Structural materials with engineered mesoscale architecture consisting of different constituents with contrasting mechanical properties are expected to offer superior combinations of strength and toughness. Whereas biological systems rely on a limited choice of organic and mineralized materials, modern additive manufacturing methods offer a wide palette of materials including metals, ceramics and polymers to design multi-material architectures that can display high performance under a wide range of loading conditions. Here, we report an investigation of the fracture behavior of a “lamellar” meso-scale architecture, which is made up of alternating layers of two steels with contrasting strength and ductility. C300 maraging steel and 304 stainless steel are used to fabricate specimens through additive manufacturing and fracture is studied in compact tension. MS is a high strength phase and SS is a high ductility phase. The lamella widths are varied between 0.3 and 10 mm, which represents the “meso-scale” for this material combination. The load-deflection response of lamellar specimens comprises of alternating segments of plateau and sharp load drops. This response for a set of lamellar width retains a peak load even higher to that of the MS specimens and energy dissipation higher than that of the SS specimens, thus demonstrating that the meso-scale architecting is an effective materials design strategy for achieving superior combinations of “effective” strength and toughness. The study shows an optimal lamellar width for maximum peak load and energy dissipation. Computational simulations of crack propagation offer insights into the mechanisms responsible for the experimental observations by revealing the size and shape of plastic zone in the lamellar architectures as the crack interacts with the interfaces. The effect of lamellar architectures on dynamic shear localization is also considered through a combination of experiments and computations.
2025-04-09 09:00:00
