Determination of Acoustic Vibration Modes in Apples

1993 ◽  
Vol 36 (5) ◽  
pp. 1423-1429 ◽  
Author(s):  
L. Huarng ◽  
P. Chen ◽  
S. Upadhyaya
Keyword(s):  
Acoustic Vibration ◽  
Vibration Modes

scholarly journals Dynamic Modal Analysis of Vertical Machining Centre Components

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Anayet U. Patwari ◽  
Waleed F. Faris ◽  
A. K. M. Nurul Amin ◽  
S. K. Loh
Keyword(s):  
Modal Analysis ◽  
Mode Shape ◽  
Modal Testing ◽  
Machine Component ◽  
Vibration Modes ◽  
Structural Dynamic ◽  
Element Simulation ◽  
Analysis Technique ◽  
Design Software

The paper presents a systematic procedure and details of the use of experimental and analytical modal analysis technique for structural dynamic evaluation processes of a vertical machining centre. The main results deal with assessment of the mode shape of the different components of the vertical machining centre. The simplified experimental modal analysis of different components of milling machine was carried out. This model of the different machine tool's structure is made by design software and analyzed by finite element simulation using ABAQUS software to extract the different theoretical mode shape of the components. The model is evaluated and corrected with experimental results by modal testing of the machine components in which the natural frequencies and the shape of vibration modes are analyzed. The analysis resulted in determination of the direction of the maximal compliance of a particular machine component.

scholarly journals Determination of the frequencies and forms of free vibrations of pentagonal plates by the finite-element method

2020 ◽  
pp. 61-66
Author(s):  
A. Grigorenko ◽  
M. Borysenko ◽  
O. Boychuk
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibrations ◽  
Vibration Modes ◽  
The Finite Element Method ◽  
Rigid Attachment ◽  
Equivalent Mass ◽  
Practical Convergence ◽  
Element Method

Frequencies and modes of free vibrations of an isotropic thin pentagonal plate of regular shape with various configurations of rigid attachment at the edges are determined using the finite element method (FEM). The results obtained for some pentagonal plates are compared with the results obtained for square plates of an equivalent mass with corresponding boundary conditions. We present the vibration modes of the studied plates and the topology of the vibration modes for some of the considered plates corresponding to the square plates with free edges and rigidly fixed edges. The reliability of the obtained results is ensured by the use of a substantiated mathematical model, the correct formulation of the problem and the practical convergence of the calculated frequencies when using the FEM.

Stability of Cracked Rotors in the Coupled Vibration Mode

1988 ◽  
Vol 110 (3) ◽  
pp. 356-359 ◽  
Author(s):  
C. A. Papadopoulos ◽  
A. D. Dimarogonas
Keyword(s):  
Harmonic Functions ◽  
Vibration Mode ◽  
Coupling Effect ◽  
Equations Of Motion ◽  
Vibration Modes ◽  
Coupled Vibration ◽  
Compliance Matrix ◽  
Stiffness Coefficients ◽  
Local Flexibility

A transverse surface crack is known to add to a shaft a local flexibility due to the stress-strain singularity in the vicinity of the crack tip. This flexibility can be represented, in the general case by way of a 6 × 6 compliance matrix describing the local flexibility in a short shaft element which includes the crack. This matrix has off-diagonal terms which cause coupling along the directions which are indicated by the off-diagonal terms. In addition, when the shaft rotates the crack opens and closes. Then the differential equations of motion have periodically varying stiffness coefficients and the solution can be expressed as a sum of harmonic functions of time. A method for the determination of the intervals of instability of the first and of second kind is developed. The results have been presented in stability charts in the frequency vs. depth of the crack domain. The coupling effect due to the crack leads to very interesting results such as new frequencies and vibration modes.

VIBRATION SPECTRA OF DISORDERED CRYSTALLINE SURFACE CLUSTER

2005 ◽  
Vol 19 (13n14) ◽  
pp. 625-635 ◽  
Author(s):  
R. TIGRINE ◽  
A. KHATER ◽  
O. RAFIL ◽  
M. BELHADI
Keyword(s):  
Present Model ◽  
Resonance Structure ◽  
General Character ◽  
Translational Symmetry ◽  
Vibration Modes ◽  
Localized Modes ◽  
Surface Cluster ◽  
Crystalline Surface ◽  
State Densities

A method is presented for the determination of the energies of the localized vibration modes around isolated inhomogeneity, inside a square crystalline surface. The defect breaks the translational symmetry in two directions and gives rise to localized phonons on its neighborhood. Typical dispersion curves for modes of energies along the inhomogeneity are given with their polarizations. These localized modes energies are compared with the vibration modes of the free molecule. The vibration Green's functions are determined for the system and the spectral and state densities are presented numerically for atomic sites that constitute a minimum representation set in the neighborhood of the defect. A hyperfine resonance structure that permits the analysis of the evolution of the dynamics from half-space to others is obtained. This analytic approach is applicable to different surface cluster configurations for the same underlying substrate square symmetry in the present model, which underlies the general character of the method.

scholarly journals A modal seismic design procedure based on a selected level of ductility demand

2019 ◽  
Vol 52 (2) ◽  
pp. 78-94 ◽  
Author(s):  
Milad Farahanchi Baradaran ◽  
Farhad Behnamfar
Keyword(s):  
Seismic Design ◽  
Design Procedure ◽  
Structural Systems ◽  
Code Design ◽  
Vibration Modes ◽  
Ductility Demand ◽  
Final Design ◽  
Ductility Capacity ◽  
Different Levels

Determination of seismic design forces of structures is performed by the building codes usually using response reduction (or behaviour) factors that incorporate indeterminacy and ductility capacity of lateral bearing systems. In this procedure story drifts are checked as a final design step approximately preventing stories from assuming excessive ductility demands, or seismic damage. If this procedure is reversed, a more logical seismic design approach may be developed by starting with a ductility-controlled procedure. It is the incentive of this research in which by using a large number of earthquakes, first nonlinear acceleration spectra are developed for different levels of ductility demand. Then an energy-based modal procedure is developed in which the system ductility demand is distributed between the important vibration modes based on their contribution. Finally, the developed method is applied to seismic design of several buildings selected from both regular and irregular structural systems. Comparison with a sample code design establishes success of the method in developing a more rational seismic design.

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