Phys.org February 21, 2022
Rapid progress in additive manufacturing methods has created a new class of ultralight mechanical metamaterials with extreme functional properties. Their application is ultimately limited by their tolerance to damage and defects, but an understanding of this sensitivity has remained elusive. An international team of researchers (UK, USA – Virginia Polytechnical Institute and State University, UCLA, industry) used metamaterial specimens consisting of millions of unit cells, to show that not only is the stress intensity factor, as used in conventional elastic fracture mechanics, insufficient to characterize fracture, but also that conventional fracture testing protocols are inadequate. With a combination of numerical and asymptotic analysis, they extended the ideas of elastic fracture mechanics to truss-based metamaterials and developed a general test and design protocol. This framework can form the basis for fracture characterization in other discrete elastic-brittle solids where the notion of fracture toughness is known to break down…read more. TECHNICAL ARTICLE 1 , 2
Material property charts of (a) E versus ρ and (b) σY versus ρ for engineering materials. Credit: Proceedings of the Royal Society A, 08 September 2010, Volume 466Issue 2121