Application of informational approach to the solution of a problem of a defectoscopy by a method of free oscillations
Acoustic devices and systems
Institute of Strength Physics and Materials Science SB RAS, 2/4, pr. Akademicheskii, Tomsk, 634021, Russia
On the example of free oscillation method, the author considered the methodology of information approach to the solution of a fault detection problem with a great number of unidentified factors. The paper presents either general conceptual, or particular functional diagrams in addition to free oscillation method, which point the place and interaction of such analysis methods as induction and deduction while opening the «black box» of a defect. These functional diagrams contain several heuristic stages of reference synthesis. The first stage features primary uncertainty elimination of solution region with respect to the presence of fundamentals within the frequency range, determined by the quality of manufactured samples, complemented by the subsequent statistical measurements, which identify the boundaries this range. Ultimately, linking the second part of the solution with the results obtained at the third stage, allow determine the uniqueness of the solution obtained, i. e. the fact of the presence of additional harmonics means the presence of the defect. As a result, the bandpass filter thus obtained, will present that significant reference, and further fault detecting equipment algorithm will be developed in relation to this reference. The formed reference herewith will be compatible with complex hardware path of contact excitation and wireless acoustic signal receiving. Such an approach to reference forming allows drastically decrease the number of calibration measurements, since the method of specified products testing is set. The paper presents positive results obtained with arbitrary signal model and practical examples of implementing the given methodology, which does not make use of complex physical calculations of complex phenomena while elastic interaction peculiar to implementation of free oscillations method. Typical defect search results on casting pump body of a complex shape located in the area of the threaded portion of large diameter and a massive disk weighing 90 kg with thickness of 70 mm with thin cracks and delamination up to 70 mcm are presented as illustrations.
Keywords:spectrum, free oscillations method, standard, acoustic waves, induction and deduction, information approach, methodology
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