A Technique to Locate Damage in a Beam Using Non-Resonant Frequency Response Vibration Data

1997 ◽  
Author(s):  
Colin P. Ratcliffe
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Vibration Data

Mechanical Contact Frequency Response Measurements

2000 ◽  
Vol 122 (4) ◽  
pp. 828-833 ◽  
Author(s):  
S. S. Kupchenko ◽  
D. P. Hess
Keyword(s):  
Frequency Response ◽  
Phase Lag ◽  
Lithium Grease ◽  
Mineral Oils ◽  
Vibration Data ◽  
Response Data ◽  
Lubricated Contacts ◽  
Wide Range ◽  
Contact Frequency ◽  
Dry Conditions

This paper presents friction frequency response measurements taken from a planar steel contact subjected to controlled random broadband normal vibration. Data are included from both dry and various lubricated contact conditions under different vibration input levels and different sliding velocities. Frequency response data for dry contacts are found to have nearly steady magnitude and negligible phase lag over a relatively wide range of frequencies. This suggests a coefficient of friction, independent of frequency but dependent on levels of normal acceleration and sliding velocity, may adequately define the dry contact frequency response. The frequency response data for lubricated contacts are mixed. For example, with MoS2 grease the frequency response may adequately be defined by a constant, as with dry conditions. However, frequency response data for contacts with pure mineral oils, mineral oils with additives, and lithium grease are found to be dependent on frequency. [S0742-4787(11)00101-9]

Resonant frequency response of plasma wave detectors

2006 ◽  
Vol 89 (21) ◽  
pp. 213512 ◽  
Author(s):  
Sungmu Kang ◽  
Peter J. Burke ◽  
L. N. Pfeiffer ◽  
K. W. West
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Plasma Wave

Resonant Frequency Response of Cymbal Transducer

2002 ◽  
Vol 273 (1) ◽  
pp. 321-326 ◽  
Author(s):  
P. Ochoa ◽  
M. Villegas ◽  
J. F. Fernández
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Cymbal Transducer

scholarly journals Control the Frequency Response of a Loudspeaker by Changing Its Enclosure

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Pavlo Olehovych Riabokon
Keyword(s):  
Resonant Frequency ◽  
Resonance Frequency ◽  
Frequency Response ◽  
Rock Music ◽  
Low Frequency ◽  
Total Quality ◽  
Frequency Range ◽  
Low Frequencies ◽  
Frequency Components ◽  
Internal Volume

This article analyzes how to control frequency response of a loudspeaker by changing the volume of its closed-box enclosure. The calculation is performed by the method of  Thiele-Small on the basic of a pre-calculated loudspeaker, the parameters of which are given in third section. This became possible because of the simplification of the circuit on figure 1 to the form of circuit on figure 2. This allowed us to consider it as a second order filter (presence of two reactive elements). Obtained results are compared with corresponding characteristics of open-box enclosure of the same loudspeaker, that was pre-calculated by the author too. Results are presented graphically in figure 3 and 4. As can be seen from them, the resonant frequency of the loudspeaker in the closed-box enclosure is higher than the resonant frequency of the loudspeaker in the open box. The result in the form of a ratio  is listed in table 2. Analyzing the obtained data, it can be noticed that with the change of the internal volume of the closed box (and hence its total quality factor), it is possible to affect both the resonance frequency and the peak amplitude values in these frequencies by changing the FR. The result shown in figure 3 and 4 is achieved by taking into account effect of radiation only on the one side of the driver (in the case of open-box enclosure). Closed box was calculating by taking into account both sides radiation of the driver. Shifting the resonance frequency of the system towards higher frequencies and increasing the sound pressure on the resonance generally worsens the FR of the loudspeaker (reduces the reproduction of low-frequency components of sound and increases the unevenness of the frequency). However, certain variants of this group of frequency characteristics may be useful depending on the reproducible frequency range and need of emphasize the low-frequency components (for example, in rock music). If you need a smoothed low-frequency sound, it is appropriate to use systems with low overall quality and increased internal volume or open-box enclosure. Therefore, the volume of the closed-box enclosure significantly affects the resonant frequency and the shape of the frequency response of the loudspeaker. Reducing the volume of the enclosure of the loudspeaker leads to a decrease in its frequency range due to low frequencies and at the same time increase in the unevenness of the frequency response. The change in the resonant frequency of the system as the volume of the closed-box enclosure decreases, the less the volume of the closed-box.

Frequency Response of Cylindrical Resonators in a Viscous Fluid

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Michael J. Martin ◽  
Brian H. Houston
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Quality Factor ◽  
Linear Models ◽  
Analytic Solution ◽  
Equations Of Motion ◽  
Offshore Structures ◽  
Crossover Frequency ◽  
Fluid Density ◽  
Cylindrical Resonators

The frequency response of a cylinder in a viscously damped fluid is a problem of fundamental engineering interest, with applications ranging from microsystems to offshore structures. The analytic solution for the drag in a vibrating cylinder in the laminar flow regime is combined with the equations of motion for forced vibration of a cylinder attached to a spring. The resulting model gives an analytic solution for the dynamic response of the system, including the gain, frequency lag, resonant frequency, quality factor, and stability of the system. The results show that the response of the system is nonlinear, with the phase of the system differing from the phase predicted by linear models. The gain, quality factor, resonant frequency, and crossover frequency all increase with the nondimensional natural frequency β and decrease with the ratio of the fluid density to the resonator density.

Design of a 2.4GHz-Microstrip Line Filter Using the Semicircle Defected Ground Structure

2018 ◽  
Vol 876 ◽  
pp. 105-109
Author(s):  
Ping Cheng Chen ◽  
Chung Long Pan ◽  
T.Y. Lai ◽  
T.U. Lin
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Microstrip Line ◽  
Higher Order ◽  
Center Frequency ◽  
Defected Ground Structure ◽  
Ground Structure ◽  
Ansoft Hfss

A design and simulation for L-shaped slot microstrip line antenna with semicircle defected ground structure has been researched, the main purpose is suppressing the existence of higher order harmonic. In this paper, simulated soft (Ansoft HFSS V.6.0) used to be simulated the frequency response under different parameters such as dimensions, amounts of SDGS. The results show good performance of SDGS in higher resonant frequency suppression. Final, an antenna with 2.4GHz center frequency had been design and fabricated.

Experimental Characterization of the Dynamics of VO2-Based MEMS Mirrors

2016 ◽  
Author(s):  
David Torres ◽  
Tongyu Wang ◽  
Jun Zhang ◽  
Sarah Dooley ◽  
Xiaobo Tan ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Frequency Response ◽  
Dynamic Performance ◽  
Band Width ◽  
Experimental Characterization ◽  
Thermal Dynamics ◽  
Step Input ◽  
Sinusoidal Input

In this work, the time and frequency response of VO2-based MEMS mirrors are characterized across the transition for individual and simultaneous actuation. First, a step input train of increasing amplitude are applied to the device up to the point of transition is reached. Second, the frequency response is measured by applying a small sinusoidal input, where the displacement remained inside the hysteresis of the VO2. The frequency of the input varied from 0.1 to 2000 Hz. The thermal dynamics of the device is found to be the factor limiting the device’s band-width to less than 10 Hz. The average resonant frequency of the present VO2-based MEMS mirror was found to be 412.5 Hz for individual actuation. These results allow for the extraction of the necessary parameters to create a model that can be used to design devices with specific dynamic performance.

Effect of functionalized multi-wall carbon nanotubes/Biresin CR82 epoxy nanocomposite on vibration attenuation of aluminum plate

2020 ◽  
pp. 107754632095051
Author(s):  
Alaa Alawy ◽  
Mohamed Abdlghany ◽  
Tamer Zakaria Wafy ◽  
Ahmed Hassan
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Resonant Frequency ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Cantilever Plate ◽  
Multi Wall Carbon Nanotubes ◽  
Epoxy Nanocomposite ◽  
Bending Modes

This article focused on further investigation of passive vibration damping of a cantilever plate using carbon nanotube/epoxy nanocomposite. A damping ratio depends on many factors, for example carbon nanotube content, type of carbon nanotubes, and frequency, so the epoxy composite reinforced with 0.2 wt. % multi-wall carbon nanotubes has been used with structural damping. Dynamic analysis for an aluminum cantilever plate has been studied to determine the effect of the epoxy nanocomposite material on the plate vibration. The main goal of the study was to minimize the frequency response function amplitude and shift the resonant frequency of the plate as high as possible, especially for the fundamental frequency. An finite element model exhibited an increase in the resonant frequency by 10.6% and 1.2% in addition to a reduction in the frequency response function amplitude by 79.5% and 43.26% at the first and second bending modes, respectively, when using 0.2 wt. % multi-wall carbon nanotubes/epoxy circular patches at an optimal position compared with the bare plate. In case of using a stiffener below the plate, the results exposed an increase in resonant frequency by 154.6% and 181.7%, whereas the frequency response function amplitude showed reduction by 95.9% and 98.2% at the first and second bending modes, respectively, when using three stiffeners of multi-wall carbon nanotubes/epoxy nanocomposite with the same mass of circular patches compared also with the bare plate.

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