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1、CEN EN*b3 77 I 3q09583 O009336 2 EUROPEAN STANDARD ” NORME EUROPENNE EUROPISCHE NORM EN 63 Edition 1 March 1977 UDC 678.5/8:677.521:620.174 Key words: plastics, glass reinforced plastics, tests, mechanical tests, flexing tests, flexural stress, modulus of elasticity, test equipment, test specimens,
2、testing conditions English version Glass reinforced plastics. Determination of flexural properties. Three point method Matires plastiques renforces au verre textile. Dtermination des caractristiques de flexion. Mthode des trois pannes G lasfaserverstrkte Kunststoffe. B iegeversuch. Drei pun kt-Verfa
3、 hren This European Standard was accepted by CEN on 1977-03-31. The CEN members are bound to adhere to the CEN Internal Regulations which specify under which conditions this European Standard has to be given, without any alteration, the status of a national standard. Up-to-date lists and bibliograph
4、ical references concerning such national standards may be obtained on application to the CEN Central Secretariat or to any CEN member. This European Standard exists in three versions (English, French, German), recognized by CEN as equivalent. National versions in other languages rank as translations
5、 and in case of doubt shall be checked against one of the recognized versions. CEN members are the national standards organizations of Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Commi
6、ttee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: Rue de Brderode, 2, B-1000 Brussels O O Copyright reserved to all CEN members - _ - . _. CEN EN*b3 77 m EN 63 Page 2 Brief history This European Standard was drawn up by CEN Technical Committe
7、e 66 Testing of glass fibre reinforced plastics, the Secretariat of which is held by AFNOR. The contents of this standard were submitted for ballot to the members of CEN in November 1974 in view of its adoption as a European Standard. This European Standard was adopted by CEN as a result of its acce
8、ptance by the following member countries: Belgium, Denmark, France, Germany, Italy, Portugal, Spain, Sweden, United Kingdom. -. ._ 3404589 0004337 4 m I c 7 CEN EN*b3 i 7 M 3404587 0004338 h EN 63 Page 3 Glass reinforced plastics. Determination of flexural properties. Three point method Foreword Thi
9、s standard is technically equivalent to Recommendation IS0 178-1975, Determination of flexural properties of rigid plastics materials insomuch as it deals with glass reinforced plastics. 2. Scope This European Standard describes a method for the determination of flexural properties of textile glass
10、reinforced plastics in the form of rectangular bars of standard or non-standard dimensions, moulded directly or cut from sheets or other moulded shapes. It only applies to simple, freely supported beams, loaded at mid-span (three point loading test) *. The following properties may be determined usin
11、g the method described: 1.1 The flexural stress and the deflection at break of materials that break before, or at, the conventional deflection. 1.2 The flexural stress a t the conventional deflection of materials that do not break before, or at, the conventional deflection. 1.3 The flexural stress a
12、t the maximum force for materials that show maximum force before, or at, the conventional deflection. 1.4 The flexural stress at break or at maximum force, when the conventional deflection is exceeded, if so required by the material specification. NOTE. If the conventional deflection is exceeded it
13、may not be possible to make direct comparison of results of flexural stress on test specimens of different thicknesses. 1.5 Optional: the apparent modulus of elasticity in flexure (modulus of elasticity determined by flexure test). NOTE. The modulus of elasticity in flexure is to be considered only
14、as an approximate value of Youngs modulus of elasticity. 2. Reference O EN 62 - Glass reinforced plastics - Standard atmospheres for conditioning and testing 3. Definitions For the purposes of this European Standard the following definitions apply. 3.1 deflection. The distance over which the top or
15、bottom surface of the test specimen at mid-span has deviated during flexure from its original position. 3.2 flexural stress at a given time of the test. The maximum outer fibre stress of the material in the section of the test specimen mid-span. It is calculated according to the relationship (4) giv
16、en in 7.1. 3.3 flexural stress at the conventional deflection. The flexural stress at a deflection equal to 1.5 times the thickness of the test specimen. 3.4 flexural stress at maximum force. The flexural stress developed when the force reaches the first maximum. 3.5 flexural stress at rupture. The
17、flexural stress developed a t the moment of rupture. 4. Apparatus Standard testing machine (shown schematically in figure 2) properly constructed and calibrated, which can be operated at art approximately constant rate, V, of relative movement of the loading nose and the supports, and in which the e
18、rror for indicated forces does not exceed k 1 % and for indicated deflections does not exceed f 2 %. The supports and loading nose shall be at least as wide as the test specimen and shall be parallel to each other. The radius r l of the loading nose and the radius r2 of the supports should be as fol
19、lows: rl : (5 * 0.1) mm r2 : (2 * 0.2) mm The distance between the supports, i, should be adjustable. 5. Test specimen If the test piece cannot be taken from a finished product, a sheet, from which the test specimens are taken, may be prepared in a pre-agreed manner approximating to the manufacturin
20、g process. 5.1 Dimensions of test specimens. The minimum length I should be 20 h, where h is the thickness. The width b should be also a function of thickness, as shown in the following table. Dimensions in millimetres Thickness I ridth h 1 h10 10 h 20 20 h 35 35h50 15 f 0.5 30 t 0.5 50 t 0.5 80 k 0
21、.5 When very coarse textile glass fibre roving is used as the reinforcement, it may be necessary to increase the width of the test specimens. 5.2 Anisotropic materials 5.2.1 In the case of anisotropic materials, the test specimens should be chosen so that the flexural stress in the test procedure wi
22、ll be applied in the same direction as that which will be applied in service to products (moulded articles, sheets, etc.) similar to those from which the test specimens are taken. The chosen test specimen and the application will determine the possibility or impossibility of using standard test spec
23、imens and, in the latter case, will govern the choice of the dimensions of the test specimens in accordance with 5.1. It should be noted that the position or orientation and the dimensions of the test specimens sometimes have a very significant influence on the test results (see figure I). 5.2.2 If
24、the material shows a significant difference in flexural properties in two principal directions, it is to be tested in those two directions (see figure 1). If, in service, this material is subjected to stress at some specific orientation to the principal direction, it is desirable to test the materia
25、l at that orientation. *It may be useful to provide an optional method in which the force is applied by two loading noses (four point loading test). A four point loading test allows measurement of a pure flexural force in the middle part of the test specimen. The compressive stresses due to the two
26、central noses are much lower in comparison with the stresses induced under the one central loading nose of the three point test. (This European Standard does not cover the four point loading test.) EN 63 Page 4 5 . 3 Number of test specimens 5 . 3 . 1 Use the number of test specimens determined by e
27、xperiment as necessary to obtain a mean with the required precision with a 95 % probability confidence level. In any case, use a t least 5 test pieces. 5.3.2 The results from test specimens that break outside the central one-third of the length between the supports should be discarded and new test s
28、pecimens should be tested in their place. Such cases should be mentioned in the test report. 5.4 Preconditioning. The test specimens shall be conditioned as required by the particular specification of each reinforced plastics material tested. If no specification exists, condition the test specimens
29、for temperature and humidity for at least 16 hours in accordance with European Standard EN 62 (atmosphere 23 “C/50 % r-h.). 6. Procedure 6 . 1 Test atmosphere. Perform the test in one of the standard laboratory atmospheres specified in European Standard EN 62. 6.2 Measurement of dimensions. In the c
30、entral part of the test specimen measure the width, 6, to the nearest 0.1 mm and make three measurements of the thickness to the nearest 0.02 mm, using the arithmetic mean for calculation. Adjust the distance, L, between supports to: (1 1 Measure this length with an accuracy of 0.5 %. NOTE. For very
31、 thick and unidirectional reinforced test specimens it may be necessary to use a distance between supports calculated on a higher ratio of Llh to avoid delamination in shear. For very thin test specimens, it may be necessary to use a distance between supports calculated on a lower value of Llh to en
32、able measurements to be made within the force capacity of the testing machine. 6 . 3 Testing. Adjust the testing machine to the rate V, determined as follows. 6 . 3 . 1 If there is no specification for the material to be tested, one or the other of the two following methods can be used, MethodA. In
33、non-routine testing of a material, a speed (expressed in mm/min) shall be chosen numerically equal to half the test specimen thickness (expressed in mm) .e. L = (16t: 1) h h V =- 2 Method B. For routine and screening tests 6 . 3 . 2 If there is a specification for the material, either V = 10 mm/min
34、(a) the rate of movement of the loading nose is specified, and is the rate to be used; or (b) the straining rate is specified, for example 0.01, in which case the rate V of relative movement of the loading nose may be calculated by the following formula: (3) Sr. L V (mm/min) = - 6 h where Sr is the
35、strain rate, per minute (0.01); L is the distance between supports, in millimetres h is the thickness of the test specimen, in millimetres. 6 . 4 Place the test specimen symmetrically across the two parallel supports (as shown in figure 2) ensuring that the length of the test specimen is at right an
36、gles to each of these. Ensure that the loading nose is positioned exactly at the mid-span position and apply the force at a uniform rate without impact. 6 . 5 If it is desired to measure the modulus of elasticity, read the force and the deflection values simultaneously sufficiently frequently so tha
37、t a smooth force/deflection curve may be plotted. A continuous registration of force and deflection, or better, a direct plotting of the force/deflection curve is preferable. 6.6 For test specimens that break before or at the moment of reaching the conventional deflection (see 3.3), record the force
38、 and deflection at break. 6.7 For test specimens that do not break before or at the conventional deflection (see 3.31, record the force at the conventional deflection. Alternatively, if required by the material specification, continue the test without interruption beyond the conventional deflection
39、until the test specimen breaks or a maximum force is reached, and record the force and deflection at whichever of these points is specified. 6.8 For test specimens that show maximum force before the conventional deflection is reached, record the maximum force and the corresponding deflection. 7. Cal
40、culation and expression of results 7 . 1 Flexural stress af at a force F is calculated in megapascals using the formula M af =w where M is the bending moment at force F, given by F L M=- 4 (4) (5) in which F is the force, in newtons, and L is the distance between supports, in millimetres; W is the s
41、ection modulus, in millimetres cubed. For a rectangular section, the section modulus is given by W=- b h2 6 where b and h are respectively the width and the thickness of the section in millimetres. Hence, flexural stress is calculated by the following formula: 3 F L af = - 2bh2 NOTE 1.1 N/mm2 = 1 MN
42、/m2 = 1 MPa. NOTE 2. For a more accurate calculation of the flexural stress which takes info account the horizontal component of the flexural moment at deflection d, the following equation may be used: where d is the deflection at mid-span, in millimetres. (7) -,-,- - CEN EN*b3 77 340i.1587 0004340
43、Y .r 7.2 Modulus of elasticity in flexure Eb. Plot a force/ deflection curve using the data collected. Determine the modulus of elasticity from the initial linear portion of the force/deflection curve by using at least five values of the deflection and the force for the test specimen E, is given by
44、the following formula: (8) L3 AF 4bh3 Ad E,=- - where Eb is the modulus of elasticity, in megapascals L is the distance between supports, in millimetres; b is the width of the test specimen, in millimetres; h is the thickness of the test specimen, in millimetres; AF is the change in force in the ini
45、tial linear portion of the force/deflection curve, in newtons; Ad is the change in deflection corresponding to the change in force AF, in millimetres. 7.3 Types of break. The calculated flexural stress is that which occurs at the surfaces of the test specimen, assuming that the neutral axis is the m
46、iddle of the thickness. During a flexural test three different types of breaks can occur, .e. those (a) initiated on the surface under tension; (b) initiated on the surface under compression; (c) showing internal shear failure The type(s) of break which occur(s) should be indicated for each test spe
47、cimen. If the types of break observed in testing a group of test specimens are different, then the values obtained for flexural stresses are statistically inhomogeneous, and great care has to be taken in their interpretation. 8. Test report The test report shall include a reference to this standard
48、and the following particulars, as necessary. h w Figure 1. Orientation of test pieces EN 63 Page 5 8.1 Trade name, identification mark, origin, date of receipt and other pertinent data concerning the tested mater al. 8.2 Data concerning preparation of the test specimens, particularly if special meth
49、ods are required (see clause 5). 8.3 Measured dimensions of the test specimens and the length of span used. 8.4 Span-to-thickness ratio used when this is other than the preferred value of 16 (see 6.2). 8.5 Testing procedure used. 8.6 If test specimens have broken, indicate for each orientation of the test specimen in relation to the sample (1) the side of the test specimen on which the loading nose was applied; (2) the type of break for each test specimen (see 7.3); (3) flexural stress at break or at maximum force
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