BS ISO 15114-2014 Fibre-reinforced plastic composites Determination of the mode II fracture resistance for unidirectionally reinforced materials using the calibrated end-loaded splp.pdf

1、BSI Standards PublicationBS ISO 15114:2014Fibre-reinforced plasticcomposites Determination of the mode II fracturer e s i s t a n c e f o r u n i d i r e c t i o n a l l y r e i n f o r c e d m a t e r i a l s u s i n g t h e calibrated end-loaded split(C-ELS) test and an effective crack length appr

2、oachBS ISO 15114:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 15114:2014. The UK participation in its preparation was entrusted to TechnicalCommittee PRI/42, Fibre reinforced thermosetting plastics and prepregs.A list of organizations represented on thi

3、s committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 70339 3ICS

4、83.120Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2014.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 15114:2014 ISO

5、 2014Fibre-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 approachComposites plastiques renforcs de fibres Dtermination de la rsistance la ruptur

6、e en mode II de matriaux renforcs de fibres unidirectionelles en utilisant lessai de dlaminage (C-ELS) et une approche de la longueur de fissure relleINTERNATIONAL STANDARDISO15114First edition2014-05-15Reference numberISO 15114:2014(E)BS ISO 15114:2014ISO 15114:2014(E)ii ISO 2014 All rights reserve

7、dCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written p

8、ermission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 15114:2

9、014ISO 15114:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Symbols and abbreviated terms . 14 Principle 25 Apparatus . 26 Specimens 46.1 Preparation of specimens 46.2 The initial defect 46.3 Attaching the load-block to the specimen

10、 . 46.4 Moisture conditioning 56.5 Final specimen preparation and measuring dimensions . 56.6 Number of specimens . 67 Procedure. 67.1 Performing the calibration of the ELS fixture. 67.2 Pre-cracking the specimens . 77.3 Testing the samples in mode II from the precrack formed in 7.2 . 88 Data analys

11、is . 88.1 The points for data analysis . 88.2 Determination of the ELS clamp correction . 108.3 Determination of GIICvalues 119 Precision 1310 Test report 14Annex A (informative) Large displacement and load-block correction factors 16Bibliography .18BS ISO 15114:2014ISO 15114:2014(E)ForewordISO (the

12、 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 committe

13、e 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 electrotechni

14、cal 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

15、 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. D

16、etails 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). Any trade name used in this document is information given for the convenience of users and does not constitute a

17、n endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee

18、responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 13, Composites and reinforcement fibres.iv ISO 2014 All rights reservedBS ISO 15114:2014ISO 15114:2014(E)IntroductionPrevious attempts to determine mode II delamination resistance curves (R-curves) for composites have been hampere

19、d 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

20、 determined to introduce errors of between 1 % and 3 % in GIICdetermination for ELS specimens (n.b. friction effects would appear to be more significant in 3 point loaded end notch flexure (3ENF) (to be standardized by ASTM) and, particularly, in the 4 point loaded (4ENF) test specimen. Stabilized E

21、NF was not popular in round-robin trials).The procedure 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 ca

22、libration has been found to significantly reduce scatter in the results between different test laboratories and secondly, it provides an accurate means by which crack lengths can be calculated and thus their measurement can be avoided. Although this procedure still includes an experimental determina

23、tion of crack length, the use of calculated (or effective crack lengths) means that values of GIICcan be determined without experimentally measured crack length values. The procedure is a development of that published by ESIS (the European Structural Integrity Society), Technical Committee 4, Polyme

24、rs and Composites1, who carried out the preliminary enabling research through a series of round-robin exercises conducted in 2004 and 2007. ISO 2014 All rights reserved vBS ISO 15114:2014BS ISO 15114:2014Fibre-reinforced plastic composites Determination of the mode II fracture resistance for unidire

25、ctionally reinforced materials using the calibrated end-loaded split (C-ELS) test and an effective crack length approach1 ScopeThis International Standard specifies a method for the determination of mode II shear load delamination resistance. GIIC, (critical energy release rate), of unidirectional f

26、ibre-reinforced plastic composites using the calibrated end-loaded split (C-ELS) test.It is applicable to carbon-fibre and glass-fibre reinforced thermosets and thermoplastics.The scope is not necessarily limited to these fibres and lay-ups, but for laminates with other types of fibres or lay-ups, n

27、o recommendations for specimen dimensions and fibre volume content are currently available.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies.

28、For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 291, Plastics Standard atmospheres for conditioning and testingISO 5893, Rubber and plastics test equipment Tensile, flexural and compression types (constant rate of traverse) SpecificationIS

29、O 15024, Fibre-reinforced plastic composites Determination of mode I interlaminar fracture toughness, GIC, for unidirectionally reinforced materials3 Symbols and abbreviated termsFor the purposes of this document, the following terms and definitions apply.a measured delamination length, distance bet

30、ween 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 delamination on the edge of the specimen (see Figure 1)aoinsert film length, measured from the load-line to the tip of the insert

31、 film (seeFigure 1)apprecrack length, the length between the load-line and the tip of the precrack formed in during the precracking stepb width of the specimenC compliance /P of the specimenCmaxcompliance of the specimen at maximum loadC0initial compliance of the specimen neglecting start-up effects

32、, e.g. due to play in the specimen fixtureINTERNATIONAL STANDARD ISO 15114:2014(E) ISO 2014 All rights reserved 1BS ISO 15114:2014ISO 15114:2014(E)C5 %initial compliance, C0,of the specimen increased by 5 % displacement of the cross-head of the testing machineE1elastic modulus determined from “three

33、-point bending” flexural test or from the clamp calibration testGIICcritical energy release rate for mode II shear loadingH height of the load-blockl total length of the specimenl1distance between the centre of the loading pin and the mid-plane of the specimen beam to which the load-block is attache

34、d (see Figure 5), i.e. equal to (H + h)/2 if the pin hole is through the centre of the blockl2distance between the centre of the loading pin and the edge of the load block, measured towards the tip of the insert (starter film) or the tip of the mode I or mode II precrack (see Figure 5), i.e. equal t

35、o l3/2 if the pin hole is through the centre of the blockl3length of the load-block (see Figure 5)L free length of the specimen between load-line and clamp (see Figure 1)MAX maximum load on the load-displacement trace (see Figure 7)m slope of C versus a3plotNL onset of nonlinearity on the load-displ

36、acement trace (see Figure 7)P load measured by the load-cell of the testing machinePROP increments of the delamination length during stable delamination growth (propagation) that are marked on the load-displacement curve (see Figure 7)r2correlation coefficient of linear fitVIS onset of visually reco

37、gnizable delamination growth on the edge of the specimen that is marked on the load-displacement trace (see Figure 7)2h total thickness of the specimen (thickness of each specimen arm is h)5 % point of intersection of a straight line with the load-displacement trace, with the slope of the straight l

38、ine corresponding to C5 %4 PrincipleThis procedure specifies a method for the determination of the delamination resistance of unidirectional fibre-reinforced polymer laminates under mode II shear load using the calibrated end-loaded split (C-ELS) test. The resistance to the initiation and propagatio

39、n of a delamination is determined from a non-adhesive insert and from a mode I (opening) or a mode II (shear) precrack. The critical energy release rate for mode II loading can be calculated and a resistance-curve (R-curve, i.e. a plot of the critical energy release rate versus delamination length)

40、determined.5 ApparatusA tensile testing machine in compliance with ISO 5893, capable of producing a constant load-rate between 1 mm/min and 5 mm/min in displacement control should be used. The load-cell should be 2 ISO 2014 All rights reservedBS ISO 15114:2014ISO 15114:2014(E)calibrated and accurate

41、 within 1 % for the chosen load-range (loads are typically expected to be in the range of 100 N to 1 000 N). The testing machine shall be equipped with a fixture to introduce the load to the pin inserted into the load-block that allows rotation of the specimen end.The recommended loading jig require

42、s a clamping arrangement to freely slide in bearings in the horizontal direction (side-ways) with a fixed load point. This is shown schematically in Figure 1. Two test fixtures used in the round-robin programmes (see Clause 9) are shown in Figure 2.Figure 1 ELS test specimen showing the clamping fix

43、ture and loadingFigure 2 Two alternative ELS test fixturesA calibrated lever arm (torque wrench) is required to apply a consistent pressure while fixing the specimens into the sliding fixture. It is recommended that this device can apply closing torsion in the range of 0 Nm to 30 Nm to a precision o

44、f 1 Nm. During the test, the load shall be applied vertically on the load-block by pulling upward provided the clamp is symmetrical with respect to the specimen. The testing machine shall be equipped with means for recording the complete load-displacement traces (loading and unloading) that allow a

45、determination of the loads and the corresponding displacements with an accuracy of 1 %. Vernier callipers or a micrometer should be used to measure the specimen thickness (2h) to an accuracy of 0.02 mm and the specimen width, b, to an accuracy of 0.02 mm. A travelling microscope (or video camera) sh

46、all be used to monitor the length of the delamination along one edge of the specimen with a magnification of between 10 and 25. ISO 2014 All rights reserved 3BS ISO 15114:2014ISO 15114:2014(E)6 Specimens6.1 Preparation of specimensThe recommended specimen width, b, and length, l, are 20 mm and 190 m

47、m, respectively. The specimen length shall not be less than the active length of the insert, ao, plus 110 mm; thus, l ao+ 110 mm. For recommendations on the length of ao, see 6.2. The free length, L, is typically 100 mm. The recommended specimen thickness (2h) is 3 mm for 60 % by volume carbon fibre

48、-reinforced and 5 mm for 60 % by volume glass fibre-reinforced composites.Other specimen dimensions can be used, but the specimen width should be between 15 mm and 30 mm. Increasing the length of the specimen is not critical, shortening will reduce the maximum delamination length that can be investi

49、gated, and thus, yield too few data points for the analysis (see 8.1). If specimens are too thin or not sufficiently stiff, delamination growth might not be induced or occur at large displacements only, or permanent deformation of the specimen might occur, invalidating the assumptions of linear elastic fracture mechanics.6.2 The initial defectA crack starter film should be placed at the laminate mid-thickness during the lay-up of the composite panel prior to moulding. The film should be PTFE or another fluoro-polymer wi