ISO 22838:2020

INTERNATIONAL ISO
STANDARD 22838
First edition
2020-12
Composites and reinforcements
fibres — Determination of the fracture
energy of bonded plates of carbon
fibre reinforced plastics (CFRPs) and
metal using double cantilever beam
specimens
Reference number
©
ISO 2020
ISO 22838:2020(E)
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ii © ISO 2020 – All rights reserved

ISO 22838:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Normative references . 1
3  Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 2
4  Principle . 3
5  Apparatus . 3
6 Specimens . 4
6.1 Number of specimens . 4
6.2 Conditioning . 4
6.3 Manufacture of adhesive joint specimens . 4
6.3.1 General. 4
6.3.2 DCB specimen measurements . 5
6.4 Preparation of specimens . 5
7  Procedure. 6
7.1 Test set-up and data recording . 6
7.2 Initial loading (precracking stage) . 6
7.3 Re-loading: Testing from the precrack . 6
7.4 Determination of the thickness ratio of the CFRP and metal beams . 9
7.4.1 Theoretical prediction of thickness ratios . 9
7.4.2 Procedure to detect the occurrence of plastic deformation during a DCB
adhesive joint test . 9
7.5 Measurement of machine compliance .10
7.6 Measurement of curvature induced by coefficient of thermal expansion difference
between metal and composite beams .10
8  Data analysis .12
8.1 Determination of the raw data from the load-displacement trace .12
8.1.1 General.12
8.1.2 Initiation values .12
8.1.3 Propagation values . .13
8.2 Determination of adhesive fracture energy .13
8.2.1 General.13
8.2.2 DCB test with identical thickness: Corrected beam theory (CBT) .13
8.2.3 DCB test with dissimilar thicknesses: modified beam theory for DCB
specimens with dissimilar thicknesses .14
8.2.4 DCB test with identical and dissimilar thicknesses: Area method .15
9  Precision .15
10  Test report .16
Annex A (informative) Work flow chart as brief guideline .18
Annex B (informative) Formula for calculating G value using (EI) or E I E I .19
eq 1 1 2 2
Annex C (normative) Measurement of test system compliance .20
Bibliography .22
ISO 22838:2020(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.
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different types of ISO documents should be noted. This document was drafted in accordance with the
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 13,
Composites and reinforcement fibres.
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.
iv © ISO 2020 – All rights reserved

ISO 22838:2020(E)
Introduction
The potential benefits to the users of CFRP/metal assemblies of implementing the adhesive fracture
energy of DCB specimen based on this document are:
a) expanding CFRP applications to the fields where it could be used in combination with metallic
components;
b) the detection or the prevention of physical properties loss — such as ion migration and time-related
degradation in sealant film, injected calking layer and glass fibre reinforced plastics (GFRPs) layer;
c) demonstrating the conformity to specified conditions for type certification requirements in the
engineering such as aircraft developments;
d) evaluating the procedures for maintenance, repair and overhaul (MRO) in the engineering
operations such as CFRP in aerospace, or in constructions such as steel bridges and industrial
applications (e.g. pipework repair, etc.)
INTERNATIONAL STANDARD  ISO 22838:2020(E)
Composites and reinforcements fibres — Determination
of the fracture energy of bonded plates of carbon fibre
reinforced plastics (CFRPs) and metal using double
cantilever beam specimens
SAFETY STATEMENT — Persons using this document should be familiar with normal laboratory
practice, if applicable. This document does not purport to address all of the safety problems, if
any, associated with its use. It is the responsibility of the user to establish appropriate safety
and health practices. It is recognized that some of the materials permitted in this document
might have a negative environmental impact. As technological advances lead to more acceptable
alternatives for such materials, they will be eliminated to the greatest extent possible. At the
end of the test, care should be taken to dispose of all waste in an appropriate manner.
1 Scope
This document specifies the test method for the determination of adhesive fracture energy of adhesively
bonded plates of carbon fibre reinforced plastic (CFRP) and metal using a double cantilever beam (DCB)
specimen. The test method is also applicable to bonded joints between metals and other composite
materials, such as glass fibre reinforced plastics.
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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 7500-1, Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1:
Tension/compression testing machines — Calibration and verification of the force-measuring system
ISO 10365, Adhesives — Designation of main failure patterns
ISO 25217, Adhesives — Determination of the mode 1 adhesive fracture energy of structural adhesive joints
using double cantilever beam and tapered double cantilever beam specimens
3  Terms, definitions and symbols
3.1  Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
ISO 22838:2020(E)
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