scholarly journals A Wave-Based Vibration Analysis of a Finite Timoshenko Locally Resonant Beam Suspended with Periodic Uncoupled Force-Moment Type Resonators

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1132
Author(s):  
Hangyuan Lv ◽  
Yimin Zhang
Keyword(s):  
Vibration Analysis ◽  
Low Frequency ◽  
Bending Moment ◽  
Analysis Approach ◽  
Structural Elements ◽  
Frequency Range ◽  
Resonant Beam ◽  
Force Moment ◽  
A Cell ◽  
Two Degree Of Freedom

This paper first employs and develops an exact wave-based vibration analysis approach to investigate a finite Timoshenko beam carrying periodic two-degree-of-freedom (2-DOF) uncoupled force-moment type resonators. In the approach, vibrations are described as structural waves that propagate along uniform structural elements and reflected and transmitted at structural discontinuities. Each uncoupled force-moment type resonator is considered as a cell which injects waves into the distributed beam through the transverse force and the bending moment at the attached point. By assembling wave relations of the cells into the beam, the forced vibration problem of the locally resonant (LR) structure is turned to be the solution to a related set of matrix equations. In addition, the parametric analysis provides an efficient method to obtain wide low-frequency range band-gaps. Accuracy of the proposed wave-based vibration analysis approach is demonstrated by the simulated and measured results of two sets of beam-like resonator samples.

scholarly journals Band-Gap Properties of Finite Locally Resonant Beam Suspended Periodically with Two-Degree-of-Freedom Force Type Resonators

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 716
Author(s):  
Hangyuan Lv ◽  
Shangjie Li ◽  
Xianzhen Huang ◽  
Zhongliang Yu
Keyword(s):  
Band Gap ◽  
Low Frequency ◽  
Degree Of Freedom ◽  
Analysis Approach ◽  
The Finite Element Method ◽  
Motion Equations ◽  
Resonant Beam ◽  
Propagation Properties ◽  
Two Degree Of Freedom ◽  
Transmission And Reflection

The propagation properties of waves in finite Timoshenko locally resonant (LR) beams resting on forced vibrations and periodically attached two-degree-of-freedom force-type resonators are studied by the wave-based analysis approach. By calculating the motion equations of the beam, the transmission and reflection matrices of waves at the resonator attached point are first derived, and the forced vibration response of the finite periodic beam is deduced by the wave-based approach. Several examples are also analyzed by the finite element method to verify the high accuracy of the developed wave-based analysis approach. Numerical results show that wider low-frequency band-gaps exist in this type of LR beams. It was also found that the resonator masses and spring stiffnesses caused different effects on the band-gap properties of the combined LR beam. The desired band-gap widths of the LR beam can be tuned by adjusting the mass blocks and spring stiffness in the resonators based on the results.

Vibration Analysis and Optimal Design for Cab’s Isolation System of Vibratory Roller

2011 ◽  
Vol 199-200 ◽  
pp. 936-940 ◽  
Author(s):  
Le Van Quynh ◽  
Jian Run Zhang ◽  
Guo Wang Jiao ◽  
Xiao Bo Liu ◽  
Yuan Wang
Keyword(s):  
Optimal Design ◽  
Optimization Model ◽  
Vibration Analysis ◽  
Ride Comfort ◽  
Dynamic Test ◽  
Low Frequency ◽  
Frequency Range ◽  
Working Capacity ◽  
Forward Motion ◽  
Isolation System

In recent years, vibration roller market has required increasingly not only on working capacity but also ride comfort. Thus, in order to reduce the effect of vibration to operators, identification and elimination of vibration sources are the most important tasks to achieve optimum design. In this paper, the attention is paid to cab’s low-frequency sloshing analysis and optimal design for cab’s isolation system of vibratory roller. When working, it often exists the problem of cab’s low-frequency sloshing in the direction of forward motion. In order to solve this problem, the dynamic test and simulations analysis are carried out; and the main reasons causing cab’s low-frequency sloshing are found out. The optimization model according to the two points response amplitude in the direction of forward motion on the cab to reach the minimum value in the low frequency range is proposed in this paper. And also, the auxiliary vibrations isolator for solving the low-frequency sloshing in the direction of forward motion is designed.

scholarly journals Advanced non-dimensional dynamic influence function method considering the singularity of the system matrix for accurate eigenvalue analysis of membranes

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110729
Author(s):  
Sangwook Kang
Keyword(s):  
Influence Function ◽  
Vibration Analysis ◽  
Function Method ◽  
Accurate Result ◽  
Low Frequency ◽  
Free Vibration Analysis ◽  
System Matrix ◽  
Frequency Range ◽  
Influence Function Method ◽  
Lower Frequency Range

An advanced non-dimensional dynamic influence function method (NDIF method) for highly accurate free vibration analysis of membranes with arbitrary shapes is proposed in this paper. The existing NDIF method has the weakness of not offering eigenvalues and eigenmodes in the low frequency range when the number of boundary nodes of an analyzed membrane is increased to obtain more accurate result. This paper reveals that the system matrix of the membrane becomes singular in the lower frequency range when the number of the nodes increases excessively. Based on this fact, it provides an efficient way to successfully overcome the weaknesses of the existing NDIF method and still maintain its accuracy. Finally, verification examples show the validity and accuracy of the advanced NDIF method proposed.

Broadband Wave Attenuation in Locally Resonant Periodic Flexural Beams With Force-Moment Resonators

2013 ◽  
Author(s):  
Michael Y. Wang ◽  
Xiaoming Wang
Keyword(s):  
Degrees Of Freedom ◽  
Wave Attenuation ◽  
Low Frequency ◽  
Flexural Wave ◽  
Frequency Range ◽  
Resonant Structures ◽  
Force Moment ◽  
Flexural Wave Propagation ◽  
Bloch’S Theorem ◽  
Attenuation Characteristics

We investigate flexural wave propagation in Euler-Bernoulli beams with periodically suspended 2-DOF force-moment resonators. We use the transfer matrix method for a unit cell in the beam in conjunction with Bloch’s theorem, to define the dispersion curves and frequency band structure. Our analysis shows that the uncoupled force-moment resonators generate rich attenuation properties that are not observed in the conventional locally resonant structures with suspended force-only (or moment-only) vibrators. As a prime focus, we identify a Bragg-like band gap below the resonance frequency of the resonator and its coupling with the resonance gap, giving rise to a potentially super-wide attenuation gap that can be tuned for any low frequency range. The analysis presented can be extended to other types of phononic meta-materials and structures of multi-degrees of freedom (and distributed) resonators, which may exhibit more practically significant wave attenuation characteristics.

scholarly journals Modeling of the MET Sensitive Element Conversion Factor on the Intercathode Distance

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5146
Author(s):  
Maksim Ryzhkov ◽  
Vadim Agafonov
Keyword(s):  
High Frequency ◽  
Sensitive Element ◽  
Conversion Factor ◽  
Conversion Coefficient ◽  
Low Frequency ◽  
Frequency Region ◽  
Frequency Range ◽  
System Parameters ◽  
A Cell ◽  
Transforming Cell

MET sensors for measuring motion parameters are used in many scientific and technical fields. Meanwhile, the geometries of the transforming cell applied practically are far from optimal, and the influence of many geometric parameters on the sensitivity has not been studied. These parameters include the intercathode distance in a four-electrode conversion cell. In this paper, a mathematical model that allows calculating the behavior of the conversion coefficient depending on the frequency for a cell with flat electrodes at different intercathode distances is constructed. The stationary current is shown to decrease monotonically with the decreasing intercathode distance at the constancy of other system parameters. At the same time, the signal current decreases in the low-frequency region and increases in the high-frequency range. Taking into account the results obtained, practically speaking, it is advisable to reduce the intercathode distance to the technologically possible minimum, which makes the frequency response more uniform and reduces the current consumed by the sensitive element.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Dynamic Damping and Stiffness Characteristics of the Rolling Tire

2001 ◽  
Vol 29 (4) ◽  
pp. 258-268 ◽  
Author(s):  
G. Jianmin ◽  
R. Gall ◽  
W. Zuomin
Keyword(s):  
Dynamic Behavior ◽  
Variable Parameter ◽  
Low Frequency ◽  
Vertical Load ◽  
Frequency Range ◽  
Inflation Pressure ◽  
Vehicle Simulation ◽  
Dynamic Damping ◽  
Speed Range ◽  
Stiffness Characteristics

Abstract A variable parameter model to study dynamic tire responses is presented. A modified device to measure terrain roughness is used to measure dynamic damping and stiffness characteristics of rolling tires. The device was used to examine the dynamic behavior of a tire in the speed range from 0 to 10 km/h. The inflation pressure during the tests was adjusted to 160, 240, and 320 kPa. The vertical load was 5.2 kN. The results indicate that the damping and stiffness decrease with velocity. Regression formulas for the non-linear experimental damping and stiffness are obtained. These results can be used as input parameters for vehicle simulation to evaluate the vehicle's driving and comfort performance in the medium-low frequency range (0–100 Hz). This way it can be important for tire design and the forecasting of the dynamic behavior of tires.

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