Computer evaluation of the depth of thermomechanical fatigue cracks according to their length
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COMPUTER EVALUATION OF THE DEPTH OF THERMOMECHANICAL FATIGUE CRACKS ACCORDING TO THEIR LENGTH P. O. Marushchak1, 2 and I. V. Konovalenko1
UDC 670.191.33
We describe the analysis and identification of a network of surface cracks on the basis of processing of digital images. A three-dimensional analysis has been performed by a combination of two measured parameters: the length and depth of a crack. On the basis of processing of a limited number of data, the system can analyze cracking of the surface of a roll of a continuous slab-casting machine. Theoretical prerequisites and experimental results are presented. Keywords: multiple cracking, digital image, degradation of surface, diagnostics.
Multiple cracking is one of the most often encountered type of damages of surfaces of durable structures operating under the conditions of thermomechanical loading [1]. In this case, an important task is to evaluate the technical state of an analyzed structure and provide its workability [1, 2]. Since thermomechanical loading causes the initiation of surface cracks, diagnostics is required to reduce the risk of unpredictable fracture of industrial equipment during the manufacturing process [3]. Thus, for the evaluation of multiple cracking, it is important to find approaches sensitive to the change in the geometry of multiple defects in long operation. Furthermore, much attention is given to the investigation and development of the so-called “interface media,” i.e., materials whose mechanical behavior is determined to a great extent by localization of strain on interfaces of structural elements (blocks). It is of prime importance to identify interfaces between these elements [4]. Individual methods of a identification of multiple defects [5], in particular, examples of the successful use of digital diagnostics of the technical state of rolls of rolling mills [6], are known. However, they call for improvement and adaptation to geometric features of real cracked structures, which is a complex scientifictechnical task [7]. Though the possibility to develop generalized approaches to the analysis and synthesis of diagnostic systems, to optimize the methods and procedures for evaluating the damage of structures, and to develop criteria for evaluation of the limiting state and risk analysis for the determination of the technical state of equipment within the limits of the scheduled operation time has been intensively studied, complex approaches that make it possible to evaluate quantitatively several parameters of a cracked surface and analyze the character of change of individual components of a cracked structure [8, 9] are absent. The aim of the work is to construct an algorithm for the identification of elements of surface cracking and to describe and analyze quantitatively elements of a network of cracks. Digital Defectometry in Technical Diagnostics Defectometry of parameters of a network of cracks is the first step to understanding the state of a material with the following damages [10, 11]. For the complex analysis of the place o
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