Frequency Wave Number–Domain Analysis of Air-Coupled Impact-Echo Tests in Concrete Slab

A new spectral plate element (SPE) is developed to analyze wave propagation in anisotropic laminated composite media. The element is based on the first-order laminated plate theory, which takes shear deformation into consideration. The element is formulated using the recently developed methodology of spectral finite element formulation based on the solution of a polynomial eigenvalue problem. By virtue of its frequency-wave number domain formulation, single element is sufficient to model large structures, where conventional finite element method will incur heavy cost of computation. The variation of the wave numbers with frequency is shown, which illustrates the inhomogeneous nature of the wave. The element is used to demonstrate the nature of the wave propagating in laminated composite due to mechanical impact and the effect of shear deformation on the mechanical response is demonstrated. The element is also upgraded to an active spectral plate clement for modeling open and closed loop vibration control of plate structures. Further, delamination is introduced in the SPE and scattered wave is captured for both broadband and modulated pulse loading.

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Estimation of Thickness of Concrete Slab Members Using Impact Echo Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.605.139 ◽

2014 ◽

Vol 605 ◽

pp. 139-142

Author(s):

Seong Uk Hong ◽

Yong Taeg Lee ◽

Seung Hun Kim ◽

J.H. Na

Keyword(s):

Concrete Slab ◽

Hardness Test ◽

Pulse Velocity ◽

Non Destructive Testing ◽

Testing Methods ◽

Destructive Testing ◽

Impact Echo ◽

Maintenance And Repair ◽

Non Destructive ◽

Impact Echo Method

Recently, the interest in maintenance and repair of existing concrete structures have increased, and it is typical to use non-destructive testing methods such as rebound hardness test or ultrasonic pulse velocity method to execute maintenance and repair of structures efficiently. Many non-destructive testing methods are being used in practice such as at construction sites, but verification for site applications are quite inadequate. Thus, this study intends to evaluate the applicability of Impact Echo Method which is one of the non-destructive testing methods using stress wave. Total of four specimens were planned and produced. The thickness of concrete slab members was estimated using I.E(OLSENs Freedom Data PC with Win.TFS Software Version 2.5.2). The estimated materials of concrete members by IE was found to be IE-1 specimen 178mm, IE-2 specimen 197mm, IE-3 specimen 191mm, and IE-4 specimen 263mm, and the error rate was found to be 4.22%~18.67% (average 9.6%), showing that they are relatively well in agreement. In this study, the experiments were executed with the objective of estimating the thickness of concrete slab members using Impact Echo Method. Through this study, the applicability of thickness estimation in concrete slab members using impact echo method could be confirmed.

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Investigation of X-band backscattering from wave breaking in a laboratory experiment

10.5194/egusphere-egu21-9084 ◽

2021 ◽

Author(s):

Nikita Rusakov ◽

Georgy Baidakov ◽

Evgeny Poplavsky ◽

Yuliya Troitskaya ◽

Maksim Vdovin

Keyword(s):

Cross Section ◽

Wave Breaking ◽

Spectral Characteristics ◽

Wave Number ◽

Scattered Signal ◽

Channel Cross Section ◽

Frequency Wave ◽

First Case ◽

X Band ◽

Working Section

The work is concerned with the study of the breaking surface wave effect on the intensity and spectral characteristics of a scattered radar signal in laboratory conditions.The experiments were carried out on the reconstructed TSWiWaT wind wave flume of the IAP RAS. The channel is 12 m long, the channel cross-section varies from 0.7 x 0.7 m at the entrance to 0.7 x 0.9 m in the working section at a distance of 9 m. The airflow speed on the axis is 3-35 m/s, which corresponds to the values of the wind speed U10 of 11-50 m/s.The wave characteristics in the flume were measured by an array of three wave gauges positioned in the corners of an equal-side triangle with 2.5 cm side, the data sampling rate was 200 Hz. Such a system gives the opportunity to retrieve 3D frequency-wave number spectra of surface waves.The airflow parameters were measured using the profiling method. The velocity profiles were measured in the working section using an S-shaped Pitot tube. Microwave measurements were carried out using an X-band coherent Doppler scatterometer with a wavelength of 3.2 cm with sequential reception of linear polarizations.&#160; The absolute value of the radar cross-section (RCS) on the wavy water surface was determined by comparing the scattered signal with the signal reflected from the calibrator with a known value of the RCS - a metal ball with a diameter of 6 cm. The dimensions of the observation cross-section were 40 cm x 40 cm, the incidence angles were 30&#176;, 40&#176;, 50&#176; for the upwind direction, the distance to the target was 3.15 m.Two series of experiments were carried out. In the first case, wind waves on the surface of pure deep water, developing under the action of a fan generated wind, were studied. In the second case, a train of three waves was generated at the beginning of the channel, with the fan turned on, in order to simulate shallow water an inclined plate was placed under water in front of the measurement area. As a result, the breaking waves occurred at a fixed point and at weaker winds compared to the first case.As a result, an increase in the scattered signal intensity during artificial wave breaking in the case of weak winds was noted. For strong winds, the effect turned out to be insignificant, despite the increased amplitude of the waves under study. The Doppler spectra analysis is also presented.This work was supported by the RFBR projects No. 19-05-00249, 19-05-00366. &#160;

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THE REPRESENTATION OF SEISMIC WAVES IN FREQUENCY-WAVE NUMBER SPACE

10.21236/ad0433611 ◽

1964 ◽

Cited By ~ 1

Author(s):

Jr Kelly ◽

E. J.

Keyword(s):

Seismic Waves ◽

Wave Number ◽

Frequency Wave

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Preliminary Study on Assessing Delaminated Cracks in Cement Asphalt Mortar Layer of High-Speed Rail Track Using Traditional and Normalized Impact–Echo Methods

Sensors ◽

10.3390/s20113022 ◽

2020 ◽

Vol 20 (11) ◽

pp. 3022

Author(s):

Ying-Tzu Ke ◽

Chia-Chi Cheng ◽

Yung-Chiang Lin ◽

Yi-Qing Ni ◽

Keng-Tsang Hsu ◽

...

Keyword(s):

High Speed ◽

Concrete Slab ◽

Amplitude Spectrum ◽

Peak Frequency ◽

High Speed Rail ◽

Impact Echo ◽

Rail Track ◽

Cement Asphalt Mortar ◽

The Difference ◽

Ca Mortar

The severe deterioration of a cement asphalt (CA) mortar layer may lead to the movement of the upper concrete slab and impair the safety of the speedy train. In this study, a test specimen simulating the structure of high-speed rail track slabs was embedded with delaminated cracks in various lateral sizes inside the CA mortar layer. Impact–echo tests (IE) were performed above the flawed and flawless locations. In present study, the IE method is chosen to assess defects in the CA mortar layer. Both traditional IE and normalized IE are used for data interpolation. The normalized IE are the simulated transfer function of the original IE response. The peak amplitudes in the normalized amplitude spectrum and the peak frequency in the traditional amplitude spectrum for the top concrete overlay were used to develop simple indicators for identifying the integrity of the CA mortar layer. The index was based on the difference of the experimental peak amplitude and frequency of the ones calculated from previously developed formulas for plates without substrates. As a result, the technique does not require an experimental baseline for the crack assessment. A field test and analysis procedure for evaluating high-speed rail slab systems are proposed.

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Harmonic Wave Propagation in a Periodically Layered, Infinite Elastic Body: Plane Strain, Analytical Results

Journal of Applied Mechanics ◽

10.1115/1.3424481 ◽

1979 ◽

Vol 46 (1) ◽

pp. 113-119 ◽

Cited By ~ 39

Author(s):

T. J. Delph ◽

G. Herrmann ◽

R. K. Kaul

Keyword(s):

Wave Propagation ◽

Asymptotic Behavior ◽

Plane Strain ◽

Elastic Body ◽

Harmonic Wave ◽

Wave Number ◽

Periodic Medium ◽

Frequency Wave ◽

Wave Numbers ◽

Band Characteristic

The problem of harmonic wave propagation in an unbounded, periodically layered elastic body in a state of plane strain is examined. The dispersion spectrum is shown to be governed by the roots of an 8 × 8 determinant, and represents a surface in frequency-wave number space. The spectrum exhibits the typical stopping band characteristic of wave propagation in a periodic medium. The dispersion equation is shown to uncouple along the ends of the Brillouin zones, and also in the case of wave propagation normal to the layering. The significance of this uncoupling is examined. Also, the asymptotic behavior of the spectrum for large values of the wave numbers is investigated.

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Detection of Sizes and Locations Air Voids in Reinforced Concrete Slab using Ground Penetrating Radar and Impact-Echo Methods

Jurnal Teknologi ◽

10.11113/jt.v74.4553 ◽

2015 ◽

Vol 74 (3) ◽

Author(s):

Nurhayati Abdul Razak ◽

Syahrul Fithry Senin ◽

Roszilah Hamid

Keyword(s):

Reinforced Concrete ◽

Ground Penetrating Radar ◽

Concrete Slab ◽

Depth Estimation ◽

Reinforced Concrete Slab ◽

Air Voids ◽

Impact Echo ◽

Void Defects ◽

Ground Penetrating ◽

Air Void

The presence of inevitable air void defects in reinforced concrete components due to poor quality control during construction can further aggravate the moisture and chloride penetration in concrete to accelerate the corrosion process of the reinforcing steel. Non-destructive test (NDT) methods, Ground Penetrating Radar (GPR) and Impact-Echo (IE), are utilised tp detect the void defects. This study is to compare the accuracy and limitations of both methods in detecting the sizes and depths of the air voids. The sample is a 600 × 400 ×200 mm3 reinforced grade 40 concrete slab with embedded air voids in the sample. The air-voids are introduced in the concrete slab by positioning air-void plastic balls with diameters of 67, 45, 27, 20 and 3 mm each at the depths of 70, 80, 100, 80 and 80 mm, respectively, from the top surface of the slab. Results show that GPR can detect the air voids with sizes larger than 20 mm in diameter with error ranging from -8.9 to 30% from their actual diameters. The IE method is only able to detect the air voids depths and not the voids’ sizes. It is also observed that the void depth estimation acquired by GPR is more accurate only for large size void (67 mm), but for sizes less than that, IE is more accurate in determining their locations. Both methos should be considered for NDT application in detecting voids depending on which parameter accuracy is inticipated.

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Effective forces and wave‐number domain analysis of piezoactuators.

The Journal of the Acoustical Society of America ◽

10.1121/1.401179 ◽

1991 ◽

Vol 90 (4) ◽

pp. 2270-2270

Author(s):

S. J. Kim ◽

V. R. Sonti ◽

J. D. Jones

Keyword(s):

Domain Analysis ◽

Wave Number

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Determination of Optimal Nondestructive Technique (NDT) Using Multi-Criteria Analysis

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.760.615 ◽

2015 ◽

Vol 760 ◽

pp. 615-620

Author(s):

Alexandru Stefan Leonte ◽

Anișor Nedelcu ◽

Razvan Gabriel Dragan

Keyword(s):

Surface Defects ◽

Concrete Slab ◽

Nondestructive Technique ◽

Impact Echo ◽

Ultrasonic Methods ◽

Different Depths ◽

Multi Criteria Analysis ◽

The Cost ◽

Non Destructive

The present paper presents an optimization model for quality control of industrial products by using two non-destructive techniques (NDT): infrared termography and ultrasonic methods. The main purpose it is to determinate the best analyzing method using multi-criteria analysis by taking into account the results that outcome from the two non-destructive evaluations. There have been studied defects like: internal defects and surface defects. Therewith were taking into consideration: safety, efficiency of the method and the cost of the equipment used in controlling the product. For this study it was created a concrete slab with embedded defects which had different depths. The sample was tested using active thermography and impact echo methods and the results were studied and integrated in an multi-criteria analysis to reveal the best method for this case.

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