1、 ISO 2016 Glass in building Determination of the bending strength of glass Part 2: Coaxial double-ring test on flat specimens with large test surface areas Verre dans la construction Dtermination de la rsistance du verre la flexion Partie 2: Essais avec doubles anneaux concentriques sur prouvettes p
2、lanes, avec de grandes surfaces de sollicitation INTERNATIONAL STANDARD ISO 1288-2 First edition 2016-02-15 Reference number ISO 1288-2:2016(E) ISO 1288-2:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland All rights reserved. Unless otherwise spec
3、ified, 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 permission. Permission can be requested from either ISO at the address below or I
4、SOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.org ISO 1288-2:2016(E)Foreword iv 1 Scope . 1 2 Normative references 1 3 Terms and definitions . 1
5、 4 Symbols 2 5 Principle of test method . 2 6 Apparatus . 3 6.1 Testing machine . 3 6.2 Loading device. 4 6.2.1 Ring load . 4 6.2.2 Surface pressure regulator 4 6.3 Measuring instruments . 5 7 Sample . 5 7.1 Shape and dimensions of the specimens 5 7.2 Sampling and preparation of specimens 5 7.2.1 Cu
6、tting and handling 5 7.2.2 Conditioning 5 7.2.3 Examination . 6 7.2.4 Adhesive film . 6 7.3 Number of specimens . 6 8 Procedure. 6 8.1 Temperature 6 8.2 Humidity . 6 8.3 Thickness measurement . 6 8.4 Base plate . 6 8.5 Positioning of specimen and loading ring . 6 8.6 Load application 7 8.7 Loading r
7、ate . 7 8.8 Location of the origin 7 8.9 Assessment of residual stresses . 7 9 Evaluation 8 9.1 Limitation of the evaluation 8 9.2 Calculation of bending strength . 8 10 Test report . 9 Annex A (informative) Example of a device for keeping the gas pressure, p, in line with the piston force, F 11 Bib
8、liography .14 ISO 2016 All rights reserved iii Contents Page ISO 1288-2:2016(E) 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
9、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
10、 closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical 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 crit
11、eria needed for the different types of ISO documents should be noted. This document was drafted in 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 o
12、f patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details 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 nam
13、e used in this document is information given for the convenience of users and does not constitute an 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 Technic
14、al Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information The committee responsible for this document is ISO/TC 160, Glass in building, Subcommittee SC 2, Use considerations ISO 1288 consists of the following parts, under the general title Glass in building Determination
15、 of the bending strength of glass: Part 1: Fundamentals of testing glass Part 2: Coaxial double ring test on flat specimens with large test surface areas Part 3: Test with specimen supported at two points (four point bending) Part 4: Testing of channel shaped glass Part 5: Coaxial double ring test o
16、n flat specimens with small test surface areasiv ISO 2016 All rights reserved INTERNATIONAL ST ANDARD ISO 1288-2:2016(E) Glass in building Determination of the bending strength of glass Part 2: Coaxial double-ring test on flat specimens with large test surface areas 1 Scope This part of ISO 1288 spe
17、cifies a method for determining the bending strength of glass for use in buildings, excluding the effects of the edges. The limitations of this part of ISO 1288 are described in ISO 1288-1. 2 Normative references The following documents, in whole or in part, are normatively referenced in this docume
18、nt and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 48, Rubber, vulcanized or thermoplastic Determination of hardness (hardness between 10 IRH
19、D and 100 IRHD) ISO 1288-1, Glass in building - Determination of the bending strength of glass - Part 1: Fundamentals of testing glass 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 bending stress tensile bending stress induced in the surfac
20、e of a specimen Note 1 to entry: For testing purposes, the bending stress should be uniform over a specified part of the surface. 3.2 effective bending stress weighted average of the tensile bending stresses, calculated by applying a factor to take into account non-uniformity of the stress field 3.3
21、 bending strength tensile bending stress or effective bending stress which leads to breakage of the specimen 3.4 equivalent bending strength apparent bending strength of patterned glass, for which the irregularities in the thickness do not allow precise calculation of the bending stress ISO 2016 All
22、 rights reserved 1 ISO 1288-2:2016(E) 4 Symbols A effective surface area of quasi-uniform stress m 2 E modulus of elasticity (Youngs modulus) of the specimen NOTE For soda lime silicate glass (see ISO 16293-1), a value of 70 GPa is used. Pa F piston force N F max piston force upon breakage, “breakin
23、g force” N F ring force transmitted by the loading ring to the specimen, “ring load” N h thickness or average thickness of specimen m L side length of the square specimens m Poisson number of specimen NOTE For soda lime silicate glass (see ISO 16293-1), a value of 0,23 is used. p gas pressure on the
24、 surface area defined by the loading ring Pa p(F) nominal gas pressure as a function of the piston force Pa p max (F max ) nominal gas pressure upon breakage Pa r location coordinate m r 1 radius of loading ring m r 2 radius of supporting ring m r 3m average specimen radius (for evaluation) m stress
25、 Pa bB bending strength Pa beqB equivalent bending strength Pa t time s F/t rate at which piston force rises N/s F*, p*, * non-dimensional quantities corresponding to F, p and see Formulae (1) to (5) 5 Principle of test method The square specimen, of side length, L, and having virtually plain parall
26、el surfaces, is placed loosely on a supporting ring (a circular ring with a radius r 2 ). The specimen is subjected to a load, F ring , by means of a loading ring (radius r 1 ), which is arranged concentrically to the supporting ring. In addition, the area, A, defined by the loading ring 0 r r 1is p
27、laced under gas pressure, p, which has a specific relationship with the ring load, F ring(see Figure 1). When the specimen is subjected to the ring load and the associated gas pressure, depending upon the dimensions r 1 , r 2 , L, and h, a radial tensile stress field, which is sufficiently homogeneo
28、us for the test purpose, is developed on the convexly bent surface over the area defined by the loading ring (see References 2, 3, 4). The tangential tensile stress is equal to the radial tensile stress at the central point (r = 0) of the specimen, but decreases as the radius, r, increases.2 ISO 201
29、6 All rights reserved ISO 1288-2:2016(E) Outside the loading ring, the radial and tangential stresses fall sharply towards the edge of the specimen, so that the risk of breakage outside the loading ring is low. On the edge of the specimen itself, the radial stress is zero and the tangential stress i
30、s a compressive stress, this being the case on both the concavely and the convexly bent sides of the specimen. The edge of the specimen is thus always under tangential compressive stress (see ISO 1288-1). By increasing the force, F, and the gas pressure, p, the tensile stress in the central part of
31、the specimen is increased at a constant rate see (6.1 b) until breakage, so the origin of the break can be expected to occur in the surface area subjected to maximum tensile stress within the loading ring. With the test apparatus as shown in Figure 1, a force, pA, acts against the piston force, F, d
32、ue to the gas pressure, p. The force transferred by the loading ring is F ring= F - pA. Thus a distinction should be made between the piston force and the ring load. The bending strength, bB , or equivalent bending strength, beqB , is calculated from the maximum value, F max , of the piston force, m
33、easured at the time of breakage, and the thickness, h, of the specimen, taking into account the prescribed dimensions of the specimen and various characteristic material values. This assumes that the gas pressure, p, follows the piston force, F, according to the nominal function p(F), (see Figure 3)
34、. 6 Apparatus 6.1 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 i
35、s stepless. b) The stressing device shall be capable of the specified rate of stressing. c) The testing machine shall incorporate a load measuring device with a limit of error of 2,0 % within the measuring range. Key 1 loading ring 2 specimen 3 supporting ring Figure 1 Basic diagram of test apparatu
36、s ISO 2016 All rights reserved 3 ISO 1288-2:2016(E) Key 1 specimen 2 rigid base plate, preferably made of steel, with supporting ring (radius r 2 ) a 3 rubber profile, adapted to the supporting ring, 3 mm thick, with a hardness (40 10) IRHD (in accordance with ISO 48) 4 rigid loading ring (radius r
37、1 ), preferably made of steel a 5 force transmitting component, with a ball mechanism to ensure the force is centred in the loading ring 6 rubber profile, adapted to the loading ring, 3 mm thick with a hardness (40 10) IRHD (in accordance with ISO 48) b 7 adjustment jaws for centring the specimen c
38、8 contact circle of the loading ring 9 contact circle of the supporting ring a The radius of curvature of the bearing surface of the ring is 5 mm. b In the case of specimens which are patterned on the loading ring side, a sponge rubber profile approximately 5 mm thick should also be used to ensure a
39、n adequate seal for the gas pressure. c The jaws are removed before the bending test is started, in order that the edge of the specimen is not clamped. Figure 2 Loading device 6.2 Loading device 6.2.1 Ring load The ring load shall be applied using a loading device as shown in Figure 2. The dimension
40、s of the loading device are given in Table 1. Table 1 Dimensions for the loading ring and supporting ring Dimensions in millimetres Loading ring r 1 Supporting ring r 2 Effective surface area mm 2 300 1 400 1 240 000 6.2.2 Surface pressure regulator The loading device for the surface pressure is sho
41、wn in Figure 2.4 ISO 2016 All rights reserved ISO 1288-2:2016(E) The regulator shall be chosen with regard to accuracy and flow rate in such a way that the nominal function, p(F), as shown in Figure 3 or Table 3, can be met (see Annex A). 6.3 Measuring instruments The following measuring instruments
42、 are required: a measuring instrument enabling the width of the specimen to be measured to the nearest 1 mm; a measuring instrument allowing the thickness of the specimen to be measured to the nearest 0,01 mm. 7 Sample 7.1 Shape and dimensions of the specimens Square specimens of the dimensions show
43、n in Table 2 shall be used. The minimum thickness given for the specimens has been calculated in such a way that the effect of the self-weight of the specimen upon the stress distribution can be ignored. Table 2 Dimensions of specimens Dimensions in millimetres Specimen side length L Minimum nominal
44、 specimen thickness Average specimen radius (for evalu- ation) r 3m 1 000 4 3 600 The following tolerances for the specimens shall be observed. In the case of specimens with flat surfaces: the evenness tolerance shall be 0,3 mm; the parallelism tolerance shall be 2 % of the specimen thickness. In th
45、e case of specimens with one or two patterned surfaces: the fluctuations of the plate thickness (see 8.3) shall be not more than 4 % and the local deviations from the average thickness (due to the depth of the pattern) shall be a maximum 30 % or 2 mm, whichever is the lower. 7.2 Sampling and prepara
46、tion of specimens 7.2.1 Cutting and handling The greatest care shall be taken that the test surface, which will be subsequently subjected to tensile stress, does not come into contact with tools, grinding agents, glass splinters, etc., and also is not damaged during storage. NOTE 1 In order to prese
47、rve specific surface conditions, the test surface can be provided with a protective coating (glued down) during specimen preparation. NOTE 2 The method of cutting specimens is not significant and no edge processing is necessary. 7.2.2 Conditioning Protective coatings shall be removed 24 h before the
48、 test (see ISO 1288-1). The specimen shall be stored in the test environment (see 8.1 and 8.2) for at least 4 h before testing. ISO 2016 All rights reserved 5 ISO 1288-2:2016(E) 7.2.3 Examination Before the bending strength test, all specimens shall be examined over the test surface area for any fau
49、lts which are not representative of the quality characteristics of the material tested. 7.2.4 Adhesive film To hold together the fragments, an adhesive film shall be fixed to the side of the specimen facing the loading ring. This facilitates location of the fracture origin and measurement of the specimen thickness. 7.3 Number of specimens The number of specimens to be tested shall be determined depending on the confidence limits required, especially with regard to estim
