ISO 17281:2018
(Main)Plastics — Determination of fracture toughness (GIC and KIC) at moderately high loading rates (1 m/s)
Plastics — Determination of fracture toughness (GIC and KIC) at moderately high loading rates (1 m/s)
This document specifies the principles and provides guidelines for determining the fracture toughness of plastics in the crack-opening mode (Mode I) by a linear elastic fracture mechanics (LEMF) approach, at load-point displacement rates of up to 1 m/s. It supplements ISO 13586 so as to extend its applicability to loading rates somewhat higher than is the case in the scope of the latter document. Fracture testing at high loading rates presents special problems because of the presence of dynamic effects: vibrations in the test system producing oscillations in the recorded quantities, and inertial loads producing forces on the test specimen different from the forces sensed by the test fixture. These effects need either to be controlled and, if possible, reduced by appropriate action, or else to be taken into account through proper analysis of the measured data. The relative importance of such effects increases with increasing testing rate (decreasing test duration). At speeds of less than 0,1 m/s (loading times of greater than 10 ms) the dynamic effects may be negligible and the testing procedure given in ISO 13586 can be applied as it stands. At speeds approaching 1 m/s (loading times of the order of 1 ms) the dynamic effects may become significant but still controllable. The procedure given in ISO 13586 can still be used though with some provisos and these are contemplated in this document. At speeds of several meters per second and higher (loading times markedly shorter than 1 ms) the dynamic effects become dominant, and different approaches to fracture toughness determination are required, which are outside the scope of this document. The general principles, methods and rules given in ISO 13586 for fracture testing at low loading rates remain valid except where expressly stated otherwise in this document. The methods are suitable for use with the same range of materials as covered by ISO 13586, i.e. — rigid and semi-rigid thermoplastic moulding, extrusion and casting materials; — rigid and semi-rigid thermosetting moulding and casting materials; and their compounds containing fibres ≤ 7,5mm in length. In general, fibres 0,1 mm to 7,5 mm in length are known to cause heterogeneity and anisotropy, especially significant in the fracture processes. Therefore, in parallel with Annex B of ISO 13586:2018, where relevant Annex C of this document offers some guidelines to extend the application of the same testing procedure, with some reservations, to rigid and semi-rigid thermoplastic or thermosetting plastics containing such short fibres. Although the dynamic effects occurring at high loading rates are largely dependent on the material tested as well as on the test equipment and test geometry used, the guidelines given here are valid in general, irrespective of test equipment, test geometry and material tested. The same restrictions as to linearity of the load-displacement diagram, specimen size and notch tip sharpness apply as for ISO 13586.
Plastiques — Détermination de la ténacité à la rupture (GIC et KIC) à vitesses de charge modérément élevées (1 m/s)
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17281
Second edition
2018-08
Plastics — Determination of fracture
toughness (G and K ) at moderately
IC IC
high loading rates (1 m/s)
Plastiques — Détermination de la ténacité à la rupture (G et K ) à
IC IC
vitesses de charge modérément élevées (1 m/s)
Reference number
©
ISO 2018
© ISO 2018
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ii © ISO 2018 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Test specimens. 2
4.1 Specimen geometry and preparation . 2
4.2 Crack length and number of test replicates . 2
4.2.1 Determination of K . 2
IC
4.2.2 Determination of G . 2
IC
4.3 Measurement of test specimen dimensions . 3
5 Test conditions . 4
5.1 Loading mode. 4
5.2 Test speed . 4
5.3 Test atmosphere and temperature . 4
6 Test equipment. 4
6.1 Loading machine . 4
6.2 Loading rigs . 4
6.3 Instrumentation . 5
7 Control of dynamic effects . 5
7.1 Electronic filtering . 5
7.2 Mechanical damping . 6
7.3 Damping level . 7
7.4 Check on speed . 7
8 Data handling . 8
8.1 Analysis of the test records and identification of fracture initiation. 8
8.2 Energy correction .10
8.2.1 General.10
8.2.2 Test piece indentation, machine compliance and damper compression .11
8.2.3 Kinetic energy and inertial loads .14
9 Expression of results .14
9.1 Determination of K .14
IC
9.2 Determination of σ .14
y
9.3 Determination of G .15
IC
10 Precision .16
11 Test report .17
Annex A (informative) Estimation of curve fit parameters .19
Annex B (informative) Recommended test report forms .21
Annex C (informative) Testing of plastics containing short fibres .26
Bibliography .29
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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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
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.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 2,
Mechanical behaviour.
This second edition cancels and replaces the first edition (ISO 17281:2002), which has been technically
revised with the addition of Annex C.
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 2018 – All rights reserved
Introduction
This document is based on a testing protocol developed by the European Structural Integrity Society
(ESIS), Technical Committee 4, Polymers, Polymer Composites and Adhesives, who carried out the
preliminary enabling research through a series of round-robin exercises which covered a range of
material samples, specimen geometries, test instruments and operational conditions (see References [3]
to [6]). This activity involved about 30 laboratories from 12 countries.
INTERNATIONAL STANDARD ISO 17281:2018(E)
Plastics — Determination of fracture toughness (G and
IC
K ) at moderately high loading rates (1 m/s)
IC
1 Scope
This document specifies the principles and provides guidelines for determining the fracture toughness
of plastics in the crack-opening mode (Mode I) by a linear elastic fracture mechanics (LEMF) approach,
at load-point displacement rates of up to 1 m/s. It supplements ISO 13586 so as to extend its applicability
to loading rates somewhat higher than is the case in the scope of the latter document.
Fracture testing at high loading rates presents special problems because of the presence of dynamic
effects: vibrations in the test system producing oscillations in the recorded quantities, and inertial
loads producing forces on the test specimen different from the forces sensed by the test fixture. These
effects need either to be controlled and, if possible, reduced by appropriate action, or else to be taken
into account through proper analysis of the measured data.
The relative importance of such effects increases with increasing testing rate (decreasing test
duration). At speeds of less than 0,1 m/s (loading times of greater than 10 ms) the dynamic effects
may be negligible and the testing procedure given in ISO 13586 can be applied as it stands. At speeds
approaching 1 m/s (loading times of the order of 1 ms) the dynamic effects may become significant but
still controllable. The procedure given in ISO 13586 can still be used though with some provisos and
these are contemplated in this document. At speeds of several meters per second and higher (loading
times markedly shorter than 1 ms) the dynamic effects become dominant, and different approaches to
fracture toughness determination are required, which are outside the scope of this document.
The general principles, methods and rules given in ISO 13586 for fracture testing at low loading rates
remain valid except where expressly stated otherwise in this document.
The methods are suitable for use with the same range of materials as covered by ISO 13586, i.e.
— rigid and semi-rigid thermoplastic moulding, extrusion and casting materials;
— rigid and semi-rigid thermosetting moulding and casting materials;
and their compounds containing fibres ≤ 7,5mm in length.
In general, fibres 0,1 mm to 7,5 mm in length are known to cause heterogeneity and anisotropy,
especially significant in the fracture processes. Therefore, in parallel with Annex B of ISO 13586:2018,
where relevant Annex C of this document offers some guidelines to extend the application of the same
testing procedure, with some reservations, to rigid and semi-rigid thermoplastic or thermosetting
plastics containing such short fibres.
Although the dynamic effects occurring at high loading rates are
...
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