ISO 22290:2020

INTERNATIONAL ISO
STANDARD 22290
First edition
Non-destructive testing — Infrared
thermographic testing — General
principles for thermoelastic stress
measuring method
PROOF/ÉPREUVE
Reference number
ISO 22290:2020(E)
©
ISO 2020

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ISO 22290:2020(E)

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© ISO 2020
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Published in Switzerland
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ISO 22290:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Infrared thermographic testing personnel . 1
5 Test Environment . 1
5.1 Installation environment for the test equipment . 1
5.2 Avoidance of disturbances . 2
6 Equipment . 2
6.1 Configuration . 2
6.2 Infrared camera . 2
6.3 Detection of temperature change by thermoelastic effect . 3
7 Measuring method . 4
7.1 Test object . 4
7.2 Load condition . 4
7.2.1 General load condition . 4
7.2.2 Average value and amplitude of load . 4
7.2.3 Load frequency . 5
7.3 Imaging method . 5
7.4 Calibration of stress value . 6
8 Implementation and reporting of tests . 7
8.1 Items described in the NDT procedures . 7
8.2 Items described in the NDT instructions. 7
8.3 Record of test conditions . 7
8.4 Report . 8
Bibliography . 9
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ISO 22290:2020(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 135, Non-destructive testing,
Subcommittee SC 8, Thermographic testing.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO 22290:2020(E)

Introduction
Thermoelastic stress measuring method, which utilizes the thermoelastic properties of materials, is a
“full-field”, “noncontact” technique for surface stress mapping of materials and structures. Unlike the
conventional technique such as strain gauge method, the unique advantage of the method is its ability
to image whole-surface stress (∆ (σ +σ )) distribution in specimens easily (ISO 10878).
1 2
Industrial applications of thermoelastic stress measuring method are getting wider along with
remarkable improvement of thermographic technologies. The effectiveness of any application of
thermoelastic stress measuring depends upon proper and correct usage of the method. The purpose of
this document is to provide general principles of the thermoelastic stress measuring method to promote
correct and effective application to various industrial non-destructive testing, such as automobiles,
aerospace products, electronic instruments, medical devices, industrial materials and so on.
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INTERNATIONAL STANDARD ISO 22290:2020(E)
Non-destructive testing — Infrared thermographic
testing — General principles for thermoelastic stress
measuring method
1 Scope
This document provides general principles for thermoelastic stress measuring method of infrared
thermographic testing in the field of industrial non-destructive testing (NDT).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 10878, Non-destructive testing — Infrared thermography — Vocabulary
ISO 9712, Non-destructive testing — Qualification and certification of NDT personnel
ISO/TS 25107, Non-destructive testing — NDT training syllabuses
ISO 10880, Non-destructive testing — Infrared thermographic testing — General principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10878 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www. iso. org/o bp
— IEC Electropedia: available at http:// www.e lectropedia. org/
4 Infrared thermographic testing personnel
Personnel who are responsible for conducting infrared thermographic testing (TT) including
thermoelastic stress measuring shall meet the following criteria.
a) TT personnel shall have an adequate knowledge of the testing including the basics of infrared
measurement and heat-transfer engineering as required by ISO 9712 and ISO/TS 25107.
b) TT personnel’s visual acuity and colour vision shall meet the requirements of ISO 9712.
5 Test Environment
5.1 Installation environment for the test equipment
Conduct the test in an environment where the temperature, humidity, and atmosphere are appropriate
for the test equipment, including the infrared camera as required by ISO 10880. Be sure to avoid
condensation on the surface of the test object.
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ISO 22290:2020(E)

In order to avoid occurrence of image blur due to fluctuation of the field of view, make sure that vibration
is not applied to the infrared camera as much as possible. However, when the vibration period of the
infrared camera is synchronized with the load cycle to the test object, the influence can be reduced by
the position correction technique.
5.2 Avoidance of disturbances
For the avoidance of disturbances, requirements and information are given in ISO 10880.
In addition, care should be taken to minimize the surface temperature change of the test object other
than based on the thermoelastic effect. For example, in order to avoid temperature change due to air
currents, reduce the influence of wind as much as possible.
6 Equipment
6.1 Configuration
Schematic of an example of equipment configuration is shown in Figure 1.
In addition to the infrared camera (key 3 in Figure 1), the measuring equipment is constituted by a
computer or the like which performs camera control, reference signal processing, image processing,
image display and the like (key 7 in Figure 1).
When applying cyclic load to the test object, the material testing machine is required to have the ability
to load the required waveform and frequency (key 1 in Figure 1).
6.2 Infrared camera
An infrared camera shall meet the requirements of ISO 10880. In addition, an infrared camera should
have an infrared measuring wavelength range about 3 μm to 5 μm or about 8 μm to 14 μm to be
capable of measuring extremely small temperature changes. A camera with a frame repetition rate that
provides a sufficient number of frames per cycle of load shall be used. In order to obtain the spatial
resolution necessary for the test, the lens viewing angle of the infrared camera, the number of effective
pixels of the camera and the distance between the camera and the test object shall be considered.
The infrared camera with appropriate temperature resolution should be used in order to obtain the
required stress (the sum of surface principal stresses) resolution.
NOTE In the case of steel, a temperature resolution of about 0,001 K is necessary to obtain 1 MPa stress
resolution. Generally, the temperature resolution can be enhanced by image processing such as image averaging,
using an infrared camera which has about 0,03 K of noise equivalent temperature difference (NETD) value.
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ISO 22290:2020(E)

Key
1 material testing machine
2 test object
3 infrared camera
4 control signal to infrared camera
5 detector signal from infrared camera
6 reference load or displacement signal from material testing machine
7 computer with signal processing unit and display
F load
t time
Figure 1 — Schematic of an example of equipment configuration
6.3 Detection of temperature change by thermoelastic effect
As signal processing methods for extracting the amount of temperature change with the thermoelastic
effect from the time series of temperature data, “temperature difference image technique” or “lock-in
techniqu
...