DECISION-MAKING IN CALCULATION OF THE STATISTICALLY VALID PROPERTIES OF POLYMER COMPOSITE MATERIALS AT THE STAGE OF OUTLIER ANALYSIS

Criteria for conducting expert estimates at the stage of outlier identification in the procedure of A- and B-basis calculation of the strength characteristics of the polymeric composite materials (PCM) are considered. Statistically-valid A- and B-basis values are lower bounds of 95%-confidence interval of the first and tenth percentile of the characteristic distribution, respectively. Basis values reflect not only the interrelation of mean and variance, but also parameters of the sample they were calculated from: sample size, probability distribution type, compatibility of data. At the steps of testing the hypotheses carrying out expert assessment is provided of in an original algorithm of bases calculation, and a number of criteria for each of steps is also offered. Practicability of application of the additional criteria promoting making the reasonable decisions allowing to increase reliability of designs from PCM is shown. An example of use of the procedure of decision-making is in detail reviewed in the analysis of results of interlaminar shear strength testing received at incoming inspection of HexPly prepreg; the maximum shear strength value of one from five specimens of one from seven batches of a prepreg was statistical outlier for the pooling data set. Recommendations about expert estimation of three basic and four additional criteria are provided. Along with a research of compatibility of data and approximating distribution type, the procedure of outlier analysis is successfully used at a stage of the exploratory data analysis, and also at quality control of material fabrication and testing process.

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