Evaluation of Structural Metal Materials Damage by Acoustic Methods

Abstract

The purpose of this research is to study the damage of structural metal materials by acoustic method under various external fatigue and thermal influences. A structural model describing the process of accumulation of scattered micro-damages in the material is proposed, the parameters of which can be measured by acoustic method. It is shown that irreversible processes occur in the structure of structural metal materials during cyclic loading, leading to changes in physical and mechanical characteristics. The assessment of changes in a large number of informative parameters of acoustic control in the process of damage accumulation was carried out. It is established that the parameters of elastic waves depend on the characteristics of the medium under study. It is shown that the state of the surface layer can be used in the tasks of earlier assessment of the developed resource of the structural material. A model that takes into account the influence of degradation processes of the surface layer on the parameters of surface waves is proposed. The results of experimental studies confirming the proposed model are presented. Methods for determining material mechanical characteristics are proposed: elastic modulus, yield strength, fracture toughness, internal stresses, grain size, etc. on structural elements, without violating their strength characteristics. The results of studies of medium influence on parameters of elastic waves serve as the basis for constructing a complex acoustic method for determining physical and mechanical characteristics of structural materials. Examples of practical use of the obtained results in the tasks of ensuring the safe operation of critical structural elements are considered. The data obtained during the study make it possible to assess the damaged state and properties of metal materials under cyclic loading quickly using the parameters of acoustic waves.