Analyzing the effect of fiber path curvature on the fracture behavior of braided composite cylinders; experimental study

Abstract

AbstractDifferent failure modes occur in textile‐reinforced composite under applied loads. Fracture mechanism of braided composites are closely related to the geometry of braids. In the present study, fracture mechanism of glass/epoxy braided composite cylinders is investigated under tensile loads. For this purpose, glass/epoxy braided composites were fabricated using braids with braiding angles of 30°, 45°, and 57° to find the role of fiber path on the fracture mechanism. To determine the fiber path, helixes on the cylinders with aforementioned angles was considered and analyzed. New fixtures (jaws) were designed and manufactured for tensile testing of cylindrical composites. Tensile tests were carried out on the prepared samples to evaluate the failure modes of composites. The SEM micrographs of samples are provided after tensile test. Various failure modes were observed regarding the angle of the braid. Fiber breakage, matrix fracture, and debonding are the dominant modes that occur in braided composites proportional to the angle of braids. Fiber breakage is the dominant mode in the 30° angle braid reinforced composite, while the dominant failure mode in the 57° angle braid reinforced composite is matrix fracture. In composites with a braid angle of 45°, a combination of fracture modes occurred. In addition, energy absorption as well as specific energy absorption (SEA) of braided composite cylinders were also investigated and obtained from load–displacement curves. The results showed that the reinforced composite with a braid angle of 30° absorbs the lowest amount of energy (21.5 J) and also the lowest amount of specific energy (5375 J/kg). The maximum absorbed energy (67.7 J) and the maximum SEA (9675 J/kg) were observed in the reinforced composite with a braid angle of 45°.Highlights Fiber breakage is the dominant mode at the 30° angle braid reinforced composite. The dominant failure mode at the 57° angle braid reinforced composite is matrix fracture. In composites with the braid angle of 45°, a combination of fracture modes occurred. The composite reinforced with a braid angle of 30° absorbs the lowest amount of energy (21.5 J) and also the lowest amount of specific energy (5375 J/kg). The maximum absorbed energy (67.7 J) and the maximum SEA (9675 J/kg) were observed in the reinforced composite with a braid angle of 45°.