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 Showing 1 - 183 of 183 Journals sorted alphabetically ACI Structural Journal       (Followers: 17) Acta Polytechnica : Journal of Advanced Engineering       (Followers: 2) Acta Structilia : Journal for the Physical and Development Sciences       (Followers: 2) Advances in Civil Engineering       (Followers: 35) Advances in Structural Engineering       (Followers: 28) Ambiente Construído       (Followers: 1) American Journal of Civil Engineering and Architecture       (Followers: 30) Architectural Engineering       (Followers: 4) Archives of Civil and Mechanical Engineering       (Followers: 1) Archives of Civil Engineering       (Followers: 10) Archives of Hydro-Engineering and Environmental Mechanics       (Followers: 2) ATBU Journal of Environmental Technology       (Followers: 4) Australian Journal of Structural Engineering       (Followers: 6) Baltic Journal of Road and Bridge Engineering       (Followers: 1) BER : Building and Construction : Full Survey       (Followers: 10) BER : Building Contractors' Survey       (Followers: 4) BER : Building Sub-Contractors' Survey       (Followers: 3) BER : Survey of Business Conditions in Building and Construction : An Executive Summary       (Followers: 4) Bioinspired Materials       (Followers: 5) Bridge Structures : Assessment, Design and Construction       (Followers: 15) Building and Environment       (Followers: 15) Building Women Built Environment Project and Asset Management       (Followers: 15) Bulletin of Pridniprovsk State Academy of Civil Engineering and Architecture       (Followers: 6) Canadian Journal of Civil Engineering       (Followers: 12) Case Studies in Engineering Failure Analysis       (Followers: 8) Case Studies in Nondestructive Testing and Evaluation       (Followers: 11) Case Studies in Structural Engineering       (Followers: 9) Cement and Concrete Composites       (Followers: 17) Challenge Journal of Concrete Research Letters       (Followers: 2) Challenge Journal of Structural Mechanics       (Followers: 5) Change Over Time       (Followers: 2) Civil and Environmental Engineering       (Followers: 7) Civil And Environmental Engineering Reports       (Followers: 5) Civil and Environmental Research       (Followers: 19) Civil Engineering = Siviele Ingenieurswese       (Followers: 4) Civil Engineering and Architecture       (Followers: 17) Civil Engineering and Environmental Systems       (Followers: 3) Civil Engineering and Technology       (Followers: 10) Civil Engineering Dimension       (Followers: 8) Cohesion and Structure       (Followers: 2) Composite Structures       (Followers: 266) Computer-aided Civil and Infrastructure Engineering       (Followers: 11) Computers & Structures       (Followers: 36) Concrete Research Letters       (Followers: 6) Construction Economics and Building       (Followers: 2) Construction Engineering       (Followers: 9) Construction Management and Economics       (Followers: 22) Construction Science       (Followers: 4) Constructive Approximation Curved and Layered Structures       (Followers: 2) DFI Journal : The Journal of the Deep Foundations Institute       (Followers: 1) Earthquake Engineering and Structural Dynamics       (Followers: 16) Enfoque UTE       (Followers: 4) Engineering Project Organization Journal       (Followers: 7) Engineering Structures       (Followers: 13) Engineering Structures and Technologies       (Followers: 2) Engineering, Construction and Architectural Management       (Followers: 14) Environmental Geotechnics       (Followers: 5) European Journal of Environmental and Civil Engineering       (Followers: 9) Fatigue & Fracture of Engineering Materials and Structures       (Followers: 16) Frattura ed Integrità Strutturale : Fracture and Structural Integrity Frontiers in Built Environment Frontiers of Structural and Civil Engineering       (Followers: 6) Geomaterials       (Followers: 4) Geosystem Engineering       (Followers: 1) Geotechnik       (Followers: 3) Géotechnique Letters       (Followers: 6) HBRC Journal       (Followers: 2) Hormigón y Acero HVAC&R Research Indoor and Built Environment       (Followers: 2) Infrastructure Asset Management       (Followers: 2) Infrastructures Ingenio Magno       (Followers: 1) Insight - 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 Journal of Nondestructive Evaluation   [SJR: 0.863]   [H-I: 27]   [11 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1573-4862 - ISSN (Online) 0195-9298    Published by Springer-Verlag  [2352 journals]
• Pulse-Inversion Chirp-Coded Weld Harmonic Imaging (PI-CWHI) of Friction
Stir Welded Butt-Joint
• Authors: M. Tabatabaeipour; J. Hettler; N. T. Sewell; J. R. Wright; J. C. S. Wright; S. Delrue; K. Van Den Abeele
Abstract: The microscopic size and the closed characteristics of zigzag line defects at the root of friction stir welded joints frequently result in a detection inability by off-the-shelf ultrasonic weld inspection techniques. To overcome this problem, we take advantage of a non-linear ultrasonic approach by employing a slanted contact pitch-catch mode scanning using chirp-coded excitation with subsequent pulse-inversion analysis. We validated that the observed nonlinearity correlates well with the micro-crack density along the weld path. Doing so, hot spots in the pulse-inversion chirp-coded weld harmonic images can be interpreted as zones with high concentrations of micro-flaws.
PubDate: 2017-10-23
DOI: 10.1007/s10921-017-0437-1
Issue No: Vol. 36, No. 4 (2017)

• 3D Point Cloud Analysis for Detection and Characterization of Defects on
Airplane Exterior Surface
• Authors: Igor Jovančević; Huy-Hieu Pham; Jean-José Orteu; Rémi Gilblas; Jacques Harvent; Xavier Maurice; Ludovic Brèthes
Abstract: Three-dimensional surface defect inspection remains a challenging task. This paper describes a novel automatic vision-based inspection system that is capable of detecting and characterizing defects on an airplane exterior surface. By analyzing 3D data collected with a 3D scanner, our method aims to identify and extract the information about the undesired defects such as dents, protrusions or scratches based on local surface properties. Surface dents and protrusions are identified as the deviations from an ideal, smooth surface. Given an unorganized point cloud, we first smooth noisy data by using Moving Least Squares algorithm. The curvature and normal information are then estimated at every point in the input data. As a next step, Region Growing segmentation algorithm divides the point cloud into defective and non-defective regions using the local normal and curvature information. Further, the convex hull around each defective region is calculated in order to englobe the suspicious irregularity. Finally, we use our new technique to measure the dimension, depth, and orientation of the defects. We tested and validated our novel approach on real aircraft data obtained from an Airbus A320, for different types of defect. The accuracy of the system is evaluated by comparing the measurements of our approach with ground truth measurements obtained by a high-accuracy measuring device. The result shows that our work is robust, effective and promising for industrial applications.
PubDate: 2017-10-17
DOI: 10.1007/s10921-017-0453-1
Issue No: Vol. 36, No. 4 (2017)

• Evaluation of a Nitrided Case Depth by the Magnetic Barkhausen Noise
• Authors: Alexandr Stupakov; Róbert Farda; Miroslav Neslušan; Alexej Perevertov; Tetsuya Uchimoto
Abstract: Applicability of magnetic methods for non-destructive evaluation of plasma nitrided cases was investigated comprehensively. Nitrided layers of 60–800 $$~\upmu \hbox {m}$$ thicknesses were produced on a 16MnCr5 steel surface varying the plasma temperature, the nitriding time and atmosphere. Low-frequency Barkhausen noise was measured by a unique laboratory system to obtain physically grounded data. The laboratory measurements were performed at the triangular waveforms of the magnetizing voltage and the surface magnetic field. A typical rms envelope with a single peak positioned near the hysteresis coercive field was obtained for the unnitrided homogeneous sample. All nitrided samples with the hardened surface layer demonstrated an additional envelope peak at higher fields. Deeper nitridation suppressed both envelope peaks equally making the classical rms parameter sensitive to variation of the nitrided case depth. An industrial method of detection of the Barkhausen noise was tested for comparison using a commercial Rollscan device. The industrial measurements gave a single-peak envelope for all studied samples and a lower depth sensitivity of the rms parameter. Bulk testing methods, the magnetic hysteresis and the magneto-acoustic emission, were not able to detect the nitrided cases.
PubDate: 2017-10-12
DOI: 10.1007/s10921-017-0452-2
Issue No: Vol. 36, No. 4 (2017)

• A Taguchi Design of Experiment Approach to Pulse and Lock in Thermography,
Applied to CFRP Composites
• Authors: Y. A. Abdulrahman; M. A. Omar; Z. Said; F. Obeideli; A. Abusafieh; G. N. Sankaran
Abstract: The current text presents a parametric study of two active thermography routines namely, Pulse and Lock-in as applied to carbon fiber reinforced plastics (CFRP) composites; using a Taguchi design of experiment approach. A set of controllable factors are highlighted and selected for each technique at different levels. Three factors have been identified for the pulse thermography (specifically; defect aspect ratio, pulse period, and experimental duration), and two factors for the Lock-in mode (that is lock in frequency and period); each factor can be manipulated at three different levels. The analysis reveals the effectiveness of the Taguchi design of experiment in consolidating the number of factorial experiments, and in quantifying the results and the associated sensitivity for each factor (its dominance), using a signal to noise ratio criterion. The analysis of variance and analysis of means show that the aspect ratio is not a controlling parameter for the pulse thermography, with the pulse time being the most dominant. Moreover, it decides on the optimal settings for each testing mode. These settings are further validated using additional CFRP artificial sample with eight and six layers of laminates.
PubDate: 2017-10-04
DOI: 10.1007/s10921-017-0450-4
Issue No: Vol. 36, No. 4 (2017)

• Scatter Signal Elimination by Localized Primary Modulation in Industrial
• Authors: Aboutaleb Kermani; Seyed Amir Hossein Feghhi
Abstract: In industrial computed radiography, same as the other projection imaging systems, quantitative integrated information of total beam path including the object is carried by primary part of the beam. It is well known that the accuracy of the image useful data carried by the primary part degrades by scattered part of the beam. In order to have the beam path quantitative information accurately, it is essential to obtain the primary part of the total signal purely. In current study, a practical approach using localized primary modulation has been proposed to extract the primary signal. A semi-transparent beam attenuation grid was used as the beam intensity modulator. Efficiency and accuracy of the approach was practically validated through thickness measurement of metallic planar steps as an illustrative example. Simplified practical implementation and availability of the required accessories are some of advantages of the proposed approach. The results are indicative of the fact that this approach can also be applied as a new technique in thickness measurement, yielding a noticeable accuracy improvement in the most radiography methods. A procedure is included to explain the approach implementation for thickness measurement in computed radiography systems. The procedure overcomes some practical limitations and difficulties of the approach adaptation for computed radiography.
PubDate: 2017-10-02
DOI: 10.1007/s10921-017-0448-y
Issue No: Vol. 36, No. 4 (2017)

• Simulation of Laser Ultrasonics for Detection of Surface-Connected Rail
Defects
• Authors: Zhong Yunjie; Gao Xiaorong; Luo Lin; Pan Yongdong; Qiu Chunrong
Abstract: Laser ultrasonic produces frequencies in the MHz range, enabling high accuracy and a strong ability to detect rail surface defects. This paper mainly studied on the simulation of detecting surface-connected rail defects on 60 kg rails with laser ultrasonic, established the finite element model of laser-excited ultrasonic Rayleigh wave, carried out the simulation, and verified the effectiveness of the technology through experiments. To solve the problem that laser ultrasonic is insensitive to the width of defects in actual detection, and unable to make quantitative detection of defects, this paper established a new model on the basis of improving the original model that has been verified, exciting ultrasonic at the two sides at the same time of a rail with two staggered beams of laser separately to detect irregular scratch defects on rail surface, and two groups of signal data were received through two probes. Each group of data can present the half-profile information of defects, and further form two detection images of the defect. At last, the two detection images were combined into a complete image through image processing. The results of the experiment indicate that the technology studied offers a new method for the effective quantitative detection of surface-connected defects on rail.
PubDate: 2017-09-26
DOI: 10.1007/s10921-017-0451-3
Issue No: Vol. 36, No. 4 (2017)

• Imaging of Barely Visible Impact Damage on a Complex Composite Stiffened
Panel Using a Nonlinear Ultrasound Stimulated Thermography Approach
• Authors: Gian Piero Malfense Fierro; Dmitri Ginzburg; Francesco Ciampa; Michele Meo
Abstract: Thermosonics, also known as ultrasonic stimulated thermography, is a rapid non-destructive evaluation technique that uses an infrared camera to visualise material defects by detecting the frictional heating at crack surfaces when a part under inspection is vibrated. These vibrations are usually produced by an ultrasonic horn being pressed against the surface of the test sample, which result in uncontrolled generations of frequency components and excitation amplitude. This makes thermosonics highly non-reproducible and unreliable. This paper presents a novel thermographic method, here named as nonlinear ultrasound stimulated thermography, for the detection and imaging of real material defects such as impact damage on a complex composite stiffener panel. This technique combines nonlinear ultrasonic techniques with thermography. A nonlinear ultrasonic approach was used as signature for a reliable frequency-selective excitation of material defects, while an infrared camera was employed to reveal the damage location and severity. A nonlinear narrow sweep excitation method was employed to efficiently excite the local resonance frequencies of the damaged region in order to give rise to the highest nonlinear harmonic response in the material leading to a high heat generation at the crack surface. The experimental tests were carried out with a laser vibrometer in order to better understand the interaction of elastic waves with nonlinear scattering. An ad-hoc nonlinear thermal-structural finite element and crack model was developed to study the heat generation caused by the movement of the crack surfaces when elastic waves with a particular frequency impinges on the crack interphase with good agreement with the experimental results. The proposed new method allows to detect single and multiple barely visible impact damage in a quick, reliable and reproducible manner and overcomes the main limitations of classical thermosonics.
PubDate: 2017-09-22
DOI: 10.1007/s10921-017-0449-x
Issue No: Vol. 36, No. 4 (2017)

• A Permeability-Measuring Magnetic Flux Leakage Method for Inner Surface
Crack in Thick-Walled Steel Pipe
• Authors: Zhiyang Deng; Yanhua Sun; Yihua Kang; Kai Song; Rongbiao Wang
Abstract: It is difficult for traditional magnetic flux leakage (MFL) methods to detect inner surface cracks of thick-walled steel pipe or plate due to magnetic shielding of the wall and strong magnetic background noise, and for eddy current testing (ECT) as well due to its skin effect. On the basis of the nonlinear magnetic permeability of ferromagnetic materials, a new non-destructive testing method (NDT) permeability-measuring magnetic flux leakage (P-MFL) is proposed, in which the magnetization is perpendicular to the inner surface crack, and the surface layer permeability distortion caused by magnetic field distortion is measured by differential pick-up coils. Afterwards, its detection mechanism is presented and analyzed, and its feasibility is verified by simulations and experiments. Finally, some application cases for steel pipe are also realized effectively. Meanwhile, its testing characteristics for cracks are given and effects of crack size, specimen thickness, scanning paths to testing signal amplitude are briefly analyzed. Finally, the proposed P-MFL method compared to traditional MFL method is discussed in detail.
PubDate: 2017-09-20
DOI: 10.1007/s10921-017-0447-z
Issue No: Vol. 36, No. 4 (2017)

• Sparse Representations to Replace TOFD Images in Non-destructive Testing
of Materials
• Authors: Thouraya Merazi-Meksen; Akila Kemmouche; Malika Boudraa; Bachir Boudraa
Abstract: This paper describes a proposed method for the selection of relevant samples of ultrasonic signals during automatic material inspection. Instead of the well-known time of flight diffraction (TOFD) images, data are stored as a sparse matrix in which the elements only indicate whether a defect has been detected. This technique avoids storage of useless signals received during probe displacement in cases of low and high signal-to-noise ratios that correspond to coarse-grained and fine-grained materials, respectively. The approach is based on comparing the positions of maximum amplitudes, which are randomly located when signals only consist of noise but are in the same signal range when a defect is detected. The matrix elements are then applied as inputs to a self organizing map by neural networks to produce a normalized sparse matrix as the output, with a constant number of elements. This approach will be beneficial to enable the use of selected data in intelligent systems requiring a fixed number of inputs to characterize defects.
PubDate: 2017-09-11
DOI: 10.1007/s10921-017-0446-0
Issue No: Vol. 36, No. 4 (2017)

• Comparison Between Different Experimental Set-Ups for Measuring the
Magnetic Barkhausen Noise in a Deformed 1050 Steel
• Authors: J. Capó Sánchez; M. F. de Campos; L. R. Padovese
Abstract: The magnetic Barkhausen emission is investigated in deformed ANSI 1050 steel samples using four experimental configurations. These configurations vary according the type of magnetization (solenoid or yoke) and the recording the magnetic signal (bobbin above or around sample).The level of total strain was 0.4, 0.8, 1.0 and 3.0%. In all cases the same monotonous decrease dependence of emission magnetic with strain was obtained, showing that the four configurations give similar results. However, the yoke–pancake configuration was the most sensitive.
PubDate: 2017-09-05
DOI: 10.1007/s10921-017-0445-1
Issue No: Vol. 36, No. 4 (2017)

• Deformation Tracking in 3D Point Clouds Via Statistical Sampling of Direct
Cloud-to-Cloud Distances
• Authors: Bahman Jafari; Ali Khaloo; David Lattanzi
Abstract: Dense three-dimensional (3D) point clouds of infrastructure systems, generated from laser scanners or through multi-view photogrammetry, have significant potential as a source of nondestructive evaluation information. The growing maturity of these techniques make them capable of reconstructing photorealistic 3D models with accuracy on the millimeter scale, adequate for inspection and evaluation practices. Manual analysis of these point clouds is often time consuming and labor intensive and does not provide explicit information on structural performance and health conditions, highlighting the need for new techniques to efficiently analyze these models. This paper presents a new 3D point cloud change analysis approach for tracking small movements over time through localized spatial analytics. This technique uses a combination of a direct point-wise distance metric in conjunction with statistical sampling to extract structural deformations. By identifying and tracking these changes, mechanical deformations can be quantified along with the associated strains and stresses. These measurements can then be used to assess both service conditions and remaining system capacity. The results of a series of laboratory experiments designed to test the proposed approach are presented as well. The findings indicate measurement accuracy on the order of +/− 0.2 mm (95% confidence interval), making it suitable for accurate and automatic geometrical analyses and change detection in a variety of infrastructure inspection scenarios. Ongoing work seeks to connect this technique to automated finite element model updating, and to field test the measurement technique.
PubDate: 2017-08-29
DOI: 10.1007/s10921-017-0444-2
Issue No: Vol. 36, No. 4 (2017)

• Simplified Ultrasonic Damage Detection in Fluid-Filled Pipes
• Authors: Bouko Vogelaar; Michael Golombok
Abstract: The location and extent of damage in a pipe can be remotely determined from weld and internal damage reflections using a single acoustic emitter/sensor pair. The use of normalised reflections yields single numbers enabling long distance data collection techniques such as wireless hopping. The attenuation is twice as high for opposite inner and outer fluids (whether air and water, or water and air) as compared to identical inner and outer fluids. The absolute recorded signals in the water-filled pipe are attenuated by a factor two compared to the empty pipe. The axial length of detection is reduced by a half. The reduction of >90% in sensors and the longer axial detection (>10 $$\times$$ current state-of- the-art- technology) means that permanent fixed sensor pairs for whole pipelines are on the horizon of possibility. The greatest advantage is envisioned in submersed pipelines.
PubDate: 2017-08-21
DOI: 10.1007/s10921-017-0443-3
Issue No: Vol. 36, No. 4 (2017)

• Application of Different X-ray Techniques to Improve In-Service Carbon
Fiber Reinforced Rope Inspection
• Authors: David Schumacher; Kim-Niklas Antin; Uwe Zscherpel; Pedro Vilaça
Abstract: Carbon fiber reinforced polymer ropes are gaining in significance in the fields of civil engineering and hoisting applications. Thus, methods of non-destructive testing (NDT) need to be developed and evaluated with respect to new challenges and types of defects. Particularly important is the development of in-service testing solutions which allow the integration in global online monitoring systems. Conventional methods like electrical resistivity or strain measurements using optical fibers are already in use. This study investigates the possibility of using various X-ray techniques to increase the reliability and significance of NDT and their applicability to in-service testing. Conventional film radiography is the most common technique; however, even after image enhancement of the digitized film, this technique lacks contrast sensitivity and dynamic range compared to digital detector array (DDA) radiography. The DDA radiography is a highly sensitive method; yet, the limitation is that it delivers 2D images of 3D objects. By the use of co-planar translational laminography the detectability of planar defects is superior to 2D methods due to multiple projection angles. Apart from this, it can be used on-site due to a rather simple setup and robust equipment. In this work two photon counting detectors (PCD) with different sensor materials (Si and CdTe) were used. The results show that the resolution and defect recognition is lower in case of DDA radiography and laminography using PCDs compared to high-resolution computed tomography. However, the DDA radiography and laminography are sensitive enough to both fiber breakage and delaminations and can be significantly advantageous in terms of measurement time and adaptability for on-site monitoring.
PubDate: 2017-08-21
DOI: 10.1007/s10921-017-0441-5
Issue No: Vol. 36, No. 4 (2017)

• Embedded PZT Sensor for Monitoring Mechanical Impedance of Hydrating
Cementitious Materials
• Authors: Arun Narayanan; Amarteja Kocherla; Kolluru V. L. Subramaniam
Abstract: An embedded PZT (Lead Zirconate Titanate)-based sensor is developed for real-time, continuous, in-situ monitoring of hydrating cementitious materials after casting. The development of a multi-layer protection for a PZT patch, which provides a physical barrier with the surrounding medium while ensuring the sensitivity of measurement is described. Electrical impedance measurements from the sensor embedded inside mortar mixtures of different compositions are shown to sensitively provide an indication of changes in the state and the mechanical impedance of the material during periods associated with setting and early strength gain. An analytical procedure is developed for extracting the mechanical impedance of the surrounding cementitious material from the electromechanical measurements of the embedded PZT sensor. Changes in the mechanical impedance of mortars through periods of setting and early strength gain obtained from the embedded PZT sensor are validated using pin penetration, isothermal calorimetry and vibration-based measurements. Kinetics of hydration reaction obtained from isothermal calorimetry and increase in the penetration resistance during the setting behavior in the material, are accurately reflected in the increase in the mechanical impedance of the surrounding mortar obtained from the embedded PZT sensor. The continued increase in the mechanical impedance of the mortar after setting, up to 28 days, correlates well with the increase in elastic modulus of material obtained from vibration-based measurements. The durability of the sensor protection scheme is verified by evaluating the performance of sensors recovered from inside the mortar after long-term embedment. The embedded PZT sensor offers the potential for monitoring the local property development in a cementitious material from within the bulk of the structure and for use in quality assessment.
PubDate: 2017-08-21
DOI: 10.1007/s10921-017-0442-4
Issue No: Vol. 36, No. 4 (2017)

• Modelling and Analysis of Power Distribution of Electromagnetic Waves on
Plane Surfaces Using Lock-in IR Thermography
• Authors: Khalid Muzaffar; Krishnendu Chatterjee; Lalat Indu Giri; Shiban Koul; Suneet Tuli
Abstract: The electric field distribution (magnitude only) near a radiating source (antenna) can be easily determined using infrared thermography. A thin screen (made of carbon fiber reinforced polymers) is placed in front of a microwave source. The electromagnetic waves impinging on the screen are partially absorbed, resulting in temperature rise of the screen. This temperature rise is monitored by an infrared camera. The temperature distribution thus observed is mapped to the electric field strength (magnitude of electric field) of the electromagnetic waves. Points on the screen where the temperature rise is low correspond to weak electromagnetic fields whereas points with high temperature rise correspond to strong electromagnetic fields. In this paper electro-thermal modelling is done so as to obtain the temperature distribution over the screen, when an electromagnetic field is incident on it. This model can conversely be used for finding electromagnetic field distributions from IR thermal images.
PubDate: 2017-08-10
DOI: 10.1007/s10921-017-0439-z
Issue No: Vol. 36, No. 3 (2017)

• A Procedure for Detecting Hidden Surface Defects in a Thin Plate by Means
of Active Thermography
• Authors: Gabriele Inglese; Roberto Olmi; Saverio Priori
Abstract: Let $$\varOmega _\epsilon$$ be a metallic plate whose top inaccessible surface has been damaged by some chemical or mechanical agent. We heat the opposite side and collect a sequence of temperature maps $$u^\epsilon$$ . Here, we construct a formal explicit approximation of the damage $$\epsilon \theta$$ by solving a nonlinear inverse problem for the heat equation in three steps: (i) smoothing of temperature maps, (ii) domain derivative of the temperature, (iii) thin plate approximation of the model and perturbation theory. Our inversion formula is tested with realistic synthetic data and used in a real laboratory experiment.
PubDate: 2017-08-10
DOI: 10.1007/s10921-017-0440-6
Issue No: Vol. 36, No. 3 (2017)

• Excitation Mechanism of Flexural-Guided Wave Modes F(1, 2) and F(1, 3) in
Pipes
• Authors: Liguo Tang; Bingzheng Wu
Abstract: The L(0, 2) and T(0, 1) modes are the two most commonly used modes in a pipe inspection; however, they are insensitive to axial cracks in the pipe. Therefore, it is meaningful to explore the excitation and utilization of the guided wave modes, which are different from the L(0, 2) and T(0, 1) modes. In this study, the excitation mechanism of two kinds of flexural-guided wave modes, F(1, 2) and F(1, 3), in a pipe is discussed in detail. The discussion is based on the dynamic response solution, which is obtained by the eigenfunction expansion method. Either mode can be excited by employing two transducer arrays. Each array is composed of sixteen elements. Moreover, the position, vibration direction, and phase of each element should be appropriately chosen. The validity of the excitation method is demonstrated by the numerical results obtained using the finite element method.
PubDate: 2017-08-07
DOI: 10.1007/s10921-017-0438-0
Issue No: Vol. 36, No. 3 (2017)

• Validation of Model Order Assumption and Noise Reduction Method for the
Impact Resonance Testing of Asphalt Concrete
• Authors: Ilker Boz; Korkut Bekiroglu; Mansour Solaimanian; Pezhouhan Tavassoti-Kheiry; Constantino Lagoa
Abstract: The impact resonance test is a free vibration-based nondestructive test method that has been increasingly used in evaluation and characterization of asphalt concrete for the past two decades. The rheological modeling of the impact resonance test is conceptualized by a linear viscous damping mechanism having single degree of freedom whose equation of the motion is assumed to be second order. In this study, the second order equation of motion assumption in the modeling of the impact resonance test response was evaluated for asphalt concrete testing. A set of asphalt concrete specimens was tested with the impact resonance test, and the obtained signals at a range of temperatures were evaluated by means of the Hankel matrix method. The results showed that the assumption is violated for asphalt concrete testing especially at high temperatures, mainly due to the presence of noise in the obtained response. However, the Hankel method was employed to filter out the noise. It was seen that the assumption could be employed for asphalt concrete at a range of temperatures including high temperatures, provided that the filtering is performed on the obtained signal. The results also showed that the employed filtering procedure produced improvements for the impact resonance test material dependent responses, resonant frequency and especially damping ratio calculations.
PubDate: 2017-08-03
DOI: 10.1007/s10921-017-0436-2
Issue No: Vol. 36, No. 3 (2017)

• Effect of Defect Size on Subsurface Defect Detectability and Defect Depth
Estimation for Concrete Structures by Infrared Thermography
• Authors: Shuhei Hiasa; Recep Birgul; F. Necati Catbas
Abstract: This study aims to reveal the effect and correlation of delamination size and defect shape for using infrared thermography (IRT) through FE modeling to enhance the reliability and applicability of IRT for effective structural inspections. Regarding the effect of delamination size, it is observed that the temperature difference between sound and delaminated area ( $$\Delta$$ T) increases as the size of delamination increases; however, $$\Delta$$ T converges to a certain value when the area is 40  $$\times$$  40 cm and the thickness is 1 cm. As for the shape of delamination, it can be assumed that if the aspect ratio which is the ratio of the length of the shorter side to the longer side of the delamination is more than 25%, $$\Delta$$ T of any delaminations converges to $$\Delta$$ T of the same area of a square/circular-shaped delamination. Furthermore, if the aspect ratio is 25% or smaller, $$\Delta$$ T becomes smaller than the $$\Delta$$ T of the same area of a square/circular-shaped delamination, and it is getting smaller as the ratio becomes smaller. Furthermore, this study attempts to estimate depths of delaminations by using IRT data. Based on the correlation between the size of delamination and the depth from the concrete surface in regard to $$\Delta$$ T, it was assumed that it was possible to estimate the depth of delamination by comparing $$\Delta$$ T from IRT data to $$\Delta$$ T at several depths obtained from FE model simulations. Through the investigation using IRT data from real bridge deck scanning, this study concluded that this estimation method worked properly to provide delamination depth information by incorporating IRT with FE modeling.
PubDate: 2017-07-31
DOI: 10.1007/s10921-017-0435-3
Issue No: Vol. 36, No. 3 (2017)

• Estimating the Depth of Concrete Pier Wall Bridge Foundations Using
Nondestructive Sonic Echo
• Authors: Saman Rashidyan; Tang-tat Ng; Arup Maji
Abstract: This application paper outlines procedure developed for conducting nondestructive sonic echo (SE) tests to determine the depth of unknown concrete pier wall foundations. The National Bridge Inventory recognizes that more than 86,000 bridges in the US have no foundation data on record. An unknown percentage of these could also be highly vulnerable to scouring and subsequent failure. A series of field tests using the SE method were conducted on concrete pier wall foundations in the current research. Finite element models were used to understand the effect of the duration of impact, superstructure and upward striking on the pier caps on the waveform detected at the sensors. Good agreement were identified between the field tests and simulated models. Finally, practical recommendations were made to improve the SE methodology based on laboratory and field tests.
PubDate: 2017-07-13
DOI: 10.1007/s10921-017-0433-5
Issue No: Vol. 36, No. 3 (2017)

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