Nominal strength of notched pseudo-ductile specimens

Abstract

Quasi-brittle materials like composites are notch-sensitive, and the stress concentration factor (Kt) 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 Kt or improves the nominal strength (σN) in notched sub-components (centre crack, elliptical hole and open hole) is unclear. In this work, we analytically determine the Kt of typical notched specimens made of an idealised pseudo-ductile material and show its accuracy using Finite Element (FE) models. Kt 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 σN than their linear elastic counterparts, in proportion to the Kt. However, pseudo-ductility decreases the σN for smaller specimens, and the notch shape is unimportant in this region.