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Ключевые слова: разрушение, поле перемещений, акустическая эмиссия,
магнитоупругая акустическая эмиссия, водород, вейвлет-преобразование, типы
разрушения.

ABSTRACT

Stankevych O. M. Methodological backgrounds of identification of materials
fracture types by the energy parameters of acoustic emission. – Manuscript.
Thesis for the Doctor’s degree in Engineering Sciences by specialty 05.02.10 –

Diagnostics of materials and structures. – Karpenko Physico-Mechanical Institute of
National Academy of Science of Ukraine, Lviv, 2019.

The dissertation is devoted to the scientific and technical problem which consists in
the development on the basis of theoretical and experimental studies the methodological
backgrounds of solids fracture diagnostics and estimation of the structural materials state
using energy parameters of acoustic emission of elastic wave.
At the base of the developed in the dissertation methodology of the solids fracture
diagnostics and their state estimation by the energy parameters of the AE signals are the
following scientific results.
A general analytical solution of the problem of elastic waves propagation initiated by
the displacement of the opposite surfaces of the penny-shaped cracks relative to their
center in a three-layer composite structure is constructed using the boundary integral
equations method.
The problem for three typical partial cases of multilayered composites (“la-
yer+halfspace with crack”, “layer+layer with crack”, “layer+layer+halfspace with crack”)
was solved numerically. It assisted to study the dynamics of wave processes on the
composite surface and to create the preconditions for efficient use of the elastic wave’s
parameters during the TD of products and elements of structures.
The displacement fields on the surface of multilayered composites depend on the
elastic characteristics and geometric dimensions of their components, the frequency of
displacement of the crack surfaces, the distance from the observation point to the fracture
epicenter and the depth of the crack in the composite. Taking into account of these
dependencies makes it possible to determine the features of fracture in the composite and
to create new methods of AE-diagnostics of products and structural elements.
A new method of local features estimation of AE signals is developed, which is based
on the determination of the energy parameters of the local maximums of the signals
continuous WT. It has been found out that the AE signal energy parameter, its frequency
and duration of radiation of are enough informative characteristics to identify types and
mechanisms of the signal generation.
A new energy criterion for quantitative estimation of the materials macrofracture
types based on the energy parameter of WT of AE signals has been constructed. So, the
AE signals with energy parameter E WT  , 0 01 correspond to the ductile fracture, with
energy parameter 01,0  E WT  1 , 0 – to the ductile-brittle (microcracking) and with energy

parameter E WT  1 , 0 – to the brittle fracture (macrocracking). Using this criterion it is