Investigation into the effects of fiber waviness in standard notched composite specimens

Abstract

This study presents a numerical and experimental evaluation of the standardized material testing specimens (tension and compression) used for determining the strength of composite materials in the presence of defects. The composite specimens contain through the thickness fiber waviness and a circular cutout. The intentional waviness levels have been applied in the out-of-plane direction of the multi and unidirectional laminate during the curing process. The standardized face-stabilized open-hole compression test based on ASTM D6484 and the open-hole tension test according to ASTM D5766 are used for evaluating the interaction of the fiber waviness and the circular cutouts. Temporal evaluations of the load-deformation response in the specimens are coupled with optical microscopy to understand the failure modes and damage progression. Laminates with multidirectional layups show different failure modes and a different damage trajectory when compared with the response in the unidirectional laminates. The damage trajectory is dominated by the notch region and also influenced by notch size and free edge effects.