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Showing papers on "Ultrasonic testing published in 2007"


Journal ArticleDOI
TL;DR: In this paper, the monitoring of the composite wing skin-to-spar joint in unmanned aerial vehicles using ultrasonic guided waves was investigated. But the authors focused on the ultrasonic strength of transmission through the joints.
Abstract: This article deals with the monitoring of the composite wing skin-to-spar joint in unmanned aerial vehicles using ultrasonic guided waves The study investigates simulated wing skin-to-spar joints with two different types of bond defects, namely poorly cured adhesive and disbonded interfaces The bond-sensitive feature considered is the ultrasonic strength of transmission through the joints The dispersive wave propagation problem is studied numerically by a semi-analytical finite element method that accounts for viscoelastic damping, and experimentally by ultrasonic testing that uses highly durable, flexible macro fiber composite transducers The discrete wavelet transform is also employed to de-noise and compress the ultrasonic measurements Both numerical and experimental tests confirm that the ultrasonic strength of transmission increases across the defected bonds

111 citations


Journal ArticleDOI
TL;DR: A technique for characterizing reflectors with subwavelength dimensions by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms is described.
Abstract: Ultrasonic arrays are increasingly widely used in nondestructive evaluation (NDE) due to their greater flexibility and potentially superior performance compared to conventional monolithic probes. The characterization of small defects remains a challenge for NDE and is of great importance for determining the impact of a defect on the integrity of a structure. In this paper, a technique for characterizing reflectors with subwavelength dimensions is described. This is achieved by post-processing the complete data set of time traces obtained from an ultrasonic array using two algorithms. The first algorithm is used to obtain information about reflector orientation and the second algorithm is used to distinguish between point-like reflectors that reflect uniformly in all directions and specular reflectors that have distinct orientations. Experimental results are presented using a commercial 64-element, 5-MHZ array on two aluminum test specimens that contain a number of machined slots and side-drilled holes. The results show that the orientation of 1-mm-long slots can be determined to within a few degrees and that the signals from 1-mm-long slots can be distinguished from that from a 1-mm-diameter circular hole. Techniques for quantifying both the orientation and the specularity of measured signals are presented and the effect of processing parameters on the accuracy of results is discussed.

107 citations


Journal ArticleDOI
TL;DR: An ultrasonic fatigue testing system capable of operating at temperatures up to 1000°C has been developed and utilized to study the fatigue behavior of a single crystal superalloy (PWA 1484) at a temperature of 1000 ÂC and loading frequency of approximately 20 Â kHz as mentioned in this paper.
Abstract: An ultrasonic fatigue testing system capable of operating at temperatures up to 1000 °C has been developed and utilized to study the fatigue behavior of a single crystal superalloy (PWA 1484) at a temperature of 1000 °C and loading frequency of approximately 20 kHz. The stress-life data generated from the ultrasonic testing system were comparable to those from conventional servo-hydraulic fatigue tests for similar single crystal alloys. Interior Ta-rich carbides were the major microstructural feature responsible for crack initiation in the alloy. Crack growth under ultrasonic loading frequency at 1000 °C for PWA 1484 occurred in a crystallographic manner on {1 1 1} octahedral slip planes, in contrast to the normal Mode-I growth mode typically observed for single crystal superalloys at high temperature (>850 °C) with conventional servo-hydraulic loading frequencies (

90 citations


Journal ArticleDOI
TL;DR: An artificial neural network is proposed to solve problems in the interpretation of ultrasonic oscillograms obtained by the pulse echo method to contribute to the automation of quality control processes in resistance spot welding.

80 citations


Patent
21 Dec 2007
TL;DR: In this paper, an ultrasonic non-destructive evaluation (NDE) system for inspection of target materials is presented, which includes an articulated robot, an ultrasound inspection head, a processing module, and a control module.
Abstract: An ultrasonic non-destructive evaluation (NDE) system operable to inspect target materials is provided. This ultrasonic NDE system includes an articulated robot, an ultrasound inspection head, a processing module, and a control module. The ultrasound inspection head couples to or mounts on the articulated robot. The ultrasound inspection head is operable to deliver a generation laser beam, a detection laser beam, and collect phase modulated light scattered by the target materials. The processing module processes the phase modulated light and produces information about the internal structure of the target materials. The control module directs the articulated robot to position the ultrasound inspection head according to a predetermined scan plan.

64 citations


Journal ArticleDOI
TL;DR: In this article, a lab-based laser-EMAT system has been developed to observe the ultrasonic surface wave propagation and interaction with surface breaking defects on the sample rail head surface.
Abstract: Electromagnetic acoustic transducers (EMATs) are non-contact ultrasonic transducers capable of generating wide band ultrasonic surface waves on metallic samples. A lab-based laser-EMAT system has been developed to observe the ultrasonic surface wave propagation and interaction with surface breaking defects on the sample rail head surface. A wide band EMAT generating surface waves with a frequency content between approximately 50 and 500 kHz is used to propagate ultrasonic waves on the surface of a rail head down the length of the sample. A stabilised Michelson interferometer is used to measure the out-of-plane displacement of the surface wave. A complete picture of the ultrasonic surface wave on the sample surface over time is reconstructed using this technique, with exceptionally high spatial and temporal resolution. Despite the curvature of the rail head, the ultrasonic surface wave propagating down the rail is found to have similar properties to Rayleigh waves by direct comparison to those observed on flat samples using the same technique.

62 citations


Journal ArticleDOI
TL;DR: In this paper, an ultrasonic wavefield propagation imaging system is introduced and then applied for ultrasonic imaging of complex curved surfaces, where a Q-switched pulsed laser is utilized as a moving ultrasonic generator, and a PZT ultrasonic sensor is fixed during the laser beam scanning and detects the ultrasonic waves propagated from the points excited by the laser.
Abstract: An ultrasonic wavefield propagation imaging system is introduced and then applied for ultrasonic wavefield imaging of complex curved surfaces. A Q-switched pulsed laser is utilized as a moving ultrasonic generator, and a PZT ultrasonic sensor is fixed during the laser beam scanning and detects the ultrasonic waves propagated from the points excited by the laser beam. The waveforms are allocated in the spatial domain of the scanned points and then manipulated in the form of a time versus wavefield movie. The visualized wavefields enable easy detection and interpretation of structural defects because anomalies during wavefield propagation can be visualized. Furthermore, this ultrasonic wavefield propagation imaging system enables reference-free inspection, complex curved surface scanning because it does not require control of focal length and incidence angle of the laser beam, and excellent adaptability with built-in structural health monitoring sensors, such as piezoelectric and fiber optic sensors. The system is demonstrated in the applications of wavefield visualization on a drill surface, detection of mass loss parts inside an elbow pipe joint, and detection and characterization of impact damage and stringer disbond in a composite skin–stringer structure.

57 citations


Patent
06 Nov 2007
TL;DR: In this article, an ultrasonic probe including a cMUT chip that has plural oscillation elements whose electromechanical coupling coefficient or sensitivity varies in accordance with a bias voltage and transmits/receives a ultrasonic wave was presented.
Abstract: An ultrasonic probe including a cMUT chip that has plural oscillation elements whose electromechanical coupling coefficient or sensitivity varies in accordance with a bias voltage and transmits/receives an ultrasonic wave, an acoustic lens provided at an ultrasonic wave transmission/reception side of the cMUT chip, a backing layer provided to the opposite surface of the cMUT chip to the acoustic lens, and a substrate provided between the backing layer and the cMUT chip. The ultrasonic probe further includes thermal stress suppressing means for suppressing thermal stress occurring due to the difference in linear expansion coefficient caused by temperature variation between the substrate and the backing layer.

55 citations


Journal ArticleDOI
TL;DR: One objective of this study is to model ultrasonic fields in both solids and fluids generated by the leaky Rayleigh wave when finite size transducers are inclined at Rayleigh critical angles.

52 citations


BookDOI
01 Jan 2007
TL;DR: In this article, the authors introduce failure mechanisms and Ultrasonic inspection of composite structures using the Distributed Point Source Method (DPSM) and NDE with Piezoelectric Wafer Active Sensors.
Abstract: Preface. Chapter 1. An Introduction to Failure Mechanisms and Ultrasonic Inspection (Kumar V. Jata, Tribikram Kundu and Triplicane A. Parthasarathy). Chapter 2. Health Monitoring of Composite Structures Using Ultrasonic Guided Waves (Sauvik Banerjee, Fabrizio Ricci, Frank Shih and Ajit Mal). Chapter 3. Ultrasonic Measurement of Micro-acoustic Properties of the Biological Soft Materials (Yoshifumi Saijo). Chapter 4. Corrosion and Erosion Monitoring of Pipes by an Ultrasonic Guided Wave Method (Geir Instanes, Mads Toppe, Balachander Lakshiminarayan and Peter B. Nagy). Chapter 5. Modeling of the Ultrasonic Field of Two Transducers Immersed in a Homogenous Fluid Using the Distributed Point Source Method (Rais Ahmad, Tribikram Kundu and Dominique Placko). Chapter 6. Ultrasonic Scattering in Textured Polycrystalline Materials (Liyong Yang, Goutam Ghoshal and Joseph A. Turner). Chapter 7. Embedded Ultrasonic NDE with Piezoelectric Wafer Active Sensors (Victor Giurgiutiu). Chapter 8. Mechanics Aspects of Non-linear Acoustic Signal Modulation due to Crack Damage (Hwai-Chung Wu and Kraig Warnemuende). Chapter 9. Non-contact Mechanical Characterization and Testing of Drug Tablets (Cetin Cetinkaya, Ilgaz Akseli, Girindra N. Mani, Christopher F. Libordi and Ivin Varghese). Chapter 10. Split Hopkinson Bars for Dynamic Structural Testing (Chul Jin Syn and Weinong W. Chen). List of Authors. Index.

48 citations


Journal ArticleDOI
TL;DR: In this paper, the authors compared the performance of magnetic Barkhausen noise and ultrasonic methods for the evaluation of the microstructure of commercial steels and determined the propagation rates of longitudinal waves with the ultrasonic pulse-echo technique.

Journal ArticleDOI
TL;DR: In this paper, the authors developed a reliable and precise non-destructive testing technique based on infrared thermography and post processing by means of neural networks for concrete structures strengthened by bonded FRP.

Patent
26 Feb 2007
TL;DR: In this paper, an ultrasonic test head is acoustically coupled to a workpiece in a curved area of its surface, and includes an arrangement comprising a plurality of individually driveable transducer elements arranged next to one another.
Abstract: In a method for the ultrasonic testing of a workpiece (2) in a curved area of its surface, in particular of a workpiece (2) made of a fiber composite material, an ultrasonic test head (10) is acoustically coupled to the workpiece in this area, and includes an ultrasonic transducer arrangement (12) comprising a plurality (N) of individually driveable transducer elements (20 i) which are arranged next to one another. In chronologically successive test cycles, a number (n) of transducer elements (20 i) are respectively combined to form a group and are driven in a plurality of test pulses within this test cycle in a time delayed manner with respect to one another such that the transmitted ultrasound beam (30 a-d) in this test cycle is swept within a predetermined angular range (α1, α2), so that one of the number of echo signals, corresponding to the number of test pulses, for each group is received from different directions of the workpiece (2).

Journal ArticleDOI
TL;DR: A finite-element modeling procedure for computing the frequency response of piezoelectric transducers attached to infinite constant cross-section waveguides, as encountered in guided wave ultrasonic inspection, is presented.
Abstract: A finite-element modeling procedure for computing the frequency response of piezoelectric transducers attached to infinite constant cross-section waveguides, as encountered in guided wave ultrasonic inspection, is presented. Two-dimensional waveguide finite elements are used to model the waveguide. Conventional three-dimensional finite elements are used to model the piezoelectric transducer. The harmonic forced response of the waveguide is used to obtain a dynamic stiffness matrix (complex and frequency dependent), which represents the waveguide in the transducer model. The electrical and mechanical frequency response of the transducer, attached to the waveguide, can then be computed. The forces applied to the waveguide are calculated and are used to determine the amplitude of each mode excited in the waveguide. The method is highly efficient compared to time integration of a conventional finite- element model of a length of waveguide. In addition, the method provides information about each mode that is excited in the waveguide. The method is demonstrated by modeling a sandwich piezoelectric transducer exciting a waveguide of rectangular cross section, although it could be applied to more complex situations. It is expected that the modeling method will be useful during the optimization of piezoelectric transducers for exciting specific wave propagation modes in waveguides.

BookDOI
TL;DR: The overall PSO-ES hybrid is capable of finding feasible transducer designs from all of the start points in a benchmark test suite, and is an important step towards the use of Continuum Probe Designer™ as a fully automated tool for the design of phased array ultrasonic transducers.
Abstract: Continuum Probe Designer™ by Acoustic Ideas Inc. is a tool that can help design the "best" phased array ultrasonic transducer for a given inspection task. Given a specific surface geometry for the ultrasonic transducer, one component of Continuum Probe Designer™ can determine the number of elements, and the required size and shape of each element to meet a list of ultrasonic inspection goals. Using the number of elements as a cost function, an optimization problem to find the best surface geometry for the transducer is created. Previous work has demonstrated that a (1+λ)-evolution strategy (ES) can be a very effective search technique for this problem. The performance of this ES was improved by starting it from "smart" (i.e. better than random) start points. Particle swarm optimization (PSO) can be used to improve the "smart" start points, and the overall PSO-ES hybrid is capable of finding feasible transducer designs from all of the start points in a benchmark test suite. This level of performance is an important step towards the use of Continuum Probe Designer™ as a fully automated tool for the design of phased array ultrasonic transducers.

Proceedings ArticleDOI
28 Mar 2007
TL;DR: In this paper, two honeycomb composites panels were produced with several embedded flaws and missing material primarily representing planar disbonds at various levels within the thickness of the panels and with different shapes.
Abstract: Honeycomb composites are increasingly finding utility in a variety of environments and applications, such as aircraft structural components, flight control components, radomes, etc. In‐service and environmental stresses can produce unwanted flaws that adversely affect the structural integrity and functionality of these composites. These flaws may be in the forms of disbonds, delaminations, impact damage, crushed honeycomb, moisture intrusion, internal cracks, etc. There are several nondestructive testing (NDT) methods that may be used to inspect these composites for the presence and evaluation of these flaws. Such NDT methods include X‐ray computed tomography, near‐field millimeter wave, shearography, and ultrasonic testing. To assess the capabilities of these methods for honeycomb composite inspection, two honeycomb composites panels were produced with several embedded flaws and missing material primarily representing planar disbonds at various levels within the thickness of the panels and with different shapes. Subsequently, the aforementioned NDT methods were used to produce images of the two panels. This paper presents the results of these investigations and a comparison among the capabilities of these methods.

Journal ArticleDOI
TL;DR: In this paper, an initial pre-crack of 30 mm was grown under fatigue loading to a final length of 60 mm over a total of 58 kilocycles run at 10 Hz frequency in an MTS-810 testing machine.
Abstract: ∗Piezoelectric-wafer active sensors (PWAS) are small, inexpensive, non-invasive, elastic wave transmitters/receivers that can be easily affixed to a structure. PWAS are wide-band nonresonant devices that can selectively tune in various Lamb wave modes traveling in a thin-wall structure. PWAS can be wired into sensor arrays and connected to data concentrators and wireless communicators. They have the potential to bring about a revolution in structural health monitoring, damage detection, and non-destructive evaluation just as significant as ultrasonic inspection did 50 years ago. However, its development is not yet complete, and a number of issues have still to be resolved. This paper will present results obtained in using a PWAS phased array to in-situ image crack growth during a simulated structural health monitoring test. The fatigue crack growth experiment was set up on a 1000 mm by 1000 mm 2024-T3 1-mm thick aluminum plate. An initial pre-crack of 30 mm was grown under fatigue loading to a final length of 60 mm over a total of 58 kilocycles run at 10 Hz frequency in an MTS-810 testing machine. During the test, insitu readings of the PWAS phased array were taken while the testing machine was running. The PWAS were excited with a 10-Vpp smoothed 3-count tone burst of 372 kHz, which excited the symmetric S0 Lamb-wave mode. To minimize the equipment requirement to just a single channel, the excitation of the PWAS array was performed in a round robin fashion. Simultaneously, all the PWAS were in term considered as receivers. In this way, an N x N matrix of signals was collected and stored. In the beginning, the received signals were unusable due to the high 10 Hz noise superposed by the testing process. Additional hardware was constructed to pre-filter the received signals prior to digitization. Consequently, usable signals with clear crack reflections were successfully collected. The received signals were post processed with the embedded ultrasonics structural radar (EUSR) algorithm to obtain a direct imaging of the crack in the test plate (similar to the C-scan from ultrasonic NDE, only that was obtained from a single location using a sweeping beam of focused Lamb waves. The imaging results were correlated with physical measurements of the crack size using penetrating liquid and a digital camera. Remarkable consistency was obtained. Subsequently, the results were used to predict further crack growth and make a prognosis of component failure using the structural health monitoring results.

Journal ArticleDOI
TL;DR: In this article, a fiber-optic system featuring strain measurement and ultrasonic detection was constructed with fiber Bragg gratings based on wavelength-light intensity conversion technique, which was applied to strain measurement in impact loading to carbon fiber-reinforced plastics and subsequent impact damage detection.

Patent
27 Jun 2007
TL;DR: In this paper, a two-dimensional array (12) of ultrasonic pulse-echo sensors (18) is placed on a surface of an aircraft structure, and an image of damage (120, 124) is generated.
Abstract: A method (200) of inspecting an aircraft structure, the method comprising: disposing (204) a two-dimensional array (12) of ultrasonic pulse-echo sensors (18) onto a surface (70) of an aircraft structure; sending (206, 208) from each particular sensor (18) an ultrasonic pulse into the surface (70); receiving (210) by each particular sensor (18) an ultrasonic echo signal resulting from the sending of the ultrasonic pulse by the particular sensor (18); graphically displaying (220) an image of damage (120, 124) within the aircraft structure, the image defined by a two-dimensional matrix of pixels each of which corresponds to a particular one of the sensors (18); determining (222) whether the damage satisfies a predetermined criterion, and selecting (222) a mode of returning the aircraft structure to flying service based on the determination of whether the damage satisfies a predetermined criterion.

Patent
25 Sep 2007
TL;DR: In this paper, an air-coupled, high-power ultrasonic transducer for generating guided waves in the pipe wall, and a high-sensitivity, air coupled transducers for detecting these waves, are disposed at a distance apart and at a chosen angle with respect to the surface of the pipe, either inside of or outside of a pipe.
Abstract: Apparatus and method for non-contact ultrasonic detection of features on or within the walls of hollow pipes are described. An air-coupled, high-power ultrasonic transducer for generating guided waves in the pipe wall, and a high-sensitivity, air-coupled transducer for detecting these waves, are disposed at a distance apart and at chosen angle with respect to the surface of the pipe, either inside of or outside of the pipe. Measurements may be made in reflection or transmission modes depending on the relative position of the transducers and the pipe. Data are taken by sweeping the frequency of the incident ultrasonic waves, using a tracking narrow-band filter to reduce detected noise, and transforming the frequency domain data into the time domain using fast Fourier transformation, if required.

Journal ArticleDOI
TL;DR: In this article, an ultrasonic test setup and data analysis procedures, which provide for continuous monitoring of the hydrating cementitious materials from a very early age through setting, are presented.
Abstract: After casting, cementitious materials exhibit a continuous change in the mechanical properties with time due to a chemical reaction known as hydration. In addition, these materials also exhibit a change in state, from a fluid to a solid, in the first few hours. Conventionally, changes in the material properties are obtained by monitoring the visco-elastic moduli with time before setting and the increase in the elastic material properties of the solid cementitious material, after setting. An ultrasonic test setup and the data analysis procedures, which provide for continuous monitoring of the hydrating cementitious materials from a very early age through setting are presented in this paper. The test procedures for obtaining the ultrasonic test data and the inversion subroutines for assessing the material properties of the cementitious material at different stages of hydration are discussed. The experimental test results obtained from mortar mixtures of varying compositions are presented. The observed experimental trends are explained considering wave propagation in visco-elastic materials. There is a two-stage increase in the value of shear modulus of mortar with time. Experimental evidence suggests that initially there is a larger relative increase in the viscous component of the shear modulus while later there is a larger relative increase in the elastic component.

Journal ArticleDOI
TL;DR: In this article, a back surface reflection prediction based on attenuation and phase velocity dispersion estimation method, in highly attenuating plastic (polyvinylidene fluoride-PVDF) has been described.
Abstract: In this paper, prediction of the back surface reflection, which is based on attenuation and phase velocity dispersion estimation method, in highly attenuating plastic (polyvinylidene fluoride—PVDF) has been described. Estimation of the attenuation law is based on the inverse transfer function of the object approximation in the frequency domain. The oscillating character of the inverse transfer function of the highly attenuating plastic material gives rise to an ill-posed problem for approximation. It has been solved in two ways: application of the Tikhonov regularization process and iterative adjustment of the approximation parameters. The estimated attenuation coefficient α 0 and power n have been used for calculation of phase velocity dispersion using the Kramers–Kronig relations and having attenuation coefficient measured at single-frequency value. The reconstructed waveforms of the ultrasonic back surface reflections using the estimated attenuation and phase velocity dispersion curves have been presented and compared with the experimental one.

Journal ArticleDOI
TL;DR: In this article, the authors developed a new ultrasonic transducer capable of transmitting and receiving guided-waves in a rotating shaft using Terfenol-D, a giant magnetostrictive alloy.
Abstract: The purpose of this study is to develop a new ultrasonic transducer capable of transmitting and receiving guided-waves in a rotating shaft. The key idea in this development is the use of wireless capability of the magnetostrictive effect. In this investigation, relatively low-frequency longitudinal waves are generated by Terfenol-D, a giant magnetostrictive alloy (GMA). After an underlying magnetostrictive transducer configuration is presented, the effects of various design parameters on the transducer performances are studied experimentally. The material behavior of Terfenol-D is also briefly discussed. To show the effectiveness of the developed transducer, the transducer is used for guided-wave damage inspection in a rotating shaft having an artificial crack.

Patent
27 Nov 2007
TL;DR: In this paper, a two-dimensional array of ultrasonic transducers and an array controller are used to detect unacceptable levels of porosity, micro-cracking or defects attributable to thermal damage.
Abstract: A method and an array-based system for inspecting a structure are provided that can identify unacceptable levels of porosity, microcracking or defects attributable to thermal damage. The inspection system includes a two-dimensional array of ultrasonic transducers, and an array controller configured to trigger at least one ultrasonic transducer to emit an ultrasonic signal into the structure. The array controller is also configured to receive data representative of backscattered signals preferentially received by at least one ultrasonic transducer from a portion of the structure offset from the at least one ultrasonic transducer that was triggered to emit the ultrasonic signal.

Patent
02 Nov 2007
TL;DR: In this article, a multi-element array ultrasonic transducer is operated with a substantial fluid layer, such as water, between the array transducers and the component surface.
Abstract: A method for ultrasonically inspecting components with wavy or uneven surfaces. A multi-element array ultrasonic transducer is operated with a substantial fluid layer, such as water, between the array transducer and the component surface. This fluid layer may be maintained by immersing the component in liquid or by using a captive couplant column between the probe and the component surface. The component is scanned, measuring the two dimensional surface profile using either a mechanical stylus, laser, or ultrasonic technique. Once an accurate surface profile of the component's surface has been obtained, data processing parameters are calculated for processing the ultrasonic signals reflected from the interior of the component that eliminate beam distortion effects and reflector mis-location that would otherwise occur due to the uneven surfaces.

Journal ArticleDOI
01 Jun 2007-Insight
TL;DR: In this paper, the authors describe the development of state-of-the-art miniaturized front-end ultrasonic and eddy-current test instrumentation for the inspection of railroad wheel sets.
Abstract: For more than 6 years, the automated ultrasonic and eddy-current systems for the inspection of railroad wheel sets, developed by Fraunhofer IZFP and Fraunhofer TEG, have been field-hardened through daily operation at various maintenance facilities of the Deutsche Bahn (DB). The testing stations are equipped with IZFP's multi-channel electronics, a modular PC integrated system operating inside 19" rack-mounted industrial computers. Special requirements for new installations of stationary systems (AURA) and underfloor testing stations (UFPE) called for the development of state-of-the-art miniaturized front-end ultrasonic and eddy-current test instrumentation. This innovation offers new dimensions for the concept and design of such systems, including features providing effortless maintenance of the inspection systems. Due to the small size of the electronic modules they can be placed in close proximity to the transducer assembly. High-speed networking techniques ensure the transfer of all the acquired digital ultrasonic and eddy-current data from the front- end modules to the workstation responsible for data acquisition and analysis. The new front-end technology is applied for the testing stations of the latest generation. One example is a system installed at the DB plant Krefeld, specifically designed for the ultrasonic testing of ICE train drive wheels. The transducer assembly for wheel rim and disk inspection includes hot-swap modules with integrated UT front-end modules adapted to inspect specific wheel disk configurations. A second example represents testing equipment operating at the Suddeutsche Rail Service GmbH, Kaiserslautern. Ultrasonic and eddy-current front-end modules are responsible for the inspection of the wheel rim of disassembled wheel sets of freight cars. In addition to the wheel rim the solid axle is inspected in the same test stand using GE's Phased Array system. Miniaturized front-end modules are also advantageous for the inspection with the wheel sets installed at the train. The concept of such an underfloor testing system is outlined.

Journal Article
TL;DR: In this article, a good correlation between velocity of ultrasonic wave propagation and the degree of strength degradation of epoxy-glass composites caused by fatigue was found, which can be applied as effective tool to assess of fatigue degradation of polymer composites.
Abstract: Materials AbstrAct Purpose: The purpose of this paper was to find relationship between the degree of strength degradation caused by fatigue and the changes of ultrasonic wave characteristics such as wave velocity and damping coefficient. Design/methodology/approach: Epoxy-glass composites were subjected to oscillatory bending loadings with constant deflection. During fatigue procedure the force needed to achieve constant deflection was measured. During fatigue tests samples were subjected to ultrasonic tests. Additionally before fatigue test and after 300 000, 850 000 and 1 900 000 cycles parts of samples were subjected to destructive bending test. Findings: A good correlation between velocity of ultrasonic wave propagation and the degree of strength degradation of epoxy-glass composites caused by fatigue was found. Ultrasounds can be applied as effective tool to assessment of fatigue degradation of polymer composites. Research limitations/implications: Achieved results showed that research have to be continued. Fatigue with other loading conditions and for other composite materials is planned. Practical implications: The results of present research can be applied to elaboration of non-destructive method of measurement of the degree of fatigue degradation of polymer composites. Originality/value: Presented correlation between ultrasound wave characteristics and the degree of strength degradation caused by fatigue is original value of this paper.

Proceedings ArticleDOI
28 Mar 2007
TL;DR: In this paper, the authors presented a new approach based on active thermography by which it is possible to produce images of porosity in Carbon Fibre Reinforced Plastics that correspond striking well with results obtained by ultrasonic testing.
Abstract: We present a new approach based on Active Thermography by which it is possible to produce images of porosity in Carbon Fibre Reinforced Plastics that correspond striking well with results obtained by ultrasonic testing We applied the method of Pulsed Thermography by using flashes of light for the generation of heat The evolution of surface temperatures which depends on the diffusivity of the sample and on the sample’s geometry could be well fitted by means of a heat conduction model Images of porosity are generated by means of an evaluation by which the influence of the light intensity distribution on the data is eliminated Thus corrections with respect to the lateral distribution of the heat generation are not necessary, nor are emissivity corrections Corrections due to the influence of geometry, however, had to be taken into account The quantitative evaluation of the porosity is based on its linear relation to the diffusivity Images of porosity obtained thermographically are compared with corresponding images as obtained by state of the art ultrasonic testing We show that the thermographic method exhibits a better sensitivity and resolution of porosity Measurements have been performed on samples with average porosities between 1 and 5 % With some modifications the method can be applied for the quantitative characterization of delaminations of multi‐layered samples as well

Journal ArticleDOI
TL;DR: In this article, an extension of this method was proposed, which utilizes multiple time and frequency windows of the received signals for computing the energy ratio with the goal of achieving the earliest possible detection of cracking.
Abstract: Angle beam ultrasonic inspection methods are well established for detection and sizing of fatigue cracks originating from fastener holes, and have recently been applied to in situ monitoring of such cracks using permanently attached transducers. Prior work utilizing a dual angle beam method has demonstrated the efficacy of an energy ratio algorithm for detection and sizing of cracks in open holes. This energy ratio is a measure of how much a crack opens under load, and is the ratio of transmitted energy for the specimen under tensile loading to the energy under no load, normalized by the ratio computed for the undamaged hole. Considered here is an extension of this method which utilizes multiple time and frequency windows of the received signals for computing the energy ratio with the goal of achieving the earliest possible detection of cracking. These windows allow different spatial regions to be selectively interrogated, and windows corresponding to the actual crack geometry should be more effective at detecting the crack. An automated algorithm is developed and implemented to permit multiple time–frequency windows to be effectively analyzed without requiring manual interpretation. Results are shown which indicate that cracking in open holes can be detected significantly earlier in the fatiguing process compared to the previously implemented full-window energy ratio method. Integral to the method is the assumption that there is a significant change in crack closure as a function of load.

Journal ArticleDOI
TL;DR: In this paper, the formation of structural noise (SN) is analyzed, and static noise characteristics are determined for them, and the requirements imposed on the procedure of discriminating echo signals from a flaw against a correlated-noise background are determined.
Abstract: Problems of ultrasonic testing of materials with complex structures are considered. Such problems arise owing to a correlated interference—structural noise (SN). The simplest models describing the formation of SN are analyzed, and static noise characteristics are determined for them. The main concepts that define the parameters of SN are introduced. The requirements imposed on the procedure of discriminating echo signals from a flaw against a correlated-noise background are determined.