Effect of stacking sequence on the mechanical properties of pseudo-ductile thin-ply unidirectional carbon-basalt fibers/epoxy composites

In this study, the flexural and impact properties of hybrid composites including the thin-ply unidirectional (UD) carbon fibers and basalt fabrics with different stacking sequences were investigated. Hybrid composites were fabricated by 2 layers of thin-ply UD carbon fibers and 6 layers of basalt fabrics in which the position of thin-ply UD carbon fibers was changed from the center to the outermost layers for different samples. Results indicated that by embedding the thin-ply UD carbon fibers in the laminates, both flexural and impact properties of the samples were considerably improved. The highest flexural strength (451 MPa) and modulus (37 GPa) values were achieved when the thin-ply UD carbon fibers were placed at the outermost layers; these values were respectively 24% and 44% higher than those of the sample without these fibers. However, results indicated that by placing the thin-ply UD carbon fibers at the center of samples, the failure behavior of samples was changed from catastrophic failure to progressive; and a pseudo-ductile behavior was observed in the mentioned samples. The highest pseudo-ductile strain value of 0.0054 was obtained by placing the thin-ply UD carbon fibers at the center of samples. Similar to the trend pseudo-ductility of samples, the flexural strain of samples improved by nearing the thin-ply UD carbon fibers to the center of samples. Similar to the flexural strain of samples, the results of Charpy impact tests indicated that by nearing the thin-ply UD carbon fibers to the outermost layers, the absorbed energy values decreased.