Enhancement of strength and uniformity in unidirectionally arrayed chopped strands with angled slits

This study proposes a technique for enhancing strength and uniformity in unidirectionally arrayed chopped strands (Enhanced UACS). Enhanced UACS is made by introducing slits at small angles to the fiber direction into a unidirectional prepreg. As the angle becomes smaller, the stress concentration around the slit decreases. Therefore, delamination initiated from the slit is effectively suppressed and the final failure is mainly caused by fiber breakage. As a result, the Enhanced UACS laminate achieves excellent tensile, compressive, flexural, fatigue and impact strength, comparable to continuous fiber composites. Moreover, we demonstrate that the laminate can be uniformly stretched without a slit opening when it is formed.