ON THE ACOUSTIC PARAMETERS OF METAL CONSTRUCTIONWHEN DAMAGE IS ACCUMULATED

In the work with the use of nondestructive control methods, the issues of determining acceptable durability or safe resource are considered. It is shown that the design monitoring procedure can be presented as follows: determines the original state zero zone, where the material of the product was subjected to low operational loads; further, with the use of nondestructive control methods, the acoustic parameter is measured (without disassembling the product)., such as the speed of elastic acoustic waves, nonlinear acoustic parameter, difference of velocities with twofrequency sensing, etc.; acoustic scanning of the product's metal is performed, in areas where there have been significant loads, signoff voltages, leading to an intensive accumulation of damage (the destruction of metal leading to cracks); defined zone “N” where the metal state parameter, for which the value is taken, characterizing the difference of the acoustic parameter (the speed of elastic waves, nonlinear acoustic parameter, the difference in velocity in twofrequency sensing) relative to the same parameter in the zone of zero exceeds the established level. The regularities established in the work linking the presence of plastic deformation with the difference in the delays (velocity) of elastic Rayleigh waves at different sounding frequencies at a fixed base between the emitter and the receiver of elastic waves, as well as the behavior of a nonlinear acoustic parameter during the safe resource time, suggest the possibility of using the observd fact as a principle for controlling the limiting state of the material due to plastic deformations on industrial structures. Based on the proposed approach, an engineering methodology for determining the technical condition of the material of the structures of production facilities is proposed, which allows to establish three stages of operation: the reliable operation mode; the controlled operation mode and the critical operation mode.