BS ISO 00037:2011 pdf download

BS ISO 00037:2011 pdf download.Rubber, vulcanized or thermoplastic-Determination of tensile stress-strain properties.
11 Marking of dumb-bell test pieces
If using a non-contact extensorneter, mark the dumb-bell test pieces with two reference marks to define the test length as specified in Table 1, using a suitable marker. The test piece shall be unstrained when it is marked
The lines shall be marked on the narrow part of the test piece, as shown In Figure 2. i.e. equidistant froni the centre of the test piece and at right angles to its longitudinal axis.
12 Measurement of test pieces
12.1 Dumb-bells
Measure the thickness at the centre and at each end of the test length with the thickness gauge. Use the median value of the three measurements to calculate the area of the cross-section. In any one dumb-bell. none of the three thickness measurements of the narrow portion shall differ by more than 2 % from the median thickness. The width of the test piece shall be taken as the distance between the culling edges of the die in the narrow part, and this distance shall be measured in accordance with Iso 23529 to the nearest 0,05 mm. Test pieces cut from products might have a non-rectangular o’oss-section, in which case the width shall be measi.vod directly on the test piece.
12.2 Rings
Measure the radial width and axial thickness at six approximately equally spaced positions around the ring The median value of each set of measurements shall be used in calculating the area of the cross-section The internal diameter shall be measured to the nearest 0.1 mm. Calculate the internal circumference and the mean circumference as follows
Internal circumference = it x internal diameter
Mean circumference = it * (internal diameter + radial width)
12.3 Comparison of groups of test pieces
If two groups of test pieces (either dumb-bells or rings) are being compared, the median thickness for each
group shall be within 7,5 % of the grand median thickness for the two groups.
13 Procedure
13.1 Dumb-bell test pieces
Insert the test piece into the tensile-testing machine, ensuring that the end tabs are gripped symmetrically so that the tension is distributed uniformly over the cross-section. It is strongly recommended that the load cell be reset to zero before each test. If necessary, apply a prestress of 0,1 MPa so that the test piece is not bent when the initial test length (see Figure 2) is measured If necessary, set up the extensometry device Start the machine and monitor continuously the change in test length and force throughout the test to an accuracy of ± 2% or as required for the purposes of Clause 15.
The nominal rate of traverse of the moving gnp shall be 500 mm/mm for type 1. type 1A and type 2 test pieces and 200 mm/mm for type 3 and type 4 test pieces.
Any test piece that breaks outside the narrow portion or yields outside the test length shall be discarded and a repeat test conducted on an additional test piece.
NOTE In making itsual measurements, ce should be taken to avoid inaccuracies due to parax.
16 Expression of results
When more than one tensile stress-strain property is being delenmned on the same test pieces, the test data shall be treated as if they had been obtained independently for each property and the result calculated as described for each pmperly separately.
In all cases, the median for each property shall be reported.
17 Precision
See Annex B.
NOTE Annex C analyses, on the basis of the precision data, the performare of the different types of dumb-bell test piece.
18 Test report
The test report shall include the following particulars:
a) details of sample and test pieces:
1) a full description of the sample and its odgin,
2) compound details and cure condition, If known,
3) the method of preparation of the test pieces (e.g buffing),
4) the type of test piece used,
5) the median thickness of the test piece,
6) the direction relative to any grain In wtiich dumb-bell test pieces were cut; b) a full reference to the test method, i.e. the number of this International Standard; C) test details:
1) the temperature of test and the relative humidity, If necessary.
2) the number of test pieces tested,
3) any deviations from the procedure specified:
d) test results:
1) the individual test results,
2) the median values of the properties determined, calculated in accordance wtth Clause 15;
e) the date of testing.