Showing papers on "Ultrasonic testing published in 2004"
TL;DR: In this paper, a piezoelectric-based built-in diagnostic technique has been developed for monitoring fatigue crack growth in metallic structures, which consists of three major components: diagnostic signal generation, signal processing and damage interpretation.
Abstract: A piezoelectric based built-in diagnostic technique has been developed for monitoring fatigue crack growth in metallic structures. The technique uses diagnostic signals, generated from nearby piezoelectric actuators built into the structures, to detect crack growth. It consists of three major components: diagnostic signal generation, signal processing and damage interpretation. In diagnostic signal generation, appropriate ultrasonic guided Lamb waves were selected for actuators to maximize receiving sensor measurements. In signal processing, methods were developed to select an individual mode for damage detection and maximize signal to noise ratio in recorded sensor signals. Finally, in damage interpretation, a physics based damage index was developed relating sensor measurements to crack growth size. Fatigue tests were performed on laboratory coupons with a notch to verify the proposed technique. The damage index measured from built-in piezoceramics on the coupons showed a good correlation with the actual fatigue crack growth obtained from visual inspection. Furthermore, parametric studies were also performed to characterize the sensitivity of sensor/actuator location for the proposed technique.
476 citations
TL;DR: In this article, the effect of pipe size, defect size, guided wave mode and frequency on the reflection from notches was analyzed for a 3-in. schedule 40 steel pipe.
Abstract: Ultrasonic guided waves are used for the rapid screening of pipelines in service and simple, standard testing procedures are already defined. The implementation of the method enables the localization of the defects along the length of the pipe and offers a rough estimate of defect size. In this article we present a systematic analysis of the effect of pipe size, defect size, guided wave mode and frequency on the reflection from notches. The maximum and minimum value of the reflection coefficient at varying axial extent are identified and used for the purpose of defect sizing. Maps of reflection coefficient as a function of the circumferential extent and depth of the defect are presented for a 3 in. schedule 40 steel pipe. An approximate formula, which allows these results to be extrapolated to other pipe sizes, is proposed and evaluated.
253 citations
TL;DR: This paper will describe how several non-contact acoustical and ultrasonic techniques currently available have been used in unique materials characterization applications.
183 citations
TL;DR: Results showed that even when very noisy signals are utilized, signal processing improve the signal/noise (S/N) ratio up to 12 dB approximately and enhance the analysis of the results, thus demonstrating its usefulness.
156 citations
TL;DR: A new approach is described, which eliminates the need for arbitrary assignment of some of the parameters associated with Wiener filtering and autoregressive spectral extrapolation, and is demonstrated by considering both simulated and experimental signals.
122 citations
TL;DR: In this article, the authors studied the propagation of ultrasonic guided waves in adhesively bonded lap-shear joints and showed that the dispersive behavior of the guided wave in the multilayer overlap is highly dependent on bond state.
Abstract: This paper deals with the propagation of ultrasonic guided waves in adhesively bonded lap-shear joints. The topic is relevant to bond inspection by ultrasonic testing. Specifically, the propagation of the lowest-order, antisymmetric a0 mode through the joint is examined. An important aspect is the mode conversion at the boundaries between the single-plate adherents and the multilayer overlap. The a0 strength of transmission is studied for three different bond states in aluminum joints, namely a fully cured adhesive bond, a poorly cured adhesive bond, and a slip bond. Theoretical predictions indicate that the dispersive behavior of the guided waves in the multilayer overlap is highly dependent on bond state. Experimental tests are conducted in lap-shear joints by a hybrid, broadband laser/air-coupled ultrasonic setup in a through-transmission configuration. The Gabor wavelet transform is employed to extract energy transmission coefficients in the 100 kHz 1.4 MHz range for the three different bond states examined. The cross-sectional mode shapes of the guided waves are shown to have a substantial role in the energy transfer through the joint.
111 citations
TL;DR: Multiode techniques using Golay complementary sequences are proposed for processing the ultrasonic signal, increasing scan rate, precision, and reliability and allowing simultaneous measurements to be made and detection of the same obstacle by different transducers without cross-talk problems.
Abstract: In recent applications based on ultrasound, several ultrasonic transducers have been geometrically and electronically associated to constitute a global sensor. There are several different methods used to process the ultrasonic signals obtained from these transducers. In this work, multimode techniques using Golay complementary sequences are proposed for processing the ultrasonic signal. The system increases scan rate, precision, and reliability. It is also capable of echo discrimination, allowing simultaneous measurements to be made and detection of the same obstacle by different transducers without cross-talk problems. The real-time implementation of the algorithm is presented on a field-programmable gate array (FPGA) device.
97 citations
TL;DR: An NDE-based model which can be used to estimate hardening time of concrete samples and a multiple regression analysis which takes into account the impact of different concrete constituents on ultrasound propagation speed are performed.
81 citations
TL;DR: In this paper, the authors developed analytical and numerical theories accounting for the crack parameters, such as closure stress and crack surface conditions, for the first time, and proved their validity by comparison with experiments on a well-defined fatigue crack in aluminum alloy, finding reasonable agreements.
Abstract: Cracks in solids can be detected by ultrasound if they are open. However, their detection is not easy when they are closed with a closure stress, and thus it is a fundamental problem in ultrasonic testing. Subharmonics with half the input frequency is potentially useful in the detection and evaluation of such cracks, although quantitative analysis has not been established. In this work, we develop analytical and numerical theories accounting for the crack parameters, such as closure stress and crack surface conditions, for the first time. We proved their validity by comparison with experiments on a well-defined fatigue crack in aluminum alloy, finding reasonable agreements. Based on these theories, it will be possible to estimate important parameters of partially closed cracks by fitting measured waveforms to theoretical predictions, which solves the fundamental problem in ultrasonic testing of cracks.
72 citations
TL;DR: The wavelet transform has been successfully experimented to suppress noise and to enhance flaw location from ultrasonic signal, with a good defect localization, and is directed to an automatic Artificial Neuronal Networks classification and learning algorithm of defects from A-scan data.
62 citations
TL;DR: In this article, the ability of non-destructive testing (NDT) methods for evaluating the integrity of nonmetallic materials is examined, in particular, the dynamic moduli of elasticity and damage states due to fracture.
TL;DR: An ultrasonic inspection robot with an electromagnetic acoustic transducer (EMAT) which did not require a coupling medium to inspect the circumferential pipe parts and which could transmit and receive alternately a Lamb wave with high sensitivity and a SH-plate wave without influence by the welded part.
TL;DR: The initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of reactive powder concrete are reported.
Abstract: Concrete is a critical material for the construction of infrastructure facilities throughout the world. Traditional concretes consist of cement paste and aggregates ranging in size from 6 to 25 mm that form a heterogeneous material with substantial compressive strength and a very low tensile strength. Steel reinforcement is used to provide tensile strength for reinforced concrete structures and as a composite the material is useful for structural applications. A new material known as reactive powder concrete (RPC) is becoming available. It differs significantly from traditional concrete; RPC has no large aggregates, and contains small steel fibers that provide additional strength and, in some cases, can replace traditional steel reinforcement. Due to its high density and lack of aggregates, ultrasonic inspections at frequencies 10 to 20 times that of traditional concrete inspections are possible. This paper reports on the initial findings of research conducted to determine the applicability of ultrasonic testing techniques for the condition assessment of RPC. Pulse velocities for shear and longitudinal waves and ultrasonic measurement of the modulus of elasticity for RPC are reported. Ultrasonic crack detection for RPC also is investigated.
TL;DR: A new method for on-line batter monitoring using ultrasound techniques is presented, which finds that changes in acoustic impedance are easier to detect than changes in density especially when air incorporation is in small quantities.
TL;DR: In this paper, a spatially sparse array of conventional piezoelectric transducers is attached to a part surface to monitor its structural health, and artificial flaws are incrementally added to simulate damage progression.
Abstract: A spatially sparse array of conventional piezoelectric transducers is attached to a part surface to monitor its structural health. Artificial flaws are incrementally added to simulate damage progression. The structure is flooded with ultrasonic energy by transmitting on a single transducer, and waveforms are recorded from other transducers in the array. Simple waveform differencing techniques between pre‐flaw baseline waveforms and post‐flaw waveforms show promise for determining the state of damage progression in both concrete and aluminum samples.
TL;DR: The use of ultrasonic testing to determine pulse velocities and small-strain elastic constants for rocks has been standardized in American Society for Testing and Materials (ASTM) standard D2845-95.
Abstract: The use of ultrasonic testing to determine pulse velocities and small-strain elastic constants for rocks has been standardized in American Society for Testing and Materials (ASTM) standard D2845-95...
Journal Article•
TL;DR: In this paper, an ultrasonic method that is able to monitor live loads in multi-wire steel strands as well as detect possible discontinuities such as indentations and broken wires is presented.
Abstract: Loaded cables made of wires, strands or bars are employed in civil structures as load carrying members in cable stayed and suspension bridges. Steel strands are also employed in prestressed structures for the pretensioning or posttensioning of concrete. Accurate and real time knowledge of the force acting on these stressing systems can contribute immensely to ensuring the safety of a bridge structure. Monitoring cable loads in service can also allow for detection of excessive wind and traffic overloads or, in the worst scenario, problems such as accidental broken wires and corrosion. The overall objective of this paper is to further the understanding of an ultrasonic method that is able to monitor live loads in multiwire steel strands as well as detect possible discontinuities such as indentations and broken wires. The characterization of wave propagation in steel strands is achieved through a broadband, laser ultrasonic setup and time frequency wavelet transform processing. Those vibrating frequencies propagating with minimal losses are identified as they are suitable for long range testing of the strands. In addition, the wave transmission spectra are found to be sensitive to the load level. Sensors based on the magnetostrictive effect are used for the wave generation and detection. The acoustoelastic effect is also considered for live load monitoring. Signal processing based on the discrete wavelet transform is used to enhance the discontinuity detection sensitivity and acquisition speed.
TL;DR: In this article, a new method for measuring and visualizing the acoustic sound waves emitted from ultrasonic transducers is developed, which is based on laser-scanning vibrometry and allows the contactless measurement of ultrasound fields with high spatial resolution.
Abstract: A laser-scanning vibrometer can be used for measuring even the smallest motions of the active area of ultrasonic transducers. Additionally, a new method for measuring and visualising the acoustic sound waves, emitted from such transducers, is developed. The new method, too, is based on laser-scanning vibrometry and allows the contact-less measurement of ultrasound fields with high spatial resolution. The combination of both techniques permits to analyse and optimise the acoustic behaviour of ultrasonic transducers. Moreover, the method is qualified for investigating and presenting numerous acoustic phenomena.
Journal Article•
TL;DR: In this article, a hybrid laser/air coupled setup was used to detect transverse cracks and a purely air coupled setup for the detection of longitudinal cracks, and the discrete wavelet transform proved effective in filtering noise from the signals by eliminating the need for averaging in the hybrid setup and reducing to three the number of averages needed in the air coupled one.
Abstract: Noncontact methods to generate and detect ultrasonic waves for the testing of railroad tracks are being investigated by a number of researchers. While noncontact testing offers potential advantages over conventional contact testing, it generally suffers from a poor signal to noise ratio of the measurements. One powerful tool to filter out noise from ultrasonic signals is the discrete wavelet transform, which can be used in high speed applications due to its computational efficiency. In this paper, discrete wavelet transform filter bank processing is applied to two noncontact ultrasonic systems for rail testing, namely a hybrid laser/air coupled setup for the detection of transverse cracks and a purely air coupled setup for the detection of longitudinal cracks. The discrete wavelet transform proves effective in filtering noise from the signals by eliminating the need for averaging in the hybrid setup and reducing to three the number of averages needed in the air coupled setup. Data compression is an added product of the discrete wavelet transform processing. The study shows the importance of selecting the proper mother wavelet function for best processing performance. In particular, the shape of the wavelet should be similar to that of the signal being analyzed. The discrete wavelet transform emerges as a powerful tool to ease the transition to the field of noncontact ultrasonic rail testing.
TL;DR: In this paper, a simple deconvolution procedure is applied to the raw ultrasonic data so as to remove the blurring effect introduced by the ultrasonic beam size, which may be related to the level of contact between the surfaces.
Abstract: In this paper the application of an ultrasonic method to evaluate size and shape of the nominal contact area between two contacting bodies is studied. The technique is based on the analysis of the quota of the ultrasonic wave reflected by the interface, which may be related to the level of contact between the surfaces. A simple deconvolution procedure is applied to the raw ultrasonic data so as to remove the blurring effect introduced by the ultrasonic beam size. The ultrasonic data acquired on a simple sphere-plane contact interface are compared with those obtained by means of a commercial pressure sensitive film and the results are discussed to evaluate the capability of the ultrasonic technique to capture the main contact patch features correctly.
TL;DR: In this paper, a method for deducing the single-crystal elastic constants of a metal using the combined ultrasonic and metallographic data for a polycrystalline specimen is presented.
Abstract: In past work we reported on measurements of ultrasonic velocity, attenuation and backscattering in nickel‐alloy materials used in the fabrication of rotating jet‐engine components. Attenuation and backscattering were shown to be correlated to the average grain diameter, which varied with position in the billet specimens studied. The ultrasonic measurements and associated metallographic studies found the local microstructures to be approximately equiaxed and free of texture in these cubic‐phase metals. In this paper we explore a method for deducing the single‐crystal elastic constants of a metal using the combined ultrasonic and metallographic data for a polycrystalline specimen. We specifically consider the case seen in the jet‐engine alloys: polycrystalline cubic microstructures having equiaxed, randomly oriented grains. We demonstrate how the three independent elastic constants {C11, C12, C44} can be deduced from the density, the mean grain diameter, the ultrasonic attenuation at one or more frequencies, and the longitudinal and shear wave speeds. The method makes use of the attenuation theory of Stanke and Kino, and the Hill averaging procedure for estimating the sonic velocity through a polycrystalline material. Elastic constant inputs to the velocity and attenuation models are adjusted to optimize the agreement with experiment. The method is demonstrated using several specimens of Inconel 718 and Waspaloy, and further tested using four specimens of pure Nickel.
TL;DR: Experimental results show that specific reconstruction techniques have been investigated to enhance the signal-to-noise ratio as well as spatial resolution, based on beam-forming summation and multi-angle inspections, allow to reduce the speckle noise and to optimise the beam resolution.
TL;DR: A new technique has been investigated for improving the signals that can be obtained in air-coupled nondestruction evaluation (NDE) using a swept-frequency "chirp" signal, which is transmitted from a transducer in air.
Abstract: A new technique has been investigated for improving the signals that can be obtained in air-coupled nondestruction evaluation (NDE). This relies on the wide bandwidth available from polymer-filmed capacitive transducers. The technique relies on a swept-frequency "chirp" signal, which is transmitted from a transducer in air. The new technique differs from existing time-domain correlation techniques, such as pulse compression, in that a single multiplication process is performed in the time domain to give a difference frequency signal. This then can be isolated easily in the frequency domain. It will be demonstrated that this new swept frequency multiplication (SFM) approach gives the potential for rapid air-coupled imaging.
TL;DR: In this article, a new methodology for evaluating the crack depth and the crack opening stress intensity factor of small closed cracks using an ultrasonic technique has been described, and the accuracy and reliability of this new non-destructive evaluation (NDE) method is verified by comparing the evaluated crack depth with the actual one.
Abstract: This paper describes a new methodology for evaluating the crack depth and the crack opening stress intensity factor of small closed cracks using an ultrasonic technique. Surface connected back-wall cracks of depth ranging from 0.4 to 4.0 mm in steel specimens are considered. The crack corner echo amplitude of an ultrasonic shear wave, SW, beam of 50° incidence in material is used. First, the ultrasonic echo response of an open crack is determined as a function of crack depth. Next, based on changing the crack closure stress, an empirical relation between the crack closure stress and the crack-echo response is formulated. The crack depth and the crack closure stress of an unknown closed crack based on these relations are determined by inverse analysis of the ultrasonic response of the crack. From the evaluated crack depth and crack closure stress, the crack opening stress intensity factor is determined. The accuracy and reliability of this new nondestructive evaluation (NDE) method is verified by comparing the evaluated crack depth with the actual one. The latter is measured on the fractured surface obtained after carrying out ultrasonic testing. The ultrasonic method developed is proved to be a powerful tool for quantitative and nondestructive evaluation of the crack depth as well as the crack closure stress.
TL;DR: In this paper, the ultrasonic transducer is configured as to include a piezoelectric element and an acoustic matching layer, wherein the acoustic matching layers are made of a dry gel of an inorganic oxide or an organic polymer, and a solid skeletal part of the dry gel has been rendered hydrophobic.
Abstract: It is an object of the present invention to provide an ultrasonic transducer, which is so configured as to reduce the variations in characteristics, thereby to enable the stabilization of the precision, as well as to enable the improvement of the durability, and the like, a method for manufacturing the ultrasonic transducer, and an ultrasonic flowmeter. In order to attain this object, in accordance with the present invention, the ultrasonic transducer is so configured as to include a piezoelectric element and an acoustic matching layer, wherein the acoustic matching layer is made of a dry gel of an inorganic oxide or an organic polymer, and a solid skeletal part of the dry gel has been rendered hydrophobic. With this configuration, it is possible to obtain the ultrasonic transducer having an acoustic matching layer 3 which is very lightweight and has a small acoustic impedance due to the solid skeletal part of the dry gel which has been rendered hydrophobic. Further, it is also possible to obtain the ultrasonic transducer which shows a narrow range of characteristic variations, and is stable due to the high homogeneity of the dry gel.
TL;DR: In this article, a measurement technique using ultrasonic interferometry is described for noncontact, quantitative measurement of acoustic vibrations, where a pair of low-cost ultrasonic transducers are used in a transmit-receive mode to direct a 40 kHz carrier wave to the surface of a solid target vibrating acoustically, such as a speaker cone.
Abstract: A measurement technique using ultrasonic interferometry is described for non-contact, quantitative measurement of acoustic vibrations. A pair of low-cost ultrasonic transducers was used in a transmit–receive mode to direct a 40 kHz carrier wave to the surface of a solid target vibrating acoustically, such as a speaker cone. Demodulation of return signals consisted of a phase sensitive detection circuit to assess interference between the carrier wave and return signal. Recovered signals were enhanced using real-time digital signal processing hardware to improve signal-to-noise ratios for audio vibration measurements. Phase resolution of at least 3.4 mrads has been demonstrated in the audio frequency range. This represented an equivalent displacement of 2.3 µm in air.
Patent•
04 Jun 2004
TL;DR: In this paper, the authors proposed a non-destructive ultrasonic test equipment for detection and visualization of damage to and in structural components through reflections of introduced ultrasound waves at inhomogeneities in the test area, consisting of primarily piezo sensors.
Abstract: The invention concerns nondestructive ultrasonic test equipment for detection and visualization of damage to and in structural components through reflections of introduced ultrasound waves at inhomogeneities in the test area, consisting of primarily piezo sensors, which, depending on how they are driven, can function as transmitter or as receiver for ultrasound waves, and which are permanently attached, for example by gluing, to the damage-critical areas of structural components to be tested and/or monitored, and also of a control device, which is connected to the relevant sensor by electrically conducting wires, so that the received reflected ultrasound waves can be used as imaging data in a suitable device (analysis unit), in order to finally be compared with expected ultrasound images to evaluate any damage that may have occurred. The essence of the invention consists in that the control unit—for example a digital FPGA (field programmable gate array)—is connected to its associated sensor with almost no separation. Another essential inventive concept is to be seen in that the sensors are designed to be two-dimensional or multidimensional such that they can also be used one-dimensionally as needed.
Patent•
26 Apr 2004
TL;DR: In this paper, the authors proposed a three-dimensional ultrasonic inspection device capable of inspecting the inside of an object to be inspected precisely and rapidly in a non-destructive manner to quantitatively and automatically judge the presence of abnormality.
Abstract: PROBLEM TO BE SOLVED: To provide a three-dimensional ultrasonic inspection device capable of inspecting the inside of an object to be inspected precisely and rapidly in a non-destructive manner to quantitatively and automatically judge the presence of abnormality. SOLUTION: The three-dimensional ultrasonic inspection device is equipped with an ultrasonic transducer 11 having a plurality of piezoelectric vibrators 20 arranged thereto in a matrix or array state, a drive element selecting part 13 for selectively operating a piezoelectric vibrator 20 mn for ultrasonic oscillation, a signal detection circuit 16 for receiving the reflected echo from the joint 15 of the object 14 to be inspected due to oscillated ultrasonic waves to detect the electric signal, a signal processing part 17 for processing the detected electric signal to form three-dimensional imaging data corresponding to the mesh in the three-dimensional imaging region of the object 14 to be inspected and a display processing device 18 for detecting the size and position of a melt coagulation part 27 and the position or size of a welding flaw part 28 of the joint 15 from the intensity distribution of the formed three-dimensional imaging data and displaying the detection result and the three-dimensional imaging data from the signal processing part 17. COPYRIGHT: (C)2006,JPO&NCIPI
01 Jan 2004
TL;DR: In this article, the authors used laser-generated surface waves to interrogate laser cladded parts in both stainless steel and Ti to detect defects on each clad layer as it is being deposited.
Abstract: Laser ultrasonics shows great promise for on-line monitoring of product integrity in a number of industrial laser processes, including welding and cladding. In the laser cladding process, we wish to detect defects on each clad layer as it is being deposited. The defect information can be then used to control critical weld parameters or alert the operator of a problem requiring maintenance. In this way, defects can then be corrected before many defective parts are produced.Laser ultrasonics uses a pulsed laser to generate an ultrasonic wave and a continuous-wave laser interferometer to detect the small surface displacement when this wave arrives at the point of detection. Laser ultrasonics is ideal for in-line measurements because there is no sensor in contact or near-contact with the workpiece. In addition, measurements can be performed on curved surfaces and in areas that are difficult to access.In this study, we have used laser-generated surface waves to interrogate laser cladded parts in both stainless steel and Ti. We have used wavelet analysis to separate the temporal signals and select the distinguishing features that are most sensitive to defect presence. The processing approach was optimized using simulated pores produced using blind holes.Laser ultrasonics shows great promise for on-line monitoring of product integrity in a number of industrial laser processes, including welding and cladding. In the laser cladding process, we wish to detect defects on each clad layer as it is being deposited. The defect information can be then used to control critical weld parameters or alert the operator of a problem requiring maintenance. In this way, defects can then be corrected before many defective parts are produced.Laser ultrasonics uses a pulsed laser to generate an ultrasonic wave and a continuous-wave laser interferometer to detect the small surface displacement when this wave arrives at the point of detection. Laser ultrasonics is ideal for in-line measurements because there is no sensor in contact or near-contact with the workpiece. In addition, measurements can be performed on curved surfaces and in areas that are difficult to access.In this study, we have used laser-generated surface waves to interrogate laser cladded parts in both stainless...
Patent•
02 Feb 2004TL;DR: In this paper, a comprehensive system for the cleaning, inspection, and testing of tubulars, particularly riser pipes, is provided, which includes cleaning, visually inspecting, corrosion mapping and testing the tubular.
Abstract: A comprehensive system for the cleaning, inspection, and testing of tubulars, particularly riser pipes, is provided. In a first aspect, a method of inspecting a tubular comprises cleaning, visually inspecting, corrosion mapping, and TOM testing the tubular. In another aspect, a specially designed or adapted tool is provided for each of the steps of the method.