scholarly journals Effects of Concrete on Propagation Characteristics of Guided Wave in Steel Bar Embedded in Concrete

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Zhupeng Zheng ◽  
Ying Lei
Keyword(s):  
Large Scale ◽  
Guided Waves ◽  
Density Ratio ◽  
Guided Wave ◽  
Wave Number ◽  
Propagation Characteristics ◽  
Civil Infrastructures ◽  
Steel Bar ◽  
Reinforced Concrete Member ◽  
Steel Bars

Techniques based on ultrasonic guided waves (UGWs) play important roles in the structural health monitoring (SHM) of large-scale civil infrastructures. In this paper, dispersion equations of longitudinal wave propagation in reinforced concrete member are investigated for the purpose of monitoring steels embedded in concrete. For a steel bar embedded in concrete, not the velocity but the attenuation dispersion curves will be affected by the concrete. The effects of steel-to-concrete shear modulus ratio, density ratio, and Poisson’s ratio on propagation characteristics of guided wave in steel bar embedded in concrete were studied by the analysis of the real and imaginary parts of the wave number. The attenuation characteristics of guided waves of steel bar in different conditions including different bar concrete constraint and different diameter of steel bar are also analyzed. Studies of the influence of concrete on propagation characteristics of guided wave in steel bars embedded in concrete will increase the accuracy in judging the structure integrity and promote the level of defect detection for the steel bars embedded in concrete.

scholarly journals Nondestructive Inspection of Corrosion and Delamination at the Concrete-Steel Reinforcement Interface

2002 ◽  
Author(s):  
Tri Miller ◽  
Christopher J. Hauser ◽  
Tribikram Kundu
Keyword(s):  
Guided Waves ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Reinforcing Steel ◽  
Electromagnetic Acoustic Transducer ◽  
Long Distance ◽  
Steel Bar ◽  
Acoustic Transducer ◽  
Steel Bars ◽  
Aging Infrastructure

This paper explores the feasibility of detecting and quantifying corrosion and delamination at the interface between reinforcing steel bar and concrete using ultrasonic guided waves. The problem of corrosion and delamination of the reinforcing steel in the aging infrastructure has increased significantly in the last three decades and is likely to keep on increasing. Ultrasonic cylindrical guided waves that can propagate a long distance along the reinforcing steel bar are found to be sensitive to the interface conditions between steel bar and concrete. Ultrasonic transducers are used to launch and detect cylindrical guided waves along the steel bar. The traditional ultrasonic testing methods, for instance the pulse-echo method, where reflection, transmission, and scattering of longitudinal waves are used for detecting large voids in concrete, are not very efficient for detecting corrosion and delamination at the interface between concrete and steel bar. For this study four sets of specimens were prepared. They are rebars and plain steel bars with corrosion and physical separation. Transducers used during the experiment are the Electromagnetic Acoustic Transducer (EMAT) and the Piezoelectric Transducer (PZT). The experiment suggests that the guided wave inspection technique is feasible for the health monitoring of reinforced concrete structures. It also reveals that the ultrasonic guided waves are sensitive to the type of steel used and to the rib patterns on the reformed steel bars.

Inspection of Concrete-Metal Rod Interface Using Guided Waves

2000 ◽  
Author(s):  
Won-Bae Na ◽  
Tribikram Kundu ◽  
Mohammad R. Ehsani
Keyword(s):  
Lamb Wave ◽  
Guided Waves ◽  
Lamb Waves ◽  
Guided Wave ◽  
Ultrasonic Transducers ◽  
Interface Debonding ◽  
Long Distance ◽  
Steel Rebar ◽  
Steel Bars ◽  
Steel Rebars

Abstract The feasibility of detecting interface degradation and separation of steel rebars in concrete beams using Lamb waves is investigated in this paper. It is shown that Lamb waves can easily detect these defects. A special coupler between the steel rebar and ultrasonic transducers has been used to launch non-axisymmetric guided waves in the steel rebar. This investigation shows that the Lamb wave inspection technique is an efficient and effective tool for health monitoring of reinforced concrete structures because the Lamb wave can propagate a long distance along the reinforcing steel bars embedded in concrete as the guided wave and is sensitive to the interface debonding between the steel rebar and concrete.

Defect Localization for Pressure Vessel Based on Circumferential Guided Waves: An Experimental Study

2018 ◽  
Author(s):  
Shuangmiao Zhai ◽  
Chaofeng Chen ◽  
Gangyi Hu ◽  
Shaoping Zhou
Keyword(s):  
Pressure Vessel ◽  
Guided Waves ◽  
Pressure Vessels ◽  
Guided Wave ◽  
Normal Operation ◽  
Propagation Characteristics ◽  
Dense Array ◽  
Imaging Algorithm ◽  
Sparse Array ◽  
Damage Imaging

Pressure vessels are normally employed under extreme environments with high temperature and high pressure. Inevitably, the defects like crack and corrosion that easily occur in the equipment and can significantly influence the normal operation. Guided wave-based method is a cost-effective means to measure the utility of pressure vessel. In this paper, finite element (FE) simulation is used to explore the propagation characteristics of circumferential guided waves in pressure vessel. Based on the propagation characteristics, the experiments with different configurations of piezoelectric transducers (PETs), which contain a sparse array and a dense array, have been conducted on pressure vessel respectively. Different imaging methods, including discrete ellipse imaging algorithm and probability damage imaging algorithm have been applied to locate the defect based on the configurations above. Furthermore, a multi-channel ultrasonic guided wave detection system has been set up for pressure vessel inspection. The experimental results show that the sparse array with the discrete ellipse imaging algorithm can locate the defect effectively. The imaging results based on probability damage imaging algorithm show that the dense array presents the better localization result.

scholarly journals Case studies of the propagation characteristics of auroral TIDS with EISCAT CP2 data using maximum entropy cross-spectral analysis

1998 ◽  
Vol 16 (2) ◽  
pp. 161-167 ◽  
Author(s):  
S. Y. Ma ◽  
K. Schlegel ◽  
J. S. Xu
Keyword(s):  
Spectral Analysis ◽  
Phase Velocity ◽  
Maximum Entropy ◽  
Case Studies ◽  
Large Scale ◽  
Phase Speed ◽  
Wave Number ◽  
Propagation Characteristics ◽  
Dominant Period ◽  
Horizontal Wavelength

Abstract. In this paper case studies of propagation characteristics of two TIDs are presented which are induced by atmospheric gravity waves in the auroral F-region on a magnetic quiet day. By means of maximum entropy cross-spectral analysis of EISCAT CP2 data, apparent full wave-number vectors of the TIDs are obtained as a function of height. The analysis results show that the two events considered can be classified as moderately large-scale TID and medium-scale TID, respectively. One exhibits a dominant period of about 72 min, a mean horizontal phase speed of about 180 m/s (corresponding to a horizontal wavelength of about 780 km) directed south-eastwards and a vertical phase speed of 55 m/s for a height of about 300 km. The other example shows a dominant period of 44 min, a mean horizontal phase velocity of about 160 m/s (corresponding to a horizontal wavelength of about 420 km) directed southwestwards, and a vertical phase velocity of about 50 m/s at 250 km altitude.Key words. Ionosphere · Auroral ionosphere · Ionosphere-atmosphere interactions · Wave propagation)

scholarly journals Array-Based Guided Wave Source Location Using Dispersion Compensation

2021 ◽  
Vol 4 (4) ◽  
Author(s):  
Andrew Downs ◽  
Ronald Roberts ◽  
Jiming Song
Keyword(s):  
Experimental Data ◽  
Guided Waves ◽  
Dispersion Compensation ◽  
Back Propagation ◽  
Source Location ◽  
Guided Wave ◽  
Wave Number ◽  
Frequency Spectra ◽  
Wave Source ◽  
Bulk Waves

Abstract An important advantage of guided waves is their ability to propagate large distances and yield more information about flaws than bulk waves. Unfortunately, the multi-modal, dispersive nature of guided waves makes them difficult to use for locating flaws. In this work, we present a method and experimental data for removing the deleterious effects of multi-mode dispersion allowing for source localization at frequencies comparable to those of bulk waves. Time domain signals are obtained using a novel 64-element phased array and processed to extract wave number and frequency spectra. By an application of Auld’s electro-mechanical reciprocity relation, mode contributions are extracted approximately using a variational method. Once mode contributions have been obtained, the dispersion for each mode is removed via back-propagation techniques. Excepting the presence of a small artifact at high frequency-thicknesses, experimental data successfully demonstrate the robustness and viability of this approach to guided wave source location.

Excitation of Guided Waves in Generally Anisotropic Layers Using Finite Sources

1994 ◽  
Vol 61 (2) ◽  
pp. 330-338 ◽  
Author(s):  
J. J. Ditri ◽  
J. L. Rose
Keyword(s):  
Phase Velocity ◽  
Nondestructive Evaluation ◽  
Guided Waves ◽  
Guided Wave ◽  
Wave Number ◽  
Excitation Spectra ◽  
Mode Expansion ◽  
Time Harmonic ◽  
Expansion Technique ◽  
Anisotropic Layers

The excitation of guided wave modes in generally anisotropic layers by finite sized strip sources placed on the surfaces of the layer is examined. The general problem of arbitrarily applied harmonic surface tractions is first solved using the normal mode expansion technique in conjunction with the complex reciprocity relation of elastodynamics. This general solution is then specialized to loading situations modelling those commonly used to excite guided waves in layers for use in nondestructive evaluation. The amplitudes of the generated modes are written as the product of an “excitation function” which depends only on the distribution of the applied tractions and an “excitability function” which depends only on the properties of the specific mode(s) being excited and which determines how receptive the modes are to the applied tractions. Expressions are obtained for the −9 dB wave number and phase velocity bandwidths (σβ and σν respectively) which determine the widths of the wavenumber or phase velocity excitation spectra at the −9 dB generation point. Finally, the problem of transient loading is addressed by superimposing time harmonic solutions via an integration over the dispersion curves of the layer.

scholarly journals Elastic Guided Waves in a Pre-Stressed Compressible Layer Imbedded in a Pre-Stressed Two-Material Structure

1999 ◽  
Author(s):  
D. A. Sotiropoulos
Keyword(s):  
Dispersion Equation ◽  
Explicit Form ◽  
Half Space ◽  
Guided Waves ◽  
Secular Equation ◽  
Standing Waves ◽  
Guided Wave ◽  
Material Structure ◽  
Propagation Characteristics ◽  
Stress Parameters

Abstract Elastic guided waves in a pre-stressed compressible layer imbedded in a pre-stressed two-material structure are examined. The waves propagate parallel to the planar layer interfaces as a superposed dynamic stress state on the statically pre-stressed layer. The stress condition in the layer and in the surrounding materials is arbitrary as are their strain energy functions. To gain understanding of the propagation characteristics, the mathematically tractable model of the materials having common principal axes of strain, one of which is perpendicular to the layering, is employed. The dispersion equation is derived in explicit form yielding guided wave phase and group speeds in terms of wavelength, stress and elastic parameters, and mass densities of the three materials. Limiting cases of the above dispersion equation give the dispersion equation of guided waves in a pre-stressed surface layer overlying a pre-stressed half space, the secular equation of interfacial waves in two semi-infinite pre-stressed materials, the secular equation of non-dispersive Rayleigh surface waves in a half-space, and the frequency equation of guided elastic waves in a pre-stressed compressible plate. Analysis of the dispersion equation reveals the propagation characteristics and their dependence on material and stress parameters. For small interlayer thickness the phase and group speeds are obtained in explicit form. This yields parameter conditions under which the structure acts as a mechanical filter to guided wave propagation. For arbitrary layer thickness, material parameter combinations are also found for which propagation cannot occur. Special attention is paid to the possible existence of interfacial standing waves as a limiting solution of the dispersion equation. Regions of material and stress parameters are defined in which standing waves exist. Numerical computations complement the analytical results for several classes of materials.

scholarly journals Complex dispersion solutions for guided waves and properties of non-propagating waves in a piezoelectric spherical plate

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401882069
Author(s):  
Xiaoming Zhang ◽  
Zhi Li ◽  
Jiangong Yu
Keyword(s):  
Guided Waves ◽  
Three Dimensional ◽  
Guided Wave ◽  
Wave Number ◽  
Polynomial Method ◽  
Propagating Waves ◽  
Complex Solutions ◽  
Spherical Plate ◽  
Complex Valued ◽  
Dispersion And Attenuation

The vibration modes of an elastic plate are usually divided into propagating and non-propagating (evanescent) kinds. Non-propagating wave modes are very important for guided wave inspection of defect size and shape. But it is difficult to obtain the complex solutions of the transcendental dispersion equation, corresponding to the non-propagating wave. In this article, we present an improved Legendre polynomial method to calculate the complex-valued dispersion and study properties of the non-propagating wave in a piezoelectric spherical plate. Comparisons with other related studies are conducted to validate the correctness of the presented method. The complete dispersion and attenuation curves are plotted in three-dimensional frequency-complex wave number space. The influences of material piezoelectricity and radius–thickness ratio on non-propagating waves in piezoelectric spherical plates are investigated. The amplitude distributions of the electric potential and displacement are also discussed in detail. All the results presented in this work can provide theoretical guidance for ultrasonic nondestructive evaluation and are promising to be applied to improve the resolution of piezoelectric transducers.

Nonlinear Guided Waves for Structural Health Monitoring: Numerical Algorithm and Application to Railroad Track

2012 ◽  
Author(s):  
Claudio Nucera ◽  
Francesco Lanza di Scalea
Keyword(s):  
Thermal Stress ◽  
Temperature Measurement ◽  
Large Scale ◽  
Guided Waves ◽  
Thermal Stresses ◽  
Numerical Models ◽  
Guided Wave ◽  
Cold Weather ◽  
Test Bed ◽  
Neutral Temperature

The University of California at San Diego (UCSD), under a Federal Railroad Administration (FRA) Office of Research and Development (R&D) grant, is conducting research to develop a system for in-situ measurement of the rail Neutral Temperature in Continuous-Welded Rail (CWR). It is known that CWR can break in cold weather and can buckle in hot weather. Currently, there is a need for the railroads to know the current state of thermal stress in the rail, or the rail Neutral Temperature (rail temperature with zero thermal stress), to properly schedule slow-order mandates and prevent derailments. UCSD has developed a prototype for wayside rail Neutral Temperature measurement that is based on non-linear ultrasonic guided waves. Numerical models were first developed to identify proper guided wave modes and frequencies for maximum sensitivity to the thermal stresses in the rail web, with little influence of the rail head and rail foot. Experiments conducted at the Large-scale Rail NT Test-bed indicated a rail Neutral Temperature measurement accuracy of a few degrees. Field tests are planned at the Transportation Technology Center (TTC) in Pueblo, CO in June 2012 in collaboration with the Burlington Northern Santa Fe (BNSF) Railway.

Acoustic emission propagation characteristics in plate structure with various materials, cracks and coating metal

2016 ◽  
Vol 231 (11) ◽  
pp. 2080-2088
Author(s):  
Kuanfang He ◽  
Zhi Tan ◽  
Yong Cheng ◽  
Xuejun Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Acoustic Emission ◽  
Guided Waves ◽  
Propagation Characteristic ◽  
Guided Wave ◽  
Propagation Characteristics ◽  
The Finite Element Method ◽  
Plate Structure ◽  
Element Method

The propagation characteristic of guided waves is important to acoustic emission nondestructive detection for the structural integrity of engineering components. The finite element method is introduced to study the propagation of guided waves in plate structure with different materials, cracks and coating metal. The displacement contours and wave curve at different receiving positions are examined first for the propagation characteristics of guided waves in plate structure with different homogeneous material of steel 45 and GCr15. Next, the interface reflection, refraction and diffraction characteristics of guided waves in plate structure with cracks and steel 45 with coating metal of aluminium 2024 are investigated. Finally, these FE results are compared with the mechanical pencil lead fracture experiment results. The results of this study clearly illustrate the accuracy and reasonableness of the finite element method to predict propagation characteristic of guided wave.

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