Trembovetska R. Theory of optimal synthesis of surface eddy current probes for computer systems of non-destructive testing

The dissertation thesis is devoted to solving the urgent scientific and applied problem of creating a theory of optimal parametric synthesis of the entire class of moving surface eddy current probes with the uniform sensitivity in the testing zone to ensure the necessary conditions for identifying defects in the continuity of materials and products when using computer systems for non-destructive testing. The first section analyzes the scientific and applied problem, studies the current state of development of computer systems of non-destructive electromagnetic testing. Based on the analysis of the computer systems of non-destructive testing, it was determined that their integral component, on which the efficiency of the systems as a whole depends on the detection and identification of defects in the integrity of products and materials, are eddy current probes, in particular surface. The section systematizes and critically analyzes certain ideas, approaches and methods known from scientific and technical sources of information to create excitation system of eddy current probes, which implement a homogeneous eddy currents density distribution in the testing object area. As a result of the analysis it is established that the optimization method is perspective among modern approaches. Methods of creating metamodels for use in optimal surrogate synthesis of eddy current probes are considered. The most perspective tendencies of their development and application are determined. In addition, the section on the basis of the analysis formulates the purpose of the dissertation research, sets a number of tasks, the implementation of which ensures its achievement. In the second section the conceptual statement of a scientific and technical problem is applied. The section proposes a methodology for surrogate optimal synthesis of the whole class of movable eddy current probes with the uniform sensitivity in the testing zone. As an example, the generalized for circular and frame excitation systems "exact" electrodynamic model of eddy current probes is given. The methods for generating multidimensional homogeneous computer designs of experiments are considered. The created additive committee neural network method of construction of multidimensional eddy current probes metamodels is presented. The approaches of the final estimation of adequacy and informativeness of the received metamodels on a set of statistical indicators are shown. The third section considers the creation of methods for optimal surrogate synthesis of circular movable surface eddy current probes with planar and volumetric excitation systems structures, providing a uniform sensitivity to defects, which is a necessary condition for recognizing defects of integrity in computer quality testing systems. These methods have been developed within the framework of a single methodology for optimal synthesis of the whole class of movable eddy current probes, which is proposed in Section 2. The construction of metamodels of excitation systems of surface eddy current probes was carried out; their adequacy was evaluated according to a number of statistical indicators. Numerical results of parametric optimal surrogate synthesis of excitation systems of surface eddy current probes with circular planar and volumetric structures are given. The fourth section presents the method of optimal surrogate synthesis of frame movable surface eddy current probes with a planar excitation systems structure, created on the basis of the proposed unified methodological approach to the synthesis of movable eddy current probes. The metamodel excitation system of surface eddy current probe has been constructed. As a result of conditional optimization with the use of the created metamodel the variants of designs of movable square surface eddy current probes with planar excitation systems structure have been synthesized. The fifth section presents a method of optimal surrogate synthesis of tangential frame movable surface eddy current probes with a volumetric excitation systems structure, created in accordance with the proposed unified methodological approach to the synthesis of movable eddy current probes. Possible variants of constructions of tangential surface eddy current probes differing in the location of the measuring coil of the probe are considered. The excitation system metamodel of the tangential surface eddy current probe has been built, its adequacy was evaluated according to a number of statistical indicators. The sixth section offers a number of possible approaches to the practical implementation of excitation systems synthesized surface eddy current probes. The errors of all methods of leveling distortions of eddy currents density distribution in the manufacture of a specific variant of the synthesized surface eddy current probe in practice have been estimated.