DIN EN 1288-3-2000 Glass in building - Determination of the bending strength of glass - Part 3 Test with specimen supported at two points (four point bending) German version EN 128.pdf

1、DEUTSCHE NORM September 2000 Glass in building Part 3: Test with specimen supported at two points (four point bending) Endish version of DIN EN 1288-3 Determination of the bending strength of glass DIN - EN 1288-3 ICs 81.040.20 Supersedes DIN 52303-1, August 1984 edition. Glas im Bauwesen - Bestimmu

2、ng der Biegefestigkeit von Glas - Teil 3: Prfung von Proben bei zweiseitiger Auflagerung (Vierschneiden-Verfahren) European Standard EN 1288-3 : 2000 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been prepared by CENTTC 129. The responsi

3、ble German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee Glasfesfigkeif und Prfung von Glas fr bauliche Anlagen. DIN IS0 48*) is the standard corresponding to International Standard IS0 48 referred to in clause 2

4、of the EN. Amendments DIN 52303-1, August 1984 edition, has been superseded by the specifications of EN 1288-3. Previous editions DIN DVM 2302 = DIN 52302: 1937-06; DIN 52303: 1957-1 1, 1976-1 1 DIN 52303-1: 1984-08. “) Currently at draft stage. EN comprises 12 pages. O No pari of this standard may

5、be reproduced without the prior permission of Ref. No. DIN EN 1288-3 : 2000-09 DIN Deufsches Institut fr Normung e. V., Berlin. Beufh Verlag GmbH, 10772 Berlin, Germany, has the exclusive right of sale for German Standards (DIN-Normen). English price group 07 Sales No. 1107 01.01 EUROPEAN STANDARD N

6、ORME EUROPENNE EUROPISCHE NORM EN 1288-3 June 2000 ICs 81.040.20 English version Glass in building Part 3: Test with specimen supported at two points (four point bending) Determination of the bending strength of glass Verre dans la construction - Dtermination de la rsistance du verre la flexion - Pa

7、rtie 3: Essais avec prouvettes supportes en deux points (flexion quatre points) Verfahren) Glas im Bauwesen - Bestimmung der Biegefestigkeit von Glas - Teil 3: Prfung von Proben bei zweiseitiger Auflagerung (Vierschneiden- This European Standard was approved by CEN on 1999-09-05. CEN members are bou

8、nd to comply with the CENKENELEC 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 stand- ards may be obtained on application to the

9、Central Secretariat or to any CEN member. The European Standards exist 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 Central Secretariat has the same status

10、as the official versions. CEN members are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committ

11、ee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, 8-1050 Brussels O 2000. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN 1288-3 : 2000 E Page 2 EN 1288-

12、3 2000 Contents Page 3 Foreword 1 2 3 4 5 6 7 8 9 Scope 4 4 Normative references . 4 Definitions , 5 Symbols . Apparatus 6 6 5.1 Testing machine . 5.2 Measuring instruments 6 Sample 6 6.1 Number of specimens 6 7 6.2 Specimen dimensions 7 6.3 Specimen condition and treatment . 6.4 Adhesive film 7 8 P

13、rocedure 7.1 Measuring width and thickness of each specimen . 8 7.2 Bending test a 9 Evaluation . 8.1 General 9 9 8.2 Bending strength of the surface area, edges included . 8.3 Bending strength of the edges 10 Test rep0 11 . . . . . Page 3 EN 1288-3 : 2000 Foreword This European Standard has been pr

14、epared by Technical Committee CENKC 129 “Glass in building“, the secretariat of which is held by IBN. 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 December 2000, and conflicting national standa

15、rds shall be withdrawn at the latest by December 2000. CENTTC 129NVG8 “Mechanical Strength“ prepared the draft “Glass in building - Determination of the bending strength of glass“ - Part 3 : Test with specimen supported at two points (four point bending)“. There are four other parts to this standard

16、: - Part 1 :Fundamentals of testing glass - Part 2 :Coaxial double ring test on flat specimens with large test surface areas - Part 4 :Testing of channel shaped glass - Part 5 :Coaxial double ring test on flat specimens with small test surface areas According to the CENKENELEC Internal Regulations,

17、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 Ki

18、ngdom. Page 4 EN 1288-3 2000 1 Scope This European standard specifies a method for determining the bending strength, including the effects of the edges, of flat glass for use in building. The method specified can also be used to determine the bending strength of the edges of glass separately. The li

19、mitations of this standard are described in EN 1288-1. EN 1288-1 should be read in conjunction with this standard. 2 Normative references This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate pla

20、ces in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication ref

21、erred to applies. EN 572-1 EN 1288-1 IS0 48 Glass in building - Basic soda lime silicate glass products - Part 1 : Definitions and general physical and mechanical properties Glass in building - Determination of the bending strength of glass - Part 1 : Fundamentals of testing glass Rubber, vulcanised

22、 or thermoplastic - Determination of hardness (hardness between 10 IRHD and 100 IRHD) 3 Definitions For the purposes of this standard, the following definitions apply: 3.1 specimen. bending stress: The tensile bending stress induced in the surface of a NOTE: For testing purposes, the bending stress

23、should be uniform over a specified part of the surface. 3.2 effective bending stress: A weighted average of the tensile bending stresses, calculated by applying a factor to take into account non-uniformity of the stress field. 3.3 bending strength: The bending stress or effective bending stress whic

24、h leads to breakage of the specimen. 3.4 4 B E Fmax 9 h k L Ls Lb Ml Y Z Ob Obeff Ob0 *bG Page 5 EN 1288-3 2000 equivalent bending strength: The apparent bending strength of patterned glass, for which the irregularities in the thickness do not allow precise calculation of the bending stress. Symbols

25、 Specimen width Modulus of elasticity (i Jungs moulus) of the specimen NOTE: for soda lime silicate glass (see EN 572-1 ) a value of 70 x 1 O3 N/mm2 is used. Maximum force NOTE: Where the bending rollers are not firmly attached to the testing machine, but are laid on the specimen, the force resultin

26、g from their weight is added to the maximum measured force. Acceleration due to gravity Specimen thickness Dimensionless factor (see 6.2 of EN 1288-1 for explanation) Specimen length Distance between the centre lines of the supporting rollers Distance between the centre lines of the bending rollers

27、Bending moment Central deflection of the specimen relative to the supporting rollers Section modulus Bending stress in the surface area defined by the bending rollers Effective bending stress Bending strength Bending stress imposed by the self-weight of the specimen Page 6 EN 1288-3 2000 P Density o

28、f the specimen 5 Apparatus 5.1 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 minimize

29、s shock and is 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 i 2,O % within the measuring range; d) The supporting rollers and the bending rollers (see figure 2) shall h

30、ave a diameter of 50 mm and a length of not less than 365 mm. All the rollers shall be free to rotate. 5.2 Measuring instruments The following measuring instruments are required: - a measuring instrument enabling the width of the specimen to be measured to the nearest millimeter; - a measuring instr

31、ument allowing the thickness of the specimen to be measured to the nearest 0.01 mm. 6 Sample 6.1 Number of specimens The number of specimens to be tested shall be determined depending on the confidence limits required, especially with regard to estimating the extremes of the strength distribution (s

32、ee EN 1288-1 for a discussion of numbers of specimens). Page 7 EN 1288-3 2000 6.2 Specimen dimensions Specimen length L : 1100mm15mm Specimen width B: 360 mm t 5 mm Specimen thickness h : thickness of the glass within the tolerance specified for the condition as supplied for test. 6.3 Specimen condi

33、tion and treatment The specimens shall be flat and their edges shall be representative of the edge finish to be tested. If the edge is asymmetrical with respect to the neutral axis of the specimen, both stressed edges shall be in the same orientation (see figure 1) and all specimens in a sample shal

34、l be tested the same way up. 1 correct incorrect 1 Wheel cut edges NOTE: The edges of cut glass are not the same on both corners, because wheel cut edges have the wheel applied to only one surface of the glass. In this instance the edge are asymmetrical with respect to the neutral axis of the specim

35、en. Figure 1: Asymmetrical edges Any intended changes to the condition of the test piece by means of edge working, prior mechanical damage, etching, etc., shall be completed at least 24 h before testing the bending strength (see EN 1288-1). Similarly, protective coatings shall be removed at least 24

36、 h before the test. The specimens shall be stored in the testing environment (see 7.2) for at least 4 h before being tested. 6.4 Adhesive film To hold together the fragments, an adhesive film shall be fixed to the side of the specimens facing the bending rollers (see figure 2). This facilitates loca

37、tion of the fracture origin and measurement of the specimen thickness. Page 8 EN 1288-3 2000 7 Procedure 7.1 Measuring width and thickness of each specimen The width shall be determined as the arithmetic mean of at least three individual measurements. The thickness shall be determined as the arithme

38、tic mean of at least four individual measurements to the nearest 0,05 mm. The measured positions shall lie outside the two bending rollers, to avoid damaging the test surface, and shall be taken from both ends of the specimen. In the case of specimens with one or two ornamental surfaces, both the pl

39、ate thickness and core thickness shall be measured. The average is taken from all these measured values. Alternatively, the thickness shall be determined from at least four fragments taken from the area between the bending rollers after fracture, if the fracture pattern makes this feasible. h I 1 2

40、3 4 b= L= Specimen Bending roller Supporting roller Rubber strips 200 mm f 1 mm 1000 mm 12 mm Figure 2: Mounting of the test specimen 7.2 Bending test The specimen shall be mounted as shown in figure 2. Strips of rubber, 3 mm thick and of hardness (40 i 10) IRHD ( in accordance with IS0 48), shall b

41、e placed between the specimen and the bending and supporting rollers. Page 9 EN 1288-3 2000 The bending test shall be carried out at (23 2 5) OC with the relative humidity between 40 % and 70 Oh. During the test the temperature shall be kept constant to 1 OC, in order to avoid the development of the

42、rmal stresses. The specimen shall be bent with a uniformly increasing bending stress at a rate of (2 f 0,4) N/(mm2.s) until failure occurs. The maximum load, Fmm, shall be measured and the time taken to reach this load shall be recorded. 8 Evaluation 8.1 General For evaluation purposes, only those s

43、pecimens shall be considered in which the origin of fracture lies between the bending rollers. The bending strength, %B, shall be calculated in accordance with equation (1) as f ollowc. For a rectangular cross section, where Z= Bh2/6, and with the load applied as shown in figure 2, the bending stren

44、gth is: The bending stress, ObG, imposed by the self-weight of the specimen shall be calculated in accordance with equation (2) 8.2 Bending strength of the surface area, edges included For calculating the overall bending strength or equivalent bending strength of the surface area, including the edge

45、s, defined by the bending rollers, the value k= k = 1 shall be used (see EN 1288-1). Page 1 O EN 1288-3 2000 8.3 Bending strength of the edges For calculating the bending strength or equivalent bending strength of the free edges of the glass, only those specimens which fracture from the edge shall b

46、e taken into consideration. NOTE: When some of the specimens do not break from the edge, the set of edge strength results is not a true representation of the distribution of edge strengths. The edge strengths of those specimens which fracture from the test surface cannot be determined, but they are

47、certainly higher than the measured values of bending strength of such specimens. There are, however, statistical techniques which can make an allowance for the unmeasured edge strength of those specimens. The factor k= k for use in equation (1) depends on the deflection of the specimen at its centre

48、. The central deflection, y, can be determined by direct measurement, or calculated with sufficient accuracy from equation (3): The appropriate value of k, for use in equation (l), shall be obtained from figure 3, which gives the value of ke as a function of the value of Mb (see EN 1288-1). Page 11

49、EN 1288-3 2000 O 5 10 15 20 VA 25 Figure 3: Dimensionless factor b) Pre-treatment and surface condition of the tested specimen surface including the sequence of treatment stages. In the case of specimens with one patterned surface, the surface which is placed under tensile stress (flat or patterned side) shall be indicated; c) Description of the edge finish and which way up it was tested; d) Inherent stress of the specimen, annealed or prestressed glass, including nature and if possible degree of prestressing; e) Number of specimens; Page 12 EN 1288-3 2000 f) For each spec