The Analysis of Electromagnetic Radiation at Destruction of Structural Materials
Electromagnetic radiation (EMR) occurs when structural materials (hereinafter simply materials) of different origin are destroyed, caused by inhomogeneities (cracks, microcracks, structural elements) of different scale levels created during the destruction and cracking phase. In this situation, the production of electromagnetic radiation is attributable to the following processes: the interatomic distance, interstitial bonds, the appearance of free electrons and vacancies, the movement of charges at the top and on the banks of the resulting cracks. There is a universal relation between the duration of elastic energy release and the size of cracks created. Under load, that is, the rise time of the elastic wave’s longitudinal component is proportional to the crack length. On a scale from nanometers to thousands of kilometres, this relationship occurs. For electromagnetic radiation, a similar relationship occurs that is proportional to the leading edge length of an electromagnetic pulse, the characteristic scale of the inhomogeneity responsible for producing this pulse. The existence of knowledge on the parameters of inhomogeneities responsible for the formation of this signal in its spectrum is determined by the physics of EMR signal formation. In this regard, the problem of defining quantitative relationships between the parameters of the EMR signal and the parameters of inhomogeneities involved in the generation of this signal has both purely scientific and practical significance. The solution of such a task enables the observation (control) of the processes that occur in a destructible object in real time. The methods developed and used by the author to analyse EMR signals are based on the time-and-spectrum method, the essence of which lies in the time-and-spectrum tables (TST) construction and subsequent analysis of the contents of these tables. The TST rows are the moments of time, and the columns are the frequencies of the spectral elements. The processes occurring at the corresponding points in time are thus expressed by each row. In this regard, the author has developed the following methods: (1) The method of constructing time-and-spectrum tables to visualise the structure of the EMR signal; (2) The method of estimating the magnitude of surface damage is based on the study of the electromagnetic radiation spectrum using an analogue of the Hurst normalised span statistics for the coo-span. The analysis of the evolution of the dependencies of the normalised range statistics in logarithmic coordinates shows that: ‘Normalized range – frequency’ helps us to classify their behavioural features, which can be viewed as a transition to the final stage of the destruction surface. 3) For the quantitative determination of the parameters of an ensemble of microcracks, a model has been developed which represents the transformation of the time-and-spectrum analysis method into a space-and-time method. In this situation, the tables obtained were called space-and-time tables (STT). The adequacy of the approach was tested using a concentration test by Zhurkov. This approach examined the electromagnetic radiation signals obtained under laboratory conditions by the destruction of a sample of marble and diabase. A phenomenon called “High Frequency Trace” has been found. The most interesting property of this phenomenon is that the number of microcracks depends on their characteristic dimensions in a nearly linear, inversely proportional way. Regions with logarithmic scale invariance have this phenomenon. A wide variety of nonlinear oscillations and waves, including a kink, were also found (topological soliton, dislocation in the Frenkel – Kontorova model). 4) We studied the microscale phenomenon of the logarithmic invariant dependence of the number (concentration) of microcracks on their characteristic sizes during the destruction of marble and diabase samples, named “High-Frequency Trace” in the early works of the author, within the context of the testing of the model described above. The ratios of the characteristic sizes of microcracks are determined at the points where their concentration is increased. The notion of the fracture coefficient is implemented by electromagnetic radiation. The self-organization phenomenon of an ensemble of microcracks was discovered. The law, which obeys the law, is shown to be An analogue of the Gutenberg-Richter rule for microscales is a portion of the dependence of the number of microcracks on their characteristic sizes in logarithmic coordinates for the “High Frequency Trace” phenomenon.
Author (s) Details
Victor D. Borisov
Department of Mechanical Engineering, Teplosnabzhenie, Belovo, Russia.
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breather concentration criterion Cracking deformation destruction electromagnetic radiation fractal analysis fracture surface Gutenberg-Richter law. logarithmic scale invariance normalized range self-organization selfsimilarity space-andtime analysis time-andspectrum analysis two-dimensional waves