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1、International Standard ) 338611 0 a 4 4!gB ,NTERNAT,ONAL ORGANlZATlON FOR STANDARDIZATION.MEXflYHAPO,I,HAf4 OPrAHMBAUMR fl0 CTAHAPTH3ALWH)RGANlSATlON INTERNATIONALE DE NORMALISATION Polymeric materials, cellular flexible - Determination of stress-strain characteristic in compression - Part 1 : Low-d
2、ensity materials Mathriaox polyrn - it does not permit the use of a cylindrical test piece. 2 References IS0 1923, Cellular materials - Determination of linear dimen- sions. IS0 2439, Polymeric materials, cellular flexible - Deterrnina- tion of hardness (indentation technique). 3 Definitions For the
3、 purposes of this International Standard the following definitions apply. 3.1 compression stress/strain characteristic KC1 : The stress, expressed in kilopascals*, required to produce a com- pression, at a constant rate of deformation during the fourth loading cycle of the test specified below, expr
4、essed as a func- tion of the compression. 3.2 compression stress value (CV40): The compression stress/strain characteristic for a compression of 40 %. 4 Apparatus 4.1 Test machine The test machine shall be capable of compressing the test piece between a support surface (see 4.2) and a compression pl
5、ate (see 4.31, which shall have a uniform relative rate of motion in the vertical direction of 100 I!I 20 mm/min. The test machine shall be capable of measuring the force re- quired to produce the specified compression with a precision of + 2 % and of measuring the test piece thickness under load wi
6、th a precision of Z!I 0,2 mm. Autographic recording of the stress-strain values is preferred. 4.2 Supporting surface Unless otherwise specified, the test piece shall be supported on a smooth, flat, horizontal and rigid surface, larger than the test piece, which may be vented with holes about 6 mm in
7、 diam- l 1 kPa = 103 N/m2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 06:59:45 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3386/l-1986 (E) e
8、ter, and approximately 20 mm pitch, to allow the escape of air from below the test piece. 4.3 Compression plate The compression plate shall be of any convenient size and shape, provided that it overlaps the test piece in all directions. The lower surface shalt be plane and smooth, but not polished,
9、and it shall be maintained parallel to the supporting surface. 5 Test pieces 5.1 Form and dimensions The test piece shall be a right parallelepiped or a right cylinder with a minimum width or diameter/thickness ratio of 2 : 1. The preferred thickness of a test piece is 50 f 1 mm and in any case the
10、thickness shall be not less than 10 mm. Sheets less than 10 mm thick shall be plied together to reach the preferred thickness range, provided that a minimum of ten cell diameters are included in the thickness of each ply. The area of the test piece shall be not less than 2 500 mm2 and shall be such
11、that at no point does the test piece overlap the compression plate. NOTE - For specimens with an area close to the lower limit, the com- pression forces may be very low, and specialized testing equipment may therefore be required to meet the precision specified in 4.1. 5.2 Samples showing orientatio
12、n If the products show an orientation of the cellular structure, the direction in which the indentation is to be carried out shall be agreed upon between the interested parties. Normally, testing is carried out in that direction in which the finished product will be stressed under service conditions
13、. 5.3 Number of test pieces Three test pieces shall be tested. 5.4 Conditioning Samples shall not be tested less than 72 h after manufacture, unless otherwise stated in the material specification. They shall be conditioned immediately before testing for a period of not less than 16 h at either a) a
14、temperature of 23 f 2 OC and a relative 50 + 5 % for use in temperate climates; or b) a temperature of 27 + 2 OC and a relative 65 + 5 % for use in tropical climates. humidity of humidity of The conditioning may form the tatter part of the 72 h following manufacture. The tests shall be carried out a
15、t a temperature of 23 + 2 OC or 27 + 2 “C as appropriate. 6 Procedure Measure the dimensions of the test piece using the appropriate procedure specified in IS0 1923 and calculate the area of the load-bearing face. Insert the test piece in such a way that the force acts along the centre line of the t
16、est machine (4.1) and compress it at 100 + 20 mm/min by means of the compression plate (4.3) until a compression of 70 z % of the initial test piece thickness is attained or until the compression strain applied equals that specified in the material specification. Then decom- press the test piece at
17、the same rate until the separation bet- ween the compression plate and the base plate is equal to the initial test piece thickness. Immediately repeat this procedure three times and on the fourth compression cycle read the force, in newtons, at the specified strain. NOTE - If measurements are requir
18、ed at multiple compression strains on a test piece, it is unnecessary to allow recovery time or to repeat the pre-loading procedure between the readings at each strain provided that measurements are taken in order of increasing magnitude of strain. 7 Expression of results 7.1 Compression stress/stra
19、in characteristic The compression stress/strain characteristic at any required percentage compression, expressed in kilopascals, is given by the equation 6x cc, = 1 000 - A where cc, is the compression stress/strain characteristic at a compression of xx %; F.c. is the force, in newtons, recorded in
20、the fourth loading cycle for a compression of xy %; A is the surface area, in square millimetres, of the test piece. 7.2 Compression stress value The compression stress value, expressed in kilopascals, is given by the equation cv,= 10cxl where cv40 is the compression stress value at a compression of
21、 40 %; Fm is the force, in newtons, recorded in the fourth loading cycle for 40 % compression; A is the surface area, in square millimetres, of the test piece. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/997254
22、5001 Not for Resale, 04/28/2007 06:59:45 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3386/l-1986 (EI 8 Repeat tests For repeat tests on the same test piece, a minimum recovery period of 16 h shall be observed. 9 Test report The test peport shall include the followin
23、g information : a) reference to this International Standard, i.e. IS0 338611; b) a description of the material; c) the temperature and humidity at which the test pieces were conditioned; d) the dimensions of the test piece used and, if applicable, the number of plies; e) the compression stress/strai
24、n characteristics for individual test pieces, and their median, and/or the com- pression stress values for individual test pieces, and their median; f) other relevant information. NOTE - An example of how to express compression stress/strain characteristics briefly is as follows : IS0 3386/l cc*5 23
25、 ?I, 50 % relative humidity Individual results Median kPa 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/28/2007 06:59:45 MDTNo reproduction or networking permitted without license from IHS -,-,-