© ISO 2016 Glass in building — Determination of the bending strength of glass — Part 5 Coaxial double ring test on flat specimens with small test surface areas Verre dans la construction — Déterminati[.]
INTERNATIONAL STANDARD ISO 1288-5 First edition 2016-02-15 Glass in building — Determination of the bending strength of glass — Part 5: Coaxial double ring test on flat specimens with small test surface areas Verre dans la construction — Détermination de la résistance du verre la flexion — Partie 5: Essais avec doubles anneaux concentriques sur éprouvettes planes, avec de petites surfaces de sollicitation Reference number ISO 1288-5:2016(E) © ISO 2016 ISO 1288-5:2016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f 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 permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) Contents Page iv Scope Normative references Terms and definitions Symbols Principle of test method Apparatus 6.1 Testing machine 6.2 Loading device 6.3 Measuring instruments Sample 7.1 Shape and dimensions of specimens 7.2 Sampling and preparation of specimens 7.2.1 Cutting and handling 7.2.2 Conditioning 7.2.3 Examination 7.2.4 Adhesive film 7.3 Number of specimens Procedure 8.1 Temperature 8.2 Humidity 8.3 Thickness measurement 8.4 Base plate 8.5 Positioning of specimen and loading ring 8.6 Load application 8.7 Location of the origin 8.8 Assessment of residual stresses Evaluation 9.1 Limitation of the evaluation 9.2 Calculation of bending strength 10 Test report Bibliography Foreword © ISO 2016 – All rights reserved iii ISO 1288-5:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f 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 o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f 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 in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary in formation The committee responsible for this document is ISO/TC 160, Glass in building, Subcommittee SC 2, Use considerations in conjunction with Technical Committee CEN/TC 129, Glass in building ISO 1288 consists of the following parts, under the general title f f : — f — f — f — f — f This International Standard has been based on EN 1288-5, f Glass in buildin g — Determin ation o th e ben din g stren gth o glass Part : Fun dam entals o testin g glass Part 2: Coa xial double-rin g test on flat specim en s with large test sur ace areas Part 3: Test with specim en supported at two points ( our-point ben din g) Part 4: Testin g o ch an n el-sh aped glass Part 5: Coa xial double-rin g test on flat specim en s with sm all test sur ace areas Glass in buildin g — Determ in ation o f th e f ben din g stren gth o glass — Part 5: Coa xial double-rin g test on flat specim en s with sm all test sur ace areas prepared by Technical Committee CEN/TC 129 “Glass in building” According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom iv © ISO 2016 – All rights reserved INTERNATIONAL STANDARD ISO 1288-5:2016(E) Glass in building — Determination of the bending strength of glass — Part 5: Coaxial double ring test on flat specimens with small test surface areas Scope T h i s p a r t o f I S O 8 s p e c i fie s a me tho d for de term i n i ng the comp a rative b end i ng s treng th o f gl as s use in buildings, excluding the effects of the edges S e e I S O 8 -1 , for an e xplanation as to why th i s te s t me tho d s hou ld on ly b e u s e d the s treng th o f typ e s o f gla s s and no t for as s e s s i ng s treng th for for for comp ari ng de s ign pur p o s e s The limitations of this part of ISO 1288 are described in ISO 1288-1 I S O 8 -1 shou ld b e re ad i n conj unc tion with th i s p a r t o f I S O 8 This test method is not suitable for patterned glass Normative references T he fol lowi ng i nd i s p en s able c u ments , i n whole or i n p ar t, are normatively re ference d i n th i s c u ment a nd are for its appl ic ation For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c u ment (i nclud i ng any amend ments) appl ie s ISO 48, Rubber, vulcan ized or th erm oplastic — Determ in ation o f h ardn ess (h ardn ess between IRHD an d 00 IRHD) Terms and definitions For the pu r p o s e s o f th i s c u ment, the fol lowi ng term s and defi n ition s apply 3.1 bending stress tensile bending stress induced in the surface of a specimen N o te to entr y: For te s ti n g p u r p o s e s , the b end i n g s tre s s s hou ld b e u n i fo rm over a s p e c i fie d p a r t o f the s u r face Symbols F load Fmax lo ad at bre a kage, “ bre a ki ng lo ad” h L K1 , K2 thickness of specimen side length of square specimens constants for calculation of bending stress © ISO 2016 – All rights reserved N N m m ISO 88-5 : 01 6(E) r1 r2 r3 r3m t σ σbB μ Δ F/Δ t Δ σ/Δ t radius of loading ring radius of supporting ring radius of circular specimens average specimen radius (for evaluation) time stress bending strength Poisson number of specimen NOTE for soda lime silicate glass (see ISO 16293-1), a value of 0,23 is used rate of increase of load rate of increase of stress m m m m s Pa Pa N/s Pa/s Principle of test method A circular or square plane-parallel specimen with radius r3 , or length of side L , resting on a supporting ring (radius r2 f r1 the supporting ring (see Figure 1) Outside the loading ring, the radial and tangential stresses in the specimen decrease towards the edge so that the risk of failure there is small For limited loads, F, (depending on the values of r1 , r2 , r3 and h) there is, in the central region of the f f 3]) extending in all directions and ) s l l b e lo ade d b y me a n s o a lo ad i ng ri ng (rad iu s ) arra nge d concentric a l ly rel ative to convexly b ent s p e c i men s u r ace, a ten s i le s tre s s field (s e e Re erence [ un i form, the are a i n th i s field b ei ng b ou nde d b y the lo ad i ng ri ng B y i ncre as i ng the lo ad, unti l fai lure , the tensile stress in the middle of the specimen is increased at a constant rate F o cc urs , the e xp e c te d p oi nt o f fai lu re b ei ng i n the mo s t s everely s tre s s e d s ur face region defi ne d b y the lo ad i ng ri ng The bending strength, σbB , shall be calculated from the maximum load, Fmax, measured when failure occurs and the specimen thickness, h , taking into account the dimensions of the square or circular specimens and the value for Poisson number, μ , of the specimen © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) Key loading ring specimen supporting ring Figure — Tes t arrangement (indicating the principle) , illustrated for a circular specimen 6.1 Apparatus Testing machine The bending test shall be carried out using a suitable bending testing machine, which shall incorporate the following features a) The stressing of the specimen shall be capable of being applied from zero up to a maximum value in a manner which minimizes shock and is stepless b) T he s tre s s i ng device sh a l l b e c ap ab le o f the s p e ci fie d rate o f s tre s s i ng c) The testing machine shall incorporate a load measuring device with a limit of error of ±2,0 % within the measuring range 6.2 Loading device The loading device shall be arranged as illustrated in Figure 2, with dimensions conforming to Table for the two combinations of loading ring and supporting ring accepted for the coaxial double-ring bending test © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) Key specimen base plate of hardened steel provided with a supporting ring spacer of silicone rubber loading ring of hardened steel load transmitting member with a centring feature for the loading ring s p acer o f p ap er o r synthetic material ap p roximately , mm thick adj us ting j aw fo r centring the s p ecimen contact circle of loading ring contact circle of supporting ring Figure — Loading device Table — D imensions of loading ring and supporting ring Dimensions in millimetres Lo ading device R30 R45 R60 R105 Radius of lo ading ring r1 20 35 Radius of supp orting ring r2 30 45 60 105 Radius r3 or L/2 of specimen as specified in Table The radius of curvature of the bearing surface of the supporting ring shall be 2,5 mm 33 50 120 210 T he s i l icone r ubb er sh a l l b e m m th ick, or a lternatively a rubb er s e c tion, m m th ick, matche d to the supporting ring with a hardness of (40 ± 10) IRHD (according to ISO 48) © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) The radius of curvature of the bearing surface of the loading ring shall be 2,5 mm 6.3 Measuring instruments The following measuring instruments are required: — a measuring instrument enabling the diameter or the length of the side of the specimen to be measured to the nearest mm; — a measuring instrument allowing the thickness of the specimen to be measured to the nearest 0,01 mm 7.1 Sample Shape and dimensions of specimens Circular or square specimens as specified in Table and Table shall be used Table — D imensions of specimens Lo ading device D iameter (= r3 ) L or Dimensions in millimetres T hicknes s h s ide length R30 R45 R60 R105 66 ± 100 ± 240 ± 420 ± minimum ma ximum see Table see Table see Table see Table 12 19 Table — M inimum thickness of specimens as a function of bending s trength Dimensions in millimetres B ending s trength σ bB M Pa σbB ≤ 100 100 < σbB ≤ 200 200 < σbB ≤ 300 300 < σbB ≤ 400 400 < σbB ≤ 500 500 < σbB ≤ 600 M inimum thickness of s p ecimens for lo ading device R45 2,0 2,5 3,0 3,5 3,5 4,0 R3 1,0 1,5 2,0 2,5 2,5 3,0 R60 2,5 3,5 4,5 5,0 5,5 6,0 R105 4,5 6,0 7,5 8,5 9,5 10,5 In cases in which not even the approximate value of the anticipated bending strength is known beforehand, the data given in the last line of Table (values for bending strength up to 600 MPa) shall be taken for the minimum thickness o f the specimens A fter the first tests have been evaluated, the appropriate minimum thickness shall be determined from Table The following tolerances shall apply to that portion o f the specimen bounded by the contact circle o f the supporting ring: — the flatness tolerance shall be 0,1 mm; — the parallelism tolerance shall be % of the specimen thickness © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) 7.2 Sampling and preparation of specimens 7.2 Cutting and handling T he gre ate s t c are s l l b e ta ken th at the te s t s u r face, wh ich wi l l b e s ub s e quently s ubj e c te d to ten s i le stress, does not come into contact with tools, grinding agents, glass splinters, etc and also is not damaged during storage NO TE I n o rder to p re s er ve s p e c i fic s u r face cond itio n s , the te s t s u r face c a n b e pro vide d with a p ro te c tive NO TE T he me tho d o f c utti n g s p e c i men s i s no t s ign i fic a nt a nd no e dge pro ce s s i n g i s ne ce s s a r y coating (glued down) during specimen preparation 7.2 Conditioning Protective coatings shall be removed 24 h before the test (see ISO 1288-1) The specimen shall be stored in the test environment (see 8.1 and 8.2) for at least h before testing 7.2 Examination B e fore the b end i ng s treng th te s t, a l l s p e c i men s sh a l l b e exa m i ne d over the te s t s u r face are a fau lts 7.2 for a ny wh ich are no t repre s entative o f the qua l ity ch arac teri s tics o f the materi a l te s te d Adhesive film To hold to ge ther the fragments , an ad he s ive fi l m s l l b e fi xe d to the s ide o f the s p e c i men fac i ng the loading ring This facilitates location of the fracture origin and measurement of the specimen thickness 7.3 Number of specimens T he numb er o f s p e ci men s to b e te s te d s l l b e de term i ne d dep end i ng on the fidence l i m its re qui re d , e s p e c ia l ly with regard to e s ti mati ng the e xtreme s o f the s treng th d i s tribution (s e e I S O 8 -1 discussion of numbers of specimens) 8.1 for a Procedure Temperature The coaxial ring bending test shall be carried out at a temperature of (23 ± 5) °C During the test, the temperature of the specimen shall be kept constant to °C in order to avoid the development of thermal stresses 8.2 Humidity T he co a xia l ri ng b end i ng te s t sh a l l b e c arrie d out at a relative hum id ity b e twe en % and 70 % 8.3 Thickness measurement To p re vent d a m age fro m b ei n g c au s e d to the s u r face b y me a s u r i ng i n s tr u ments , the th ickne s s s h a l l be measured at four points on the edge of the specimen The average shall be taken from these measured values 8.4 Base plate T he b as e plate i s centre d by movi ng down the and s p e ci men) i nto the adj u s ti ng cone (s e e force tran s m itti ng comp onent (without the lo ad i ng ri ng Figure 2) The base plate shall be locked in this position © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) Glass splinters and other hard and sharp-edged particles shall be cleaned from the supporting ring Damage to the supporting ring shall be eliminated 8.5 Positioning of specimen and loading ring The silicone rubber spacer shall be positioned between the specimen and the base plate in such a The specimen shall be placed in position with the surface to be tested downwards The loading ring, which has been cleaned to remove splinters, shall then be lowered onto the top side of the specimen (see Figure 2) way that, at e ach p oi nt, it pro trude s b eyond the b e ari ng an nu lu s on e ach s ide b y no t le s s th an m m and centre d, with the p ap er or s ynthe tic s p acer place d b e twe en the lo ad i ng ri ng and the s p e ci men 8.6 Load application The test load, F f rises at a rate of (2 ± 0,4) MPa/s until failure of the specimen occurs For calculating the rate of increase of the bending stress, Formula (1) shall be used for circular specimens and Formula (2) for square specimens: , s l l b e i ncre as e d i n s uch a way that the b end i ng s tre s s i n the m idd le o ∆σ ∆t = K1 h ⋅ the s p e ci men ∆F ∆t (1) ∆σ = K2 ⋅ ∆F (2) ∆t h ∆t NOTE The values of K1 and K2 depend on the Poisson number of the specimen For soda lime silicate glass, the value of K1 is 1,09 and the value of K2 is 1,04 (see ISO 1288-1) for both the R30 and the R45 rings while the value of K1 is 0,686 and the value of K2 is 0,674 for both the R60 and the R105 rings The maximum load, Fmax, shall be read from the load measuring device of the testing machine 8.7 Location of the origin The location of the origin of the fracture 4] shall be determined from the fragments The position of the [ origi n o f the frac tu re “i n s ide or outs ide the contac t ci rcle o f the lo ad i ng ri ng” s l l b e de term i ne d for ever y s p e ci men NOTE After fracture, further thickness measurements, for control purposes, can be made on fragments f f f origin as possible from 8.8 the centre o the s p e c i men b o u nde d b y the lo ad i n g r i n g contac t c i rcle , p re erab l y a s clo s e to the rac tu re Assessment of residual stresses I f the s p e ci men s are s idere d to b e fre e from i n herent s tre s s e s , (that i s , they are o f a n ne a le d gl as s) , th i s cond ition s l l b e e xam i ne d to - el as tic a l ly, i n the c as e o f tra n s p arent gla s s e s , on s p e ci men s or s uitable fragments Stre s s- fre e s p e ci men s place d b e twe en c ro s s -p ola ri z e d p ol ari z i ng fi lters sha l l no t show a ny s ign i fic a nt brightne s s variation s when viewe d th rough the c ro s s- s e c tion over an op tic a l p ath length of mm 9.1 Evaluation Limitation of the evaluation For eva luation pu rp o s e s , on ly tho s e s p e ci men s sh a l l b e s idere d i n wh ich the origi n o f the frac tu re l ie s with i n the are a defi ne d b y the lo ad i ng ri ng © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) 9.2 Calculation of bending strength The bending strength, σbB associated with the maximum load Fmax shall be calculated from Formula (3) for circular specimens and from Formula (4) for square specimens σ bB = K1 Fmax h2 (3) σ bB = K Fmax h2 (4) Test report The test report shall include the following information, with reference to this part of ISO 1288: a) typ e a nd na me o f gla s s; b) pre-treatment and condition of specimen surface including the sequence of treatment stages performed; c) inherent stress of the specimen, annealed or prestressed glass, including nature and, if possible, degree of prestressing; d) shape of specimens (circular or square); e) typ e o f lo ad i ng device (R45 or R3 0) ; f) number of specimens; g) for each specimen, the following information: 1) specimen thickness, h , in mm to the nearest 0,05 mm; 2) bending strength, σbB , in MPa, rounded to the nearest 0,1 MPa, of each specimen broken in accordance with 9.1; 3) time to breakage in seconds to the nearest s No average for the measured results shall be given; h) number of specimens not broken in accordance with 9.1; i) a ny deviation from th i s p ar t o f I S O 8 wh ich may h ave a ffe c te d the re s u lts © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) Bibliography [1] ISO 8 -1 , Glass in buildin g — Determ in ation f o f th e ben din g stren gth o f glass — Part : Fun dam entals o testin g glass [2 ] ISO 62 -1 , Glass in buildin g — Basic soda lim e silicate glass products — Part : Defin ition s an d gen eral physical an d m ech anical properties [3 ] R.W., B lank K., S ch nbrunn G f f ; Sprechsaal 116 ( 1983), No.5, pp.397-405 and printing error correction in Sprechsaal 116 (1983),No.8, p669 erkho f F ; Deutsche Glastechnische Gesellschaft, Frankfurt/Main 1970, p 209 ff S chmitt ö Doppelrin gver ahren (Experim ental stress an alysis [4] K Experim entelle Spannun gsan alyse zum or th e double rin g m eth od) Bruchvorgan ge in Gläsern (Fracture Processes in Glass.) © ISO 2016 – All rights reserved ISO 88-5 : 01 6(E) ICS 81.040.20 Price based on pages © ISO 2016 – All rights reserved