locations. Modal Assurance Criterion (MAC) is lesser reliable to indicate crack damage compare to eigenfrequencies. Next to these, capacity for damage detection and localization of Coordinate Modal Assurance Criterion (COMAC) and the flexibility matrix method are also examined and compared. This paper introduces in detail the dynamic properties and damage localization methods in SCC, which provide basal databases of damage diagnosis for SCC structures and promote the popularization of SCC in civil infrastructures.

Abstract: Since the atomic structure of carbon nanotubes demonstrates evidently anisotropic mechanical properties an analytical molecular structural mechanics model is introduced in order to derive longitudinal and circumferential moduli of nanotubes. The identification is based on the eigenfrequencies analysis of the proposed computational model. It is combined with the FE analysis and the interatomic potentials. Detailed derivations are presented and the predicted results are shown and discussed with a few computational examples.

Abstract: This paper is disserted to the vibrations of the sandwich panels with pyramidal truss cores. Firstly, based on the Hamilton principle the governing equations of a sandwich panel with pyramidal truss cores are obtained and the eigenfrequencies of the sandwich panel is studied. Then the dynamic response of the sandwich subjected to uniformly distributed sinusoidal loading is studied. The influences of the sizes of the panel on the eigenfrequencies of the panel are discussed. The maximum deflections of the panels of equal mass subjected to the same loading are compared.