Mechanical properties of hybrid composites reinforced by carbon and basalt fibers

In virtue of higher thermal resistance, superior ductility, and lower cost than carbon fiber, basalt fiber has attracted extensive attention recently to be an alternative to reinforcement materials. Nevertheless, relatively fewer works have been reported on the mechanical properties of such fibers and their hybrid forms with other fibers available on the market. In this study, mechanical properties of carbon/basalt fiber reinforced epoxy hybrid composite were investigated through experimental, analytical and numerical methods. Seven symmetric composite laminates with different hybrid ratios and stacking sequences were fabricated by the vacuum assisted resin transfer molding (VARTM) technology and tested under tensile and bending loads, respectively. The test results showed that the stacking sequences had an evident influence on strength and flexural modulus, but less influence on tensile modulus. Tensile properties extracted from the experimental data exhibited good agreement with the results obtained from the analytical model. Further, the finite element analysis (FEA) was carried out in ABAQUS/Explicit through developing a VUMAT subroutine program to investigate the flexural properties in detail. The numerical simulation and experimental tests show good correlation for the flexural modulus. A modified analytical model was derived for predicting flexural strength by comparing with the FEA and experimental results. Both analytical model and numerical results are validated against the experimental results. In this study, scanning electron microscopy (SEM) study on the failed specimens revealed that use of ductile basalt fiber may to a considerable extent prevent cracks from propagation across the thickness and alter the failure modes from a no-kink pattern, commonly seen in pure carbon composites, to a kink band pattern. This indicated that the failure resistance of pure carbon fiber composites was improved after inserting basalt fiber layers.