Investigation of mechanical properties of hybrid fiber reinforced composites

Nowadays, studies on composite materials to meet the increasing need for durable and lightweight materials have gained importance. In particular, the focus is on the mechanical properties of composite structures formed by different alignment angles of synthetic and natural fiber sources. Natural fiber, gourd fiber, was preferred because it is an environmentally friendly and sustainable material. Carbon fiber was used as an artificial fiber due to its high mechanical properties and strength. In the study, carbon fiber fabric and gourd fibers aligned with different orientation angles were used in a hybrid manner and the mechanical properties of this structure were investigated. In this study, carbon fiber fabrics with alignment angles of [0°], [90°] and [45°] were used as upper and lower layers for composite layer production. Natural gourd fiber was used as the core material. Hand lay-up and hot press molding methods were used in production. Prepared test samples were cut with a precision table-top band saw in sizes appropriate to standards. Low-speed impact, three-point bending and tensile tests were performed on the prepared test samples. In order to test the maximum strengths in the impact tests, each layer was tested at different energies. Four and six layered specimens were tested at different energies of 5-15 joules and 10-20 joules, respectively. 5 J and 15 J impact energies were applied to four layers (0°, 45°, 90°), and 0° orientation showed the highest force capacity with 3500 N at 5 J and 6000 N at 15 J. 10 J and 20 J impact energies were applied to two different orientation combinations (45°-0°, 90°-0°, 90°-45°). While the 45°-0° combination reached the highest force capacity with 7500 N at 20 J impact energy, the 90°-45° combination exhibited the lowest force capacity with 4000 N at the same energy. Three-point bending and tensile test results confirm the low speed impact test results. It was observed that the fiber alignment angle and the number of layers in fiber-reinforced composites significantly affect the material performance. These results reveal the decisive effect of the fiber orientation angle on the impact resistance of composite materials.