In this paper, a study on finite element dynamic model optimization is conducted on the basis of taking the inherent frequency of the aircraft structure measured from the vi-bration experiments as the larger.
The first work of the second part in this paper was to deduce the dynamic equation of cable-net problem, than inferred the eigenvalue equation for narrow range vibration of cable-net by using BEM , Finally the dynamic problem for cable-net was resolved precisely , because the solution of the cable-net's inherent frequency also was found by using BEM.
Hilbert-Huang Transform (HHT) is applied to the damage identification and intrinsic frequency confirmation of time-variable structures. Furthermore, a kind of inverse calculation is presented to calculate structural stiffness. This method can solve three main problems: the time that damage occurred, the location and the degree of damage.
During the low strain dynamic test of the foundation pile, the adoption of the velocity sensor to the direct measurement of the relative displacement of the pile head is helpful to reducing the improper dependence upon the measured intrinsic frequency valuesof the pile soil system in calculating vertical bearing capacity of the single pile, and is hence conducive to raising the accuracy of the calculated vertical bearing capacity of the single pile.
This study investigated the dynamic modulus of elasticity (DMOE) of wood panels of Fraxinus mandshurica, Pinus koraiensis, and Juglans mandshurica using the natural frequency measurement system of fast Fourier transform (FFT).
The natural frequency reached 1.201-kHz using finite element analysis, and the practice measurement result was 1-kHz.
Using the differentials of a stiffness matrix to design parameters, a method for calculating the sensitivity of natural frequency is presented.
Through the mode analysis of the liquid-solid coupled system, the first-order natural frequency, diaphragm vibration shape and amplitude-frequency relationship are obtained.
The natural frequency of the system was less than that of the structure on rigid foundation if the SSI is not taken into account, while its damping ratio was larger than that of the structure.
Code combining is used to exploit the multiple signal copies resulting from the inherent frequency diversity of spread spectrum.
Even though the gain due to selection in frequency selective channels is reduced compared to that in flat fading channels due to the inherent frequency diversity, the performance improvement is significant when the system is interference limited.
Each device operates at some inherent frequency, with wide variation among devices.
The windowing helps by reducing the inherent frequency broadening of each interferer caused by the finite duration of the FFT.
The forward problem is to solve the natural frequencies through a cracked structural model and the inverse problem is to quantitatively determine the crack parameters using the experimental testing frequencies.
Contour plots of normalized crack location versus normalized crack size were plotted by using the first three natural frequencies as the inputs.
The estimations of natural frequencies and damping coefficients of the platform found as a result of data processing of microacceleration measurements made during its free oscillations are obtained.
Determining the natural frequencies of fluid oscillations in complex pipelines
Below we formulate the problem of the natural frequencies of small oscillations of a liquid for the general case of an equilibrium liquid surface in a weak potential mass force field.
On this assumption, deviations of the Zeitgeber-frequency from the intrinsic frequency of the dependent systems cause phase-angle differences between the two systems.
Also, with short and relatively weak intersegmental connections, the network remains robust against perturbations as well as intrinsic frequency differences along the chain.
The temporal variation of the tidal component of the wind changes the observed frequency, sometimes substantially, while leaving the intrinsic frequency unaltered.
The intrinsic frequency and vertical and horizontal wavelengths of gravity waves in the stratosphere are 2f-3f, where f is the Coriolis parameter, and 2-3?km and 300-500?km, respectively.
Numerical evidence is given here that the family of such orbits is a continuous function of the rotation frequency Ω which varies between Ω?=?0, for the planar figure eight orbit with intrinsic frequency ω, and Ω =?ω for the circular Lagrange orbit.