Mechanical properties and micro-fracture behaviors of flat braided composites with a circular hole

In this study, attention is paid to braided fabrics as the form of reinforcing fiber in composite materials and the influence of a circular hole on the mechanical properties of a flat braided composite is investigated. Two types of specimens were prepared: a flat braided bar with a braided hole which fiber bundle continuously oriented around the hole and with a machined hole. From the results of static tensile test, the strength of the flat bar with a braided hole was higher than that of the one with the machined hole. Furthermore, difference of damage propagation in the two types of flat braided composites with a circular hole was confirmed by micro-damage observation and factors that caused initial micro-fracture obtained by experiments were identified by numerical approaches