Nondestructive Evaluation Methodology Research Articles

A Kriging-Based Magnetic Flux Leakage Method for Fast Defect Detection in Massive Pipelines

Abstract Systems in service continue to degrade with the passage of time. Pipelines are among the most common systems that wear away with usage. For public safety, it is of utmost importance to monitor pipelines. Magnetic flux leakage (MFL) testing is a widely used nondestructive evaluation (NDE) technique for defect detections within the pipelines, particularly those composed of ferromagnetic materials. Pipeline inspection gauge (PIG) procedure based on line scans can collect accurate MFL readings for defect detection. However, in real world, applications involving large pipe sectors such as extensive scanning techniques are extremely time consuming and costly. In this article, we develop a fast and cheap methodology that does not need MFL readings at all the points used in traditional PIG procedures but conducts defect detection with similar accuracy. We consider an under-sampling based scheme that collects MFL at uniformly chosen random scan points over large lattices instead of extensive PIG scans over all lattice points. On the basis of readings from the chosen random scan points, we use kriging to reconstruct MFL readings. Thereafter, we use thresholding-based segmentation on the reconstructed data for detecting defective areas. We demonstrate the applicability of our methodology on synthetic data generated using finite element models and on MFL data collected via laboratory experiments. In these experiments, spanning a wide range of defect types, our proposed novel MFL-based NDE methodology is witnessed to have operating characteristics within the acceptable threshold of PIG-based traditional methods and thus provide an extremely cost-effective, fast procedure with competing error rates.

Repeatable part authentication using impedance based analysis for side-channel monitoring

The rise of the interconnected manufacturing enterprise has extended its vulnerability space to malicious cyber-physical attacks. To improve the resilience of a manufacturing enterprise to cyber-to-physical attacks, a robust set of quality tools for part and process authentication and verification are needed. However, current Non-Destructive Evaluation (NDE) methodologies, which focus on verifying a small subset of geometric features of a part such as its length, width or depth among others, are easier to circumvent by an attacker. This work presents a novel approach to improve the resilience of a manufacturing enterprise via side channels, specifically using electromechanical impedance signatures measured by piezoelectric transducers (PZTs) to verify if a part conforms to its design intent. Since electromechanical impedance signatures take into account all geometric features and material characteristics in a holistic manner, they can provide a new class of robust quality metrics that can be used in tandem with traditional NDE methodologies to verify a part or a process. Two major contributions of this work include (1) demonstrate the feasibility of using a PZT mounted to a fixture to facilitate side channel analysis for part authentication and compare its performance to other PZT mounting methods, and (2) develop a new damage metric that properly distinguishes between nominal parts and various altered groups. The results of our study show that using PZTs as a side channel has the potential for part and process authentication in a manufacturing setting. Furthermore, we show that a PZT mounted to a secondary device, such as a fixture, can be used for NDE in a manufacturing setting.

Non-Destructive Evaluation of Crack Initiation and Propagation in Continuously Reinforced Concrete Pavements

Transverse crack pattern significantly affects performance of continuously reinforced concrete pavement (CRCP). However, field and modeled crack spacing are based on visual surveys of fully developed transverse cracks visible on the slab surface. Because of the difficulties in detecting incipient cracks in concrete slabs, the effect that such cracks may have on CRCP performance is not currently considered. To address this issue, this paper presents a non-destructive evaluation methodology based on an ultrasonic linear-array system for detection of incipient cracks in CRCP slabs. Two ultrasonic signal-processing techniques were used. First, the Hilbert Transform Indicator was used to identify the presence of damage in the concrete slab indicating potential crack locations. Then ultrasonic image reconstructions of these locations were used to further evaluate crack presence. The methodology was applied to four sections of an experimental short CRCP composed of 50-m long slabs – short in comparison to traditional CRCP. The locations of 58 potential incipient cracks were identified updating the short CRCP crack spacing; 10 of these incipient cracks were confirmed as surface-visible cracks in later visual surveys. Additionally, the methodology shows potential to detect undesired crack patterns such as cluster and Y-cracking before the cracks emerge on the slab surface.

A Novel Methodology for Spatial Damage Detection and Imaging Using a Distributed Carbon Nanotube-Based Composite Sensor Combined with Electrical Impedance Tomography

This paper describes a novel non-destructive evaluation methodology for imaging of damage in composite materials using the electrical impedance tomography (EIT) technique applied to a distributed carbon nanotube-based sensor. The sensor consists of a nonwoven aramid fabric, which was first coated with nanotubes using a solution casting approach and then infused with epoxy resin through the vacuum assisted resin transfer molding technique. Finally, this composite sensor is cured to become a mechanically-robust, electromechanically-sensitive, and highly customizable distributed two-dimensional sensor which can be adhered to virtually any substrate. By assuming that damage on the sensor directly affects its conductivity, a difference imaging-based EIT algorithm was implemented and tailored to offer two-dimensional maps of conductivity changes, from which damage location and size can be estimated. The reconstruction is based on a newly defined adjacent current–voltage measurement scheme associated with 32 electrodes located along the boundary of the sensor. In this paper, we evaluate our methodology first by introducing well-defined damage where sections are either removed or narrow cuts are made on a series of sensor specimens. Finally, a more realistic damage scenario was investigated to show the capability of our methodology to detect impact damage on a composite laminate. The resulting EIT maps are compared to visual inspection and thermograms taken with an infrared camera.

Quantification of defects depth in glass fiber reinforced plastic plate by infrared lock-in thermography

The increasing use of composite materials in various industries has evidenced the need for development of more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production cost. Infrared thermography is a noncontact, fast and reliable non-destructive evaluation technique that has received vast and growing attention for diagnostic and monitoring in the recent years. This paper describes the quantitative analysis of artificial defects in Glass fiber reinforced plastic plate by using Lockin infrared thermography. The experimental analysis was performed at several excitation frequencies to investigate the sample ranging from 2.946 Hz down to 0.019 Hz and the effects of each excitation frequency on defect detachability. The four point method was used in post processing of every pixel of thermal images using the MATLAB programming language. The relationship between the phase contrast with defects depth and area was examined. Finally, phase contrast method was used to calculate the defects depth considering the thermal diffusivity of the material being inspected and the excitation frequency for which the defect becomes visible. The obtained results demonstrated the effectiveness of Lock-in infrared thermography as a powerful measurement technique for the inspection of Glass fiber reinforced plastic structures.

磁性体材料の磁場解析における等角写像を活用した欠陥モデリング手法

In this presentation, extended finite element method using the conformal mapping is proposed as the magnetic field analysis methodology for non-destructive evaluation. The magnetic field around the crack is analyzed easily by this method. The effectiveness of this methodology is demonstrated by the numerical examples.

High-resolution thermal imaging methodology for non-destructive evaluation of historic structures

This paper presents a methodology for automated, portable thermography, for the acquisition of high-resolution thermal image mosaics supporting the non-destructive evaluation of historic structures. The presented approach increases the spatial resolution of thermal surveys to a level of detail needed for building scale analysis. The integration of a robotic camera platform enables automated alignment of multiple images into a high-resolution thermal image mosaic giving a holistic view of the structure while maintaining a level of detail equaling or exceeding that of traditional spot surveys using existing cameras. Providing a digital workflow for automated data and metadata recording increases the consistency and accuracy of surveys regardless of the location or operator. An imaging workflow and instrumentation are shown for a case-study on buildings in Florence, Italy demonstrating the effectiveness of this methodology for structural diagnostics.

Laser Lock-In Thermography for Fatigue Crack Detection

This study proposes a new nondestructive evaluation methodology named laser lock-in thermography (LLT) for fatigue crack detection. LLT utilizes a high power continuous wave (CW) laser as a heat generation source for lock-in thermography instead of commonly used flash and halogen lamps. The advantages of the proposed LLT method are that (1) the laser heat source can be positioned at an extended distance from a target structure thank to the directionality and low energy loss of the laser source, (2) thermal image degradation due to surrounding temperature disturbances can be minimized because of high temperature gradient generated by the laser source and (3) a large target surface can be inspected using a scanning laser heat source. The developed LLT system is composed of a modulated high power CW laser, galvanometer and infrared camera. Then, a holder exponent-based data processing algorithm is proposed for intuitive damage evaluation. The developed LLT is employed to detect a micro fatigue crack in a metal plate. The test result confirms that 5 μm (or smaller) fatigue crack in a dog-bone shape aluminum plate with a dimension of 400 x 140 x 3 mm3 can be detected.

Application of Wavelet Parameters for Impact Damage Detection in Plates

This study proposes a new nondestructive evaluation methodology named laser lock-in thermography (LLT) for fatigue crack detection. LLT utilizes a high power continuous wave (CW) laser as a heat generation source for lock-in thermography instead of commonly used flash and halogen lamps. The advantages of the proposed LLT method are that (1) the laser heat source can be positioned at an extended distance from a target structure thank to the directionality and low energy loss of the laser source, (2) thermal image degradation due to surrounding temperature disturbances can be minimized because of high temperature gradient generated by the laser source and (3) a large target surface can be inspected using a scanning laser heat source. The developed LLT system is composed of a modulated high power CW laser, galvanometer and infrared camera. Then, a holder exponent-based data processing algorithm is proposed for intuitive damage evaluation. The developed LLT is employed to detect a micro fatigue crack in a metal plate. The test result confirms that 5 μm (or smaller) fatigue crack in a dog-bone shape aluminum plate with a dimension of 400 x 140 x 3 mm3 can be detected.

Nondestructive damage detection in Euler-Bernoulli beams using nodal curvatures-Part II: Field measurements

The objective of this paper is to evaluate, using field measurements, the performance of the nondestructive evaluation methodology presented in the accompanying paper ‘Nondestructive damage detection in Euler–Bernoulli beams using nodal curvatures – Part I: Theory and numerical verification’. Experimental modal data collected from the Interstate 40 bridge are utilized to accomplish the stated objective. Prior to the replacement of the bridge in 1993, researchers from New Mexico State University and Los Alamos National Laboratory introduced incremental levels of damage on the structure and performed experimental modal analyses at each damage stage. The results of the experiments were utilized to evaluate the performance of five previously published nondestructive damage identification methods. Utilizing the measured modal parameters from the Interstate 40 bridge study, structural damage is localized and quantified with the nondestructive evaluation methodology presented in the accompanying paper. The results of this study indicate that the proposed methodology performed equally as well as the damage index method for damage localization and additionally provided realistic estimates of damage severity. Copyright © 2013 John Wiley & Sons, Ltd.

Porosity and Inclusion Detection in CFRP by Infrared Thermography

The ever wide use of composite materials in the aeronautical industry has evidenced the need for development of ever more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production costs. Infrared thermography has been recently enclosed amongst the standardized non destructive testing techniques, but its usefulness needs still complete assessment since it can be employed in several different arrangements and for many purposes. In this work, the possibility to detect slag inclusions and porosity is analyzed with both lock-in themography and pulse thermography in the transmission mode. To this end, carbon-fiber-peinforced polymers different specimens are specifically fabricated of several different stacking sequences and with embedded slag inclusions and porosity percentages. As main results, both of the techniques are found definitely able to reveal the presence of the defects above mentioned. Moreover, these techniques could be considered complementary in order to better characterize the nature of the detected defects.

A review on non-destructive evaluation of rails: State-of-the-art and future development

Rails are systematically inspected for internal and surface defects using various non-destructive evaluation (NDE) techniques. During the manufacturing process, rails are inspected using automated optical cameras and eddy current sensing systems for any surface damage, while the presence of internal defects is assessed through ultrasonic inspection. Similarly, ultrasonic transducers and magnetic induction sensors have been extensively used by the rail industry for the inspection of rails in-service. More recently, automated vision techniques and hybrid systems based on the simultaneous use of pulsed eddy current probes and conventional ultrasonic probes have been introduced for the high-speed inspection of rail tracks. Other NDE techniques, such as electromagnetic acoustic transducers, laser ultrasonics, guided waves, and alternating current field measurement probes, are also under development for application in the rail industry. This paper comprehensively reviews NDE methodologies in use around Europe and North America for rail defect detection. This includes a detailed overview of the background theory and the techniques used to incorporate condition data into maintenance procedures. It also presents a review of the current state-of-the-art in NDE of railways coupled with a discussion of future developments and novel inspection methodologies in the field.

Novel Methodology for Nondestructive Evaluation of Brick Walls: Fuzzy Logic Analysis of MASW Tests

This paper presents a novel methodology for the nondestructive evaluation of brick walls using fuzzy logic and summarizes the results of the nondestructive evaluation of the relative condition of a sidewall of a brick masonry channel using the multichannel analysis of surface waves (MASW) test. The new methodology addresses the critical problem of considering the inherent variability of field data in the analysis of seismic tests. Wave propagation measurements were taken on the sidewall at 161 locations; the total length of wall tested was 80 m . Each MASW test consisted of the simultaneous measurement of the impact response of the wall with an array of 15 transducers (accelerometers); each test assessed the relative condition of a wall section 7.5 m long. For one of the sections, measurements were taken before and after a uniform grouting. The relative condition of the wall is evaluated by considering five wave propagation characteristics: group velocity, minimum and maximum phase velocities, predominant...

Characterization Methodology of the Interface in Multilayer Composites

The quality of the interfaces in multilayer composites is a critical issue in the reliability testing of the composite product during the manufacturing process and in-service. Weak interfaces have often gone undetected and may become potentially defective at a later stage. One example is the interface between mold compound and silicon (MC/Si) in IC packaging. There is a desire to study the interface quality quantitatively, so the potential defective area can be evaluated and identified early. In this paper, a nondestructive evaluation methodology is proposed to measure the available strength of the interface by using ultrasonic reflection coefficients. It is known that interface degradation can be either due to poor manufacturing process and stress loading. Characterization of the interface quality of the MC/Si interface is first conducted by measuring longitudinal ultrasonic wave reflections from the interface samples fabricated under varying conditioning processes that simulate the degradation. A combined test that measures the reflection coefficient of the interface under stress load has also been conducted to quantify the effect of the load. Finally, it is shown that the overall effect on the reflection coefficient and available strength of the interface is derived and can be used as a quantitative indicator.

Detection of Debonding in Concrete Members Retrofitted with FRP Using Electromagnetic and Ultrasonic Methods

Microwave and ultrasonic methods have been used for the detection of debonding between concrete and fiber-reinforced plastic (FRP). To determine the capability of the microwave method in detecting thin delamination between two materials of concrete and FRP, concrete specimens are made with the dimensions of 600 mm (length) x 600 mm (width) x 50 mm (depth). Specimens have artificial delamination of 5 and 10 mm thick Styrofoam, which represent debonding in structures. Then, the specimens are partially covered with 1.5 mm thick FRP on the top of 3 mm thick epoxy. A horn antenna with a center frequency of 15 GHz and a frequency bandwidth of 10 GHz is used for the measurements. By transmitting and receiving microwave signals from the horn antenna, differences have been detected for the different types of the targets. Also, measurements using ultrasonic method at 5 kHz have been made on the same series of specimens. This work is directed toward a development of an effective and practical microwave based non-destructive evaluation methodology for the detection and quantification of damages in FRP-covered reinforced concrete members in bridges and buildings.

Characterisation of IC packaging interfaces and loading effects

In IC packaging, the quality of the interfaces such as that between mold compound and silicon is a critical issue in the reliability testing during the manufacturing process and in-service. Weak interfaces have often gone undetected and may become potentially defective at a later stage. Furthermore, the stress due to mechanical or thermal loading may further deteriorate the interface quality, making the interface unreliable. There is a desire to study the interface quality quantitatively, so potential defects can be evaluated and identified early. In this paper, finite element analysis using multilayer interface model is used to study the reflection coefficient from the interface of varying quality. Different conditioning techniques were used to degrade the interface quality. Characterisation of the interface quality of the MC/Si interface was conducted using longitudinal ultrasonic wave propagation with contact transducers. A combined test that measures the reflection coefficient of the interface under stress load was also conducted to quantify the effect of the load. A nondestructive evaluation methodology is proposed that measures the available strength of the interface by using ultrasonic reflection coefficients, and it shows the correlation between the reflection coefficient and available strength of the interface can be developed and used as a quantitative indicator.

Wave boundary element to study Lamb wave propagation in plates

By using analytical mode shapes as the interpolating functions for both displacements and stresses on the reference edges of a plate, a wave element is formulated for use in the boundary element method to study Lamb wave propagation and interaction in plates, to achieve both accuracy and computational efficiency. Lamb wave interaction with a notch is investigated using this method. The results with respect to wave transmission, reflection and mode conversion are consistent with physical considerations of Lamb mode shape and energy conservation. It is shown through the reflection coefficients that S 0 Lamb wave is more sensitive than A 0 wave for detecting a shallow notch in a plate. These coefficients can be used to aid the characterization of the presence of a notch and contribute to quantitative non-destructive evaluation methodology for plate structures. Time history results are obtained by conducting Fourier transform on the coefficients solved in frequency domain. Comparison with experiment results shows the suitability of the method for wave propagation studies in relation to damage detection.

Impedance measurements of coating properties on bridge structures

Impedance measurements allow early evaluation of the protective properties of paint coatings and linings. They are applied for comparison of coatings, monitoring of their properties and determination of the protection mechanism. This methodology is being used more and more frequently in laboratory investigations. On site studies are more difficult due to the need of using complex computer controlled apparatus and its susceptibility to atmospheric conditions, electric fields and mechanical damage. In this lecture a proposal has been made of application of the impedance methodology of paint coating evaluation in “in situ” conditions on bridges. Good correlation has been stated with results obtained in the laboratory, allowing application of this methodology for non-destructive evaluation of the properties of thick coatings and organic linings on industrial structures.

Science and technology of non-destructive testing, evaluation and characterisation

The quality of life available to the majority of citizens of any country is a direct measure of its state of economy. India has shown the quality consciousness through its rich tradition, heritage, monuments and idols. From the heritage to the atomic, space and information age, India has matured as a nation endowed with expertise in relevant and critical technologies. In India there has been a sustained and comprehensive approach to the development of industries for production of precision, strategic and heavy components of high quality through the application of non-destructive evaluation (NDE) techniques and procedures. A large number of non-destructive testing techniques have been developed in India by strategic and core sectors for in-house requirements. Academic institutes have played a key role in nurturing excellence in the area. The knowledge base is made available to the needy industries. With the availability of these techniques, together with the advent of advanced electronics, innovations in sensor technology, availability of computers and signal and image processing methodologies, improvement in detection sensitivity and quantitative characterisation of defects and assessment of microstructural degradation have taken place. The outcome of these developments is the improvement in fitness for purpose of fabricated components and their performance in service with a possibility for their life extension. An example is the front line research carried out and the expertise developed at IGCAR in the area of NDT&E in the last two decades. The expertise has been effectively utilised for finding reliable, comprehensive and cost-effective solutions for many unique and challenging problems in strategic (nuclear, space, and defence) and core (power, chemical and petrochemical) sectors. In this paper an overview of the authors' experience in the developments and applications of advanced NDE methodologies for a variety of applications has been given.

Structural health monitoring of materials by high critical temperature SQUID

Nowadays, tailoring the material properties is essential for advanced product design in engineering systems. The need to provide key information about micro- and macro-structural behaviour of materials, without destructively sectioning the sample, has spurred the development of nondestructive evaluation methodologies. These techniques are required during material production, quality testing of components during manufacturing, and in-service inspection of structural integrity. To ensure the highest possible operational safety along with an economic efficiency, it is necessary to carry out inspections with a high sensitivity and a proven reliability. Due to its unparalleled magnetic field sensitivity over a wide frequency range and large dynamic range, SQUID-based nondestructive evaluation has unique advantages for materials and structures characterization. We will present an overview of eddy-current nondestructive analysis utilizing high T c SQUIDs with an emphasis on examples relevant to the aeronautical industry. These include the detection of deep-lying defects in multi-layer structures of Al–Ti alloys and damage of extremely lightweight graphite/epoxy composites. Both of these can be successfully treated by this approach where conventional electromagnetic probes often fail. In addition some results based on the volume integral formulation, successfully developed to simulate the response of the system to different type of flaws in Al-alloy planar structures and to solve the inverse electromagnetic problem, will be shown.