Application of Topological Measures in Estimation of Reinforcing Fibers Distribution in Composites

Roving composites are used in the production process of critical supporting structures. The mechanical properties of the composites depend on the even distribution of the fibers. Monitoring of geometrical measures of composites microstructure can be used for prediction of material strength and durability. In the paper results from the research performed on the production samples of girders of helicopter blades are presented. Some geometrical properties, like: the average fiber diameter D, matrix film thickness average G_AB and its standard deviation were used for specimens classification by the value of the flexural elastic modulus. The topological measure G_AB is intendent to evaluate of the fibers distribution. Applicability of the measure has been checked based on strength tests results. The uniformity of the fiber distribution expressed by the averaged G_AB measurement allows for estimation of the composite strength. Additionally the quantitative character of the measure G_AB take in defects occuring in the internal structure of composites. (paper)