Page 41 - АвторефМокрий21

39

Созданы и развиты методики определения распределения скорости
поверхностных акустических волн реализованы с помощью установки, которая
позволяет определять время прохождения поверхностных акустических волн с
ошибкой в несколько наносекунд.
Разработанные методики апробированы во время определения
распределения скорости поверхностных акустических волн в пластически
деформированных, а также насыщенных водородом низкоуглеродных сталях.
Ключевые слова: диагностирование, неразрушающий контроль, скорость
акустических волн, поверхностные акустические волны, лазерная
интерферометрия, пьезоэлектрические преобразователи.

Abstract

Mokryy О. M. Methodological background of diagnostics of the state of
materials and structural elements by the velocity distribution of surface acoustic
waves. – Manuscript.
Thesis for the Doctor’s degreein Engineering Science by specialty 05.02.10 ‒
diagnostics of materials and structures. ‒ Karpenko Physico-Mechanical Institute of
National Academy of Science of Ukraine, Lviv, 2020.
The dissertation is devoted to creation of methods and means of determining the
distribution of the surface acoustic waves velocity, suitable for non-destructive
testing and technical diagnostics.
New methods for determining the velocity of surface acoustic waves and their
distribution on the basis of contactless laser and contact piezoelectric primary
transducers are developed and created. A new simple method for stabilizing the
operation of the Michelson interferometer under conditions of vibration and
temperature drift is proposed. The method is based on creating an interference pattern
on the surface of the photodetector in the form of parallel interference fringes. These
fringes are formed due to the angle between the interfering beams. Based on the
numerical simulation, as well as experimenta data, the effectiveness of the proposed
scheme is confirmed.
A new technique for determining the velocity of surface acoustic waves with a

small measurement base, based on an extended probe laser beam has also been
created. The proposed method allows us to reduce significantly the error of
determining the velocity of the surface acoustic waves in the case of a measurement
base of several mm. The error is reduced due to a decrease in the distance
determination error.
The methods of reducing the effect of transducer temperature change on the
measurement of the surface acoustic waves velocity are developed. A method to
reduce the influence of the surface irregularity on the control object as a source of
error when using contact converters is proposed. The method is based on
measurements using contact fluids with different velocities of acoustic waves
propagation.