BS-2782-3-METHOD-335A-19993.pdf

BRITISH STANDARD Plastics - Determination of flexural properties The European Standard EN I s 0 178: 199ôhas the stains o f a Britishstandard IMPORLANT NOTE. Before reading t h i s method i t i s essentiai to read BS 2782 : part O, inîmduction, issued separat. BS EN IS0 178 : 1997 BS 2782 : Part3: Method 336A : 1993 IS0 178 : 1993 Incoyporatz ns Amendmat No. 1 to BS2782 : Part 3 : M e W 335A : 1993 (raumbersBSas BSENISûl78: 1997) NO CopyLNG W“0UT BSI PERMISSION EXCEPT AS PERMITFED BY COPYRíGIïï LAW u Ü - STDWBSI BS EN IS0 L78-ENGL 17'77 = Lb24bb9 Ob23854 III1 = BS EN IS0 178 : 1997 Issue 2, June 1997 National foreword This method has been prepared by Technical Commiaee PRbZl and i s the Engiish ianguage version of EN I s 0 178 : 1996 plastics - DeterminuM ofJlmumi pmpmtks. It is identicaì with I s 0 1 7 8 : 1993, pubìished by the internaîional OrganMion for Standadkation (BO). It superseàes E S 2782 : Method 335A : 1978 which is withdrawn. Cross-references International rrtuiâud Corresponding British Standard I S 0 291 : 1977 IS0293: 1986 Bs 2782 M e t h o d s o f testing plasciCs Parto: 1995littroduccion (Appendix A i s identicai) Method 9OiA : 1988 CampressW d i n g test specimens o f tvumhpht2cmatenals (identiad) Methoci 91OA : 1977 IqjectzOn d i n g test Spanmens o f thennqplaSt2cmataals (identicai) Method 902A : 1992 Compression d i n g o f test qpe rigid thermoplastics sheets; 1.6 Flexural properties can only be used for neering design purposes for materials with linear stresdstrain behaviour. For non-linear material behav- ¡our the flexural properties are only nominal. The bending test should preferentially be used with brittle materials, for which tensile tests are difficult. - thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets, including laminates; 2 Normative references - fibre-reinforced thermoset and thermoplastics composites, incorporating unidirectional or non- unidirectional reinforcements such as mat, woven fabrics, woven rovings, chopped strands, combi- nation and hybrid reinforcements, rovings and milled fibres; sheets made from pre-impregnated materials (prepregs); - thermotropic liquid-crystal polymers. The method is not normally suitable for use with rigid cellular materials and sandwich structures containing cellular material. NOTE 1 For certain types of textile-fibre-reinforced plas- tics, a four-point bending test is preferred. This is currently under consideration in ISO. The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicated below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 291 : 1977, Plastics - Standard atmospheres for conditioning and testing. IS0 293:1986, Plastics - Compression moulding fest specimens of thermoplastic materials. 1 - STD=BSI BS EN IS0 178-ENGL 1777 1bZVbb7 Ob238b0 715 m IS0 178: 1993 (E) IS0 294:-”, Plastics - Injection moulding of test specimens of thermoplastic materials. IS0 295: 1991, Plastics - Compression moulding of test specimens of thermosetting materials. IS0 1209-1 : 1990, Cellular plastics, rigid - Flexural tests - Part 1: Bending test. IS0 1209-2: 1990, Cellular plastics, rigid - Flexural tests - Part 2 : Determination of flexural properties. IS0 1268: 1974, Plastics - Preparation of glass fibre reinforced, resin bonded, low-pressure laminated plates or panels for test purposes. IS0 2557-1 : 1989, Plastics - Amorphous thermoplas- tics - Preparation of test specimens with a specified maximum reversion - Part 1: Bars. IS0 2557-2: 1986, Plastics - Amorphous thermoplas- tics - Preparation of test specimens with a specified reversion - Part 2: Plates. IS0 2602:1980, Statistical interpretation of test re- sults - Estimation of the mean - Confidence interval. IS0 281 8:-2J, Plastics - Preparation of test speci- mens by machining. IS0 31 67:31, Plastics - Multipurpose test speci- mens. IS0 5893:1985, Rubber and plastics test equipment - Tensile, flexural and compression types (constant rate of traverse) - Description. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 speed of testing, Y: Rate of relative movement between the supports and the striking edge, ex- pressed in millimetres per minute (mrnlmin). 3.2 flexural stress, uf: Nominal stress of the outer surface of the test specimen at midspan. It is calculated according to the relationship given in 9.1, equation (31, and is expressed in megapascals (MPa). 3.3 flexural stress at break, OfB: Flexural stress at break of the test specimen (see figure 1, cutves a and bl . - It is expressed in megapascals (MPa). . 3.4 flexural strength, ofv: Maximum flexural stress sustained by the test specimen during a bending test (see figure 1, curves a and b). It is expressed in megapascals (MPa). 3.5 flexural stress at conventional deflection, aft: Flexural stress at the conventional deflection sC ac- cording to 3.7 (see figure 1, curve cl. It is expressed in megapascals (MPa). 3.6 deflection, s: Distance over which the top or bottom surface of the test specimen at midspan has deviated during flexure from its original position. It is expressed in millimetres (mm). 3.7 conventional deflection, sc: Deflection equal to 1,5 times the thickness h of the test specimen. It is expressed in millimetres (mm). Using the span L = 16h, the conventional deflection corresponds to a flexural strain of 3,5 % (see 3.8). 3.8 flexural strain, q: Nominal fractional change in length of an element of the outer surface of the test specimen at midspan. It is expressed as a dimensionless ratio or a percent- age (%). It is calculated according to the relationship given in 9.2, equation (4). 3.9 flexural strain at break, ve: Flexural strain at break of the test specimen (see figure 1, curves a and b) . It is expressed as a dimensionless ratio or a percent- age (%). 3.10 flexural strain at flexural strength, qM: Flexural strain at maximum flexural stress (see figure 1, curves a and b). It is expressed as a dimensionless ratio or a percent- age (%). 3.11 modulus of elasticity in flexure; flexural modulus, 4: Ratio of the stress difference af2 - of, to the corresponding strain difference values (q2 = 0,002 5) - (E, = 0,000 5) see 9.2, equation (511. It is expressed in megapascals (MPa). 1) To be published. (Revision of IS0 294:1975) 2) To be published. (Revision of IS0 2818:1980) 3) To be published. (Revision of IS0 3167:19831 2 -,-,- 'STDOBSI BS EN IS0 L7B-ENGL 1797 = Lb24bb7 IS0 178:1993(E) NOTES 2 The flexural modulus is only an approximate value of Young's modulus of elasticity. 3 With cornDuter-aided eaubment. the determination of determined value. During this procedure the force applied to the specimen is measured. 5 Apparatus the modulus E, using two distinct stresslstrain points can be replaced by a linear regression procedure applied on the 5.1 Testing machine part of the curve between these tWo points. 5.1.1 General The machine shall comDIy with IS0 5893 and the re- quirements given in 5.1'.2 to 5.1 -4, as follows. 4 Principle 5.1.2 Speed of testing The testing pachine shall be capable of maintaining the speed of testing (see 3.11, as specified in tablel. The test specimen, supported as a beam, is deflected at constant rate at the midspan until the specimen fractures or until the deformation reaches some'pre- L b II /I I I I I I I I I 1 I I I I I I I / ,i/ I I I I I l I I I I I I I I I r I I I I I E tB Etn 4 9 Et - Curve a Curve b Curve c Specimen that breaks before yielding Specimen that shows a maximum and then breaks before the conventional deflection s , Specimen that neither has a yield point nor breaks before the conventional deflection s , Figure 1 - Typical curves of flexural stress of versus flexural strain q and deflection s 3 IS0 178:1993(E) S P d mm/min 1 1) 2 5. 10 20 50 1 O0 200 500 Tolerance % f 202) f 202) f 20 f 20 f 10 f 10 f 10 f 10 f 10 5.1.3 Supports and striking edge Two supports and a central striking edge are arranged according to figure2. The parallel alignment of the supports and the striking edge shall lie within f 0,02 mm. The radius R, of the striking edge and the radius R2 of the supports shall be as follows: R, = 5,O mm f 0,l mrn - . R2 = 2,O mm f 0,2 mm for thicknesses of the test - - ? specimen 3 mm. The span L shall be adjustable. 5.1.4 Indicators for load and deflection The error for the indicated force shall not exceed 1 %, and the error for the indicated deflection shall not exceed 1 % of full scale (see IS0 5893). 5.2 Micrometers and gauges 5.2.1 Micrometer, or equivalent, reading to Q 0,Ol mm (for measuring the thickness h and width b of the test specimen, see figure3). 5.2.2 Vernier caliper, or equivalent, accurate to within f 0,l % of the span L, for determining the span (see 8.2 and figure2). 6 Test specimens 6.1 Shape and dimensions 6.1.1 General The dimensions of the test specimens shall comply with the relevant material standard and, as applicable, with 6.1.2 or 6.1.3. Otherwise, the type of specimen shall be agreed between the interested parties. Apptled force F * v A 1- - 1 Figure 2 - Position of test specimen at the start of the test 4 -,-,- 6.1.2 Preferred specimen type Moulding and extrusion compounds, thermoplastic and thermosetting sheets Nominal thickness, h The preferred dimensions, in millimetres, shall be Textile and longfibre- reinforced materia,s length: f=80f2 width: thickness: b = 10,o f 0,2 h = 4,O f 0,2 In any one test specimen, the thickness within the central third of the length shall nowhere deviate by more than 2 % from its mean value. The correspond- ing maximum deviation for width is 3 %. The cross- section shall be rectangular, with no rounded edges. l dated, the other page has been reprint 1977 Preparacum o f test Spacimens bp machining w w equivalent) Method 93lA : 1993 piparation and use o f rnzlltipurpose test specimt?ns (Identical) The Technical Committee has reviewed the provisions of I s 0 12041 : 1990, Is0 12092 : 1990 and I s 0 5893 : 1986 to w h i c h nonnative reference is made i n the text, and has decid4 that they are acceptable for use i n coqjunction with this standara Warning note. This British standard, which i s identicai with IS0 178, does not necesmi& detaii aii the precautons necessary to meet the requ9emenís of the Health and Safe a t Work e t c . Act 1974. Attention should be paid t o any appropriale safety precautions and the method &odd be operated o r by trallied pemonnei. Compliance with a British Standard does not of itself confer immunity from legal obligations. O BSi 1997 -,-,- - STDOBSI BS EN IS0 178-ENGL 1997 M Lb24bb9 Ob23872 q37 M iasue 2 2 1 blank * 2 blank Issue 1 , June 1997 BS EN IS0 178 : 1997 Pwe b u e EN cover page 1 iib 1 lto8 Onginai inside back cover Onginai Back cover 2 Summary of pages The foilowing table identifies the current issue of each page. issue 1 indicates that a page has been intmäuced for the niSt time by amendment Subsequent issue numbers indicate an updated page. Vertical sidelining on replacement pages i n d i c a t e s the m o s t recent changes (amendment, adàition, deletion). Front cover Inside front cover a b i ii Change of identifier Wherever ES 2782 : Method 336A : 1993 appears i n t h i s standard, it should be read as Bs EN Is0 178 : 1997. a -,-,- STD-BSI BS EN IS0 L78-ENGL 1777 = Lb2'4bbS Ob23873 373 Issue 2, June 1997 BS EN IS0 178 : 1997 Contents page National foreword inside front page Committees responsible Back page Foreword Method 1 scope 1 2 Nonnative Teferences 1 3 Definitions 2 4 Principle 3 5 Apparatus 3 6 WSpeCimens 4 7 Conditioning 6 8 Procedure 7 9 calculation and expression of results 7 10 precision 8 11 lwreport 8 '18bles 1 Recommended values for the speed of testing 4 2 m 1 2 3 Wues for the width 6 i n the relation to the thickness h 'Qpicaì curves of flexuraì stress of uf versus flexural stiain ef and defieetion s 3 Position of test specimen at the start of the test 4 Fbsition of test specimen i n reiation t o M o n of product and âirection of force 6 5 STD-BSI BS EN IS0 L78-ENGL 1777 W Lb2Libb7 Ob23874 ZUT EUROPEAN SI'ANDARD NORME EUROPÉENNE E X J R 0 P m NORM EN I s 0 178 Demmber 1996 ICs 83.080 Descriptors: plastics, tests, bend tests, determinaöon, flexural strength, test specimens E l - & version Plastics - Detemination of flexural properties (ISû i78 : 1993) plastiques - Détermination des propriétés en flexion BiegeeigenSchaften (ISû 178: 1993) Kunststoffe- Eksthmung der ( E 3 0 178: 1993) This European Standarà was approveà by CEN on 1994-1214. CEN members are bound t o comply with the CENKENELEC internai Regdations w h i c h stipuiate the conditions for giving this h p e a n Standard the status of a national stanàard without any altmation. Uptmiate lists and bibiiographicaì references concerning such nationai standards may be obtained on application to the Centrai Secretariat or to any CEN member. This European standard exists i n three officiai versions (English, French, German). A version i n any other ianguage made by transiaion under the responsibility of a CEN member into its own ianguage and notifíed t o the Central Secretariat has the same status as the official versions. CEN members are the national stanàards bodies of Awtria, Beigium, Denmark, Finland, France, Germany, Greece, Iceland, ïreiand, Itaiy, Luxembourg, Netherlanàs, Norway, Portugal, Spain, Sweden, Swimriand and United Kingdom. CEN European Commiaee for standardization Comité Enopéen de Normalisation e Europaisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1060 Brussels O 1996 copyright reseived to CEN members Ref. No. EN IS0 178 : 1996 E EN IS0 178 : 1996 Issue 1, June 1997 Foreword The text of the intemationai standard from lkhnical Commiaee IsoRy= 61, Plaseics, o f the intemationai - o n for Stan-on (Ise) has been taken overasanEuropeandardby Technicalcommiaee CENIIY: 249, P l a s t i c s , the secretariat of w h i c h i s held by IBN. This European slandardshalìbe giventhe status of a national standard, either by pubìidon of an identicai or by endorsement, a t the latest by June 1997, and conflicting monal standards shall be withdrawn a t the latest by June 1997. According to the CEN/CENELEC Internai Reguìations, the national standards orgarhtbns of the foììowing countries are bound to implement t h i s European Stan- Austria, Beigium, Denmark, Fínian4 Fiance, Gemmy, Gme, Ice