BS EN 14869-1:2011 BSI Standards Publication Structural adhesives — Determination of shear behaviour of structural bonds Part 1: Torsion test method using butt-bonded hollow cylinders (ISO 11003-1:2001, modified) BS EN 14869-1:2011 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 14869-1:2011 It was derived from ISO 11003-1:2001 It supersedes BS EN 14869-1:2004 and BS ISO 11003-1:2001, which are withdrawn The UK participation in its preparation was entrusted to Technical Committee PRI/52, Adhesives A list of organizations represented on this committee can be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 © BSI 2011 ISBN 978 580 72246 ICS 83.180 Compliance 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 30 June 2011 Amendments issued since publication Date Text affected BS EN 14869-1:2011 EN 14869-1 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM May 2011 ICS 83.180 Supersedes EN 14869-1:2004 English Version Structural adhesives - Determination of shear behaviour of structural bonds - Part 1: Torsion test method using butt-bonded hollow cylinders (ISO 11003-1:2001, modified) Adhésifs structuraux - Détermination du comportement en cisaillement de collages structuraux - Partie : Méthode d'essai en torsion de cylindres creux collés bout bout (ISO 11003-1:2001, modifié) Strukturklebstoffe - Bestimmung des Scherverhaltens struktureller Klebungen - Teil 1: Torsionsprüfverfahren unter Verwendung stumpf verklebter Hohlzylinder (ISO 11003-1:2001, modifiziert) This European Standard was approved by CEN on 10 March 2011 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels © 2011 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 14869-1:2011: E BS EN 14869-1:2011 EN 14869-1:2011 (E) Contents Page Foreword 3 Scope 4 Normative references 4 Terms and definitions 4 Principle 4 Apparatus .4 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.1.5 6.2 Test specimen 6 Preparation .6 Substrate material 6 Preparation of the surface 6 Bonding 6 Adhesive bond .8 Dimensions 10 Number of specimens 10 7.1 7.2 Test conditions 10 Temperature 10 Shear rate 10 Procedure 11 Calculations 11 10 Precision 13 11 Test report 13 BS EN 14869-1:2011 EN 14869-1:2011 (E) Foreword This document (EN 14869-1:2011) has been prepared by Technical Committee CEN/TC 193 “Adhesives”, the secretariat of which is held by AENOR This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2011, and conflicting national standards shall be withdrawn at the latest by November 2011 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document supersedes EN 14869-1:2004 SAFETY STATEMENT — Persons using this document should be familiar with the 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 and to ensure compliance with any regulatory conditions ENVIRONMENTAL STATEMENT — It is understood that some of the material permitted in this standard may have negative environmental impact As technological advantages lead to acceptable alternatives for these materials, they will be eliminated from this standard to the extent possible At the end of the test, the user of the standard should take care to carry out an appropriate disposal of the wastes, according to local regulation According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom BS EN 14869-1:2011 EN 14869-1:2011 (E) Scope This European Standard specifies a shear test for the characterization of adhesives in a bond The shear stress/strain properties of the adhesive (including the shear modulus) are useful for advanced design work, e.g in finite element analysis methods 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 EN 923:2005+A1:2008, Adhesives ― Terms and definitions EN 13887, Structural Adhesives ― Guidelines for surface preparation of metals and plastics prior to adhesive bonding EN ISO 291, Plastics ― Standard atmospheres for conditioning and testing (ISO 291:2008) EN ISO 10365, Adhesives ― Designation of main failure patterns (ISO 10365:1992) Terms and definitions For the purposes of this document, the terms and definitions given in EN 923:2005+A1:2008 apply Principle The shear deformation of the adhesive in an annular bond between two hollow cylinders, and the corresponding torque, are measured and recorded up to failure of the joint 5.1 Apparatus Torsion-testing machine, with a capacity of at least 300 N·m and preferably of 000 N·m Alternatively, a suitably adapted tensile-testing machine may be used The machine shall include equipment for recording the torque instantaneously with an error of less than % The gripping heads shall be accurately aligned and, if no hydraulic gripping mechanism is available, all bolts and holes shall be precisely machined so that the specimens are mounted in the apparatus and tested free of uncontrolled loads The machine shall be equipped with an adequately thermostatted chamber if tests are to be carried out at temperatures different from the ambient temperature 5.2 Displacement sensor (see Figure 1), capable of measuring, as near as possible to the bond line, the displacement of the two adherends relative to each other and hence the deformation of the adhesive The sensor and its associated target shall be rigidly mounted on the two adherends as shown in Figure The range of the displacement-measuring equipment shall be adjustable to permit the full-scale reading to be varied between µm and 000 µm The equipment shall be capable of measuring displacements to an accuracy of ± µm The sensor shall be of lightweight and robust construction since it is subjected to high accelerations on failure of the specimen BS EN 14869-1:2011 EN 14869-1:2011 (E) Key Adherends Target support (on upper adherend) Butt joint Sensor support (on lower adherend) Displacement sensor Target Figure — Adhesive-layer specimen with displacement sensor mounted in the test apparatus BS EN 14869-1:2011 EN 14869-1:2011 (E) Test specimen 6.1 6.1.1 Preparation Substrate material Aluminium alloy or steel are suitable materials for the adherends Other materials are acceptable provided the material (including pre-treated surface layers) has a shear modulus at least ten times higher than that of the adhesive 6.1.2 Preparation of the surface The surfaces to be bonded shall be prepared in accordance with EN 13887 or by any method leading to a cohesive failure within the adhesive layer 6.1.3 Bonding Prepare the specimens in accordance with the instructions of the manufacturer of the adhesive Information about conditioning of the specimen shall be included in the test report A joint completely filled with adhesive is essential for the reliability of the test The two adherends shall be bonded coaxially, with a maximum lateral displacement between their two axes of 0,002 ro (= outer radius), and a maximum angular deviation so that the bond line thickness varies by no more than % of the recommended thickness The joining device shall prevent the adhesive from running out of the joint and any displacement of the two adherends during curing NOTE To achieve this, the two hollow cylinders may be aligned with the help of a plug made of polytetrafluoroethylene (PTFE) or any other suitable device A temperature-resistant O-ring, inserted into the PTFE plug and placed just below the bond, stops the adhesive from running out of the joint At the other ends of the adherends, two plates fastened to a threaded rod passing through the PTFE plug prevent any displacement during curing (see Figure 2) BS EN 14869-1:2011 EN 14869-1:2011 (E) Key Top plate Polytetrafluoroethylene plug Adhesive layer O-ring Rod with screw thread Bottom plate Figure — Coaxially aligned hollow cylinders in a suitable joining device BS EN 14869-1:2011 EN 14869-1:2011 (E) 6.1.4 Adhesive bond The preferred thickness of the bond is 0,2 mm NOTE For special adhesives, a thickness in the range from 0,05 mm to 0,5 mm can be used The thickness of the bond may be defined by the use of a bondline thickness material included in the adhesive, such as glass beads, a net or cloth consistent with the adhesive manufacturer's recommendations The adhesive shall be prevented from running out of the joint using a non-adherent flexible band around the outside of the two adherends Alternatively, the thickness of the bond can be defined by a rim which is machined along the outer perimeter of one adherend The rim acts as spacer between the two adherends The adhesive is applied to the machined adherend to fill the space adjacent to the rim, prior to joining the two adherends The rim is removed on the lathe after the adhesive is cured (see Figure 3) The resulting adhesive layer shall have a width at least ten times its thickness BS EN 14869-1:2011 EN 14869-1:2011 (E) Dimensions in millimetres Key Adherends Adhesive Bolt Fixture NOTE The rim spacer that controls the thickness of the bond is shown in the upper detail view Before testing, the spacer is removed, as shown in the lower details view Figure — Dimensions of the specimen and specimen holders BS EN 14869-1:2011 EN 14869-1:2011 (E) 6.1.5 Dimensions Three sizes of specimen (A, B, C) are recommended (see Table 1), although intermediate sizes are acceptable provided that: ri ≥ 0,8 ro (1) where ri is the inner radius of each cylinder; ro is the outer radius of each cylinder The width of the bond (ro - ri) zone may be reduced to a minimum of 0,1 ro if the available torque is not sufficient to produce failure of the specimen Suitable values for the length of the specimen and the dimensions of the specimen holders are given in Figure Table — Recommend specimen sizes Radii Specimen 6.2 ro ri mm mm A 36 30 B 24 20 C 12 10 Number of specimens At least five specimens shall be tested for a given adhesive Test conditions 7.1 Temperature The temperature of the test shall be one of the standard temperatures specified in EN ISO 291 The temperature of the specimen shall be measured at the outer surface of the hollow cylinder, close to the bond (e.g with thermocouples) Agreement to within ± °C is required 7.2 Shear rate ⋅ -1 -1 The rate of shear γ of the adhesive shall lie within the range from 0,000 s to 0,02 s NOTE 10 -1 The preferred rate of shear is 0,01 s BS EN 14869-1:2011 EN 14869-1:2011 (E) The corresponding rate of angular displacement (α) to be set on the torsion-testing machine is given by the equation: ⋅ α= ⋅ γd (2) ro where d is the thickness of the adhesive bond, expressed in millimetres; ro is the outer radius of the specimen, expressed in millimetres (see Table 1) Procedure Fix the specimens in the test apparatus, equipped with a temperature cabinet if required Adjust the apparatus so that the joint is free from any load While increasing the shear deformation continuously up to the requested maximum value, record the torque displacement curve If the specimen fails, check the surfaces of the bonded parts and reject any specimens with incompletely filled adhesive bonds (due e.g to the presence of bubbles or voids) Sometimes the adhesive layer will not fail after reaching the maximum shear deformation, especially when loading with a low shear rate If this happens, repeat the test with an increasing torque rate until the specimen fails As before, check the adhesive layer for defects of fabrication Ensure that cohesive failure is achieved Calculations 9.1 The shear stress, τ , expressed in megapascals, in the bond line close to the outer radius is given by the equation: τ= π × M ro ro4 − ri4 (3) where M is the torque, expressed in newton millimetres, acting across the joint; ro is the outer radius, expressed in millimetres, of the cylinders; ri is the inner radius, expressed in millimetres, of the cylinders 9.2 The displacement (dm) measured during the test is composed of the displacement (da) of the adhesive and the displacement due to the twist of the two adherends (dt) (see Figure 4) Therefore, the shear strain (Щ) in a bond of thickness (d) is given by the equation: tan γ = d a d m − dt = ≅γ d d (4) where da, dm, dt and d are measured in millimetres; dt is calculated from the shear modulus Gt of the adherend material and the shear stress acting in the adherends (alternatively, the deformation of the adherends dt may be determined experimentally at 11 BS EN 14869-1:2011 EN 14869-1:2011 (E) the appropriate temperatures for an unbonded specimen made of the same material and having the same dimensions) This equation is valid only for small values of gamma Figure — Schematic diagram of the displacement of the surfaces of the bonded cylinders 9.3 The shear modulus G a ( = τ / γ ) of the adhesive is determined from the slope of the linear portion of the stress-strain curve 9.4 Calculate the arithmetic mean of the results and the standard deviation for the shear modulus, as well as the highest shear stress (shear strength) and corresponding shear strain and, if applicable, the shear stress and strain at specimen failure 12 BS EN 14869-1:2011 EN 14869-1:2011 (E) 10 Precision The precision of this test method is not known, because interlaboratory data are not available When interlaboratory data are obtained, a precision statement will be added at the following revision 11 Test report The test report shall include the following items: a) a reference to this European Standard, i.e EN 14869-1; b) all information necessary for complete identification of the adhesive tested; c) the material of which the adherends were made; d) the type of specimen used (A, B or C) (or give inner and outer diameters if different from the recommended sizes); e) detailed information on all methods of surface preparation used; f) a description of the bonding method, including the bonding temperature and pressure, the adhesive curing time and information on the conditioning of the specimens; g) the thickness of the adhesive layer; h) the test temperature; i) the number of specimens tested and used for the calculation; j) the individual results for the shear modulus, the highest shear stress and corresponding shear strain, and additionally, if applicable, the shear stress and shear strain at failure; k) the ranges of torque and displacement used; l) the averaged results, including the standard deviation; m) the stress-strain curve obtained; n) observations concerning the debonded surfaces in accordance with EN ISO 10365; o) any deviation from the specified procedure which may have influenced the results; p) the date of the test 13 This page deliberately left blank This page deliberately left blank NO COPYING WITHOUT BSI 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