An Acoustic Emission Method for Assessing the Degree of Degradation of Mechanical Properties and Residual Life of Metal Structures under Complex Dynamic Deformation Stresses

Abstract

An acoustic emission method for assessing the degree of degradation of mechanical properties under conditions of complex dynamic deformation stresses is proposed. It has been shown that changing the operating conditions of metal structures, peak loads, external collisions, and thermally changing loads, which cannot be taken into account, leads to uncertainty and unpredictable structural changes in the material. This in turn makes it difficult to identify the state of the structure material to ensure trouble-free operation of the equipment. Changes in the mechanical properties under difficult loading conditions are identified by polynomial approximation of the results of AE measurements and the construction of boundary curves separating the operability region from the fracture region. This is achieved by approximating the experimental dependences of the acoustic parameters for various types of loading. This approach significantly expands the capabilities of the technical means of identification systems of metal structures, and in particular, allows the current state of the equipment and its suitability for further operation to be assessed without stopping the equipment in real time. It is of interest not only to fix the damage, but also to diagnose the processes of reducing the mechanical properties during the operation of the equipment.

The Theory of Similarity and Analysis of Dimensions for Determining the State of Operation of Structures under Difficult Loading Conditions

“…In the case of multiparameter loading, to determine the safety factor, one should take into account how the deformation parameters change when the loading parameters change with respect to the limiting state. The boundary curve of the area of operability of structures under difficult loading conditions, constructed from the results obtained from samples of St3sp steel [ 19 ], is shown in Figure 1 .…”

“…The condition for operability is the failure of the loading trajectory to go beyond the area of determining the state of operability of the structure. The intersection of the boundary curve with the coordinate axes is determined by the values of the strength properties of the material σ B and σ 0.2 [ 19 ].…”

“… Boundary curve 1 and loading trajectory 2 in the coordinates of mechanical stress (I—area of operability, II—area of destruction) [ 19 ]. …”

Experimental and Theoretical Study of Plastic Deformation of Epoxy Coatings on Metal Substrates Using the Acoustic Emission Method

“…One of the common structural carbon steels St3sp was chosen as the material used for the substrate. Mechanical properties and international analogs are presented in [ 1 , 2 ].…”

“…The relationship between the processes occurring in the structure of materials under loading and the accompanying AE effects makes it possible to predict changes in materials’ mechanical properties and structure based on acoustic measurements [ 1 , 2 ]. A literature review is presented, with a general target orientation and practical implementation on experimental and theoretical studies of plastic deformation of polymer coatings on a metal basis using the acoustic emission method.…”