MATHEMATICAL ALGORITHM FOR ESTIMATING THE ACOUSTIC CONDUCTIVITY OF THE WAVEFRONT FOR VERIFICATION OF A DIAGNOSTIC MODEL IN AN ANALYSIS OF DEFECTS IN A POLYMER COMPOSITE MATERIAL

The modal analysis is considered as one of the lines of technical diagnostics for evaluating the quality of polymer composite materials (PCMs). It allows one to link the structure of modal characteristics of PCM element base in the amplitude frequency domain. In the course of modal analysis, the complex construction of PCM as a heterogeneous material is transformed into a set of easy-to-understand independent systems with one degree of freedom. This structural approach is used to analyze the structure of PCM components. A laser is used to form an external action, with the help of which PCM components can form a wave field when vibrations pass through its thickness. Vibrations and deformations of PCM structural elements under a mechanical excitation are considered as the intrinsic vibration forms (vibration modes) of PCM elements the filler and matrices. High frequency laser actions extracts a constant wavefront, which is used for constructing an algorithm for recognition of the structure of PCM, including the detection of possible defects, such as changes in its density and various stratifications. To assess the technical condition of structural elements of PCM, a mathematical model was developed to assess the effect of defects on passage of a wave and the excitation of modal vibrations by the element base of PCM. The mathematical algorithm for estimating the acoustic conductivity of the wavefront, together with experimental data, was used for constructing a wave diagnostics algorithm. It made it possible to create an algorithm for a technical diagnostics of PCM elements. An experiment was conducted on the laser action on a carbon fiber panel with specially created defects. The frequency values found in various zones of carbon fiber showed a qualitative and quantitative change in the structure of PCM. It is shown that, to construct an effective model for diagnosing the technical condition of PCM elements, more experimental studies are required.