Adjustable low-frequency bandgap of flexural wave in an Euler-Bernoulli meta-beam with inertial amplified resonators

2021 ◽  
Vol 417 ◽  
pp. 127671
Author(s):  
Shuai Wang ◽  
Minqing Wang ◽  
Zhiwei Guo
Keyword(s):  
Low Frequency ◽  
Flexural Wave

Local and global fluid-flow effects on dipole flexural waves

Geophysics ◽  
2020 ◽  
Vol 85 (1) ◽  
pp. D1-D11
Author(s):  
Elliot J. H. Dahl ◽  
Kyle T. Spikes
Keyword(s):  
Fluid Flow ◽  
Low Frequency ◽  
Summation Method ◽  
Sensitivity Analyses ◽  
Flexural Wave ◽  
Biot Theory ◽  
S Wave ◽  
Local Flow ◽  
Flow Effects ◽  
Wave Induced

Wave-induced fluid flow (WIFF) can significantly alter the effective formation velocities and cause increasing waveform dispersion and attenuation. We have used modified frame moduli from the theory of Chapman together with the classic Biot theory to improve the understanding of local- and global-flow effects on dipole flexural wave modes in boreholes. We investigate slow and fast formations with and without compliant pores, which induce local flow. The discrete wavenumber summation method generates the waveforms, which are then processed with the weighted spectral semblance method to compare with the solution of the period equation. We find compliant pores to decrease the resulting effective formation P- and S-wave velocities, that in turn decrease the low-frequency velocity limit of the flexural wave. Furthermore, depending on the frequency at which the local-flow dispersion occurs, different S-wave velocity predictions from the flexural wave become possible. This issue is investigated through changing the local-flow critical frequency. Sensitivity analyses of the flexural-wave phase velocity to small changes in WIFF parameters indicate the modeling to be mostly sensitive to compliant pores in slow and fast formations.

Experimental Research of AE Inspection on Stress Corrosion Crack for Small Pressure Vessel

2013 ◽  
Author(s):  
Zhongzheng Zhang ◽  
Hua Liang ◽  
Cheng Ye ◽  
Wensheng Cai ◽  
Jun Jiang
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pressure Vessel ◽  
Low Frequency ◽  
Reference Value ◽  
Ferric Chloride Solution ◽  
Pressure Vessels ◽  
Flexural Wave ◽  
Small Pressure ◽  
Ae Signals

To study acoustic emission (AE) signals characteristics of stress corrosion crack (SCC) on in-service pressure vessels. The small pressure vessel with a pre-crack, filled 6% ferric chloride solution was monitored by AE technique. Conventional parameter-based approach and signal-based analysis were combined to deal with recorded AE signals, and micromorphologic observation and ray detection were performed for further verification. The results showed that the Kaiser effect of Q345R material is obvious, AE hits rate and amplitude & energy of the first pressure cycling was higher. Signal band is mainly distributed in 40 ∼ 400 KHz, Signal waveform was mainly composed of high -frequency (>100 KHz) expansion wave with larger amplitude & energy and low-frequency (<100 KHz) flexural wave with lesser amplitude & energy. The research results have a certain reference value for AE test on SCC for practical in-service pressure vessel.

Research on Acoustic Emission Signals Characteristics of Pitting Corrosion on 304 Stainless Steel

2013 ◽  
Author(s):  
Zhongzheng Zhang ◽  
Hua Liang ◽  
Cheng Ye ◽  
Wensheng Cai ◽  
Jun Jiang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Pitting Corrosion ◽  
High Frequency ◽  
Low Frequency ◽  
Ferric Chloride Solution ◽  
304 Stainless Steel ◽  
Flexural Wave ◽  
Higher Temperature ◽  
Ae Signals

In order to study acoustic emission (AE) signals waveform characteristics of pitting corrosion on 304 stainless steel under higher temperature than lower one, Pitting corrosion process on 304 stainless steel in 6% ferric chloride solution at 70°C was monitored by AE technology. Wavelet transform and mode acoustic emission technology were combined to deal with recorded AE signals, and micromorphologic observation was performed for further verification. The results showed that signal waveform was mainly composed of low-frequency (<100KHz) flexural wave with larger amplitude & energy and high-frequency (>100KHz) expansion wave with lesser amplitude & energy. The research results have some certain significance for AE monitoring of pitting corrosion on 304 stainless steel.

A nonlinear resonator with inertial amplification for very low-frequency flexural wave attenuations in beams

2019 ◽  
Vol 96 (1) ◽  
pp. 647-665 ◽  
Author(s):  
Jiaxi Zhou ◽  
Lingling Dou ◽  
Kai Wang ◽  
Daolin Xu ◽  
Huajiang Ouyang
Keyword(s):  
Low Frequency ◽  
Flexural Wave ◽  
Very Low Frequency ◽  
Nonlinear Resonator

Flexural waves in elastically coupled telescopic metabeams

2021 ◽  
pp. 1-28
Author(s):  
Rajan Prasad ◽  
Arnab Banerjee
Keyword(s):  
Wave Propagation ◽  
Band Gap ◽  
Wave Attenuation ◽  
Dynamic Stiffness ◽  
Equations Of Motion ◽  
Low Frequency ◽  
Length Ratio ◽  
Beam Equation ◽  
Flexural Wave ◽  
Constitutive Components

Abstract This paper investigates the flexural wave propagation through elastically coupled metabeams. It is assumed that the metabeam is formed by connecting successive beams with each other using distributed elastic springs. The equations of motion of a representative unit of the above mentioned novel structural form is established by dividing it into three constitutive components that are two side beams, modeled employing Euler-Bernoulli beam equation and an elastically coupled articulated distributed spring connection (ECADSC) at middle. ECADSC is modeled as parallel double beams connected by distributed springs. The underlying mechanics of this system in context of elastic wave propagation is unique when compared with the existing state of art in which local resonators, inertial amplifiers etc. are attached to the beam to widen the attenuation bandwidth. The dynamic stiffness matrix is employed in conjunction with Bloch-Floquet theorem to derive the band-structure of the system. It is identified that the coupling coefficient of the distributed spring layer and length ratio between the side beams and the elastic coupling plays the key role in the wave attenuation. It has been perceived that a considerable widening of the attenuation band gap in the low-frequency can be achieved while the elastically distributed springs are weak and distributed in a small stretch. Specifically, 140% normalized band gap can be obtained only by tuning the stiffness and the length ratio without adding any added masses or resonators to the structure.

Determination of formation shear attenuation from dipole sonic log data

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. D73-D79 ◽  
Author(s):  
Qiaomu Qi ◽  
Arthur C. H. Cheng ◽  
Yunyue Elita Li
Keyword(s):  
Reservoir Characterization ◽  
Wave Attenuation ◽  
Synthetic Data ◽  
Low Frequency ◽  
P Wave ◽  
Flexural Wave ◽  
S Wave ◽  
Additional Energy ◽  
Log Data ◽  
Sonic Log

ABSTRACT Formation S-wave attenuation, when combined with compressional attenuation, serves as a potential hydrocarbon indicator for seismic reservoir characterization. Sonic flexural wave measurements provide a direct means for obtaining the in situ S-wave attenuation at log scale. The key characteristic of the flexural wave is that it propagates at the formation shear slowness and experiences shear attenuation at low frequency. However, in a fast formation, the dipole log consists of refracted P- and S-waves in addition to the flexural wave. The refracted P-wave arrives early and can be removed from the dipole waveforms through time windowing. However, the refracted S-wave, which is often embedded in the flexural wave packet, is difficult to separate from the dipole waveforms. The additional energy loss associated with the refracted S-wave results in the estimated dipole attenuation being higher than the shear attenuation at low frequency. To address this issue, we have developed a new method for accurately determining the formation shear attenuation from the dipole sonic log data. The method uses a multifrequency inversion of the frequency-dependent flexural wave attenuation based on energy partitioning. We first developed our method using synthetic data. Application to field data results in a shear attenuation log that is consistent with lithologic interpretation of other available logs.

Model-based dispersive processing of borehole dipole wave data using an equivalent-tool theory

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. D35-D43 ◽  
Author(s):  
Sheng-Qing Lee ◽  
Xiao-Ming Tang ◽  
Yuan-da Su ◽  
Chun-Xi Zhuang
Keyword(s):  
Data Processing ◽  
Dispersion Curve ◽  
Low Frequency ◽  
Wave Dispersion ◽  
Flexural Wave ◽  
Dispersion Characteristics ◽  
Acoustic Data ◽  
Model Based ◽  
Dispersion Data ◽  
Application Procedure

We have developed a model-based processing technique for borehole dipole S-wave logging data to estimate formation shear slowness from the data. During dipole acoustic logging, the presence of the logging tool can significantly affect the dispersion characteristics of flexural waves. Therefore, modeling the effects of the tool is essential for model-based processing. We have determined that an equivalent-tool theory using only two parameters, tool radius, and modulus, can adequately model the flexural-wave-dispersion characteristics. We used this theory, together with a calibration procedure, to determine the tool parameters to formulate an inversion method for the logging data processing. Our use of the equivalent tool theory played an important role in fitting the theoretical dispersion curve to the actual flexural-wave-dispersion data, enabling fast processing of the field acoustic data. An advantage of this model-based method is its prediction power, which, in the absence of low-frequency dispersion data, allows for predicting formation shear slowness from the low-frequency limit of the model-fitted dispersion curve. We have also developed an application procedure of the method for field-data processing and demonstrated its effectiveness in the dispersion correction using field acoustic data from fast and slow formations.

Low-frequency flexural wave attenuation in metamaterial sandwich beam with hourglass lattice truss core

Wave Motion ◽  
2021 ◽  
pp. 102750
Author(s):  
Zhenkun Guo ◽  
Guobiao Hu ◽  
Vladislav Sorokin ◽  
Lihua Tang ◽  
Xiaodong Yang ◽  
...  
Keyword(s):  
Wave Attenuation ◽  
Sandwich Beam ◽  
Low Frequency ◽  
Flexural Wave ◽  
Truss Core

A Refinement of Mindlin Plate Theory Using Simultaneous Rotary Inertia and Shear Correction Factors

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
High Frequency ◽  
Plate Theory ◽  
Low Frequency ◽  
Rotary Inertia ◽  
Mindlin Plate ◽  
Flexural Wave ◽  
Correction Factors ◽  
Flexural Mode ◽  
Mode Dispersion ◽  
Mindlin Plate Theory

We revisit Mindlin's theory for flexural dynamics of plates using two correction factors, one for shear and one for rotary inertia. Mindlin himself derived and considered his equations with both correction factors, but never with the two simultaneously. Here, we derive optimal values of both factors by matching the Mindlin frequency–wavenumber branches with the exact Rayleigh–Lamb dispersion relations. The thickness shear resonance frequency is obtained if the factors are proportional but otherwise arbitrary. This degree-of-freedom allows matching of the main flexural mode dispersion with the exact Lamb wave at either low or high frequency by choosing the shear correction factor as a function of Poisson's ratio. At high frequency, the shear factor takes the value found by Mindlin, while at low frequency, it assumes a new explicit form, which is recommended for flexural wave modeling.

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