ISO 15114:2014

DRAFT INTERNATIONAL STANDARD ISO/DIS 15114
ISO/TC 61/SC 13 Secretariat: JISC
Voting begins on Voting terminates on

2012-10-08 2013-01-08
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION    МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ    ORGANISATION INTERNATIONALE DE NORMALISATION

Fibre-reinforced plastic composites — Determination of the
mode II fracture resistance for unidirectionally reinforced
materials using the calibrated end-loaded split (C-ELS) test and
an effective crack length approach
Composites plastiques renforcés de fibres — Détermination de la résistance à la rupture en mode II de
matériaux renforcés de fibres unidirectionelles en utilisant l'essai de délaminage (C-ELS) et une approche de
la longueur de rupture effective

ICS 83.120
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©  International Organization for Standardization, 2012

ISO/DIS 15114
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ii © ISO 2012 – All rights reserved

ISO/DIS 15114
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references. 1
3 Symbols and abbreviated terms. 1
4 Principle . 2
5 Apparatus . 3
6 Specimens . 4
6.1 Preparation of specimens . 4
6.2 The initial defect . 4
6.3 Attaching the load-block to the specimen . 4
6.4 Moisture conditioning . 5
6.5 Final specimen preparation and measuring dimensions . 5
6.6 Number of specimens . 6
7 Procedure . 6
7.1 Performing the calibration of the ELS fixture . 6
7.2 Pre-cracking the specimens . 7
7.2.1 Mode I precracking . 7
7.2.2 Mode II precracking . 7
7.3 Testing the samples in mode II from the precrack formed in 7.2 . 8
8 Data analysis . 8
8.1 The points for data analysis . 8
8.1.1 Initiation points . 8
8.1.2 Propagation points . 9
8.2 Determination of the ELS clamp correction . 9
8.3 Determination of G values . 10
IIC
8.3.1 Method 1: Experimental Compliance Method (ECM) . 11
8.3.2 Method 2: Simple Beam Theory (SBT) . 11
8.3.3 Method 3: Corrected Beam Theory using Effective Crack Length (CBTE) . 11
9 Precision . 12
10 Test report . 13
Bibliography . 14
Annex A (informative) Large displacement and load-block correction factors . 15

ISO/DIS 15114
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 through ISO technical committees. Each member body interested in a subject for which a
technical committee has been established has the right to be represented on that committee.
International organizations, governmental and non-governmental, in liaison with ISO, also take part in
the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all
matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives,
Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
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.
ISO 15114 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 13,
Composites and reinforcement fibres.
This second/third/. edition cancels and replaces the first/second/. edition (), [clause(s) /
subclause(s) / table(s) / figure(s) / annex(es)] of which [has / have] been technically revised.

iv © ISO 2012 – All rights reserved

ISO/DIS 15114
Introduction
Previous attempts to determine Mode II delamination resistance curves (R-curves) for composites
have been hampered by the experimental difficulty of determining crack length in the absence of any
applied beam opening displacement and when a complex damage zone develops ahead of the crack
front. The effects of friction in the different Mode II test specimens have also been widely debated and
have typically been determined to introduce errors of between 1-3 % in G determination for ELS
IIC
specimens (n.b. friction effects would appear to be more significant in 3 point loaded end notch
flexure (3ENF) [to be standardised by ASTM] and, particularly, in the 4 point loaded (4ENF) test
specimen. Stabilised ENF was not popular in round-robin trials).
The test protocol presented here uses the end loaded split test apparatus and specifies an
experimental procedure to calibrate the clamping fixture and simultaneously determine the flexural
modulus of the specimen. This serves two purposes. Firstly, the clamp calibration has been found to
significantly reduce scatter in the results between different test labs and secondly, it provides an
accurate means by which crack lengths may be calculated and thus their measurement can be
avoided. Although this protocol currently still requires an experimental determination of crack length
to be attempted, the use of calculated (or effective crack lengths) is intended to make this requirement
redundant when sufficient data have been collected in round-robin programmes to validate the newly
proposed scheme. The protocol is a development of that published by ESIS (the European Structural
Integrity Society), Technical Committee 4, Polymers and Composites,[1] who carried out the
preliminary enabling research through a series of round-robin exercises conducted in 2004 and 2007.

DRAFT INTERNATIONAL STANDARD ISO/DIS 15114

Fibre-reinforced plastic composites — �Determination
of the Mode II fracture resistance for unidirectionally
reinforced materials using the calibrated end loaded split
(C-ELS) test and an effective crack length approach
1 Scope
1.1 This International Standard specifies a method for the determination of Mode II shear load
delamination resistance. G , (critical energy release rate), of unidirectional fibre-reinforced plastic
IIc
composites using the Calibrated End Loaded Split (C-ELS) test.
1.2 It is applicable to carbon-fibre and glass-fibre reinforced thermosets and thermoplastics.
1.3 The scope is not necessarily limited to these fibres and lay-ups, but for laminates with other types
of fibres or lay-ups, no recommendations for specimen dimensions and fibre volume content are
currently available.
Annex A is informative.
2 Normative references
The following referenced documents are indispensable for the application 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 4588, Adhesives; preparation of metal surfaces for adhesive bonding
ISO 5893, Rubber and plastics test equipment; tensile, flexural and compression types (constant rate
of traverse); description
ISO 14125, Fibre-reinforced plastic composites — Determination of flexural properties
ISO 15024, Plastics — Determination of the mode I energy release rate for fibre-composites using the
double cantilever beam (DCB) test specimen
3 Symbols and abbreviated terms
For the purpose of this protocol the following symbols and conventions apply
a measured delamination length, distance between the load-line (intersection of the plane
through the pin-hole centre of the load-block normal to the specimen width and the plane of
delamination) and the tip of the pre-crack or delamination on the edge of the specimen
(Figure 1)
A starter delamination (insert) length, distance between end of specimen on which the load-
block is mounted and tip of the insert
b width of the specimen
ISO/DIS 15114
C compliance /P of the specimen
C initial compliance of the specimen neglecting start-up effects, e.g. due to play in the specimen
fixture
C compliance of the specimen at maximum load
max
C initial compliance C of the specimen increased by 5 %
5% 0
 displacement of the cross-head of the testing machine
E elastic modulus determined from "three-point bending" flexural test or from the clamp
calibration test
G critical energy release rate for Mode II shear loading
IIC
2h total thickness of the specimen (thickness of each specimen arm is h)
H height of the load-block
l total length of the specimen
l distance from the centre of the loading pin to the mid-plane of the specimen beam to which
the load-block is attached (Figure 5), i.e. equal to (H+h)/2 if the hole is through the centre of
the block.
l distance between the centre of the pin-hole of the load-block and its edge, measured towards
the tip of the insert (starter film) or the tip of the Mode I or Mode II precrack (Figure 5),
i.e. equal to l /2 if the hole is through the centre of the block.
l length of the load-block (Figure 5)
L free le
...