ISO 527-1:2019 pdf free

ISO 527-1:2019 pdf free.Plastics一Determination of tensile properties
The methods specify preferred dimensions for the test specimens. Tests which are carried out on specimens of different dimensions, or on specimens which are prepared under different conditions,may produce results which are not comparable. Other factors, such as the speed of testing and the conditioning of the specimens, can also influence the results. Consequently, when comparative data are required, these factors shall be carefully controlled and recorded.
Commonly used optical extensometers record the deformation taken at one broad test-specimen surface: In the case of such a single-sided strain-testing method, ensure that low strains are not falsified by bending, which may result from even faint misalignment and initial warpage of the test specimen, and which generates strain differences between opposite surfaces of the test specimen. It is recommended to use strain-measurement methods that average the strains of opposite sides of the test specimen. This is relevant for tensile modulus determination, but less so for measurement of larger strains.
Specimens may also be instrumented with longitudinal strain gauges; the accuracy of which shall be 1 % of the relevant value or better. This corresponds to a strain accuracy of 20×10-6 (20 microstrains) for the measurement of the tensile modulus. The gauges, surface preparation and bonding agents should be chosen to exhibit adequate performance on the subject material.
If optical extensometers are used, especially for thin sheet and film, gauge marks on the specimen may be necessary to define the gauge length. These shall be equidistant from the midpoint (±1 mm), and the gauge length shall be measured to an accuracy of 1 % or better.
Gauge marks shall not be scratched, punched or impressed upon the test specimen in any way that may damage the material being tested. It shall be ensured that the marking medium has no detrimental effect on the material being tested and that, in the case of parallel lines, they are as narrow as possible.Extension of the gauge marks due to stretching shall not influence the strain measurements.ISO 527-1