Acoustic Emission: Fracture Detection in Structural Materials

231 Pages·2022·8.402 MB·English

by  Valentyn Skalskyi, Zinoviy Nazarchuk, Olena Stankevych

Foundations of Engineering Mechanics
Valentyn Skalskyi
Zinoviy Nazarchuk
Olena Stankevych
Acoustic
Emission
Fracture Detection in Structural
Materials
Foundations of Engineering Mechanics
Series Editors
Vladimir I. Babitsky, School of Mechanical, Electrical and Manufacturing
Engineering, Loughborough University, Loughborough, Leicestershire, UK
Jens Wittenburg, Karlsruhe, Germany
The series “Foundations of Engineering Mechanics” includes scientific monographs
and graduate-level textbooks on relevant and modern topics of application-oriented
mechanics. In particular, the aim of the series is to present selected works of Russian
and Eastern European scientists, so far not published in Western countries, drawing
from the large pool of experience from major technological research projects. By
contributing to the long tradition of enrichment of Western science and teaching
by Eastern sources, the volumes of the series address to scientists, institutional and
industrial researchers, lecturers and graduate students.
· ·
Valentyn Skalskyi Zinoviy Nazarchuk
Olena Stankevych
Acoustic Emission
Fracture Detection in Structural Materials
Valentyn Skalskyi Zinoviy Nazarchuk
Karpenko Physico-Mechanical Institute Karpenko Physico-Mechanical Institute
of the National Academy of Sciences of the National Academy of Sciences
of Ukraine of Ukraine
Lviv, Ukraine Lviv, Ukraine
Olena Stankevych
Karpenko Physico-Mechanical Institute
of the National Academy of Sciences
of Ukraine
Lviv, Ukraine
ISSN 1612-1384 ISSN 1860-6237 (electronic)
Foundations of Engineering Mechanics
ISBN 978-3-031-11290-4 ISBN 978-3-031-11291-1 (eBook)
https://doi.org/10.1007/978-3-031-11291-1
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Preface
The problem of technogenic and environmental safety of significant objects of indus-
trial and social infrastructure is becoming more and more urgent both for many
economically developed countries and for the world in general.
During long-term operation under the influence of various physical factors,
structural materials degrade, i.e., change their basic physicochemical and physi-
comechanical characteristics. The consequences of this phenomenon are especially
dangerous for the objects of the energy complex, chemical industry, pipeline trans-
port, machine building, and bridge structures, where there are factors of aggres-
sive working environment (corrosion, hydrogen, and radiation embrittlement, etc.).
Degradation of structural materials contributes to the initiation and development of
the most dangerous defects such as cracks, which can cause spontaneous fracture of
structures, which, in most cases, lead to significant material damage, environmental,
and human casualties losses.
The most important problem of technical diagnostics (TD) and nondestructive
testing (NDT) for the objects of long-term operation is to determine their residual
life and establish such period and conditions under which they can be safely operated.
According to the concept of “safe damage”, the presence of cracks may not always
be the reason for removing the product or some structural element from the service.
To ensure their normal functioning, it is necessary to be able to identify the critical
parameters of the crack and the mechanisms of its propagation, which characterize
main points of fracture: the moment of start, subcritical growth, and transition of
fracture to the supercritical stage.
It is possible to determine the level of wear of structural materials and choose
methods for determining the residual life of relevant objects and products by deter-
mining the types of their fracture. Such data can be obtained in the laboratory by
destructive test methods; however, they are non-effective for TD of the elements of
structures and products in the operating conditions.
At present, the method of acoustic emission (AE) is effective for studying the
dynamics and stages of defects growth in the structure of materials and assessing the
real state of objects during their TD. The possibility to use it to assess the damage
of materials is based primarily on correct physical models of elastic wave radiation.
v
vi Preface
They provide solving the corresponding non-stationary dynamic problems of crack
theory in terms of displacements. Their solutions make it possible to determine
the expected amplitudes of the AE electric signals generated during initiation or
propagation of fracture. At the same time, it serves as a basis for the creation of
original methodological approaches and means of selection and processing of AE
signals with the appropriate software.
Along with theoretical research, the development of methodological bases of AE-
diagnostics with the use of new approaches to the processing of AE signals to identify
the types of fracture and their experimental confirmation is an important problem.
The Fourier transforms are mainly used to obtain information about the spectral
components of the signal. At the same time, from the standpoint of analysis of any
signals and functions in the frequency domain and their exact recovery after trans-
formations, the Fourier series expansion of signals has a number of disadvantages
and limitations: having good localization by frequency, it has no temporal resolu-
tion; limited informativeness of the analysis of non-stationary signals and almost
complete lack of possibility to analyze their specific features (singularities); it gives
global information about the frequencies of the studied signal and does not give an
idea of its local properties with rapid time changes in the spectral composition. If it
is necessary to perform time localization of spectral components, one should refer
to the frequency–time representation of signals. The wavelet transform (WT) is one
of the transformations that provide this representation.
The monograph presents topical theoretical and experimental studies aimed at the
creation of modern methods for diagnosing macrofracture of solids and assessing of
the structural materials state. New mathematical models of displacement fields due
of the crack-like defects development in materials and a new criterion for assessing
types of macrofracture of materials by energy parameters of WT of AE signals are
built.
Lviv, Ukraine Valentyn Skalskyi
Zinoviy Nazarchuk
Olena Stankevych
Contents
1 Macrofracture of Structural Materials and Methods
of Determining Its Type ......................................... 1
1.1 Types of Structural Materials Fracture ......................... 1
1.1.1 Ductile Fracture ..................................... 3
1.1.2 Brittle Fracture ...................................... 5
1.1.3 Mixed-Mode (Ductile–Brittle or Brittle–Ductile)
Fracture ............................................ 6
1.2 Application of the Acoustic Emission Method to Detect
the Fracture of Structural Materials ........................... 7
1.2.1 General Information About Acoustic Emission ........... 7
1.2.2 Some Approaches to the Identification of Fracture
Types by the AE Method .............................. 8
1.2.3 Identification of Fracture Mechanisms of Composite
Materials ........................................... 15
1.3 Detection of Defects by Signals of Magnetoelastic Acoustic
Emission .................................................. 17
1.4 Methods of Spectral Analysis of AE Signals .................... 19
1.4.1 Continuous Wavelet Transform ........................ 19
1.4.2 Discrete Wavelet Transform ........................... 24
1.5 Application of Wavelet Transform for Analysis of AE Signals .... 28
1.5.1 Wavelet Analysis of AE Signals in the Course of TD ...... 28
1.5.2 WT in the Problems of AE Sources Location
and Identification of Defects in Structural Materials ....... 29
1.5.3 Identification of the Mechanisms of Composites
Fracture by Using the WT of AE Signals ................ 31
1.5.4 Wavelet Analysis in the MAE Signals Processing ......... 34
1.5.5 Application of the κ-Criterion for the Evaluation
of the Fracture Types of Structural Materials ............. 36
References ..................................................... 38
vii
viii Contents
2 Mathematical Models for Displacement Fields Caused
by the Crack in an Elastic Half-Space ............................ 51
2.1 Basic Relations of Three-Dimensional Dynamic Problems
of the Theory of Elasticity for Bodies with Cracks ............... 52
2.2 Modeling of Wave Displacements Field on the Half-Space
Surface Due the Displacement of the Internal Crack Faces ........ 57
References ..................................................... 85
3 Energy Criterion for Identification of the Types of Material
Macrofracture ................................................. 87
3.1 Methods for Identifying the Types of Macrofracture ............. 87
3.2 Construction of the Energy Criterion .......................... 89
3.2.1 Analysis of Fracture Types for Carbon Steel ............. 94
3.2.2 Specific Features of Alloyed Steel Fracture .............. 98
3.2.3 Specific Features of Brittle Materials Fracture ............ 99
3.3 Continuous Wavelet Transform of the AE Signals Emitted
Under Fracture of Aluminum and Its Alloy ..................... 102
3.3.1 Investigation of the Aluminum Fracture by Parameters
of the CWT of AE Signals ............................. 102
3.3.2 Analysis of AE Signals During Fatigue Fracture
of Aluminum Alloy .................................. 107
3.4 Specific Features of the Acoustic Emission Signals
During Fracture of Aluminum Alloy Welded Joints Under
Quasi-Static Loading ........................................ 109
3.4.1 Identification of Fracture Sources of Different Zones
of Aluminum Alloy Welded Joints by Fractographic
Analysis of the Fracture Surfaces ....................... 109
3.4.2 Peculiarities of AE Signals During Fracture
of the 1201-T Alloy Welded Joint ...................... 110
3.5 AE-Identification of the Types of Fracture During
Low-Temperature Creep Crack Growth ........................ 114
3.6 Application of the Wavelet Transform to Study the Features
of Nonmetallic Materials Fracture ............................ 117
References ..................................................... 121
4 Evaluation of the Types and Mechanisms of Fracture
of Composite Materials According to Energy Criteria ............. 125
4.1 Specific Features of Macrofracture of the Glass
Fiber-Reinforced Composites ................................ 126
4.1.1 Substantiation of the Research Technique ................ 126
4.1.2 Results and Discussion ............................... 127
4.2 AE-Diagnostics of Fracture of the Aramid Fiber-Reinforced
Composites ................................................ 132
4.2.1 General Characteristic of the Aramid Fibers ............. 132
4.2.2 Influence of Various Factors on the Mechanical
Properties of CM Reinforced with the Aramid Fibers ...... 134
Contents ix
4.2.3 Mechanisms of Unidirectional CM Fracture .............. 134
4.2.4 Substantiation of the Research Methods ................. 136
4.2.5 Results and Discussion ............................... 136
4.2.6 Analysis of AE Signals During Tension
of the Composite of Type 1 ............................ 139
4.2.7 Peculiarities of AE Signals During Tension
of the Composite of Type 2 ............................ 143
4.2.8 Characteristics of AE Signals During Tension
of the Composite of Type 3 ............................ 144
4.2.9 Parameters of AE Signals During Tension
of the Composite of Type 4 ............................ 147
References ..................................................... 150
5 Ranking of Dental Materials and Orthopedic Constructions
by Their Tendency to Fracture .................................. 155
5.1 State of the Art of Researches on Mechanical Properties
of Dental Materials ......................................... 156
5.2 Determination of the Characteristics of Materials
for Temporary Fixed Constructions of Dentures ................. 157
5.2.1 Materials for Investigations ............................ 157
5.2.2 Evaluation of Strength Characteristics of Polymers ........ 157
5.2.3 Evaluation of Water Absorption of Polymer Materials ..... 165
5.2.4 Determination of a Shrinkage .......................... 167
5.2.5 Microhardness of Polymers ............................ 168
5.3 Evaluation of the Types of Dental Polymer Fracture
by the Energy Criterion ...................................... 169
5.3.1 Analysis of AE Under Tensile Fracture of Polymers ....... 169
5.4 Peculiarities of Some Tooth-Endocrown Systems Fracture
Under Quasi-Static Loading .................................. 175
5.4.1 Preparation of the Samples ............................ 175
5.4.2 The Initiation of Fracture in the Fixed Orthopedic
Tooth-Endocrown Restorations ......................... 177
5.4.3 Specific Features of AE Signals Under Fracture
of the Tooth-Endocrown Restorations. Analysis of AE
Signals During Tooth Fracture ......................... 183
5.4.4 Evaluation of AE Signals Under Fracture
of the Samples Made of Different Materials .............. 185
5.4.5 Analysis of AE Signals During Fracture
of the Tooth-Endocrown Restorations ................... 187
References ..................................................... 188
6 Rating of Hydrogen Damaging of Steels by the Wavelet
Transform of Magnetoelastic Acoustic Emission Signals ........... 193
6.1 Some Aspects of Operation of the Technical Systems
in Hydrogenous Medium .................................... 194
6.1.1 Peculiarities of Oil and Gas Pipelines Operation .......... 194