Effects of stacking sequence of fibers and thermal environments on the flexural properties of the basalt fibers/thin-ply unidirectional carbon fibers/epoxy hybrid composites

In this study, the effects of temperature and stacking sequences of fibers on the flexural properties of the hybrid composites including epoxy resin, basalt fibers, and thin-ply unidirectional (UD) carbon fibers were investigated. The hybrid composites were prepared by hand lay-up method with 2 layers of carbon thin-ply and 6 layers of basalt fibers. The samples were fabricated with three different stacking sequences of fibers in which the position of thin-ply UD carbon fibers changed from the center to the outermost layers. Also, the temperature effects on the flexural properties of samples were investigated by applying different temperatures of 25, 60, and 95 ºC. All samples were fractured gradually and showed pseudo-ductility phenomenon due to thin-ply UD carbon fibers. Results showed that by placing the thin-ply UD carbon fibers at the outermost layers, the flexural strength and modulus of samples increased significantly. For example, at the temperature of 25 ºC, the flexural modulus of the samples was about 42% higher than that of the sample with thin-ply UD carbon fibers at the center of samples. However, the strain values of samples increased by nearing the thin-ply UD carbon fibers to the center layers. Also, results indicated that increasing the temperature caused the reduction of flexural strength and modulus of samples while the strain values increased.