Mean values and standard deviations are often used to characterize certain mechanical properties. It is widely known that some properties, e.g., tensile strength of brittle solids and their standard deviations, are affected by the volume studied. In the pres ent study, the mean value and the standard deviation for the longitudinal elastic modulus of a cuboid specimen are treated. A model to predict the mean values and standard devia tions for varying lengths and widths is presented. Experimental data from the literature for glass mat reinforced polypropylene is used to show that the model shows excellent ac curacy with experimental data.
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