Nominal strength of notched pseudo-ductile specimens

Quasi-brittle materials like composites are notch-sensitive, and the stress concentration factor (K-t) determines their strength knock-down. To alleviate this notch sensitivity, researchers are pursuing pseudo-ductility to stimulate stress redistribution around the notches. However, how such a pseudo-ductile material reduces K-t or improves the nominal strength (sigma(N)) in notched sub-components (centre crack, elliptical hole and open hole) is unclear. In this work, we analytically determine the K-t of typical notched specimens made of an idealised pseudo-ductile material and show its accuracy using Finite Element (FE) models. K-t increases after the specimen transitions from localised yielding to net-section yielding. Then, we elucidate the size-effect behaviour of the notched sub-components using FE models. The study reveals that the notched pseudo-ductile specimens recover higher sigma(N) than their linear elastic counterparts, in proportion to the K-t However, pseudo-ductility decreases the K-t for smaller specimens, and the notch shape is unimportant in this region.