Use of Constants of Carbon and Ultrahigh-Molecular-Weight Polyethylene Fiber for Calculation of Density of Unidirectional Composites

A method making it possible to calculate the density and matrix volume fraction of two-component and hybrid composites reinforced with unidirectional rovings of carbon fibers (CF) and ultrahigh-molecular-weight polyethylene (UHMWPE) fibers is presented. Experimentally found constants of the rovings were used in calculation. The values of calculated density and matrix volume fraction were compared with an actual data of samples. The samples were obtained by resin impregnation of the rovings at free air. The impregnation was implemented simultaneously with laying of the rovings. This procedure does not permit saving the prespecified sample volume without volume control. The effects of volume deviations on the actual density of sample and the actual volume fraction of matrix were investigated on the samples with uncontrolled and controlled volume. The roving volume fractions and concentrations of hybrid and two-component composites were specified as the basic data of calculations. The actual densities of samples, as well as the value of matrix volume fractions, were compared with the calculated ones. The experimental data are in good agreement with the calculated data.