ASTM C565:15(R2021) pdf free download – Standard Test Methods for Tension Testing of Carbon and Graphite Mechanical Materials.
9. Report
9.1 Report the following:
9.1.1 Identification; manufacturer, grade number, lot number, and original material size;
9. 1 .2 Average ultimate tensile strength (MPa):
9.1.3 Method of loading (see Section 7);
9.1.4 Number of samples tested;
9.1.5 Number of samples reported;
9.1.6 Standard deviation (MPa): and
9.1.7 Specimen orientation.
10. Precision and Bias
10.1 These test methods are intended to be less sophisticated than the method described in Test Method C749. For this reason an interlahoratory test program was not performed. but rather a direct comparison of the two tensile-test techniques was made. Two graphite grades of low variability were tested by two different laboratories, one with extensive experience with Test Method C749, the other in the technique of this standard.
10.3 Precision—Approximately 20 specimens of the two materials were supplied for testing under these test methods and ten specimens for testing under Test Method C749. The resulting data were examined for outliers by the Dixon Test, T-Test, and skewness. The data sets were examined for normality by the Kolmogorov-Smirnov Test and for skewness and kurtosis. No outliers were found and only kurtosis for the two ten-specimen sets was found to be significant. This does not invalidate a test Ofl means.
10.3.1 By the approximate T-test, the means for the two techniques were found to he the same for any significance level a equal to or less than 0.60 (two sided) corresponding to an observed difference in means of 0.9 %. An F-test on variance ratios between the two tests showed a significant difference at a equal to or greater than 0.025 (one sided) for the observed variance ratio of about five.
10.3.2 It is concluded that these test methods will quite satisfactorily produce mean values of tensile strengths. but are not satisfactory for producing good estimates for variance (standard deviation) unless proven by other measurement techniques for the material in question.
10.4 Bias—Bias has not been determined.
11. Keywords
11.1 carbon: graphite: tensile strength.