Non-destructive Evaluation of Foods using Spectroscopy

Reliable performance of a component or structure depends on pre-service quality of the component and in-service degradation of the component under operating conditions. The role of non-destructive evaluation (NDE) in ensuring pre-service quality and also monitoring in-service degradation to avoid premature failure of the components/structures is ever increasing. There are many NDE techniques based on various physical principles. The end objective of NDE is detection and characterisation of anomalies such as defects, stresses and microstructural degradations in materials. This is accomplished by establishing correlation between a nondestructively measured physical/derived parameter and quantitative information on defects/stresses/microstructures. The NDE information together with design parameters are taken into consideration for evaluation of integrity and life assessment of the components/structures. In this paper, a brief description of the physical concepts of NDE methods and the physical/derived parameters that are used for assessing defects, stresses and microstructures are given. A few case studies highlighting the importance of non-destructive testing and evaluation for structural integrity assessment are also discussed based on the investigations carried out at the authors’ laboratory. Emerging concepts like intelligent processing of materials, expert systems, neural networks, use of multisensors with fusion of data and exploitation of signal analysis and imaging approaches are also addressed in this paper.

Problem be used for evaluating products quality: - Destructive evaluation, in which the product is destroyed in order to analyse its properties and internal structure; - Non destructive evaluation (NDE), used for identifying defect and irregularities, without damaging the product. These non destructive evaluation methods include [1-4]: ‐ Visual and optical testing – VT; ‐ Magnetic particle testing – MT; ‐ Liquid penetrant testing –PT; ‐ Radiographic testing – RT ; ‐ Ultrasounds testing – UT; ‐ Eddy current testing – ET; One of the most frequently used method of non destructive examination is PT or dye penetrant testing (DPT), due to the low costs involved, ease of use and flexibility, suitability to a large number of applications. This method evaluates the presence of open discontinuities (or cracks) on the surface part, based on reverse capillary action and on the developer absorption effect which draw out penetrant and produces indications visible for the inspector (see fig.1 for a principle scheme of LP examination [5]). Although widely used, PT has several disadvantages: - Limitation to surface defects or to the defects which communicates with the surface; - Only products with non porous surfaces (or with low porosity) can be inspected; - Important amount of time used for manipulating the parts during inspection; - Results interpretation heavily depends on subjective aspects such as operator experience, knowledge and motivation. In order to eliminate or reduce the operator involvement in the process steps, research has being made for automating the process, such examples of liquid penetrant inspection lines can be found in [10-15]. However, in all analysed automated PT systems, the inspection is still made visually by an inspector, who gives a pass/fail grade for the inspected parts. The difficulty of fully automating the liquid penetrant inspection process is due not only to the necessity to precisely determine and control process parameters (dwell time, developer time, drying time, quantity of penetrant, developer and cleaning water, pressure for spraying solutions with penetrant, developer and cleaning water, transport speed, etc.) but also to the evaluation and results interpretation process. Thus, even if there are patents [16-17] which present approaches and general frameworks for fully-automated LPT systems, including also automatic image processing of the flaws, to the best of the authors’ knowledge, these equipment are not yet implemented. In this context, this paper presents an experimental stand for a fully automated liquid penetrant inspection line, which includes the development and use of dedicated imaging software used for real time interpretation of the images acquired using a digital camera. The novelty of the research consist in designing and building a fully-automated LPT stand, controlled by a soft which contains also a module for acquisition and image processing in real time without no human implication.

A rulemaking issued by the Department of Transportation (DOT) revises Hazardous Materials Regulations (HMR) to replace the hydrostatic pressure test with appropriate nondestructive evaluation (NDE) methods. The rule change is contained in Federal Register 49 Code of Federal Regulations (CFR) Part 180.509, “Requirements for inspection and test of specification tank cars,” paragraph (e) “Structural integrity inspection tests” [1]. The CFR authorizes liquid penetrant (PT), magnetic particle (MT), radiography (RT), ultrasonic (UT), and optically aided visual testing (VT) as allowable NDE methods for structural integrity inspections and tests. Other NDE methods may be allowed under special exemption issued by the Federal Railroad Administration (FRA) Office of Safety. Also included under the requirements of 49 CFR Part 179.7 is the need to qualify not only NDE personnel, but the procedures used to perform NDE reliably. In order to be effective, federal regulations require that the NDE methods have a proven sensitivity and reliability for finding the type and size of flaws likely to cause a tank car failure. In the early 1970s, an internationally accepted quantitative approach that assesses the probability of detection (POD) was developed for the National Aeronautics and Space Association (NASA) and was published in NASA CR-2369, February 1974 [2]. Transportation Technology Center, Inc. (TTCI), under contract with the FRA, and along with industry participation, uses the NASA approach to determine the POD for various NDE methods used in the inspection of railroad tank car circumferential butt welds (girth seam welds), fillet welds, and leak test samples. The emergence of a damage tolerance approach to determine inspection intervals for an engineered structure — in this case a railroad tank car — requires the quantification of the detectable flaw size for the NDE methods used during inspection. Damage tolerance techniques have initiated an evolution in NDE understanding, methods, and requirements. National Transportation Safety Board safety recommendations R-92-21 through R-92-24 address the suggested process of performing reliable inspection of railroad tank cars based on a damage tolerance approach [3]. NDE quantification using the POD approach is a key measure of NDE effectiveness and is integral to damage tolerance requirements. TTCI, working with the FRA, Railroad Tank Car Industry and D&W Enterprises (A NDE consulting company providing expertise in the area of NDE POD), has developed baseline POD curves for the allowed NDE methods. Initial evaluations were performed on the inspection of tank car circumferential butt welds. Subsequent efforts focused on butt welds, longitudinal fillet welds and leak test samples requiring inspection under the CFR. This paper reports quantitative results obtained during this research effort that address system safety and risk analysis during handling and transportation of railroad tank cars carrying hazardous materials.

As the requirements on the accuracy of nondestructive testing and evaluation are increasing, multiple nondestructive evaluation (NDE) methods are often employed to increase the reliability and reduce the uncertainty of the testing and evaluation. The need to process and analyze data from multiple sources uses the technique named data fusion, which has been growing rapidly in the NDE community in recent years. This paper reviews the progress in NDE data fusion techniques and examines the mathematical fusion algorithms, which include but are not limited to optimization methods, multiresolution approaches, heuristic methods, probabilistic methods, and scientific visualization. In the light of recent applications in NDE data fusion, important issues in handling the acquired data and applying the fusion algorithms are identified and discussed. A generic framework to apply the NDE data fusion process is described. The study on fusion of advanced NDE and sensor techniques opens up prospects for the diagnostic and prognostic health monitoring applications in the future.

Nondestructive evaluation (NDE) contributes to the integrity and safe operation of engineered components and structures, providing information on the presence of defects and the actual conditions during production and operation, as well. The use of appropriate models for NDE techniques, which are capable to predict the output of an NDE system quantitatively, have an important impact on the reliability and efficiency of modern NDE methods. During the last years there has been remarkable progress made in the development and the use of models to describe the total transfer chain of NDE systems. Actually there are available a number of CAD-based NDE simulation tools for several standard NDE techniques such as ultrasonics, eddy currents, and radiography. It turns out that the following areas are of major interest for the application of NDE simulators: — the use of models during the design process to ensure the inspectability of the engineered components at the earliest possible stage — the use of models for feasibility analysis, e.g. for damage analysis to investigate whether the producer or the user of the component have considered all state-of-the-art NDE techniques to ensure the safe operation of the component while avoiding its damage, or to investigate the applicability of standard techniques for specialized testing problems — the use of models to develop new NDE techniques, extend their measurement capabilities including model-based data interpretation and 3-dimensional reconstruction of material properties, or to optimize standard techniques for special applications — the use of models for reliability investigations and validation tasks in terms of the prediction of probability of detection (POD) to describe the potential capability of the NDE method excluding human factor, the definition of parameters essentially influencing the response of the NDE system including their accessible ranges, or the application of models as a part of a modular validation procedure — the use of models for education and training purposes where interactive training tools will improve the learning experience, and reduces the time on task for students and the material costs as well

Performance evaluation of NDE methods

Since the inception of the National Bridge Inspection Program, much time and money have been invested in the development of nondestructive evaluation (NDE) techniques. These techniques provide bridge inspectors with tools to more accurately assess the condition of highway structures. These nondestructive evaluation methods, however, are sometimes used without a clear understanding of the factors that affect their reliability, performance, and implementation. Before NDE systems can be used with confidence, the technology and methods must be validated and all factors affecting their reliability identified. In response to this need, FHWA established the NDE Validation Center to identify and evaluate the factors affecting NDE reliability and performance. The NDE Validation Center uses a series of unique resources to evaluate and assess the factors affecting the reliability and performance of NDE systems. The Validation Center is based out of a combination of specialized laboratory and office space located at the Turner Fairbank Highway Research Center in McLean, Virginia. To supplement the capabilities of the laboratory facilities, a series of bridges located in northern Virginia and eastern Pennsylvania is used to conduct field investigations. Additionally, a collection of component test specimens is used in various test programs. The NDE Validation Center is a national resource for the evaluation of existing and emerging NDE techniques. The resources of the NDE Validation Center are available to federal and state agencies, the academic community, and industry. The Validation Center was developed to perform critical evaluations of NDE technologies and to provide a source of information and guidance to users and developers of NDE systems.

The House of Bagheri is one of the most important buildings in Gorgan city (North of Iran) which is a tourist site and the House is a Cultural Heritage Construction. Solid wood was utilized extensively for structural members in association with other traditional materials. It has been exposed to natural environmental conditions for a long time, so some faults have developed including decay of the wooden members. The mechanical properties of decayed members have been measured in laboratory tests and the buildings have been non-destructively evaluated. Samples from the buildings were prepared which are representative of the whole structure. Flexure and compression tests were then performed on these samples. The results of NDE (nondestructive evaluation) tests on the samples were correlated with those on the buildings.

Steel winding ropes which are heterogeneous in nature are subjected to severe working conditions and their behaviour vary on different environment and nature of service. Due to this, they are subjected to rope deterioration such as corrosion, abrasion and broken wire leading to rope failure (Singh, S.D. and Ghara, B., Steel Wire Rope Condition Monitoring by Non-Destructive Investigation and Evaluation while on Installation/Service, 15th World Conference on Non-Destructive Testing, Rome, Italy, 2000). Deterioration of a rope during its lifetime leads to a reduction of the rope safety and to its possible destruction. There are rejection criteria for ropes in national and international rules on the safe use of drive ropes. All wire ropes wear out eventually, gradually losing work capability throughout its useful life making periodic inspections, lubrication and tensioning necessary. Defects detected during a non-destructive evaluation can help pinpoint the factors leading to an eventual rope failure. Many ropes have to be retired due to damage caused by other, outside sources. Non-destructive evaluation can help the client to diagnose these conditions before its too late.

Ni-base superalloys exhibit high deformation resistance characteristics, even at elevated temperatures. However, it is difficult to determine the state of damage from the appearance and observation of the microstructure. Although it is possible to quantitatively estimate plastic strain and creep strain using electron backscatter diffraction (EBSD), it is a destructive method. On the other hand, X-ray diffraction using the Laue method has the potential to non-destructively evaluate material damage. In this study, we investigated the effect of sample thickness on the evaluation using the Laue method. We also compared the creep damage evaluation results of solidification-controlled Nibase superalloys using the EBSD and Laue methods and examined the possibility of non-destructive evaluation of creep damage using the Laue method. The specimens used to investigate the effect of sample thickness were single-crystal blocks of Ni-base superalloys. Samples were prepared with five different thicknesses. Next, we compared the full width at half maximum (FWHM) of Ni-base superalloys in single-crystal blocks of different thicknesses. The measured FWHM were almost constant, independent of the thickness. This may be because the combination of subgrains and X-ray microbeams results in a sparser distribution of detected diffraction spots and a decrease in the number of high-intensity diffraction lines. The specimens for comparison of the EBSD and transmission Laue methods were Ni-base directionally solidified (DS) superalloys, and damaged pieces were fabricated at several stages of creep testing up to rupture and evaluated using each method. As a result of comparing the EBSD and transmission Laue methods, the technique is capable of detecting microstructural changes associated with the later stages of creep deformation. These results indicate the transmission Laue method is a promising non-destructive evaluation method because the FWHM does not depend on the sample thickness and can perform evaluations like the EBSD method.

Industry 4.0 concepts enabled smart factories equipped with advanced surface and subsurface sensing systems and embedded analysis software to collect and analyze data for better inspection and automatic decision of various industrial components and structures. During Industry 4.0 globalization and in recognition of the progress made in non-destructive inspection for industrial quality control along with the Internet of Things and artificial intelligence, a software concept is under industrial implementation that restructures industrial manufacturing with full automation. Non-destructive evaluation 4.0 (NDE 4.0) has previously been described as A Cyber-Physical Non-Destructive Inspection resulting from the fusion of Industry 4.0 digital technology, whole field remote inspection methods, and decision-making for safety, sustainability, and quality assurance. Because of its quick, remote, noninvasive, full-field, and quantitative evaluation characteristics, active infrared thermography (IRT) has developed into a trusted non-destructive testing and evaluation (NDT&E) approach. Thermal waves are produced inside the test object using active IRT, which uses heat input externally with a specified bandwidth, magnitude, and time period. The quantitative investigation of the subsurface anomalies is aided by these heat stimulus pre-defined properties. A proper processing strategy is additionally needed to enhance the contrast for the evaluation of subsurface information by improving the signal to noise ratio. In this chapter a mathematical model for evaluation of temporal thermal response for the nonperiodic frequency-modulated thermal wave imaging (FMTWI) approach has been introduced. To examine the effectiveness of FMTWI, a brand-new three-dimensional heat diffusion model is presented. The chapter also covers the use of the normalized correlation coefficient (NCC) as a measure of merit in the temporal domain (TD) data processing approach for enhanced analysis of anomalies in a mild steel sample.

The applicability of a material-treatment laser pulse in non-destructive evaluations

Bridges are one of the critical civil infrastructure for safety of traveling public. The conditions of bridges deteriorate with time as a result of material aging, excessive loading, and inadequate maintenance, etc. In this paper, the development of an autonomous robotic system is presented for highly-efficient bridge deck inspection and evaluation. An autonomous mobile robot is used as a platform to carry various non-destructive evaluation (NDE) sensing systems for simultaneous and fast data collection. Besides the NDE sensors, the robot is also equipped with various onboard navigation sensors. A sensing integration scheme is presented for high-accuracy robot localization and navigation. The effectiveness of the autonomous robotic NDE system is demonstrated through extensive experiments and field deployments.

Nondestructive testing (NDT), also called nondestructive evaluation (NDE) and nondestructive inspection (NDI), is testing that does not destroy the test object. The activ-ity primarily involves looking at (or through) or meas-uring something about an object to determine some property of the object or to determine whether the object contains irregularities, discontinuities, or flaws. The terms irregularity, discontinuity, and flaw can be used inter-changeably to mean something that is questionable in the part or assembly, but specification, codes, and local usage can result in different definitions for these terms. As all these terms describe what is being sought through testing, inspection, or examination, the term NDE (non-destructive evaluation) has come to include all NDE used to find, locate, and sizing flaws and allow the investi-gator to decide whether or not the object or flaws are acceptable.A flaw that has been evaluated as rejectable is usually termed a defect.

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.