Investigation of torsional behaviour of the fiber reinforced hybrid composite tubes

It is known that fiber reinforced composites are an area of interest for moment transmitting equipment as well as in many engineering applications. In this study, the deformation behavior of circular aluminum tubes (6063-T5), which are reinforced internally and externally, under torsional load, the effect of stacking sequence, and fiber orientation angle on mechanical properties were experimentally investigated. Aluminum tubes are reinforced with glass fiber using the fiber winding method. First, the deformation of the aluminum tube under torsional load, then the damage initiation and progression of the holed aluminum tube, in addition to holed hybrid composite tube, were investigated. From the test results, it was understood that the aluminum tube was deformed by buckling in the 45-degree axis, and as a result of the buckling, the inward and outward orientation of the wall occurred. It has been observed that internal and external reinforcement of the tube structure using glass fiber and epoxy increases torque transmission and rigidity. Test results revealed that the fibers with a 45-degree orientation provide the highest contribution to torque transmission, while the layer with a 90-degree orientation contributes to maintaining the integrity of the other layers. It has been determined that 90-degree layers partially increase the transmitted torque value and increase the stiffness significantly, and it has also been determined that these properties can cause differences depending on the stacking sequence. It was understood that the [(±45)2/90/Al] sequence gave the best results in terms of stiffness, while the structure with the [±45/90/±45Al] sequence gave the best results in terms of transmitted torque and energy. Moreover, it has been determined that the structure with the [902/±45/Al] sequence has a higher moment carrying capacity than the [90/±45/90/Al] structure due to the effect of the angle difference between the layers. With the reinforcement of the aluminum tube, the specific moment value increased a maximum of 1.5 times, and the specific energy value increased a maximum of 2.0 times.