ISO 179-1:2010 pdf free download – Plastics一Determination of Charpy impact properties一 Part 1: Non-instrumented impact test.
B.1 General
B.1.1 Tables B.1 and B.2 are based on round robins1) performed in accordance with ASTM E691. For each material, all the test bars were prepared by one source, except for notching. Notches were verified by the laboratory responsible for specimen distribution. Tables B.1 and B.2 are presented by analysis, day 1 and day 2. Each analysis is based on participating laboratories testing 10 specimens of each material. One specimen (determination) is a test result for calculating the statistics as per ASTM E691 statistical software.
B.1.2 Table B.1 is based on a round robin involving nine laboratories and three materials and Table B.2 is based on a round robin involving seven laboratories and two materials. The laboratories and materials were grouped by the required velocity (2,9 m/s or 3,8 m/s) due to the difficulty in finding laboratories that had the necessary pendulums to carry out testing at both velocities.
NOTE The following explanations of r and R (see Clause B.2) are only intended to present a meaningful way of considering the approximate precision of this test method. The data in Tables B.1 and B.2 are not intended to be rigorously applied to acceptance or rejection of material, as those data are specific to the round robin and might not be representative of other lots, conditions, materials or laboratories. Users of this test method are recommended to apply the principles of ASTM E691 to generate data specific to their laboratory and materials, or between specific laboratories. The principles of Clause B.2 would then be valid for such data.
B.2 Concept of r and R
If Sr and SR have been calculated from a large enough body of data, and for test results that were from one test determination, then:
For the repeatability, i. (comparing two test results for the same material, obtained by the same operator using the same equipment on the same day), the two test results should be judged not equivalent if they differ by more than the ,‘-value for that material.
For the reproducibility, R (comparing two results for the same material, obtained by different operators using different equipment on different days), the two test results should be judged not equivalent if they differ by more than the R-value for that material.
Any judgment in accordance with the above would have an approximately 95 % (0,95) probability of being correct.
C.1 The Charpy test result is sometimes very sensitive to the radius of the notch tip. In such cases, it is necessary for the radius to be measured accurately. This annex illustrates the effect of notch tip radius on the Charpy impact strength and describes the CCD microscope method as a suitable way of measuring the notch radius.
C.2 Figure C.1 shows the effect of the notch radius on the Charpy impact strength of four types of plastics material.
C.3 Table C.1 compares three methods of determining the notch radius.
C.4 Figure C.2 shows a CCD microscope and a view of a typical notch. The notch radius can be determined from measurements at three points, using the following equations.