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Author: Timothy Lardner Publisher: ISBN: Category : Languages : en Pages : 416
Book Description
The push for more efficient operation of power generation stations has led to the development of advanced alloys designed to cope with the stresses of running at elevated temperatures. The micro-structure of these new alloys makes the inspection process difficult due to large grains that scatter ultrasonic energy. Aerospace components such as aircraft engine turbine blades are made from similar materials and pose the same difficulties for inspection. In addition, the complex geometries of many of these parts hinder the use of existing advanced imaging methodologies. The current inspection process involves using both individual transducers and phased arrays to collect pulse-echo data from structures.This process is not sufficient for such difficult materials and a new process must be devised, tested and deployed. This thesis presents an investigation of new practical techniques to process ultrasonic array data collected via a Full Matrix Capture.Two novel signal processing techniques are presented, evaluated and compared to the Total Focusing Method, which is currently considered as the gold standard in ultrasonic array processing. A study into efficient imaging has also been completed, which involved development of an algorithm to focus upon any point through an arbitrary refracting interface. This algorithm was implemented on a commercially available graphics card and is able to account for a curved interface in real time with no prior knowledge of the surface profile.Spatially Averaged Sub-Aperture Correlation Imaging splits the full matrix of data into a set of sub-apertures which are imaged independently from each other. These images are then combined into two sets and are input to a two-dimensional cross-correlation algorithm that outputs a weighting matrix that can be applied to the sum of all images. Signals that are from legitimate reectors are highly correlated while less-correlated indications are the result of noise from scattering and multi-path propagation. SASACI has been shown to perform well experimentally through inspection of defects within multiple highly scattering welds at a frequency of 5 MHz.Correlation for Adaptively Focused Imaging aims to correct for anisotropy within difficult materials. The longitudinal velocity within a difficult material can vary with position and using an average velocity does not guarantee a well-focused image. For each pixel in an image,CAFI calculates which samples will be used to calculate the amplitude of the pixel before cross-correlating the signals from adjacent array elements and shifting the delay to the point of maximum focus. This methodology is effective when a small area with a known reflector is being imaged, and for this reason the algorithm is suited to characterisation of reflectors. This technique was experimentally validated on a block of Inconel 625 with a number of side-drilled holes.
Author: Timothy Lardner Publisher: ISBN: Category : Languages : en Pages : 416
Book Description
The push for more efficient operation of power generation stations has led to the development of advanced alloys designed to cope with the stresses of running at elevated temperatures. The micro-structure of these new alloys makes the inspection process difficult due to large grains that scatter ultrasonic energy. Aerospace components such as aircraft engine turbine blades are made from similar materials and pose the same difficulties for inspection. In addition, the complex geometries of many of these parts hinder the use of existing advanced imaging methodologies. The current inspection process involves using both individual transducers and phased arrays to collect pulse-echo data from structures.This process is not sufficient for such difficult materials and a new process must be devised, tested and deployed. This thesis presents an investigation of new practical techniques to process ultrasonic array data collected via a Full Matrix Capture.Two novel signal processing techniques are presented, evaluated and compared to the Total Focusing Method, which is currently considered as the gold standard in ultrasonic array processing. A study into efficient imaging has also been completed, which involved development of an algorithm to focus upon any point through an arbitrary refracting interface. This algorithm was implemented on a commercially available graphics card and is able to account for a curved interface in real time with no prior knowledge of the surface profile.Spatially Averaged Sub-Aperture Correlation Imaging splits the full matrix of data into a set of sub-apertures which are imaged independently from each other. These images are then combined into two sets and are input to a two-dimensional cross-correlation algorithm that outputs a weighting matrix that can be applied to the sum of all images. Signals that are from legitimate reectors are highly correlated while less-correlated indications are the result of noise from scattering and multi-path propagation. SASACI has been shown to perform well experimentally through inspection of defects within multiple highly scattering welds at a frequency of 5 MHz.Correlation for Adaptively Focused Imaging aims to correct for anisotropy within difficult materials. The longitudinal velocity within a difficult material can vary with position and using an average velocity does not guarantee a well-focused image. For each pixel in an image,CAFI calculates which samples will be used to calculate the amplitude of the pixel before cross-correlating the signals from adjacent array elements and shifting the delay to the point of maximum focus. This methodology is effective when a small area with a known reflector is being imaged, and for this reason the algorithm is suited to characterisation of reflectors. This technique was experimentally validated on a block of Inconel 625 with a number of side-drilled holes.
Author: Lester W. Schmerr Jr. Publisher: Springer ISBN: 3319304631 Category : Technology & Engineering Languages : en Pages : 765
Book Description
This extensively revised and updated second edition of a widely read classic presents the use of ultrasound in nondestructive evaluation (NDE) inspections. Retaining the first edition's use of wave propagation /scattering theory and linear system theory, this volume also adds significant new material including: the introduction of MATLAB® functions and scripts that evaluate key results involving beam propagation and scattering, flaw sizing, and the modeling of ultrasonic systems. elements of Gaussian beam theory and a multi-Gaussian ultrasonic beam model for bulk wave transducers. a new chapter on the connection between ultrasonic modeling and probability of detection (POD) and reliability models. new and improved derivations of ultrasonic measurement models. updated coverage of ultrasonic simulators that have been developed around the world. Students, engineers, and researchers working in the ultrasonic NDE field will find a wealth of information on the modeling of ultrasonic inspections and the fundamental ultrasonic experiments that support those models in this new edition.
Author: J. Blitz Publisher: Springer Science & Business Media ISBN: 9780412604706 Category : Technology & Engineering Languages : en Pages : 286
Book Description
Ultrasonic Methods of Non-Destructive Testing covers the basic principles and practices of ultrasonic testing, starting with the basic theory of vibration and propagation, design and properties and probes, and then proceeding to the principles and practice of the various ultrasonic techniques for different types of components and structures, both metallic and non-metallic. The design and operation of various types of equipment are covered and references to appropriate national and international standards are provided. Numerous applications are discussed comprehensively and special attention is paid to latest developments. A large number of references is provided so as to enable the reader to obtain further information.
Author: Chi-hau Chen Publisher: World Scientific ISBN: 9812704094 Category : Medical Languages : en Pages : 682
Book Description
Ultrasonic methods have been very popular in nondestructive testing and characterization of materials. This book deals with both industrial ultrasound and medical ultrasound. The advantages of ultrasound include flexibility, low cost, in-line operation, and providing data in both signal and image formats for further analysis. The book devotes 11 chapters to ultrasonic methods. However, ultrasonic methods can be much less effective with some applications. So the book also has 14 chapters catering to other or advanced methods for nondestructive testing or material characterization. Topics like structural health monitoring, Terahertz methods, X-ray and thermography methods are presented. Besides different sensors for nondestructive testing, the book places much emphasis on signal/image processing and pattern recognition of the signals acquired.
Author: Lester W. Schmerr Jr Publisher: Springer Science & Business Media ISBN: 0387490639 Category : Technology & Engineering Languages : en Pages : 602
Book Description
Using a systems level approach, this book employs aspects of linear systems theory and wave propagation and scattering theory to develop a comprehensive model of an entire ultrasonic measurement system. This integrated approach leads to a new model-based engineering technology for designing, using and optimizing ultrasonic nondestructive evaluation inspections. In addition, the book incorporates MATLAB examples and exercises.
Author: Gerhard Huebschen Publisher: Woodhead Publishing ISBN: 008100057X Category : Technology & Engineering Languages : en Pages : 322
Book Description
Materials Characterization Using Nondestructive Evaluation (NDE) Methods discusses NDT methods and how they are highly desirable for both long-term monitoring and short-term assessment of materials, providing crucial early warning that the fatigue life of a material has elapsed, thus helping to prevent service failures. Materials Characterization Using Nondestructive Evaluation (NDE) Methods gives an overview of established and new NDT techniques for the characterization of materials, with a focus on materials used in the automotive, aerospace, power plants, and infrastructure construction industries. Each chapter focuses on a different NDT technique and indicates the potential of the method by selected examples of applications. Methods covered include scanning and transmission electron microscopy, X-ray microtomography and diffraction, ultrasonic, electromagnetic, microwave, and hybrid techniques. The authors review both the determination of microstructure properties, including phase content and grain size, and the determination of mechanical properties, such as hardness, toughness, yield strength, texture, and residual stress. Gives an overview of established and new NDT techniques, including scanning and transmission electron microscopy, X-ray microtomography and diffraction, ultrasonic, electromagnetic, microwave, and hybrid techniques Reviews the determination of microstructural and mechanical properties Focuses on materials used in the automotive, aerospace, power plants, and infrastructure construction industries Serves as a highly desirable resource for both long-term monitoring and short-term assessment of materials
Author: Rui Gongzhang Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
In Non-Destructive Evaluation (NDE) inspection, a range of materials exist that exhibit a heterogeneous or acoustically scattering microstructure, for example austenitic steels and Inconel alloys, and are used extensively across many industrial sectors. When inspected using conventional ultrasound techniques, defect signals are significantly corrupted by noise from randomly distributed scatterer associated with the material microstructure. In some cases, even defects that are much larger than the grain size distribution in the microstructure can be difficult to detect. This Thesis presents an investigation into the development of new algorithms to suppress backscattering noise in the received ultrasonic echoes associated with both individual transducers and phased arrays. Using the fact that structural noise in these difficult materials is frequency coherent, frequency diversity based techniques like the well-known Split Spectrum Processing have been developed. However, conventional algorithms are either ineffective or sensitive to the variations of material characteristics, especially when the signal to noise ratio (SNR) is low. A frequency diversity based technique, Moving Bandwidth Split Spectrum Processing (MB-SSP), has been developed, which is less influenced by material characteristics. MB-SSP first selects an ascending series of frequency bands and a trace is reconstructed for each selected band in which a defect is present: this occurs when all frequency components are in uniform sign. Combining all reconstructed signals through averaging gives a probability profile of potential defect positions. A range of supervised machine learning techniques has also been employed to further improve detect capability, if the pre-acquired training data is available. Instead of investigating the structure and pattern of the spectrum of an individual echo, the proposed method focuses on the distinction between the ensembles of defect signals and clutter noise. A training process is used to establish the statistical analysis, based on which a hypothesis test is then applied to the received echoes to indicate defects. The approach is designed to be adaptive to the material microstructure and characteristics due to the statistical training aspect of the technique. The concept of applying clustering algorithms to further reduce the influence of artefact noise remaining in A-scan data after processing by MB-SSP or a conventional defect detection algorithm is also discussed. The segmental signals that potentially contain defects in the processed A-scans are clustered into groups. The distinction and similarity between each group and the ensemble of randomly selected noise segments can be observed by applying a classification algorithm. Each class will then be labelled as either a 'legitimate reflector' or 'artefact' based on this observation and the expected probability of detection (PoD) and the probability of false alarm (PFA) determined. Finally, the developed A-scan based noise reduction algorithms have been extended into phased array imaging. Here the techniques are applied to the raw Full Matrix Capture (FMC) datasets prior to processing by an appropriate imaging algorithm. Total Focusing Method (TFM) and the focused B-scan imaging is applied to both standard and pre-processed FMC datasets on both simulated data and experimental data from coarse-grained materials. Importantly, the background noise is significantly suppressed in every case using the pre-processed FMC data.
Author: Pietro Burrascano Publisher: Springer ISBN: 3319105663 Category : Technology & Engineering Languages : en Pages : 345
Book Description
This book deals with a number of fundamental issues related to the practical implementation of ultrasonic NDT techniques in an industrial environment. The book discusses advanced academic research results and their application to industrial procedures. The text covers the choice and generation of the signals energizing the system to probe position optimization, from quality assessment evaluation to tomographic inversion. With a focus to deepen a number of fundamental aspects involved in the specific objective of designing and developing an ultrasonic imaging system for nondestructive testing, aimed to automatically classify the entire production of an industrial production line, targeted to the field of precision mechanics. The contents of this book is the result of the common effort of six University Research Groups that focused their research activities for two years on this specific objective, working in direct conjunction with primary industrial firms, in a research project funded by the Italian government as a Strategic Research Project.
Author: Timothy Lardner
Author: Timothy Lardner
Author: Lester W. Schmerr Jr.
Author: J. Blitz
Author: Chi-hau Chen
Author: Lester W. Schmerr Jr
Author: J. A. Jackson
Author: Gerhard Huebschen
Author: Rui Gongzhang
Author: Pietro Burrascano
Author: