The work presented in this thesis concerns the development of vision based systems for two hardness (destructive) tests, namely; the Shore and Vickers and a quality assurance non-destructive test. In each case the vision system is based on an IBM PC compatible computer fitted with a commercially available frame store. Bespoke image analysis software was written using the C language for each system. In the Shore test, hardness is judged by the maximum rebound height attained by an indenter incident on a test sample. The purpose of the vision system is to measure the rebound height automatically. Laser light is used to illuminate the indenter and a vidicon vision camera is used to view its motion. Two approaches to the problem are considered; one in which image data is analysed in real time and one in which image·data is merely stored in real time and analysed a posteriori. Non-real time analysis is shown to be superior to real time analysis in terms of accuracy and reliablity and its software implementation is discussed in detail. The Vickers test uses the size of the permanent impression left by an indenter forced into the test material under a known load as a hardness index. In this case the purpose of the vision system is to measure the size of the indentation automatically. The original image analysis algorithms are shown to be capable of analysing good quality samples but are unreliable when applied to poor quality specimens. Further, fault-tolerant, algorithms are described to provide reliable and accurate results over wide variations in sample quality.The quality assurance application involves automated visual inspection of novel ferrite components for defects. Each component is approximately 8 mm in diameter, annular in shape, and coated with aluminium. Laser light is used to illuminate individual components which arc viewed using a charge-coupled device (CCD) video camera. Image analysis algorithms for characterising defects in component geometry and surface finish arc discussed. The system is shown to capable of measuring component edge eccentricity and hole offset as well as providing a quantitative description of surface chips and cracks. The system is further shown to be capable of separately classifying surface defects extending to the edge of a component. Calculation of shape parameters for surface defects also provides a means of distinguishing cracks from surface chips.

Reliability and repeatability are fundamental concepts in ultrasonic nondestructive testing. An inspection technique must be able to accurately detect, characterize, position and size any defect indication. In manual ultrasonic inspection, however, the operator can be a frequent source of error. Mistakes often arise due to the volume of information the operator must memorize and process. Existing solutions require mechanical probe manipulators that restrict the operator's movements and often require changes to trusted methods and procedures. The aim of this research programme was to investigate the potential of a computer system that assists the operator in the analysis of echodynamic patterns. The system allows the operator to record A-scan sequences, store them to disk, and recall them for review. The system's flexible user interface gives the operator freedom to retain existing inspection practices, in addition to the benefits of computer recording. A novel feature of the system was a speech recognition system to provide hands-free control, which minimizes disruption to the flow of the inspection. Trials were conducted to assess the recognizer's reliability under various conditions. The trials showed that focusing upon echodynamic pattern analysis is a valid and useful approach. Only a limited trial was conducted, however, so the research program was not able to conclusively show that the system will reduce operator errors or improve inspection reliability. In user testing sessions, operators agreed that such a system would be helpful during a manual inspection and there were few objections to the imposition of new hardware. Users quickly became used to the speech recognizer, and the speed of interaction and 'flow' of inspection were greatly enhanced. The author suggests that a computerized assistant is worthy of further development, and has the potential to be a valuable tool in manual ultrasonic inspection.

This work examines the application of different magnetic flux leakage (MFL) inspection concepts to the non destructive evaluation (NDE) of residual (elastic) stresses in CANDU reactor feeder pipes. The stress sensitivity of three MFL inspection techniques was examined with flat plate samples, with stress-induced magnetic anisotropy (SMA) demonstrating the greatest stress sensitivity. A prototype SMA testing system was developed to apply magnetic NDE to feeders. The system consists of a flux controller that incorporates feedback from a wire coil and a Hall sensor (FCV2), and a magnetic anisotropy prototype (MAP) probe. The combination of FCV2 and the MAP probe was shown to provide SMA measurements on feeder pipe samples and predict stresses from SMA measurements with a mean accuracy of ±38MPa. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2010-03-11 15:59:23.978

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No description available.

This Thesis describes the design, manufacture and evaluation of a single sided through-air Lamb wave scanner for Non-Destructive Evaluation (NDE). The new scanning system utilises novel wideband piezocomposite transducers and specialised receive electronics to detect and monitor the thickness of faults within the structure under investigation using a frequency agile approach. Based upon the superheterodyne principle, this frequency agility dispenses with the costly requirement for precision manipulation of the transducer alignment, by effectively tuning the system for the thickness of the sample. Several important applications are identified, including defect detection on samples with tapered thicknesses and defect depth characterisation on plates with thickness erosion, in addition to conventional defect evaluation. Through the application of finite element modelling and practical analysis, a new range of wideband composite transducer have been developed which offer a considerable improvement in operational bandwidth in comparison to conventional piezocomposites. Moreover, a specialised ultra low noise heterodyning amplifier was designed and constructed to provide sufficient gain and selectivity to detect the Lamb waves generated in the various structures under examination. Experimental results obtained from the prototype system illustrate a capability to distinguish defects within test specimens of differing materials and determine the thickness of the given defect. The current system is capable of resolving defects down to less than 2mm in diameter or 20% thinning in a 1mm thick aluminium plate for a Lamb wave with a wavelength of 3mm. Moreover, the handheld nature of the scanning head employed within this system has facilitated the examination of practical NDE examples, such as disbonds between vehicle support structures and outer panelling over curved structures.

Thesis (M.A.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

Promotionsarbeit--Eidgenössische Technische Hochschule, Zürich. / Lebenslauf.

Thesis (Ph. D.)--Columbia University, 1917. / Vita.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 89).